Here is a nice read I thought was very informative and helped me shed some light on a few things I didn't understand. I thought I'd share this with everyone.
Horsepower Vs Torque
What’s The Difference, Why It Matters, And How To Get It
By John Baechtel
Engine dyno testing is the time-honored method of determining an engine’s torque and horsepower output. The dyno&8217s numerous sensors allow engine builders and component designers to accurately measure the various temperatures, pressures, vacuum and forces generated by testing different components on the engine.
Straight, smooth cylinder bores are critical to reducing frictional losses that rob torque and horsepower. Honing the cylinder block with torque plates bolted in place to simulate the stress and clamping forces of the cylinder head bolts is the norm in any high-performance engine buildup.
Cylinder bores must have a cross-hatch pattern rough enough to seat the rings, but smooth enough to avoid excessive friction. Most high-performance engines fitted with moly rings require a 400-grit honing stone, while race engines are typically finished with near-mirror finishes produced with cork-bonded stones or stones wrapped with 600-grit wet or dry sandpaper.
Single-plane intake manifolds are generally intended for applications that require horsepower derived from higher engine speeds, but they can be very effective at lower engine speeds when properly modified and teamed with the correct carburetor size and high-efficiency boosters.
Typical torque and horsepower curves show torque increasing rapidly at lower engine speeds and peaking somewhere between 4500 and 5500 rpm, while horsepower starts slowly and climbs steadily before falling off well beyond the torque curve. Don’t believe in curves that you see if the torque and power curves don’t cross at 5250 rpm.
Maximum torque requires optimum cylinder sealing with minimal friction. Piston rings must fit the ring land with minimum possible side clearance to ensure a stable ring package. The ring must be able to move, but not very much. Use manufacturer&8217s recommended specifications for side clearance.
Ring endgap is also critical to producing maximum torque. High-performance engines should always be built with ring sets that have to be hand-fit for minimum endgap clearance. This ensures the best possible cylinder sealing. Rings that are end-gapped too tight will cause friction to soar and are likely to fail early, even if they don&8217t directly butt.
Combustion chamber efficiency has tremendous influence on an engine&8217s ability to make torque. Large unshrouded valves will help with cylinder filling, and a tight quench area will promote the turbulence necessary for a fast burn and complete combustion.
Because frictional losses have such a dramatic effect on torque, you should also look closely at the engine bearings. Cylinder blocks should be align-honed to provide a straight set of bearing saddles in which the crankshaft can rotate.
Bearing clearances should be set to the loose side of the recommended tolerance to help reduce friction.
With any engine combination, it&8217s the total package that determines the overall power curve. All of the engine components have to be well matched to the intended application if an engine is going to produce a broad torque curve and strong top-end power.
Even if you have all your ports sized and shaped correctly, the wrong camshaft can eliminate most torque gains. In general, it is beneficial if you can open the intake valve a little sooner than normal and open the exhaust valve a little later than normal. Your cam grinder&8217s recommendations will be pretty good if you can tell the grinder exactly what your application is.
Large displacement is the quickest path to torque and horsepower. Current mountain-motor big-blocks displacing up to 800 cubic inches allow cars to run speeds unattainable by small-block engines, even with the assistance of nitrous oxide injection and/or forced induction.
Another way to increase torque and horsepower dramatically is to force-feed the engine with a supercharger. In this case you must still get the cam timing, ignition timing and other factors correct to take maximum advantage of the supercharger&8217s boost capacity.
Improper ignition timing can kill all your efforts, but a properly set advance curve can really pump up the torque down low, without hurting high-speed horsepower.
The carburetor’s metering ability is largely related to engine speed versus venturi diameter and booster sensitivity. Displacement, engine speed, cam timing and intake-runner length and configuration all dictate a booster’s effectiveness. Dogleg and stepped boosters, as shown here, make good top-end power, but they don&8217t meter as effectively on the low end. Annular discharge boosters are far more sensitive at low engine speeds. Hence, they can provide torque gains where you need them. However, if you run them at very high engine speeds, you will need a carburetor modified with removable air bleeds so that you can tune out the excessive fuel flow at a high rpm.
The trend is to remain conservative on carburetor size and use vacuum secondaries for sharp throttle response on street applications. If you have a light car, you can use a slightly bigger carburetor to enhance high-speed breathing, while tuning the boosters and air bleeds to optimize the fuel curve.
Dual-plane intake manifolds have long been a staple of the low-rpm, high-torque environment. Some of these manifolds can hang on to 6000 rpm and a little higher, but they are generally more effective at making torque in the 2000- to 5500-rpm range.
Bigger ports do not necessarily make more power, and they almost always kill torque. Because the intake port length is fixed by the head, you can only deal with port shape, taper, area and volume. Keep it conservative if you are looking for torque.
Exhaust ports can help boost torque if they are properly shaped and sized to provide efficient cylinder scavenging with your chosen exhaust system. It is okay to enlarge exhaust ports, but the port area next to the valve should remain relatively untouched in order to maintain high-exit velocity near the end of the exhaust stroke so that reversion is minimized.
Tri-Y headers are a good choice for low-end torque production. They typically use small-diameter primary tubes, which favor torque.
Late-model emission-controlled cars make good torque with aftermarket headers and aftermarket cat-back exhaust systems.
