Acknowledgements:

Aasyranth- Wrote the boost mini-FAQ, which this builds upon
Protonus
Excidium
SunfighterGT
And anybody else who may have added info that I forgot

General questions-

What is better, a turbocharger or supercharger?
----It totally depends on what you are going for. Some superchargers are known for excellent reliability (Eaton/Magnuson roots types have been known to last over 100,000 miles) but are limited in power potential. Turbochargers are will known for having vast potential and requiring a bit more TLC and maintenance than most superchargers. The fastest cars bearing J-body names are turbocharged, and the fastest cars on the J-body.org are turbocharged. But it's likely that the most reliable boosted cars are those running low levels of boost with the GM Supercharger kits. What are your goals and priorities? Turbochargers offer the option to easily upgrade to more boost, while superchargers can generally have a set boost limit. Adding smaller pullies to superchargers can get a couple PSI, but for our vehicles, a supercharger will never out boost a turbocharger.

How much boost can I run without sacrificing reliability?
---- Boost is so much more than PSI. Imagine for a moment that you have a box, its 1 cubic foot big (1 foot x 1 foot x 1 foot). One turbo can take 10lbs of air (it's a lot of air), and compress it to 5 PSI, and stick it in that box. Another turbo can take 20lbs of air, compress it to 5 PSI, and also stick it into that box. Obviously the 20lbs of air will make more power than the 10lbs of air of the smaller turbo charger (provided you have the right fuel mixture).

If you are worried about reliability and how much downtime your car will have, then your best bet is to stay away from turbochargers and aftermarket superchargers that weren't designed for your vehicle. The problem with people who add boost to their vehicle is that they are looking to add boost, but don't want to spend the money to do it right. They add the boost, but forget about the fuel, hoping that their stock injectors will hold up. Depending on the turbo or supercharger, the injectors might hold up for a little while, but don't count on it.

Long story short, there is no magic number to tell anybody. There are too many variables from type of turbo or supercharger, to the long term previous maintenance of the engine. Every motor has different breaking points. It is generally accepted that you should be able to run the following:

Assuming a T3 Style turbo

2.4 / 2.2 Ecotec
6-8 PSI Non-Intercooled with proper fuel and timing mods
8-12 PSI Intercooled with proper fuel and timing mods

2.2 / 2200 SFI
4-5 PSI Non-Intercooled with proper fuel and timing mods
6-10 PSI Intercooled with proper fuel and timing mods

Another thing people seem to forget when running boost is the transmission. If you have a 5 speed I would suggest a clutch at the very minimum. ACT or SPEC are great clutches, don't buy cheapo E-Bay clutches. Auto transmissions hold up to boost better than manual transmissions. Especially the Isuzu, they seem to have a tendency for the differential to self destruct. Your axles and CV's are also weak points.


Will XXXXXX turbocharger/supercharger work on my car?
----As stated above, normally aspirated cars are not designed to run turbo or superchargers. You will need a custom exhaust manifold for a turbo, and a custom intake manifold for a supercharger (there are rare exceptions, but custom work would still be required).

----There is so much more to adding a turbo to your car than the turbo itself. The turbo is just one piece of many, just like you need more than an engine to have a car. Other than the Sunbird 2.0 Turbo, and a couple prototype GM cars, our engines were not designed to run a turbo or supercharger. With the 2.4L, GM later developed a GM Supercharger system for 2000 and up engines only. GM is slated to debut a 2.2 Ecotec supercharger sometime in 2005, but that system is developed for the new Cobalt.

Look through the rest of this FAQ to see a basic list of parts that you need to add boost to your car.

How much boost can I run using the stock fuel system?
----It is not recommended that you use any amount of boost on the stock fuel system. The stock system was designed to support a stock engine. Adding more air requires more fuel. The stock injectors can be used to a point, but you can be sure that you are putting undue stress onto the injectors and fuel system as a whole.


Turbocharger questions-

Where can I find a turbo kit?
----A kit is a relative term. Some ¡§kits¡¨ don't include everything you should be putting on your car, and some kits aren't bolt-on. There are a couple manufacturers out there for turbo kits, the websites of which are listed below:

Cavalier Connection: http://www.cavalierconnection.com
Hahn Racecraft: http://www.hahnracecraft.com
Twistec: http://www.twistecproducts.com


Are there any cheaper ways to set up turbo on my car?
----There are always cheaper ways to do things. Just remember one thing, cheaper isn't always better, and cheap now means expensive later. You can buy turbo's from junkyards, but most are high mileage and need rebuilding anyway. You can buy the parts to make your own turbo manifold, but unless you can weld, that can get pretty expensive as well. Some OEM turbo's off of old turbo cars are difficult to find weld flanges for. Make sure you research what you are buying before you buy it, and how well it will fit into your system before you spend money.

