Turbo reference material

[KryptoSol]

http://www.mygen.com/users/dbruce/myz31/TurboMaps/L28ET%20Engine%20Air%20Flow%20and%20Turbo%20Compre ssor%20Maps.htm

I think this is worthy of a sticky!

[rrussell]

Nice find!!!

It would make a nice Sticky

[BlackMagic]

done

[thursday]

very nice, didn't understand the maps until now, that made it very simple. Or so I think, I made a quick graph of my turbo matched with my engine.

http://www.hybridka.com/misc/joeavatar/myenginemap.JPG

i was drinkin a couple beers while making it so let me know what you guys think.

Also, there is one value that isn't discussed much on that page, and that is Ev, which I assume to be volumetric efficiency? I used .85 in all my equations, but I wonder how compression ratio affects it? It has to affect it somewhat correct?


great thread guys

[KryptoSol]

looks good Joe!

Maybe one of the other guys can chime in, but wouldn't our turbo Hondas have a ve of maybe something closer to .90 or .95??

The t04e 50trim compressor maps check out soo killer...

[thursday]

yeah, i was pretty sure my ve was on the conservative side.

although, the y7 head probably isn't the best for flow either.

[KryptoSol]

whats interesting is that according to my calculations the 50trim is even still more efficient than the 57trim at my current 2.8 Pressure Ratio, and 37.14lbs/min.

But it seems real world testing says otherwise... either that or its possible that the stock z6 intake manifold and other stuff is choking it up.


**i used a .90 ve.

[BlackMagic]

Technically, the turbocharger increases VE beyond 100%, but for some reason all turbocharger calculations I have seen still use a VE less than 100%.

Typical 4 valve pent-roof combustion style cylinder heads have a VE range from 0.95-0.99 according to www.turbobygarrett.com

[thursday]

well it is really interesting to see that CFM is directly related to horsepower. While reading this thread i came across some other good writeups, here is one:

http://www.rbracing-rsr.com/turbotech.html

So in the equation for airflow, or CFM : (Cid X RPM X 0.5 X Ev) / 1728

the only true variable that separates a stock engine from a modified engine is the volumetric efficiency value, you guys are saying most likely an import engine with a modern-style combustion chamber will produce near 100 percent efficiency, well this number must be changed when changing compression ratio and cams and such correct? These types of modifications increase the horsepower so they must increase cfm right?

basically i'm just making sure i'm on the right track thinking CFM is directly related to horsepower.

[BlackMagic]

The more air you can get into an engine the more power you can make, so yes, airflow is directly related to horsepower.

As far as VE goes, we had a very good discussion going on the old website. Peak VE for a modern naturally aspirated 4 valve engine will be around 80-90%. Also, take note that we talk about peak VE. This value will only be achieved at one point throughout the powerband corresponding to the peak torque value. This value may change slightly with modifications, however, it is more likely that upgrades such as cams and valves will yield higher VE values at RPM ranges other than that which peak VE occurs. Changes in VE can have dramatic affect on power.

To answer your question, changing cams and valves can increase VE by allowing the engine to ingest more air at various RPMs. Compression ratio doesn't directly affect VE. It increases combustion efficiency which creates more power from the aif/fuel mix you already have in the engine.

[thursday]

thanks for the reply blackmagic, very good info

now one more question:

c/r doesn't change ve, but it must change the cfm of the engine throughout the rev range correct?

[BlackMagic]

Thinking about it some more I guess you could make an argument that CR changes the overall displacement of the engine, which in turn affect the VE, but it would be a very small change...on the order of +/- 13 or 14 cc at most, and thus could be considered negligible.**

So, engine volume remains constant (with the exception of a few CC's in the chamber) regardless of the CR of an engine.**The only way to increase engine volume is larger bore, or longer stroke.**There really is no "cfm" for an engine, cfm is simply a volumetric flow rate of air ingested into the engine.**To change the flow rate of the engine, you would have to make modifications that would allow more air into the cyinders (cams, valves, turbo, etc), but compression ratio does not have an substantial affect on the amount of air ingested by the engine.

[thursday]

well, my future future plans are a 400 whp d, so i am going to be comparing compressor maps a lot more now, so i can buy a sweet ramhorn and a big honkin t3/t4 or something the y7 :)

once again, great thread.

[KryptoSol]

well, my future future plans are a 400 whp d, so i am going to be comparing compressor maps a lot more now, so i can buy a sweet ramhorn and a big honkin t3/t4 or something the y7 :)

once again, great thread.


Joe,

Mapout the 50trim and gt32, They looks super duper sweet!!
also don't forget to get those t-clamps, 500 oz/inch of clamping powa.

[boost_addict]

The best info on turbocharging I've found to date is a book by Corky Bell entitled, "Maximum Boost."