Engines don&8217t make horsepower; they convert fuel into torque. Torque is the twisting force imparted to the crank flange and then transmitted to the transmission and the rest of the drivetrain. To some degree torque is the grunt that gets things moving, and horsepower is the force that keeps things moving. An engine is most efficient at its torque peak, wherever that happens to occur. Below the torque peak, engines generally have more than enough time to fill the cylinders; above the torque peak, they don’t have enough time to completely fill the cylinders. This is generally beneficial in that it lets engines produce most of the desirable grunt work (torque) at lower engine speeds, which means reduced wear-and-tear and better fuel economy. The ability to extend an engine’s speed-range allows it to stretch that torque curve out farther, provided that the high-speed efficiency is there to make horsepower.
Power is torque multiplied by engine speed to produce a measurement of the engine's ability to do work over a given period of time. The story of its origin is well known, but worth repeating, briefly. In the 18th century, steam engine inventor James Watt sought a way to equate the work his steam engine could perform to the number of horses required to perform the same task. Watt performed simple tests with a horse as it operated a gear-driven mine pump by pulling a lever connected to the pump. He determined that the horse was capable of traveling 181 feet per minute with 180 pounds of pulling force. This multiplied out to 32,580 lbs-ft per minute, which Watt rounded off to 33,000 lbs-ft per minute. Divided by 60 seconds, this yields 550 lbs-ft per second, which became the standard for 1 horsepower. Thus, horsepower is a measure of force in pounds against a distance in feet for a time period of one minute. By substituting an arbitrary lever length for the crankshaft stroke, you can calculate the distance traveled around the crank axis in one minute multiplied by engine speed (rpm) and known torque to arrive at the formula for horsepower:
Because torque and rpm are divided by 5252, torque and horsepower are always equal at 5252 rpm. If you solve the equation at 5252 rpm, the rpm value cancels out, leaving horsepower equal to torque. If you plot torque and horsepower curves on a graph, the lines will always cross at 5250 rpm (rounded off). If they don't, the curve is undoubtedly bogus.
Torque is the static measurement of how much work an engine does, while power is a measure of how fast the work is being done. Since horsepower is calculated from torque, what we are all seeking is the greatest-possible torque value over the broadest-possible rpm range. Horsepower will follow suit, and it will fall in the engine speed range dictated by the many factors that affect the torque curve.
Increased displacement is the easiest way to achieve increased torque. Very large cylinders and a long stroke offer the greatest cylinder volume and overall piston area for the fuel charge to push against the crankshaft or lever, if you will. Stationary industrial engines that produce tremendous amounts of torque are typically quite large. The mass and bulk of one of these engines makes extremely large displacement engines impractical for use in cars.
Hence, we are limited to displacement values that are easily packaged within the confines of your typical automobile engine compartment. The practical limit is between 400-500 cubic inches for most large automobile engines. Big-block engines in this range deliver tremendous torque, and they are easier on parts for the same amount of power output. Car crafters have stretched displacement out as far as 800 cubic inches with highly modified cylinder blocks and crankshaft strokes, but these engines are not practical or economical for general high-performance applications.
This leaves us searching for ways to increase torque in smaller engines by increasing efficiency through the manipulation of mechanical components, gas dynamics and thermodynamics (to increase and harness cylinder pressure). There are many ways to do this, but most involve some sort of tradeoff somewhere in the power curve. To a great degree, we are forced to build engines for greater efficiency within a chosen engine speed range. Some combinations will function very well at low speeds, others will be strong in the mid-range, and still others will only run hard at a high rpm. The key is selecting the combination of components that will stretch and fatten the torque curve (improve efficiency) as much as possible in the driving range we prefer. Our saving grace is the relatively forgiving nature of internal combustion engines wherein torque dissipates gradually as engine speed increases. As long as the induction system can carry the airflow demand created by the cylinders at high engine speeds, the torque curve will remain broad. This allows engine speed and horsepower to carry the engine farther in the rpm range before the net effect of induction restrictions at high engine speeds chokes off efficiency. The following are some basic methods for increasing torque and, thus, horsepower across the typical range of modern-performance engine speeds.
Mechanical Efficiency
Friction robs a great deal of power from an engine. The greatest friction losses are caused by the pistons and piston rings. We overcome this with meticulous cylinder wall and piston preparation. Cylinder blocks that are bored and honed with a torque plate in place always contribute to a reduction in friction. This practice reduces cylinder-wall distortion caused by head-bolt clamping forces. Thus, the piston travels in the same properly sized bore throughout its stroke, and the piston rings are not subjected to changes in tension due to wall distortion. The piston manufacturer's recommended skirt clearances should be followed in most cases, because they have spent countless hours developing a skirt that stabilizes the piston and the ring pack in the bore with minimal friction.
A smooth bore generally improves ring seal and reduces friction. The best honing finish depends on the type of rings and the final application. The piston-ring manufacturer's recommendations are your best bet. Rings should be hand-fit with ring gaps set to the minimum recommended clearance. Piston rings should also be very carefully checked in each individual piston to ensure the minimum recommended side clearance. If a ring is sticking due to too little side clearance, friction will soar. If a ring is too loose, it may flutter and drag intermittently while bleeding off precious cylinder pressure.