At what boost level will I need to install an intercooler?
----It is generally accepted that you can run 5 or 6 psi without an intercooler. Keep in mind that it'll be safer if you use an intercooler even at low boost levels. The cooler air coming into the engine can yield more peak power as well, so it's a good idea all around. Most junkyard intercoolers will work just fine, but if you're planning on squeezing some major power out of your turbo, it'd be best for you to get an intercooler that is built for racing applications. There are sources of cheap intercoolers out there, such as http://www.johnnyracecar.com. There is almost no excuse not to put an intercooler on your setup. It could mean the difference between a great turbo kit, and a 2000 pound paperweight sitting in your driveway.

What size exhaust piping should I use with my turbocharger?
----You want the area after the turbocharger exhaust outlet to be under as little pressure as possible. 2.5 inch piping with a high flow muffler should be installed at the very minimum. 3 inch piping would be even better, and an exhaust cut out would be a great idea for racing. Any muffler shop that works with performance applications should be able to assist you.


Supercharger questions-

Where can I find a supercharger kit?
----RSMracing.com produces kits for the 2.2/2200, 2.4, and Ecotec motors. GM produces a supercharger kit for the 2000+ 2.4L engine. It can also be made to work with pre 2000 2.4 models by swapping to the 2000+ starter and installing a fuel management unit and/or a digital fuel control device (Apexi S-AFC, Greddy E-manage). The GM supercharger kit can be ordered from http://www.gmpartsdirect.com and http://wwww.paceperformance.com as well as the dealerships. For the pre-2000 cars, I would suggest getting some 320cc injectors and an adjustable FPR.

Is it possible to make a junkyard supercharger setup?
----Yes. Most junkyard superchargers will require a custom intake manifold to work. These manifolds tend to be more complicated and difficult to make than turbo manifolds, which is one of the reasons that custom turbo setups are more popular. Just like custom turbo setups, the quality will depend on the time and care you put into it. The other style of supercharger you could use is a Vortec style supercharger that is belt driven, but would be difficult to find.

Can I use an intercooler with a supercharger setup?
----Roots superchargers http://www.magnusonproducts.com must have the intercooling system integrated into the intake manifold. It would be a complicated and expensive fabrication. Centrifugal superchargers http://www.vortechsuperchargers.com run a pipe to get air to the throttle body, just like turbochargers do. They can use any intercooler that turbo cars use.

What size exhaust piping should I use with my supercharger?
----Treat a supercharged motor like any high-powered application as far as the exhaust is concerned. 2.5 inches should be appropriate for most supercharged street applications.


The Great Fuel Debate

Fuel seems to be a sensitive area. Setups that work for some people, don't seem to work for other people. So lets start off with the basics:

Take a mental trip back to grade school. Remember the fire triangle? There are three things you need for fire, a fuel source, oxygen, and heat. A turbo or supercharger adds oxygen by compressing a large amount of air and stuffing it into the cylinders. Too little fuel causes multiple flame fronts in the cylinder, and increased cylinder pressures. It also causes the exhaust gases to heat up, which eventually leads to detonation.

Detonation is when the multiple flame fronts collide causing a hammer type effect that is usually followed by a metallic pinging or knocking noise. This results in broken pistons, snapped rods, and large holes in your engine block.

On the other hand, too much fuel causes a slow flame, and a lot of unburned fuel being sent through your exhaust system. While not as dangerous as a lean condition, it robs power.

There is no magic number for us to tell you what you need to run for an air-fuel ratio. A car could be perfectly tuned in Boulder, Colorado, but when that person drove down to Florida, their car would probably run way too rich. Generally accepted numbers is that you don't want your A/F ratio to be more than 12:1, and you don't want it less than 14.7:1.

Well, the first thing you need to do in order to plan your fuel injector setup is to determine how much power you plan on making. This has to be a realistic number, you are never going to get 250 BHP from 10 PSI out of the TD04 on your 2.2 OHV. Take a guess at what your horsepower is going to be.

So lets say I think my max horsepower is going to be 225 BHP. There is a real neat formula that will tell you a basis (note, basis, not exact) for what size injectors you need.

IFR = (HP * BSFC) / (# of Injectors * .8)

IFR is the Injector Flow Rate in lbs per hour
BSFC is the Brake Specific Fuel Consumption. A good number to use is .55 for NA, .65 for boosted engines.
# of Injectors are the number of equally sized injectors you will be using.
The .8 number is the maximum duty cycle of the injectors. You can't run injectors at 100% all the time, they will heat up and burn out. .8 is the highest duty cycle that you should use, which is why you don't want to use stock injectors.

So, my 225 BHP car, with a BSFC of .65, I will use this formula:

IFR = (225 * .65) / (4 * .8)

IFR = 46 lb/hr, multiply that by 10.55 to get CC's, 485cc

Now, those are some huge injectors for a 225 BHP car, yes. In fact they are too big. So why use that formula? Well we need a basis, that is how much fuel the engine should be using at the horsepower peak. The formula above assumes you are going to be running your fuel system at 45 PSI, which you won't be.

