Ok in preparation for my turbo project, i have been doing a TON of homework... reading books and websites and all sorts of stuff....
I have gotten to understand compressor maps pretty well, which i under stand to be quite a bragging right....
Anyway... where i am stuck at is how to plot your engines needs on the map, so you know if the compressor fits your needs.....
Like how do you know how much flow you need at what point?
I have the 2.4L LD9.... and a very good flowing one at that.... (check out my profile for details)
I plan to have her rev limiter around 7000-7250.... And would like to run as much boost as possible with my 8.5:1 pistons and 93 octane.
I do have my engine pretty well mapped out as far as VE goes in HP tuners... can the VE tables in HPT somehow be converted into something that can be plotted into a compressor map?
ken soggs wrote:One thing i wouldlike to know is how does the build of the engine effect plotting on the compressor maps....
Like almost all calculators i have seen base everything entirely on displacement. they just ask the size of your engine, the restriction of your intercooler, and then just some questions about where you want what to happen.... and then they give you the info you need to find out where you fall on a compressor map.
but i mean i fully built 2.4L twincam with cams and ported heads, and dished pistons, and the works is going to fall in a slightly different place on the map than a bone stock 2.2L ohv engine... but according to the calculators, it is "only .2 liters different"
I want to know how you can factor in the "flow" of an engine into the compressor maps. I would assume a ported tuned and built motor could run a much different turbo than the same engine bone stock.
any chance someone could help me out with this? (pasted from another thread... but belongs here.. so just cross thread quoting...)
the above calculator is awesome by the way.... but how do you figure for your engines own flow in this calculator or others?
Garrett has pretty good "ball-park" figures that will give you an idea of what to put in for the VE....
Garrett Turbo Tech 103
From this page:
Quote:
· Engine Volumetric Efficiency. Typical numbers for peak Volumetric Efficiency (VE) range in the 95%-99% for modern 4-valve heads, to 88% - 95% for 2-valve designs. If you have a torque curve for your engine, you can use this to estimate VE at various engine speeds. On a well-tuned engine, the VE will peak at the torque peak, and this number can be used to scale the VE at other engine speeds. A 4-valve engine will typically have higher VE over more of its rev range than a two-valve engine.
Theres lots of info on this page, they basically walk you through how to map a motor on a compressor map.....
The ONLY way to really have the information you require is to have the head flowed on a flow bench along with measuring your CC in the head with water and then calculating the cylinder volume via math equations that are based off your bore size, piston size, stroke, etc. There is a LOT that goes into finding exactly what your engines specs are. General equations can only be used if you know the correct information to enter into it. When it comes to porting your head it is more an art than just a simple opening of the head like most think. Serious HP can be lost via a port job that was performed incorrectly. Best way to know whether it was done correctly is to again flow it on a bench (with a bench that is capable of actually flowing your head). Multi port heads require special techniques and benches to test it. A complete blueprinting will reveal your answers but its not likely you will want to do that cause its very time consuming and meticulous. Good luck.
ASE Master Certified Automotive Technician
well i have a head that was professionally ported and flowbenched... It is the mantapart sport head... i am in regular contact with mantapart, and could prob get all the specs from them...
the head is sitting on the table next to me... i could find the head CC pretty easy.
ok give me your thoughts....
I have a lead on a really nice turbonetics 60-1 turbo....
it is a hybrid T3 turbine with a .63 a/r
60-1 compressor
It has the ball bearing option... (it only comes in a single ball bearing version, compressor is BB, turbine is journal still)
it only has a few thousand miles on it and still looks BRAND new, and no shaft play at all.