One way to improve mechanical efficiency that most people ignore is through the use of special antifriction coatings for pistons, rings and bearings. These coatings are available in do-it-yourself kits from mail-order houses such as Summit Racing. When properly applied, the coating can get you another 10 horsepower or so. The ideal application would use coated components with optimized clearances and a good synthetic oil for maximum friction reduction. Altogether, there may be as much as 20 horsepower available with the right combination of friction-reducing ingredients.
Another component of friction reduction is the preparation of the cylinder-block bearing saddles and the crankshaft. Cylinder blocks should be align-honed to minimize frictional losses. This gives the crankshaft a straight set of bearings on which to run. Likewise, the crankshaft must be straightened to eliminate runout, and the entire reciprocating assembly must be properly balanced to minimize drag created by uneven forces.
More torque may be gained if you use a well-designed oil pan with an effective oil scraper and aerodynamic shaping of the crank-throw leading edges. Small-block Chevy builders should avoid the temptation to use a big-block-style oil pump. Use a properly clearanced small-block pump, and set it to deliver only the pressure necessary to provide optimum lubrication. Most small blocks never need more than about 60 psi, even at a high rpm. Excessive oil pressure or a bigger pump with taller gears robs power throughout the entire rpm range. Also consider the pumping losses caused by the induction and exhaust system. This should lead you to careful consideration of each system, because the engine's ability to work efficiently is largely controlled by these systems. See the accompanying sections for further discussion of these subjects.
Thermodynamic Efficiency
This is really combustion efficiency, and it all has to do with getting the correct air-fuel mixture in a well-sealed, active combustion chamber with a properly timed high-energy spark. Spark timing and chamber shape influence this tremendously, but most engines make optimum power at wide-open throttle with a 13.1:1 air-fuel ratio. You want your carburetor or fuel injection system to optimize this air-fuel ratio as fast as possible when you go WOT, and you want them to maintain that fuel curve throughout the rpm range. This can be no small trick with a carburetor and is certainly easier with electronic fuel injection, in which oxygen-sensor monitoring of the exhaust gas allows the computer to continuously adjust the fuel ratio.
Engines with a large quench area and a smaller combustion chamber are generally more combustion-efficient. The quench area is the flat, top portion of the piston adjacent to the valve reliefs. The flat portion of the piston deck corresponds to the flat portion of the cylinder-head chamber roof. When the piston approaches the cylinder head at high speed, this area squashes the charge toward the ignition source or spark plug to promote turbulence and a faster burn. Some studies suggest that you can have too much quench, but most engine builders feel that optimizing combustion-chamber quench is a proven path to power. On many steel-rod engines, you can juggle the head-gasket thickness and the piston deck height to maximize quench. Steel rods allow the quench clearance to be set as tight as 0.030 inch, or slightly less in some cases. This promotes maximum charge activity to increase combustion efficiency.
If you have the luxury of custom pistons, your piston manufacturer can also move the ring package higher on the piston to provide greater piston stability. A higher ring package will also reduce the very small area between the piston and the cylinder wall above the top ring. Because all pistons experience some small degree of rocking as they reverse directions, the piston is generally machined smaller or tapered above the top ring land to keep it from hitting the cylinder wall during this rocking. The space created here is very tight and can collect unburned or partially burned gases; these intermittently mix with the fresh, incoming charge and contaminate the mixture or alter the air/fuel ratio ever so slightly. Paying close attention to these kinds of details can add up to a significant torque bonus. When you add up all the small amounts of torque that you gain from these details, you'll be surprised at how much total power you have really gained.
Compression Ratio
Much like increased engine displacement, higher compression ratios are a sure path to increased torque. The overriding factor is, of course, fuel quality and detonation. There are numerous factors to consider here. Finer atomization of the fuel and more precise control of air/fuel ratios via electronic fuel injection has allowed O.E.M. manufacturers to increase compression ratios above 10:1 in some late-model, high-performance cars. The very latest LT4 Corvette engines are actually sneaking up on 11:1 compression ratios again because of the inherent efficiency of electronic controls and the combustion-efficiency gains made in the cylinder heads and induction system. Carburetors are less precise, but there are other ways to increase torque with higher compression in carbureted engines running 92-octane gasoline. Many street engine combinations running a big cam for top-end power experience a significant loss of low-end torque. This occurs because the intake valves close much later when the piston is farther up the bore. Thus, the dynamic compression ratio is less than the theoretical compression ratio that assumes full-stroke piston travel. If you are going to run a big cam, one of the bonuses is that you can increase the compression ratio slightly without incurring a detonation penalty. The increased compression will boost the low-end torque and extend the top-end power range. Experienced engine builders have found that 9:1 compression engines require at least a 270-degree (advertised duration) cam. On the other hand, 10:1 engines are happy with a 280-degree cam, and a 290-degree cam will allow you to run nearly 11:1 compression. Depending on other engine variables, such as combustion-chamber shape, bore diameter and ignition timing, some engines will detonate under these conditions. In these cases you need to go to a smaller cam or run slightly less total timing. In any event, the idea is to use as much compression as possible relative to the cam profile in order to gain low-end torque without detonating.