So, lets say we want to see if we can get away with some 36 lb/hr injectors. Lets say we are running 60 PSI at the HP Peak. You can use this formula to figure out what the fuel injector flows at a certain PSI:

F2 = (P2 * F1) / P1

F2 = Flow (in lbs/hr) at the new PSI
P2 = Desired fuel pressure
F1 = Fuel injector flow at the rated PSI (P1)
P1 = Rated fuel injector PSI

In our example:
F2 = (60 * 36) / 45
F2 = 48 lbs/hr

Wow, at 60 PSI, the 36lb/hr injectors will outflow the 46lb/hr injectors. As an added bonus, higher fuel pressure means the fuel injector doesn't need to use such a long duty cycle, has better fuel atomization, and improves injector life. On the down side, too much fuel pressure will cause the injector to ¡§clip¡¨, or not provide any fuel. This is the problem with just increasing the fuel pressure on stock injectors.

Now that you know what size injectors you need, how about we figure out how to use them so they don't provide too much or two little fuel:

As a basic setup, you can use an adjustable FPR and an FMU. Why do you need both? Well you can't have the fuel system without an FPR. This allows you to set your idle fuel pressure and a basis for the rate at which you increase the fuel pressure. The FMU is going to allow the system to increase your fuel pressure as the boost pressure increases. You need to do this so the injectors provide more fuel as you start stuffing more air into your engine.

But how do you know where its perfect?

You don't. The only way to tune it is to use a dynamometer (dyno) or to put a wideband oxygen sensor and data logging system so you can monitor your fuel. You can use an A/F gauge to get a basis for where you are at, but they are no where near accurate to be able to tell you if you are running too lean or too rich.

You can use better fuel systems, such as piggy back units such as the Apex'i S-AFC or the Greddy E-Manage. These will allow you to ¡§dial-in¡¨ a fuel setup, and you can easily change them through knobs or even computer interfaces.

There are setups that allow you to run your stock injectors, but add additional injectors to the system. These are called ¡§Extra Injector Controllers¡¨ (EIC's). They work by welding injector bungs into your charge pipe and injecting the fuel right into the air. You need to provide fuel to the injectors through either a fuel line or fuel rail. Some people really like this setup, and some don't.

I will say I don't like EIC's. Why?

Anybody who knows what fuel puddling is, knows it's a very real possibility with injecting the fuel before the manifold. The fuel gets injected into the throttle body, and gets the chance to puddle inside the intake manifold. If a condition known as pre-detonation occurs, it can produce a flame that actually exits into the intake manifold. This will ignite the fuel inside the intake manifold and cause damage to the manifold and even the engine itself. Also if you inject fuel before the throttle body, the fuel atomizes out of the injector, then reconstitutes before the cylinder, causing odd flame patterns.

But people are happy with EIC setups, don't let that deter you if you just need a little extra fuel. I've seen setups that worked extremely well with an EIC, and I've seen intake manifolds blown right off the engine.

Please put a lot of research into your fuel setup. This is what saves your engine. All the forged internals in the world won't stand up to a super lean setup, they aren't indestructible and can break just like the stock parts. They just happen to be stronger.


Turbo Kit Parts List (Thanks SunfighterGT)

For a basic kit, you will need, at the minimum:

Turbocharger, T3 or larger, don't use Mitsubishi turbos smaller than a 16g
External wastegate (if the turbo is not internally gated)
Turbo Manifold (Either with a wastegate flange if externally gated, or without if internal gate)
Exhaust Manifold Gasket
Turbo Downpipe Flange (To attach the downpipe)
Downpipe (2.5¡¨ or larger, match your exhaust)
Oil Feed kit, braided steel line
Oil Return kit (Needs a weld bung in the oil pan for the return)
Charge Pipes (Make your own with U-Bends, straights, and pipe connectors)
Pipe Connectors (Silicone connectors)
T-Bolt Clamps to hold the pipe connectors together
Blow Off Valve (Can be cheap 1g DSM ones, or others such as TurboXS)
Blow Off Valve Weld Flange
Miscellaneous Vacuum Hose
Air Filter for Turbo
Colder Spark Plugs
Boost Gauge
Air-Fuel Ratio Gauge

Those are the basics, you might also want to pick up:
Adjustable FPR
Rising Rate FMU (Cartech, Vortech)
Injectors
Injector Controller
Motor Mounts
Intercooler
Screw-in GM IAT Sensor

Where to get parts:

Turbos:
http://www.cheapturbo.com
http://www.turbocalculator.com

There are hundreds really, search on Yahoo¡K

DIY Manifolds and flanges: http://www.jgsturbo.com/turbo/

Pipe U-Bends and Lengths:
http://www.summitracing.com

Pipe Connectors:
http://www.airflowonline.com

People can add more, I don't recall all the sites at this time.