I can get it for a hell of a deal... problem is acording to squirrels calc... i am RIGHT on the borderline... depending on how i configure it, i could surge it...
that is why the sudden interest in engine flows effects on the map... i just left most of the details "as is" on the calc... like VE and all... i just plugged in 2.4L and my redline and rpm targets... and that is where it shows me nearing the surge lines... let me see if i cant link to it with my specs plugged in...
ok here is the link with the "defaults" 400hp was selected, as that would be a nice (and reasonable) goal. i also bumped redline to 7300 (cams and 2.3L oil conversion) and peak power to 6300 (as that is where my engine should be at)
http://www.squirrelpf.com/turbocalc/index.php?version=4&target_peak_power=400&engine_disp=2.4&engine_disp_factor=0&target_af=12&bfsc=0.43&max_ic_loss=1.7&rpm_redline=7300&rpm_peak_powe
r=6000&rpm_max_boost=3800&rpm_min_boost=3000&vol_1=89&vol_2=93&vol_3=90&vol_4=87&vol_1=89&vol_2=93&vol_3=90&vol_4=87&intake_temp_1=90&intake_temp_2=120&intake_temp_3=135&intake_temp_4=140&turbo_n=1&ma
p_sel0=62
so as you can see.. if this was a "default 2.4l" i would probably kill the turbo in no time with that surge. it rides right up the surge line... but doesnt cross it till the very top
but with all i have in my engine, i am sure i flow a little better than the "defaults" allow... I also read that a 4 valve DOHC engine should be closer to 95% VE thru most of its range... the defauls leave you at 87%-93%... so if we adjust that up to a liberal 95%.... and lets give it a little more time to spool up... say max boost at 4000, min boost at 3500, lets even give it till 6500 to make peak HP.
http://www.squirrelpf.com/turbocalc/index.php?version=4&target_peak_power=400&engine_disp=2.4&engine_disp_factor=0&target_af=12&bfsc=0.43&max_ic_loss=1.7&rpm_redline=7300&rpm_peak_powe
r=6500&rpm_max_boost=4000&rpm_min_boost=3500&vol_1=95&vol_2=95&vol_3=95&vol_4=95&vol_1=95&vol_2=95&vol_3=95&vol_4=95&intake_temp_1=90&intake_temp_2=120&intake_temp_3=135&intake_temp_4=140&turbo_n=1&ma
p_sel0=62
this gets it away from the surge line... the turbo may not be the most efficeint choice, (the fact there are no island labels doesnt help much... but lets assume the center island is 75% to be conservative) i should still be in the range of like 65% where i am at out by the surge line there...
But the thing is that this engine is actually well over 100% VE... because it will be twin charged... (i am toying with the idea of a solenoid operated supercharger bypass valve operated by a rpm or boost switch to bypass the supercharger above a given threshold) but for the most part the LOWER RPM range should be well above 100% ve while the SC is helping out. once the SC looses efficiency, that is when the bypass valve (might) be opened to allow the turbo to work on its own.
so i have NO IDEA how i would plot that all on a turbo map.... but i have to imagine it would move me further yet from the surge line, and into more effiecint parts of the map.
(i also have a lead on a REALLY good intercooler, so that will help make up for loss of compressor efficiency too.) and there is always the alchy injection as well to offset the SC heat.
So just taking a wild stab in the dark here.... this is what i MIGHT imagine the map would look like....
http://www.squirrelpf.com/turbocalc/index.php?version=4&target_peak_power=400&engine_disp=2.4&engine_disp_factor=0&target_af=12&bfsc=0.43&max_ic_loss=1.0&rpm_redline=7300&rpm_peak_powe
r=6500&rpm_max_boost=4000&rpm_min_boost=3500&vol_1=140&vol_2=140&vol_3=100&vol_4=95&vol_1=140&vol_2=140&vol_3=100&vol_4=95&intake_temp_1=90&intake_temp_2=120&intake_temp_3=135&intake_temp_4=140&turbo_
n=1&map_sel0=62
but yeah.... i dont fully understand the calculator... so i could be WAY off....
so anyone want to help me out?
To start off, I highly highly Highly doubt that you are going to have a 100% efficient VE, most all out dedicated race motors typically are between 90-95% efficient. A realistic idea of VE for a high-performance, street driven car is 80-85%. There have only been VERY few specialty race engines with HIGHLY tuned intake and exhaust systems to produce over 100% efficiency.