Camshaft Timing
When you consider valve-timing events, you also have to consider all the other elements acting on the fuel charge and combustion gases in the cylinders. An earlier-closing intake valve starts building cylinder pressure sooner. This increases low-speed torque due to greater cylinder pressures, but it means that the engine is having to work harder to compress the charge. As previously explained, a later-closing intake can enhance top-end torque at the expense of low-end torque, but you can get most of the torque back on the low end with an increased compression ratio. What you look for is a cam profile that promotes increased cylinder filling with earlier intake opening so that the valve is farther off the seat during the early portion of the intake stroke. Then you want to delay the exhaust-valve opening as much as possible to take advantage of all the energy you can from the combustion process before you blow down the cylinder. A quick-opening exhaust valve is helpful here, but, again, there are trade-offs.
This combination builds good torque but tends to increase valve overlap at TDC. This is where the cam lobe separation angle takes control. The lobe separation angle is the angle between the peak of the intake lobe and the peak of the exhaust lobe expressed in cam degrees. Tighter lobe separation angles (less than 110 degrees) make more torque and horsepower, but, with more overlap, the engine experiences poor idle quality and high fuel consumption. Opening up the lobe separation angles (more than 110 degrees) broadens the power band while improving idle and part throttle characteristics. With these wider lobe separation angles, peak torque and power are generally reduced, but the engine becomes very smooth and drivable.
Most street and high-performance engines will perform best when overlap is between 35 and 70 degrees (measured from intake-valve opening to exhaust-valve closing) with the duration as short as possible within the overlap guidelines. If you choose 50 degrees as a middle-of-the-road overlap figure for a pretty hot street machine, the shortest possible duration with this overlap will produce the most torque. You could make more torque with a bigger cam--but only at the expense of driveability and economy.
Cylinder Head Selection
Cylinder heads are where the power is, but there are limitations. You are generally limited to what's available, and, for most people, porting is a luxury. Increased airflow always means more top end power. For the most part, it is better to run a larger valve, if possible, and a shorter camshaft. This allows the larger valve opening to do the work of filling the cylinder while the cam remains relatively mild. Torque will be increased. Bigger valve heads may give you more overall torque than a simple cam swap. If your heads have stock-sized valves and you put in a larger cam, you will have to spin the engine faster to make the same torque and power.
That's the simplified version, but there are other considerations. The length, area and volume of the intake system all affect the engine's output. Most hot street engines will benefit from bowl porting and a good valve job, but you should avoid significantly enlarging the ports. The minute you start enlarging the port, you are bleeding off potential torque. Unless your engine will spend a lot of time at elevated engine speeds, don't start hogging out those ports.
If you have the ability to modify heads, you can extract more torque and horsepower by porting for efficiency, but the process is tedious at best. Street enthusiasts aren't generally in a position to flow heads and check port dimensions. If you are, the intake port area should be about 80 percent of the valve area, and the port should enlarge at a 2- to 4-degree taper out to the plenum. This is pretty standard on most available heads.
Exhaust ports should not be enlarged significantly unless you're running nitrous oxide, which produces a greater exhaust requirement. Most good aftermarket headers have been sized and built to create a negative pressure at the exhaust valve during overlap. This ensures good cylinder scavenging and reduces the potential for exhaust reversion: Exhaust gas speed remains high, and the pulse waves are tuned to aid the exiting exhaust charge.
Exhaust Systems
Much of your cylinder head work is diminished if you are running stock exhaust manifolds and mufflers. Exhaust headers are louder and require more attention than cast iron manifolds, but they offer substantial power advantages. While most aftermarket performance headers are of the standard four-into-one collector design, many street applications could make better use of the old four-into-two-into-one Tri-Y design, which broadens the torque curve and is still capable of making power up to about 6000 rpm. These headers are more expensive and time consuming to produce; hence, they are only available from a few manufacturers.
One of the biggest mistakes made in exhaust-header application is the selection of primary tubes that are too large. Big primary tubes are only necessary to carry the gas volume generated at high engine speeds. Most headers with 1-1/2-inch primary tubes will carry an engine well into the 300hp range, while 1-5/8-inch headers can support up to 400 horsepower, and a little beyond in some cases. This depends a great deal on displacement and engine speed. We have seen 1-3/4 headers support up to 550 horsepower without affecting power on a single four-barrel 350 Chevy running at 7500 rpm. Meanwhile, a 480hp, twin carburetor 302 Ford running at 8000 rpm gained 13 horsepower by switching to 1-7/8-inch primaries. It is usually better to err on the small side for a street engine so that torque remains strong. Pipes that are too large generally hurt the bottom end more than small pipes hurt the top end.
Exhaust-system backpressure--as a result of restrictive mufflers, catalytic converters and multiple sharp bends in the exhaust system--can be severely detrimental to good torque and power. Exhaust-pumping losses caused by restrictive exhaust backpressure can be substantial in some applications, and the problem increases dramatically with engine speed. Performance camshafts are also rendered less effective because backpressure typically negates any improved cylinder scavenging during the overlap period. The Catch 22 with exhaust systems is your own personal comfort with the sound level of the mufflers. You can run mufflers with virtually no restriction, but the drone may drive you crazy the first time you take a 100-mile trip. The best approach for most street engines is to complement all the other torque-building efforts you have applied by using a Tri-Y header with at least 2.5-inch diameter exhaust pipes and the least restrictive muffler you can stand relative to sound levels. A crossover tube to balance the pulses from each cylinder bank can help smooth the sound a bit, and it may add a very slight amount of torque depending on the rest of the application. It is usually worthwhile.