Some words about Turbos:

As I had said before, PSI really is a relative term. The big thing you want to look at is CFM, usually expressed in lbs/hr. Some turbochargers are just too small for our vehicles, such as the Mitsubishi 14 series. A turbo has something called a surge. Surge is what happens when you try to push more air through the exhaust than the turbo is designed to handle. This can cause the turbo to stop spinning, or even spin backwards.

As a turbo pushes more air, it hits a max (surge), the smaller turbos just won't provide enough air to support our engines. You simply can't provide enough air with certain turbos, no matter how much PSI you push.

You may have heard of Turbo Maps. They are very difficult to read, but there are websites out there that can help. I would suggest this site to help you understand what a turbo map is, and how to read one. Correctly sizing your turbo will reduce turbo lag (time it takes for the turbo to produce boost), and provide excellent power gains.


Protonus seemed pretty bent on having this, so I'll add it:

Oh yeah. the BIG one I want to see in this FAQ

All the T3, T4, T61, T25, etc refers to is a series of compressor housings, and it's used to refer to which compressor housings are compatible with what center housings and exhaust housings.

The Turbocharger and manifold off a sunbird turbo, be it the 1.8 OHC OR the 2.0 OHC

WILL NOT Bolt up to ANY other engine. Period. The 2.0/2.2/2200 OHV IS NOT the same engine as the 2.0 OHC

I get asked this almost weekly via e-mail. The manifold is completely specific to the Sunbird OHC motors.

THAT IS ALL

While most T4's are larger then T3's and most are larger then T25's, this is the GENERAL understanding. IT is often, not true at all.

You need to compare SPECIFIC models of turbo's based on impeller inducer/exducer sizes, and the A/R ratio's of the housings before ANY comparison can be made.

T3, T4, T25, THEY ARE NOT SIZES OF TURBOS. THEY ARE STYLES OF TURBOS.

Terminology (Courtesy of Protonus)

BOV = Blow off valve
Mounts between the turbo and the throttle body, allows excess boost pressure to be released when the throttle plate closes when you let off to shift or slow down.. makes that nice sound, and prevents compressor damage from a sudden wave of high pressure smacking into the turbo trying to force it backwards.

BPV = Bypass valve
Same thing as a BOV, only the air isn't vented to the engine bay, it's vented to PAST the throttle body. Not only does it not make a noise, but it's needed for cars using a MAF sensor, so that all "air in the system can be explained" Cars that use MAF and BOV's stutter/stall when the BOV goes off.

W/G = WasteGate
Limits maximum boost by allowing some exhaust gas to bypass the turbo, can either be external to the turbo (looks like a BOV) or internal (is a flapper door). Externals generally allow for higher boost levels without "creep" where maximum boost slowly get's higher.

MBC = Manual Boost Controller
A simple twist valve normally, that changes the amount of boost pressure required before pressure is sent to the wastegate, thus opening it. this is used to actually SET maximum boost.

EBC = Electronic Boost Controller
Just like a MBC, but computer controlled. All stock turbo cars after the mid eighties have these.

I/C = Intercooler
A "radiator for air" that absorbs intake air heat to cool down the hot air charge from the turbo. There are several types of I/C's but this isn't the pace to discuss them.

MAP = Manifold Air Pressure sensor
Measures the pressure OR vacuum of the intake air. These are used as the primary means of measuring air in "Speed density" style fuel injected cars, like j-bodies.

MAF = Mass AirFlow sensor (note, our cars don't use these, yay!)
the "modern alternative for MAP's, this actually measures the amount of ACTUAL air entering an engine via weird technical voodoo you don't want me to explain. You don't have this, forget you heard of it.

IAT = intake (or incoming) air temperature
Measures the temperature of the intake air, is used in fueling calcs by the ECM

E/M = Exhaust Manifold
Bolts to the head, directs exhaust air out. duh.

T/M = Turbo manifold
Bolts to the head, directs exhaust air into the turbo. duh.

I/M = Intake manifold
Bolts to the head, directs air from the T/B to the head. derrr duh.

T/B = Throttle body
Do I have to explain this?

D/P = DownPipe
Bolts to the turbo, then to the exhaust. it's the "intermediate" usually it's cast iron.

Cat = Catalytic Converter
Scrubs excess emissions causing chemicals from you're exhaust and excess fuel via more voodoo you don't need to know.

Vac = Vacuum
What you're engine is under, when it isn't boosted

DIS = Distributorless ignition system
A ignition system without a distributor, a fully computerized ignition system. Digital if you will. all j-bodies after like 90ish are DIS

Tach = Tachometer
Measure engine RPM.