Another thing I would point out is that a BSFC that is more ideal for a street-driven turbo motor is .5-.6. When calculating with BSFC I would use 0.5, this is the most realistic number.
So if you had 100% VFR (volumetric flow rate) then you would be pushing 253.47 CFM of air, we found this by taking the displacement of the motor in cid, multiplying it by our Peak HP RPM and then dividing by 3456. But let's use a high end realistic VE of .9, or 90%, and you get an actual VFR of 228.13 CFM, to find this we simply multiplied our 100% VFR by our realistic VE of .9, or 90%. Next we need to calculate the air density. Let's assume you're at sea level so the pressure will be 14.7 psia and let's say the temperature of the ambient air is 85*, this would give us an air density of .073 lb/ft^3. With the VFR and air density we can now determine the Mass Air Flow Rate (MFR) for this motor in N/A form. It's simply VFR time air density, which gives us a flow rate of 16.7 lb/minute.
Now to figure the MFR for the turbo application we need to figure our density ratio. But in order to do that, we need to know the Pressure Ratio of the compressor and intake system as well as the temperature into the compressor and out of it. Let's say you plan to run 10 psi on this motor. You add the ambient air pressure (since we're assuming sea level we plug in 14.7) to the psi you are running and then divide by the ambient air pressure. This will give us a Pressure ratio of 1.68 at the compressor. Now we take that and seeing that we are using an intercooler we need to take the pressure drop into account. We'll use 1psi as this is a good/typical pressure drop for a decent intercooler. The formula is basically the same as the compressor ratio formula except you need to subtract the pressure drop from the psi you are running, then add ambient pressure and finally divide by ambient pressure again. Doing this give us a Pressure Ratio for the intake system of 1.61. Next we need to know the air temperature out of the compressor. To do this we would need to know the efficiency of the compressor we are working with. Since most compressor are typically between 70-80% efficient we'll meet in the middle and use 75% for our efficiency. Let's also assume the ambient air temperature is still 85*F. Our ideal air temperature assuming a 100% efficient compressor is calculated by adding 460 to the ambient temp and multiplying that by the Pressure Ratio we found earlier ^ 0.283 square and finally subtract 460. This would give us an ideal outlet temperature of 171*F. But seeing that our compressor is only 75% efficient our actual temperature out will be calculated by subtracting the ambient temp from the Ideal outlet temp, dividing that by our compressor efficiency and finally adding the ambient temp. This will give us an actual outlet temperature of 200*F. Finally, now we can determine our density ratio, which is basically how many air molecules we'll be cramming into the the cylinder. To do this we add 460 to the ambient temp and divide that by (temp out actual + 460) and then multiply that answer by the Pressure Ratio we found earlier. Since we are using an intercooler let's assume we'll have about an 80*F temperature drop so our temp out actual will be 120*F. There is a way to found out how cool the temp will be after the intercooler, but that's for another time. So we finally get our Density ratio of 1.51.
At last we can figure our MFR for our turbo application on the 2.4L motor. Running 10psi with a 75% efficient compressor and a good intercooler you can expect your MFR to be 25.22 lb/min. Most compressor maps will read in lb/min, but you can adjust it to whatever unit you need to accordingly. So as you can see these are basically the formulas you need to be able to plot your points on a compressor map. Simply change the RPM and VE % when determining your actual VFR and change your psi when determining the Pressure ratios. There are 3 key rpms that you need to plot when looking at a compressor map, 3500, 5500 and 7500 (since you plan to run this many rpm). That will give you a really good idea of where you are, but don't limit yourself to just these three plots, do as many as you care to.
Sorry if this isn't too coherent, it's late and I need to be up in 5 hours for work. If you have any questions or what not just let me know. Also, I referenced most of this information from the book "Street Turbocharging" by Mark Warner, P.E. This book can be purchased at Barnes and Nobles and I HIGHLY recommend it to anyone who is serious about turbocharging.