Ignition Timing
Incorrect ignition timing has the potential to stall most of your efforts to improve torque and horsepower. Cylinder pressure or best combustion pressure provides its maximum effect at about 12 to 18 degrees after the piston has passed TDC (top dead center). A faster burning charge will require less timing, while a slower burning charge needs more timing. If you have concentrated all your engine building and tuning efforts toward building maximum cylinder pressure (relative to fuel quality and detonation resistance), at the end of the compression stroke you will have a fast-moving flame front that needs less timing. If you have compromised cylinder pressure in some way, the charge will burn more slowly and require more timing. If you have done your job well by increasing breathing efficiency and the compression ratio, you will need less overall timing.
In most cases you will have selected a big cam to complement your desired power combination. This usually reduces breathing efficiency at low engine speeds, while enhancing it at high engine speeds. To make this work to its best advantage, you should alter spark advance to fire the plug sooner at low engine speeds. A competent distributor shop or tune-up shop can set your advance curve to take maximum advantage of your combination. This is absolutely critical to taking full advantage of all your other modifications.
Carburetor Sizing
Carburetor selection is frequently an afterthought based on what a friend is running or what is available for the cheapest price. Carburetors are typically chosen according to an engine's displacement and rpm range. To some degree, this has made 750-cfm Holleys the default carburetor for all applications. This only works because the carburetor has the ability to meter fuel over a broad range, but carburetor sizing plays an important roll in building optimum torque and horsepower. Smaller carburetors are commonly suggested for building torque, because their smaller venturis keep air velocity high to promote good fuel atomization. If you want to broaden the power band to retain good torque at the low end and extend power at the top end, you can make a case for a larger carburetor if it is teamed with the appropriate mix of components. The primary reason for keeping venturi size small is to maintain air speed through the boosters. This is especially critical with single-plane manifolds and larger cams, which generate weak booster signals at low rpm and the resulting loss of atomization quality and metering accuracy. This results in reduced torque output and poor driveability, but correcting it with smaller high-speed venturis may limit power at the high end.
Holley's annular discharge boosters offer the increased sensitivity to deliver low-speed booster sensitivity in a larger venturi bore while allowing greater airflow at high engine speeds. Different variations of these boosters must be properly applied to get the greatest gain, so the carburetor has to be custom-built in the aftermarket to match your application.
Cold Air Efficiency
Finally, anything you can do to enhance cool air flow into the engine will be good for torque and horsepower across the entire rpm band. Remotely sourced inlet air is almost always cleaner and cooler than engine compartment air. Use an aluminum intake manifold with the carburetor exhaust heat passage blocked off. Manifolds with the runners separated from the valley keep the charge cooler. Duct your inlet air from outside the car and keep the ducting insulated from engine compartment heat. Make your inlet ducting at least 4 inches or larger in diameter, and keep the path as short and unrestricted as possible. Be sure to duct the air through a high-flow air filter prior to entering the carburetor or throttle body. These simple modifications can increase torque from 3 to 5 percent, and they will also increase power at high engine speeds due to unrestricted airflow and a cooler charge.
Your engine is a delicately balanced system that depends on more variables than you can shake a camshaft at. By carefully considering all your options and being totally honest about your expectations and the way you will use your car, you can blend a power recipe that will tear your head off with torque and catapult you into the next county with horsepower. There's no smoke and mirrors--just mechanical teamwork and efficiency
Good Read... lots of good stuff in there
nice. but ppl who dont know better, the information is based on V8's. small engine's details are different. so dont be confused by the specs.
Working on obtainting an M-Class license... ?? Hint: 2 wheels.
HP is how fast you hit the wall, torque is how far you go through the wall.
It's not "through the wall," it's how far you push the wall with you. If you just burst through it it wouldn't require much torque after that moment.
Horsepower is how hard you hit the wall, torque is how far you push the wall with you, understeer is when you hit the wall with the front of the car, oversteer is when you hit the wall with the rear end.
2001 Olds Alero (LD9)
650 whp / 543 ft-lb
@turboalero
WhAt is V-Tak?
and does it make TorQue?
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
Toronto Cavalier wrote:nice. but ppl who dont know better, the information is based on V8's. small engine's details are different. so dont be confused by the specs.
In principle all combustion engines work the same no matter how many pistons they have. There may be one main difference is that ours are over head cams, but even some v8's are ohc engines. As far as I can tell other then that mechanically they are the same. There's no magic here that would make anything work differently as far as i can see. I know our 4cyl engines only have half the displacement, but that don't change the physics of things. This article still explains things nicely and it applies to all engines, with the exception of the carburetor. However runner lengths do matter even on your 4cyl, just like the size does, and that also applies to headers.
I always loved my old Fiero with the 2.5 Iron Duke motor, it had no low end at all even though it was a 2.5 liter 4 banger, but it for whatever reason, had a lot of high end response with very little mods. I wish I had the Quad 4 with 200hp equiped on that Fiero (I would never have sold it if it did), that is one incredible engine.
The 2.8 V-6 I had in my old Formula Fiero was the complete opposite.
Most cars I have had it's area where it had pep and where it fell on it's face.
The Ecotec honestly has been one of the top motors for being linear on the lows, mids and highs.
It is not the fastest, just one of the most linear.