WBO2 = Wide Band Oxygen sensor
0-5 volts range, linear scale, for measure A/F ratios very accurately, Dynos and serious tuners and smart people use these can be found stock on some uber-low emmisions cars (read honda's toyotas, etc). Costs about 100 bucks per sensor :-O

NBO2 = Normal Band O2
What j-bodies normally have. these measure a/f on 0-1 volt scale, and it's very UNLINEAR, that is to say it gets very unaccurate when measuring anything other then perfect A/F

EGR = Exhaust Gas recirculation system
Takes a small amount of exhaust gas from combustion, at high throttle, and feeds it back into the intake, to "cool" the combustion temp off so that NoX (nitrosomething of Oxygen aka Greenhouse Gas) cant' form. J-bodies after 2K don't have these (thank god). It also reduces detonation when the engine is stock (there are better ways to fight it).

PFI = Port Fuel injection
Generic name for MPFI. All j-bodies after 90ish have some form of MPFI.

MPFI = Multiport fuel injection
Generic name for PFI, lol. I don't want to cover injection types sorry.

SFI = Sequential fuel injection
Another type of MPFI, again, blah about this.

TBI = Throttle body injection
You don't have this Only pre 90ish j-bodies do. It's like a carb with a single fuel injector.

Adv. = Advance (timing)
Someone else handle timing I'm getting sleepy. bah

Ret. = Retard (timing)
see above


FPR = Fuel Pressure Regulator
Regulates fuel pressure to a constant level to maintain fuel rail pressure for the injectors. it's the little can on your fuel rail.

AFPR = Adjustable FPR
A FPR you can change the pressure setting of. Also, some factory boosted cars (like mine) have a vacuum line running to their FPR that raises fuel pressure based on Boost pressure. Also called a "rising rate" FPR then.

FMU = Fuel Management unit
A piggy back FPR or sorts that raises fuel pressure based on boost. It's a handicap for turbo cars with improper fuel systems for running happy amounts of boost.

ECM = Electronic control module
THE BRAIN! This baby does it all! and I refuse to call it anything other then a ECM. That's what my fuse box says for it

ECU = Emissions control unit (same thing as an ECM, or a PCM)
If you call an ECM this you are gay.

PCM = Powertrain control module
if you call a ECM this you are gay AND a ford lover! that's like 2x the gay.

F/P = Fuel Pressure
Um, the pressure of fuel in the rail.

P&P = Port and Polish
To smooth the ports in a cylinder head, to enlarge them slightly, to make the air enter the combustion chamber smoother, and to put a mirror polish on the exhaust ports and a rougher one on the intake ports. WHy? That's another lesson.

LSD = Limited Slip Differential
Locks both tires when accelerating in a straight line, so that not just one tire is gripping the road. Better ones even lock in turns at lower speeds. These give you better traction.

T/C = Torque Converter
The automatic tranny equivilent of a clutch (damn I'm oversimplifying)

BAR = Unit of pressure 1 bar = 1 atmosphere, 2 bars about 15 PSI of boost
^^

PSI = Unit of pressure (american)
If you don't know this you can't even fill your tires. Get out of here.

Kpa = Unit of pressure (metric)
Canadian eh?
<br>


4cyltuner.com - Information Source For 4 Cylinder Tuners
Buy stuff from CarCustoms Ebay! Won't be disappointed!

There are some really wierd characters in there, they are all the quote (") sign. I guess word didn't like to go to pure text.

<br>


4cyltuner.com - Information Source For 4 Cylinder Tuners
Buy stuff from CarCustoms Ebay! Won't be disappointed!

damn! that is going to cost too much. i think i will just buy a car that is built for turbos. thanks any way

Corrections:
Converting CC/Min to Lbs/hr, multiply CC/Min by 10.5, not 10.55

Website for Turbo Map reading:
http://pergatory.net/turbo/turbochoose.html

<br>


4cyltuner.com - Information Source For 4 Cylinder Tuners
Buy stuff from CarCustoms Ebay! Won't be disappointed!

Additional Parts for a turbo kit:
EGT Gauge
Wideband Oxygen Sensor
Oil Pressure Gauge
Fuel Pressure Gauge (Essential for tuning an FPR)

<br>


4cyltuner.com - Information Source For 4 Cylinder Tuners
Buy stuff from CarCustoms Ebay! Won't be disappointed!

Very good information. I may post some more in depth details of verious things when I get a chance. <br>


Cardomain|Myspace

Good list. Hopefully others appreciate the good information it contains.

Some suggestions:

Add MAT, Manifold Air Temp to the list of abbreviations. It's close enough to IAT that it's often used interchangeably.

Quote:

A car could be perfectly tuned in Boulder, Colorado, but when that person drove down to Florida, their car would probably run way too rich.

Other way around. Less oxy available at high altitude.

Quote:

you don¡¦t want your A/F ratio to be more than 12:1, and you don¡¦t want it less than 14.7:1.

14.7:1 is more than 12:1. 12:1 is less than 14.7:1. lol. You don't want less than 12 parts air to 1 part fuel, or more than 14.7:1.