Jason
yep, i have that book right in front of me... it is one of the resources i look to all the time in these matters.
sadly, it doesn't answer my questions for my specific application....
A few things i guess i still don't "get" (at least on that calculator) it seems like ALOT of it is backwards... like many of the inputs it wants from us are the very things we are trying to find out.
like i would love my air temps to be cooler than ambient... so sure i could just plug in 60 temps... but that isn't realistic... but i don't know what to put in there cuz i DONT know how it is all going to come together. it shouldnt be ASKING us for our intake temps.... it should be asking us ambient temp, and telling us how hot the compressed air will be.
same with min and max boost at RPM. This would be based on the compressor we choose. we wont really know this until we have a turbo... and we wont know what turbo we have till after we use a calculator. but the calculator wants to know what turbo we are using. kind of a catch 22 if ya ask me.
so i guess i need to know some "dummy figures" to plug in here (i dont trust the ones that just show up... who knows who put those there or what engine they had in mind or how much crack they were on)......
Like what is a typical min and max boost rpm of a turbo system? (doesnt min boost occur whenever the exhaust spins the turbo fast enough to create positive pressure? wouldn't this then completely depend on how heavy our foot was in it? or is all this ASSUMING WOT?) and then max boost... i would ASSUME this would be just min boost + how many rpms it took us to get from 0pis to full boost. but this would depend on the exhaust pressure of the engine and the resistance of the turbo... i dual ball bearing turbo would have alot earlier max boost than a journal bearing turbo would... (and i notice that moving the max boost point hugely effects the curve of the points on the map. so again... what should one ASSUME here as far as realistic min and max boost points?)
Engine redline i can handle....
Peak power... sounds easy enough... but wouldnt this again be a combination of efficiency of engine and turbo? I would assume up closer to redline is where you would end up with the most power. torque x rpm = HP.... so higher HP will always be had at higher RPM... so again... they are asking us for things they should be TELLING us.
as far as the VE's go... is there a way to figure out these values based on HPT VE tables? i dont think HPT uses % VE... but dont recall what figures they do use.. so anyone know how we could convert this?
Since this is my first run with turbo charging... can anyone explain in a lil more detail how we can "control" aspects of the system... i mean i know that a wastegate keeps the boost levels to a determined max psi. opend a valve to bypass the turbine once a pressure is reached. and i know a BOV or BPV vents air and releases excess pressure (typically when the throttle blade is closed while the turbo is still spinning)
but apart from the "parts" we put into the build.... arent these the only 2 controls we have over a turbo? max PSI, and BOV sensitivity... everything else depends on the engine and the other "parts" doesnt it?
I don't think that calculator is a very good tool in all honesty. You have the control over your boost level and that calculator in no way allows you to override it. That book will tell you what to expect for charge temps after the intercooler, I would suggest looking over that and doing that calculations.
What I would suggest is this, contact the manufacturer of the turbo you're interested in and let them know you are looking at purchasing that particular model and would like to see a compressor map so you can be sure it will be the correct purchase. They should be more than happy to supply you with it. Once you receive it then you can do the calculations and plot your points on the map.
The boost levels are controlled by you, the maximum is what you set it to via either the wastegate or boost controller. There's nothing more to it than that. When you get your compressor map you should use the max efficiency island for calculating your Pressure ratio at the compressor for your max psi and horsepower level, at least that's where you want it to be. Then you need to plot your other points and calculate the MFR and pressure levels accordingly. Let me see if I can find a link to a compressor map and I'll use it as an example, ok, let's use
THIS compressor map because I believe based on your max MFR this one should fall right where you need it. I'll post back up in a few minutes, I'm going to go ahead and try to plot some points along this map and show what I found and try to explain how I got it better.
86svo wrote:I don't think that calculator is a very good tool in all honesty. You have the control over your boost level and that calculator in no way allows you to override it. That book will tell you what to expect for charge temps after the intercooler, I would suggest looking over that and doing that calculations.