You can find it at Barnes and Noble or Borders pretty easy, and its fairly cheap.

[lostkuase]

"volumetric effeciency" is this airflow loss values? relating towards airflow in / out? is this also why our (4 cyl) valve size in/out are different? i know on alot of n/a v8's ive seen same size valves used, with the degree varying? Is this true? im curious due to the fact ive opened my airways more with mild gasket matched porting, and 1mm oversized valves, would it be better to match my exhaust valves more closer based off my intake? as my stock intake valves being larger than stock exhaust?-- obviously im still new, but i hope my questions are still understandable?
Thanks

[BlackMagic]

VE is the actual air intake of the engine/theoretical intake of the engine. It is a measure of how much air can actually be pulled into the cylinders and is directly related to the torque curve of the engine.

As I understand, I believe the exhaust valves (and ports) are smaller to maintain velocity of the exhaust gas as it leaves the engine. Also, the pressure differential across the exhaust opening is MUCH greater on the exhaust stroke than it would be on the intake stroke. This would mean the same amount of air(fuel/air mix) can escape out of a smaller opening in the same amount of time.

Someone else can chime in if they want...its been a while since I have been into my engine theory books.

[domesticated]

well id figure id chime in here. a turbo will raise the Ev to about 85-90% not make it go over 100% engines actually have very poor Ve's actually. i ran some testing early this summer on a few cars and thats why som much more power can be made N/A with cams and bolts on etc. heres a list of the cars i did.
Bone Stock 08 Hyundai tiburon Ev=53%
Bone Stock 07 Hyundai Tiburon GT Ev=66%
Full bolt on 98 Neon R/T Ev=78%
Intake/Exhaust 02 Mustang GT Ev=64%
Bone Stock Toyota Tundra 4.7 Iforce Ev=65%
Point being is most stockish cars have poor Ev. A turbo will raise the Ev because its using more of the engines power to force air down the intake, but the reason it doesnt increase Ev is because your raising the density of the air (CID x Ev x 0.5 x RPM)/1728 only applies to an N/A engine then you multiply the CFM by the bars. ill post a write up i did on my other forum about this, i couldnt find the link in the OP so heres mine.

[domesticated]

i guess i need more than 15 posts before i can link urls so ill get around to it later those from NWTuner know its info worth lookin at

[Jetblack]

PM me the link and I'll post it Jon.

[98Z28]

I ran across some easy to use calculators. Thought someone might need to use them.
Nitrous Express Next Generation Nitrous Oxide Systems (http://www.nitrousexpress.com/calculator.php)

[Jetblack]

well id figure id chime in here. a turbo will raise the Ev to about 85-90% not make it go over 100% engines actually have very poor Ve's actually. i ran some testing early this summer on a few cars and thats why som much more power can be made N/A with cams and bolts on etc. heres a list of the cars i did.
Bone Stock 08 Hyundai tiburon Ev=53%
Bone Stock 07 Hyundai Tiburon GT Ev=66%
Full bolt on 98 Neon R/T Ev=78%
Intake/Exhaust 02 Mustang GT Ev=64%
Bone Stock Toyota Tundra 4.7 Iforce Ev=65%
Point being is most stockish cars have poor Ev. A turbo will raise the Ev because its using more of the engines power to force air down the intake, but the reason it doesnt increase Ev is because your raising the density of the air (CID x Ev x 0.5 x RPM)/1728 only applies to an N/A engine then you multiply the CFM by the bars. ill post a write up i did on my other forum about this, i couldnt find the link in the OP so heres mine.

Here're the links that would have gone in that post.

Get to Know Your Turbo! - NWTuner.com - Northwest Tuner Community (http://www.nwtuner.com/forum/showthread.php?t=1813)

Know Your Injectors! - NWTuner.com - Northwest Tuner Community (http://www.nwtuner.com/forum/showthread.php?t=2033)

[lostkuase]

okay... so say my turbo starts to spool, i have a gt4294r for example with a 2.2. liter. my valves are "stock size".


~bare with me here~

the turbo is pushing air through the intercooler to the throttlebody than into the runners of the intake where depending on where the motor is sitting is than pushed either against a closed valve or opened. i believe ve is more related to valves than anything. because i consider the whole piping/intake mani to be a big chamber. the second a intake valve opens, theres the shotgun effect of air being "pushed" & "pulled".

so everything is dependent on how much air is "allowed" in by the valve size right?

so smaller valves make velocity as discussed earlier as larger valves do what? because i believe the larger valves will "allow" that much more air in. However i do not believe it would be as effiecent on a n/a car rather than one with a supercharger or turbo (another air pump shoving air into the chamber.)


granted lift and duration come into play on this idea as well. because how long the valve stays open blahblahblah.

so would ve be better on Larger valves for my setup or smaller?

if airflow is directly related to power which i believe it is...