Also, in terms of air density, IIRC, a 1 lb increase in boost provides roughly the same increase in usable air as a 10 degree reduction in air temps. Those of us in the colder climes really know about this in the winter.

Maybe I can add some common conversion factors for pressure and whatnot later.

-->Slow

Shifted, you are the MAN!!!

Slow,

LOL, I had a mental fight with the wording on the AF thing. My thinking was that you didn't want to have your AF to me more than 12:1 (more fuel than 12:1), I know that 14.7:1 is more than 12:1, but 12:1 is richer (more fuel), than 14.7:1.

<br>


4cyltuner.com - Information Source For 4 Cylinder Tuners
Buy stuff from CarCustoms Ebay! Won't be disappointed!

Quote:

---- Boost is so much more than PSI. Imagine for a moment that you have a box, its 1 cubic foot big (1 foot x 1 foot x 1 foot). One turbo can take 10lbs of air (it¡¦s a lot of air), and compress it to 5 PSI, and stick it in that box. Another turbo can take 20lbs of air, compress it to 5 PSI, and also stick it into that box. Obviously the 20lbs of air will make more power than the 10lbs of air of the smaller turbo charger (provided you have the right fuel mixture).

If I may propose a change in terminology, in interest of the way that statement will be perceived. I have yet to find an argument explaining psi/cfm/mass relationships of this type (with the box) that was able to get the point across and NOT instill the "bigger is better" mentality for turbochargers. Now here's what I think you were saying:

AT ANY GIVEN RPM, two turbos can deliver differing masses of air (turbo efficiency) at the same pressure, which therefore would mean the same volume. It's the same volume of air, because the engine can only take in a certain volume of air (volumentric efficiency) and if you were to flow any more air you would simply be increasing the pressure.

Quote:

As I had said before, PSI really is a relative term. The big thing you want to look at is CFM, usually expressed in lbs/hr.

For my current application (7-8 psi MAX, I would rather have a "smaller turbo" that was well sized to my engine and provided quick spool and satisfactory high rpm throughput, than a "bigger turbo" that MAY have a larger HP potential(and a high CFM rating), but gave unacceptable lag and identical power output at my low boost setting anyway. In this case, a huge turbo would be wasting money AND power. It must be remembered that ANY two turbos that compress air with the same efficiency and at the same pressure will produce the SAME EXACT POWER. PSI does NOT = power. CFM does NOT = power.

By any means we should keep misconceptions about PSI and CFM out of the forums.
There are SOOO many COMMON misconceptions on this exact topic that it is almost a necessity to explain it absolutely correctly in a FAQ type atmosphere. I would expect the level of common courtesy to be low in a thread like this, being that this is the first stop and potential source for keeping the common questions and more importantly, misconceptions, out of the forums.I've noted a few turbo gods that have gone MIA from the boost forum, most likely because of this. Not a good thing for us intermediates. <br>

<br>
<img src="http://home.nycap.rr.com/xenox/jbody/jbody_shocker.jpg">

Shifted wrote:

Quote:

LOL, I had a mental fight with the wording on the AF thing. My thinking was that you didn't want to have your AF to me more than 12:1 (more fuel than 12:1), I know that 14.7:1 is more than 12:1, but 12:1 is richer (more fuel), than 14.7:1.

Yeah, it can be confusing. You're talking air:fuel ratio and thinking fuel:air ratio. A fuel:air ratio of 1/14 is definitely less than 1/12.

Excidium wrote:

Quote:

two turbos can deliver differing masses of air (turbo efficiency) at the same pressure, which therefore would mean the same volume. It's the same volume of air, because the engine can only take in a certain volume of air (volumentric efficiency) and if you were to flow any more air you would simply be increasing the pressure.

It's about air density, really. An engine _always_ displaces the same volume of air. Whether the air is more or less "compressed" in the cylinder, the maximum cylinder volume never changes.

-->Slow

Slow-

No, I'm thinking air-fuel.

For example:

You have 12 oz of air, and 1 oz of fuel, your a-f ratio is 12:1

You have 14 oz of air, and 1 oz of fuel, your a-f ratio is 14:1

Obviously the 12:1 is richer (more) than 14:1.

Got my line of thinking now?

Excidium-

Good points, I was just trying to express that PSI has no direct correlation to power, but for a certain PSI, the more volume of air you can shove in, the more power you should be making, since the oxygen content of the air combined with the fuel mixture, static compression of the cylinders, all that good stuff, if the only variable is the volume of air and amount of fuel, the more volume should mean more power.

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slowolej wrote:It's about air density, really. An engine _always_ displaces the same volume of air. Whether the air is more or less "compressed" in the cylinder, the maximum cylinder volume never changes.

Exactly what I thought I wrote. The way I interpreted what shifted said was differing masses in the same volume, which is a difference in density. I should have just said density

Shifted (KickAzz) wrote:if the only variable is the volume of air and amount of fuel, the more volume should mean more power.