What I would suggest is this, contact the manufacturer of the turbo you're interested in and let them know you are looking at purchasing that particular model and would like to see a compressor map so you can be sure it will be the correct purchase. They should be more than happy to supply you with it. Once you receive it then you can do the calculations and plot your points on the map.
The boost levels are controlled by you, the maximum is what you set it to via either the wastegate or boost controller. There's nothing more to it than that. When you get your compressor map you should use the max efficiency island for calculating your Pressure ratio at the compressor for your max psi and horsepower level, at least that's where you want it to be. Then you need to plot your other points and calculate the MFR and pressure levels accordingly. Let me see if I can find a link to a compressor map and I'll use it as an example, ok, let's use THIS compressor map because I believe based on your max MFR this one should fall right where you need it. I'll post back up in a few minutes, I'm going to go ahead and try to plot some points along this map and show what I found and try to explain how I got it better.
I think you should calculate it for the 60-1 or the Garret GT30 or GT35. Those are the ones i am toying with at the moment... the 60-1 i have a killer deal on... i know it prob isnt the best choice, but for more less than 40% the retail price... i am having a hard time passing it up.
I could always buy it, use it for a bit, and then sell it again for a profit, and then buy something more fitting to my needs once i know a lil more about how it all works from experience.
ken soggs wrote:86svo wrote:I don't think that calculator is a very good tool in all honesty. You have the control over your boost level and that calculator in no way allows you to override it. That book will tell you what to expect for charge temps after the intercooler, I would suggest looking over that and doing that calculations.
What I would suggest is this, contact the manufacturer of the turbo you're interested in and let them know you are looking at purchasing that particular model and would like to see a compressor map so you can be sure it will be the correct purchase. They should be more than happy to supply you with it. Once you receive it then you can do the calculations and plot your points on the map.
The boost levels are controlled by you, the maximum is what you set it to via either the wastegate or boost controller. There's nothing more to it than that. When you get your compressor map you should use the max efficiency island for calculating your Pressure ratio at the compressor for your max psi and horsepower level, at least that's where you want it to be. Then you need to plot your other points and calculate the MFR and pressure levels accordingly. Let me see if I can find a link to a compressor map and I'll use it as an example, ok, let's use THIS compressor map because I believe based on your max MFR this one should fall right where you need it. I'll post back up in a few minutes, I'm going to go ahead and try to plot some points along this map and show what I found and try to explain how I got it better.
I think you should calculate it for the 60-1 or the Garret GT30 or GT35. Those are the ones i am toying with at the moment... the 60-1 i have a killer deal on... i know it prob isnt the best choice, but for more less than 40% the retail price... i am having a hard time passing it up.
I could always buy it, use it for a bit, and then sell it again for a profit, and then buy something more fitting to my needs once i know a lil more about how it all works from experience.
or u could just buy it and then sell it right away and not use it, using profit to buy something a bit more suited and have that turbo all the time vs. down the road
gmanz24 wrote:or u could just buy it and then sell it right away and not use it, using profit to buy something a bit more suited and have that turbo all the time vs. down the road
yes i could do that... but at the moment i dont have a way of knowing EXACTLY what i need. there are no calculators that let me pick out a good turbo to go along with my supercharger in a twin charged setup.
I can only guestimate till i get something setup and test in the real world.
I would have to imagine that i will need something that flows MORE than a stock 2.4L. All the calculators show me that a GT30 would work best for my goals on a 2.4L using most of the defaults given on the page..
it shows the 60-1 as being a lil higher flowing than i would need. handles the PR as well as the GT's but is designed for a few more CFM's... and i think it is going to be the CFM's that my dual charged setup is going to want more of....
i just feel that this turbo MAY be a good fit... I should stay out of the surge area, which is the big issue... and if i notice i am getting more heat than i should be seeing.... then i know i need something smaller.
unbolt it and list it for sale...
the fact that i can get this 60-1 turbo locally (Pay cash, no tax, no shippiong, no waiting) and really cheaply, and its already used (so i dont have to take a huge hit on buying new, realizing it isnt what i want, then reselling for half of what i paid for it)
means that i can buy it try it and sell it again in no time with nothing to loose and alot to gain.
and still do what you said in the end if it comes to that....