2003 Sunfire with 2 1/4 inch turbo muffler, 2 1/4 piping, 2 1/2 inch resonator, a 2 1/4 inch catalytic converter, 2 1/2 inch down-pipe, a 4:2:1 RK Sports 'clone' header, E-bay strut brace, ground wire kit and an AEM true cold air intake NOPI edition.
Mike85220 wrote:I always loved my old Fiero with the 2.5 Iron Duke motor, it had no low end at all even though it was a 2.5 liter 4 banger, but it for whatever reason, had a lot of high end response with very little mods. I wish I had the Quad 4 with 200hp equiped on that Fiero (I would never have sold it if it did), that is one incredible engine.
The 2.8 V-6 I had in my old Formula Fiero was the complete opposite.
Most cars I have had it's area where it had pep and where it fell on it's face.
The Ecotec honestly has been one of the top motors for being linear on the lows, mids and highs.
It is not the fastest, just one of the most linear.
Ever hear of the Ford 302ci (5.0l) V-8? It was an amazing winder. Had a 4"-bore with a 3"-stroke... Just like the Iron-Duke had! The LN2 is a complete opposite, favoring stroke length over a larger bore size. The result is a more efficient lil' workhorse "Stump-puller" that doesn't need to rev as high to pull as hard. In fact, it puts out better numbers than the 'Duke ever did... Even in it's final years. If I could get hold of an 4-cyl/auto Fiero, I'd swap-in a LN2 w/4T40E transaxle. It's a lighter engine, makes more power, and the overdrive will aid to the mileage gain of going with that engine even more. Choose the right FDR & you'll have essentially a street-legal go-cart: Quick, well-handling car that's easy to operate & cheap on fuel . A real ball to drive!
Go beyond the "bolt-on".
Quote:
Ever hear of the Ford 302ci (5.0l) V-8? It was an amazing winder. Had a 4"-bore with a 3"-stroke... Just like the Iron-Duke had! The LN2 is a complete opposite, favoring stroke length over a larger bore size. The result is a more efficient lil' workhorse "Stump-puller" that doesn't need to rev as high to pull as hard. In fact, it puts out better numbers than the 'Duke ever did... Even in it's final years. If I could get hold of an 4-cyl/auto Fiero, I'd swap-in a LN2 w/4T40E transaxle. It's a lighter engine, makes more power, and the overdrive will aid to the mileage gain of going with that engine even more. Choose the right FDR & you'll have essentially a street-legal go-cart: Quick, well-handling car that's easy to operate & cheap on fuel . A real ball to drive!
Right on!
I thought the Iron Duke was very slow on the low end, it is amazing how even though it was a 2.5 liter engine, engine design is what is the really in the end what is to be analyzed and not the liter displacement.
When I added a DIS-2 by MSD along with the 2 Accel coil packs, it made the 2m4 Fiero a little rocket on the freeway.
Seriously... I never seen an ignition box make that much of a difference. It was to the point of disbelief and would totally undestand if someone called bs on it.
I thought it worked so great I had to have one for my Formula 2.8, but I chose the Jacob's Electronics Pro Street kit.
Unfortunately, I could not tell the thing was on at all. No difference. I then bought a Hypertech chip and low temp thermostat, and it too seemingly did nothing at all.
I am guessing that the 2.8 had an optimum ignition already, whereas the the 2.5 Iron Duke did not.
The 2.8 absolutely loved it when I ported the intake manifold. The lows, mids and highs were better, so I think it lacked on breathing.
Point being, it is all about the engine design and some things will work on some engines whereas some will not.
It is not as easy as just going in and adding gadgets.
2003 Sunfire with 2 1/4 inch turbo muffler, 2 1/4 piping, 2 1/2 inch resonator, a 2 1/4 inch catalytic converter, 2 1/2 inch down-pipe, a 4:2:1 RK Sports 'clone' header, E-bay strut brace, ground wire kit and an AEM true cold air intake NOPI edition.
Mike85220 wrote:Quote:
Ever hear of the Ford 302ci (5.0l) V-8? It was an amazing winder. Had a 4"-bore with a 3"-stroke... Just like the Iron-Duke had! The LN2 is a complete opposite, favoring stroke length over a larger bore size. The result is a more efficient lil' workhorse "Stump-puller" that doesn't need to rev as high to pull as hard. In fact, it puts out better numbers than the 'Duke ever did... Even in it's final years. If I could get hold of an 4-cyl/auto Fiero, I'd swap-in a LN2 w/4T40E transaxle. It's a lighter engine, makes more power, and the overdrive will aid to the mileage gain of going with that engine even more. Choose the right FDR & you'll have essentially a street-legal go-cart: Quick, well-handling car that's easy to operate & cheap on fuel . A real ball to drive!
Right on!
I thought the Iron Duke was very slow on the low end, it is amazing how even though it was a 2.5 liter engine, engine design is what is the really in the end what is to be analyzed and not the liter displacement.
When I added a DIS-2 by MSD along with the 2 Accel coil packs, it made the 2m4 Fiero a little rocket on the freeway.
Seriously... I never seen an ignition box make that much of a difference. It was to the point of disbelief and would totally undestand if someone called bs on it.
I thought it worked so great I had to have one for my Formula 2.8, but I chose the Jacob's Electronics Pro Street kit.
Unfortunately, I could not tell the thing was on at all. No difference. I then bought a Hypertech chip and low temp thermostat, and it too seemingly did nothing at all.