At WOT, the volume will always be the same (volume neglects density), despite however compressed the mixture is. That was primarily my point and is why CFM should not be the defining factor in choosing any turbo over another. The mentality that Turbo A flows x amount of air and Turbo B flows x + 1 amount of air, and therefore Turbo B must be better is the wrong way to think about turbos. Your example was fine because you were talking in lbs/air which means mass and you were working with a constant volume, its just that I think it got the idea across that volume/cfm was the most important role in power. Anyway, great info in this thread Shifted. Good job. <br>

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LOL, I always mix up volume and density In the quote I meant density, not volume, gotta let the brain process more before posting

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Quote:

Slow-... Got my line of thinking now?

Yep. And I know exactly what you're saying about the "more or less" issue. It happens too often.

I guess I'm just saying that it might help to keep air:fuel ratio terms in perspective. An AFR of X:1 really describes the amount of air. Sure, an afr of 12:1 is richer than 14:1, but only because there's less air (12 parts vs 14). There's still 1 part fuel in both cases. That's why I said you're thinking in fuel:air ratios and talking in air:fuel. It's not a big deal, I only wanted to point out the difference because you're one of the few people that seems to enjoy working with the math behind the car.

I had to deal with the same thing with "spark advance" and "spark retard." Is advanced spark always greater than zero degrees, or is it just greater than than a previous value? And what do you do when the numbers involved in generating spark advance are getting more negative as the amount of advance increases? Ya, right. I decided "positive spark timing" and "negative spark timing" are a whole bunch better. And anyway it turned out that "spark retard" was a flunky in the shop that was dumb enough to grab a plug wire on a running car and get shocked... on 4 different occasions! So I couldn't use that term with a straight face anymore.

Good info nonetheless. It should be helpful for anyone able and willing to read.
-->Slow

Great and really useful info Ron. Also great info and help Slowolej, sExcidium, Protonus, SunfighterGT, ....... and the others that help here. That is the type of info and talking that we need in this forums.

Personally I suggest that this post need to be "STICKY"

And to add something to the post:
1.- Psi/CFM/Volume are differents ways to describe the characteristics of a fluid that pass through a path. Is something like displacement/velocity/acceleration. Let me show you and example. Imagine a garden hose filling up a tank. Volume is the quantity of water in the tank, CFM is the quantity of water that goes in the tank per space of time (the width of the water column going out the tip of the garden hose) and PSI is the force that column of water produce to move some quantity of water from the point A to the point B (in other words the time that takes the water to go from the beginning of the hose to the end of it. Also you can imagine PSI as how long can reach the column of water from the end of the garden hose)

So in the way to put more volume in each cylinder, the engine will produce more power. CFM and PSI indicates only indicates how much air we need and how fast (time), a quantity of air goes in the engine.

2.- A/F is directly connected to the quatity of oxygen (density) and the composition of the air. That is why cold air produce power than hot one, simply, have more oxygen in the same volume. Also the humidity of the air is important, because can improve detonation characteristcs of a A/F mix (how fast the a/f mix burns). Of course all have it practical limits. That is why a mechanical tuned boosted engine change it a/f readings from one place to another (of course at the limits). So the engine can't compensate at all for altitude, air density, air temperature, etc........ in a wider set of values. Here is when timing is involved taking it to the limit previous of detonation, to get the maximun amout of safe power.

I hope this info could be useful. I am not an expert, so if I make an error please correct me.

Best Regards,
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Hi friends I found good info about anti-detonation techniques for max power in boosted engines. I think this note is really informative and want to share with you.

You can find it here.

Anyway I post here.

Application Note by Innovative Motorsports:

You CAN be too Rich

By Klaus Allmendinger, VP of Engineering, Innovate Motorsports

Many people with turbochargers believe that they need to run at very rich mixtures. The theory is that the excess fuel cools the intake charge and therefore reduces the probability of knock. It does work in reducing knock, but not because of charge cooling. The following little article shows why.

First let’s look at the science. Specific heat is the amount of energy required to raise 1 kg of material by one degree K (Kelvin, same as Celsius but with 0 point at absolute zero). Different materials have different specific heats. The energy is measured in kJ or kilojoules:

Air ~ 1 kJ/( kg * deg K)
Gasoline 2.02 kJ/( kg * deg K)
Water 4.18 kJ/( kg * deg K)
Ethanol 2.43 kJ/( kg * deg K)
Methanol 2.51 kJ/( kg * deg K)

Fuel and other liquids also have what's called latent heat. This is the heat energy required to vaporize 1 kg of the liquid. The fuel in an internal combustion engine has to be vaporized and mixed thoroughly with the incoming air to produce power. Liquid gasoline does not burn. The energy to vaporize the fuel comes partially from the incoming air, cooling it. The latent heat energy required is actually much larger than the specific heat. That the energy comes from the incoming air can be easily seen on older carbureted cars, where frost can actually form on the intake manifold from the cooling of the charge.