Ok, after finding what the PR and MFR was going to be at certain RPM's I searched and found tons of maps and think I found one that will suit your needs about perfectly. It does run a little close to the surge line at low rpms, but you should be fine.
This Compressor Map which I plotted your points on looks like it would fit perfect. It is the GT30r-71 turbo.
When I did your calculations I underestimated your VE % on purpose. The first plotted point is assuming 15psi by 3000 rpm with an 80% VE. The second plotted point is full boost of 25psi at 3500rpm with an 85% VE. The third point is plotted at full boost again at 7500 rpm and I figure your VE will drop a good bit to 75% VE. The fourth and final point is your max HP with max boost at 6500 RPM and a 90% VE.
Now, if you know what your VE % is for a given RPM through HP Tuners, then you can get an EXACT plot. I don't know HP Tuner, so I can't answer your question about if you can figure VE % from it.
The 60-1 turbo ran way into the left side of the surge line as well as most to4 turbo maps. This should give you a pretty good idea of the turbo you need. Also, I ran the calculations and @25psi with a 90%VE, BSFC of .5, a/f of 12:1 and RPM @6500 you should have damn near 400hp @ the crank. Now this can obviously be manipulated in many means, but puts your right at where you wanted to be power wise.
Here's those same points plotted on the 60-1 compressor map.
Just out of curiosity, why are you planning to twin charge (supercharger and turbo)? Not downing it by any means just seems like it is more of something for show rather than go?
Hope things are going well with the project though!
86svo wrote:Just out of curiosity, why are you planning to twin charge (supercharger and turbo)? Not downing it by any means just seems like it is more of something for show rather than go?
Hope things are going well with the project though!
well i bought the car with the superchargers. and loved it.
so i slowly built it up and loved it even more...
got to 7psi and still wanted more.... but my poor m45 was almost at her limits...
i toyed with trying to make a remote mount M62 or M90...
all the guys on here talk about making a intake to direct mount the m62... but it never gets done...
and even then.. the m62 is on all cobalts and comes bolt on for all ecos...
so even with all the work of doing an m62, it wouldnt be anything overly special.
so i was rebuilding my engine... and about the same time got talking to some friends who had just turboed their cavaliers... and it sounded easy and like alot of fun... BUT i love my low end torque and mid range punch this supercharger has...
and again... there are alot of turbo cars out there... even the new cobalt comes in a turbo flavor now...
i didnt want to give up the supercharger, and i didnt want JUST a turbo cavalier...
but i did want a personal challenge that would result in something cool and unique.
that is when i mentioned twin charging as more of a "crazy idea" sorta thing... and then josh F chimmed in saying he did it... and loved it. and he is in canada, and did his on a sunfire... so i thought "hmmm i could be the first twincharged cavalier ever, and the first twincharged Jbody in the states"
so here i am... starts with a crazy idea... ends in something crazy but fun... and alot of sweat and money inbetween
It is definitely quite a unique project! I wonder if you might be able to contact a company such as turbonetics and tell them what your plans are and see what they might suggest. It's a fairly uncharted territory, twin-charging, so maybe they could help out. I have a feeling with the supercharger a typical compressor map will not be accurate for you :dunno:
Worth a shot anyway, looking forward to seeing how this comes out!
ok here ya go...
this is my VE table for my car as it was before the engine rebuild.
mind you this is SUPERCHARGED only... with a stock bottom end...
but you can see i am well over 100% efficiency in many areas.
the top is RPM, the right side is KPA boost pressure (100 is 0psi the 140 is about 7psi)
7 was the most boost i got out of my SC..... and when i did my VE tune, my redline was 6000, so 5800 is as high as it goes right now.
but i hope this will give you guys some indication of my engine and its needs as far as a turbo goes...
the figures in the table are actual VE values. so at 100% VE the engine is filled with 2.4L of air.