I am guessing that the 2.8 had an optimum ignition already, whereas the the 2.5 Iron Duke did not.
The 2.8 absolutely loved it when I ported the intake manifold. The lows, mids and highs were better, so I think it lacked on breathing.
Point being, it is all about the engine design and some things will work on some engines whereas some will not.
It is not as easy as just going in and adding gadgets.
Yeah, the "Spider" intake manifold on the 2.8 was somewhat restrictive.
As for the ignition, I've placed a full MSD system on my "88 Dodge Ramcharger w/TBI & saw some very notable increases. A 20% increase in mileage, and start-up so easy that it's turn half a rev & catch. The whole while I ran it, I left the Champion Truck Plugs gapped to stock & used an Autozone HD cap & rotor (Brass terminals like the MSD cap, and alot less expensive) and got 30,000mi between plug changes. Not all aftermarket systems are like MSD, so don't expect the same results.
And as for engine building, here's an interesting note:
A friend of mine whom did service on fork-lifts let me look at an industry parts catalog one night, and I saw long-blocks & a stroker kit for the Duke that brought the displacement up to 3.0L! Another fellow, from another site I'm member to,has a father who has an inboard-motor speedboat that has this engine in marine trim. Says it gets the 15-footer up on a plane at 40mph real quick. Now... Imagine that in you Fiero. Only one problem, though... The kit is meant for distributor-ignition Duke's, which means it doesn't have the notched crank-trigger wheel that was found on '88-later Duke's that were placed in FWD apps. Since the Fiero uses a FWD powertrain placed behind the driver, it uses the same engine. So, no stroker for DIS-equip'd Dukes. Sorry...
Still, I'd like to pursue the notion of using the management from a '92-'97 LN2 to retrofit MPI to a DIS'd Duke... Since they use
exactly the same design DIS, trigger-wheel & all!
Go beyond the "bolt-on".
Oh yeah... Your note on design reminds me of an old sayin' of mine:
It's not what you displace, but how you displace it!
Go beyond the "bolt-on".
its about making it move more air.
^ That's only part of the rule. Not to mention the happy balance between displacement & design that goes hand-in-hand for the intended application.
Yes, a 2.56L V-10 with a bore of 3.06" and a stroke of 1.03" can be built... but what good would it be for? Certainly not in a compact car, where the goal is to achieve as best fuel efficiency as possible. The best way to do that is to minimize the number of revolutions the engine turns & number of pulses needed to ingest whatever air it displaces mixed with fuel, ignite it then spew it out so as to achieve a complete & useful burn to achieve said goal.
And the opposite is true for something that's full-race. A 9L I-3 is hardly useful in a F-1 car, since the idea there is to get the car to run along as fast as possible. There the most RPMs an engine can turn without undesired stress upon all the parts involved takes president. Esecially on the connecting rods. So laying the displacement out among as many cylinders as possible, with as short as stroke & as long as rod that can be gotten away with, is the way to go.
I should also mention here that the importance of idle quality in either situation also takes effect. In a econo-car, the less you need to touch the throttle to keep it runiing is critical, since how much total open-throttle time it sees effects mileage. In the Indy-car, not such a big deal.
I know, this has all been spoken about before... But a happy medium is importance for the sake of drivability sought by the operator as well. If you're fully performance-minded, high RPM operation is nothing to you. If you're the opposite, a more docile-acting engine will be your "Cup-of-tea". It all comes into play... and it all must considered for all those whom wish to take part in this game of internal-combustion usage.
Go beyond the "bolt-on".
I can only imagine how an Iron Duke 3.0 would run.
I would 'guess' that it would have some incredible up and go when at WOT on the freeway.
Converting it from a TBI to port injection would give this engine a lot more response too, and probably wouldn't be so bogged down from a stop.
2003 Sunfire with 2 1/4 inch turbo muffler, 2 1/4 piping, 2 1/2 inch resonator, a 2 1/4 inch catalytic converter, 2 1/2 inch down-pipe, a 4:2:1 RK Sports 'clone' header, E-bay strut brace, ground wire kit and an AEM true cold air intake NOPI edition.
MadJack wrote:Mike85220 wrote: I can only imagine how an Iron Duke 3.0 would run.
I would 'guess' that it would have some incredible up and go when at WOT on the freeway.
Maybe like the old Goody's Dash Pontiac Super Duty Fours with their 175cid, 12:1 cr and roller cam! Can you say 300+ HP N/A 4 cylinder! 168mph on Daytona Speedway with a restricter plate and 350cfm Holley Carb.
As for DIS ignitions, you can get a Hall Effect triggering system to fit just about any motor, if you have decent fabrications skills (or know some one who does). Same goes for an MPFI system and aluminum welding. (A good friend of mine just got a wire feed aluminum welding set-up! 
And I can use it whenever I need it.) Now, what do I need here???
Well IIRC, GM still has some Super-Duty parts for the Duke. Including an aluminum head & 4-bbl intake! So...
And Brody... Ever hear of the gov-backed design that used two opposing pistons in one cylinder & a positive-displacement supercharger? It had an efficiency of 70-80%! So, design FTW!
Go beyond the "bolt-on".
I dont think i have seen them or read about them. But did you see how massive that engine is? a two stroke diesel turbo 25,480 ltr Maximum power: 108,920 hp at 102 rpm
Maximum torque: 5,608,312 lb/ft at 102rpm thats one heck of a boat motor. i'm still in ahhh over this so lets not ruin it by over analyzing it yet.