The latent heat values of different liquids are shown here:

Gasoline 350 kJ/kg
Water 2256 kJ/kg
Ethanol 904 kJ/kg
Methanol 1109 kJ/kg

Most engines produce maximum power (with optimized ignition timing) at an air-fuel-ratio between 12 and 13. Let's assume the optimum is in the middle at 12.5. This means that for every kg of air, 0.08 kg of fuel is mixed in and vaporized. The vaporization of the fuel extracts 28 kJ of energy from the air charge. If the mixture has an air-fuel-ratio of 11 instead, the vaporization extracts 31.8 kJ instead. A difference of 3.8 kJ. Because air has a specific heat of about 1 kJ/kg*deg K, the air charge is only 3.8 C (or K) degrees cooler for the rich mixture compared to the optimum power mixture. This small difference has very little effect on knock or power output.

If instead of the richer mixture about 10% (by mass) of water would be injected in the intake charge (0.008 kg Water/kg air), the high latent heat of the water would cool the charge by 18 degrees, about 4 times the cooling effect of the richer mixture. The added fuel for the rich mixture can't burn because there is just not enough oxygen available. So it does not matter if fuel or water is added.

So where does the knock suppression of richer mixtures come from?

If the mixture gets ignited by the spark, a flame front spreads out from the spark plug. This burning mixture increases the pressure and temperature in the cylinder. At some time in the process the pressures and temperatures peak. The speed of the flame front is dependent on mixture density and AFR. A richer or leaner AFR than about 12-13 AFR burns slower. A denser mixture burns faster.

So with a turbo under boost the mixture density raises and results in a faster burning mixture. The closer the peak pressure is to TDC, the higher that peak pressure is, resulting in a high knock probability. Also there is less leverage on the crankshaft for the pressure to produce torque, and, therefore, less power.

Richening up the mixture results in a slower burn, moving the pressure peak later where there is more leverage, hence more torque. Also the pressure peak is lower at a later crank angle and the knock probability is reduced. The same effect can be achieved with an optimum power mixture and more ignition retard.

Optimum mix with “later” ignition can produce more power because more energy is released from the combustion of gasoline. Here’s why: When hydrocarbons like gasoline combust, the burn process actually happens in multiple stages. First the gasoline molecules are broken up into hydrogen and carbon. The hydrogen combines with oxygen from the air to form H2O (water) and the carbon molecules form CO. This process happens very fast at the front edge of the flame front. The second stage converts CO to CO2. This process is relatively slow and requires water molecules (from the first stage) for completion. If there is no more oxygen available (most of it consumed in the first stage), the second stage can't happen. But about 2/3 of the energy released from the burning of the carbon is released in the second stage. Therefore a richer mixture releases less energy, lowering peak pressures and temperatures, and produces less power. A secondary side effect is of course also a lowering of knock probability. It's like closing the throttle a little. A typical engine does not knock when running on part throttle because less energy and therefore lower pressures and temperatures are in the cylinder.

This is why running overly-rich mixtures can not only increase fuel consumption, but also cost power.

Best Regards,

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J-Body of Michigan -

Not bad, but i would have to say that you left one thing out after attacking the EIC setups. This is what gets me everytime you talk about them, you dont know what the cuase of the "problems" with them are. Here is the deal..
The reason why an EIC can puddle is because people have no idea what they are doing when they install these. They think its ok to run alot of extra fuel and THAT is what causes the puddling and damaged manifolds. Like anything this can be overcome by proper tuning. Those who tune an EIC system properly (it is easy) never have that problem, hence those are the people serious about doing it right and enjoy the system.
The fault is not that of the EIC; its the owner/ installer fault. EICs do not cause puddling, people do by running too much fuel. EICs therefore are the safest thing available for fuel upgrades.

Mike Andrews wrote: EICs therefore are the safest thing available for fuel upgrades.

I'm not gonna get into this here, in the FAQ........but that is a very biased statement....and could cause alot fo trouble.

There is not trouble to be made unless with you RUSS.
I am only stating the facts.

Where are those facts coming from? You have nothing to back them up. As a matter of MY OPINION, a stand alone is the safest way to increase fuel to your car. You keep saying EIC's are the best thing since sliced bread, but where is your proof other than your word? What I stated in in the FAQ is a matter of my opinion, and I put that right in there for everybody to read.

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Coming on here and saying that EIC's are the safest thing for fuel upgrades is flatout retarded. I'm not gonna have this arguement with u in the FAQ...again...as u've been proven wrong over and over again....its your opinion, thats fine.....but do not tell people that EIC's are the best. They are one of many available options.

Please see my comment about self improvement i made in the other thread....

if u feel the need to spread your innacurate information..... I hear HAAS has their own forum now. try there.