)
I did a little reading about the engine your talking about so I thought i'd copy and past what I read. Some variations of the Opposed Piston or OP designs use a single crankshaft like the Doxford ship engines[1] and the Commer OP truck engines.[2] They should not be confused with flat engines. Though flat engines are sometimes referred to as horizontally opposed, they are very different mechanically.
A more common layout uses 2 crankshafts, with the crankshafts geared together, or even 3 geared crankshafts in the Napier Deltic diesel engines. The Deltic uses three crankshafts serving three banks of double-ended cylinders arranged in an equilateral triangle, with the crankshafts at the corners. These were used in railway locomotives and to power fast patrol boats. Both types are now largely obsolete, although the Royal Navy still maintains some Deltic-powered Hunt Class Mine Countermeasure Vessels.
The first opposed-piston diesel engines were developed in the beginning of 20th century. In 1907, Raymond Koreyvo, the engineer of Kolomna Works, patented and built opposed-piston two-stroke diesel with two crankshafts, connected by gearing. Although Koreyvo patented his diesel in France in November, 1907, the direction would not go on to manufacture opposed-piston engines.
An April, 1950 print advertisement for Fairbanks-Morse opposed piston engines, touting their greater thermodynamic efficiency and lower maintenance cost than standard configurationsThe first Junkers engines had one crankshaft, the upper pistons having long connecting rods outside the cylinder. These engines were the forerunner of the Doxford marine engine, and this layout was also used for two- and three-cylinder car engines from around 1900 to 1922 by Gobron-Brillie.[3]. There is currently a resurgence of this design in a boxer configuration as a small diesel aircraft engine, and for other application, called the 'OPOC'[4] engine by Advanced Propulsion Technologies, Inc. of California.[5] Later Junkers engines like the Junkers Jumo 205 diesel aircraft engine, use two crankshafts, one at either end of a single bank of cylinders. There are efforts to reintroduce the opposed-piston diesel aircraft engine with twin geared crankshafts for General aviation applications, by both Dair and PowerPlant Developments in the UK.[6]
This configuration has also been used for marine auxiliary generators and for larger marine propulsion engines, notably Fairbanks-Morse diesel engines used in both conventional and nuclear US submarines. Fairbanks-Morse also used it in diesel locomotives starting in 1944. With the addition of a supercharger or turbocharger, opposed piston designs can make very efficient two-stroke cycle Diesel engines. Attempts were made to build non-diesel 4-stroke engines, but as there is no cylinder head, the bad location of the valves and the spark plug makes them inefficient.
Koreyvo, Jumo and Deltic engines used one piston per cylinder to expose an intake port, and the other to expose an exhaust port. Each piston is referred to as either an intake piston or an exhaust piston depending on its function in this regard. This layout gives superior scavenging, as gas flow through the cylinder is axial rather than radial, and simplifies design of the piston crowns. In the Jumo 205 and its variants, the upper crankshaft serves the exhaust pistons, and the lower crankshaft the intake pistons. In designs using multiple cylinder banks, such as the Junkers Jumo 223 and the Deltic, each big end bearing serves one inlet and one exhaust piston, using a forked connecting rod for the exhaust piston.
The Doxford Engine Works of the UK designed and built very large opposed-piston engines for marine use. These engines differ in design from Jumo and Fairbanks-Morse engines by having external connecting rods outside the cylinder linking the upper and lower pistons, thus requiring only a single crankshaft. The first engine of this type was developed by Karl Otto Keller in 1912. Doxford obtained a sole UK license from Oechelhauser and Junkers to build this design of engine. After World War I these engines were produced in a number of models, such as the P and J series, with outputs as high as 20000 hp. Certain models were license-built in the US. Production of Doxford engines in the UK ceased in 1980
Shown (at right) is the layout of an Otto cycle two-stroke engine similar to the one developed by engineer Kurt Bang at the Prüssing Office on the basis of the prewar DKW race engine. There existed two versions: one with a displacement of 250 cm³, and one with 350 cm³ displacement. The engine had two cylinders with four pistons, two crankshafts and a supercharger. The crankshafts were connected by gears. The fuel-air mixture was produced by a carburetor. This resulted in a high fuel consumption.
The supercharger takes in the fuel-air mixture, compressing it and pushing it into the airbox. From here it reaches the crank housings. On the outlet side it cools the thermically high loaded piston. After ignition the pistons move outwards, performing the power stroke. At first, the outlet piston opens its slots in the cylinder. The remaining pressure accelerates the gas column towards the exhaust. Then the other piston opens the inlet slots. The pressurized fresh mixture pushes the remaining waste gas out. While the inlet is still opened, the outlet is closed. The supercharger forces additional gas into the cylinder until the inlet slots are closed by the piston. Then the compression stroke starts and the cycle repeats. This type of two cycle system is similar to the famous Grey Marine Diesel, later to be known as the GM Diesel (Detroit Diesel). In 1998 the production of that brand was halted as well due to the lower cost of available four cycle diesels.
The U.S. and British Militaries still purchase remanufactured engines if needed due to high demand.
Some of these engines have over 24 cylinders. Could you imagine the cost to maintain an engine like this? It is impressive though especially since the design has been around since the early 1900's.
