Pump Gas@25 psi.

[VtecRex]

So, I was reading some threads here in the turbo section, and I was seeing that people are recommending bigger turbo's for pump gas applications. My question is: How is it that you can use pump gas on a FP Green@25 psi... but I have to use racegas for my 16g to safetly run 25 psi... Whats the theory behind this... is the 25 psi in a larger turbo different between the 25 psi in my turbo??

 

[Lunch_Box]

They are complete different trubos different wheel, housings, size and are made for different applications. Do you also wonder why you can run 30+ psi on a T4, GT35R, FP 3065... but not on a 16G or 14B?

 

[2gGSX]

It all comes down to efficiency.

 

[VtecRex]

I understand the fact that my 16 cant hit them high boost levels, i just simply isnt big enough to push that much air. I just want to know how is it save to run a FP Green (larger) turbo at 25psi on street gas, but yet it isnt save to run my 16g at 25psi on street gas?

 

[D@nno]

It all boils down to detonaton. It is the fact that the green wheel is more efficient than the 16g, which means it will be putting out much cooler air temps. The cooler the the intake charge the less fuel you will need. I was able to run more boost on a 57 trim than my 16g before hitting detonation.

 

[TurboDSMer]

You can run 25psi on pump on an FPGreen!

 

[definitiveno]

all turbo's have their limits......for a 16g 25 psi is all that little sucker can handle.... for the green it is more like 31psi.....


that can vary with displacement and RPM though....

 

[pickens]

Two reasons:

A.) Compressor efficiency.

And B.) More importantly, exhaust manifold pressure. Smaller turbos generate more manifold pressure than larger turbos to make 25 psi. High exhaust manifold pressure leads to more knock. Hence, why things like race gas is needed for a 16g equipped motor to be happy at 25 psi.

 

[TurboDSMer]

I have a question then. On www.roadraceengineering.com if you go under thier injector section i think it talks about what is need in order to run so much psi. when you get to about the 25psi it says you need 660cc injectors in order to run that much psi. It says the larger the injector you run the more boost you can run on crappier gas, so does that mean since i am going to be running 720cc injectors on 93 octane with an evo16g i can run 25psi?

 

[NOSLO2PT0]

The 16G turbo heats up the air so much trying to achieve 25psi, that 93 octane isn't able to keep detonation at bay. The mixture is so hot, that it pre-ignites before the spark plug does. That's why fmic's help you run a little more boost. It cools off the intake charge.

A 50 trim comp. wheel is very efficient at moving large amts. of air without heating it up too much. That's what allows you to run higher boost on pump with that turbo. Now, take something even bigger. You can run less boost with a bigger turbo, and still make the same power. You are flowing the same amt. of air, just at a lower boost level, due to comp. wheel size. The comp. wheel isn't working as hard, so it doens't heat up the air as much.

 

[TurboDSMer]

What would you say is the most on pump that you should run the EVO16g at then?

 

[nine5raptor]

It depends on your pressurized air cooling system, ignition timing advance, amount of excess fuel in the combustion chambers, ignition system strength, carbon buildup/heat risers, and other things.

There really is no way to just say: XX psi.

I run 21 psi w/ a 14b on 92 octane with a small fmic and water injection. No knock. This might not be the case for another.

You need to log the car and slowly raise the boost while keeping detonation under control.

 

[oldman]

http://www.streetrodstuff.com/Articles/Engine/Detonation/index.php

Read throught that, it should help you understand what every one is trying to tell you.

 

[flinguist]

Aren't you taking a chance of lifting the head at 25 pounds of boost with stock headbolts?

 

[NOSLO2PT0]

Aren't you taking a chance of lifting the head at 25 pounds of boost with stock headbolts?

Only if you are detonating. Stock head bolts on a 6 bolt can and have done 35psi. Detonation is your enemy.

 

[pickens]

25 psi will not lift a head if you are not making much power. Cylinder pressure is what lifts heads not boost pressure per say. Also, you can run as much boost as want w/ larger injectors (i.e. 720cc). However, the catch is...you'll need to fight detonation so hard that you'll need to supply waaay more fuel than needed to keep knock away, and in doing so you'll end up running super rich and making dismal power increases (if any) over a lower boost settting. Here's a quick break down on what I know from experience:

T-25: Max 15 psi (boost falls anyway so no sense in setting it higher)

14B: Max 19 psi ( good intercooling and fuel required)

Small 16g: Max 21ish psi (good intercooling and fuel required)

This is w/ 91 pump and conservative timing.

 

[VtecRex]

NOSLO2PT0:

You are the main reason I started this thread, thanks for all the help too, you definatly cleared up my question.

I understand detonation and all, plus I am still running a SMIC. So, I guess that answers my questions... Ill get a EGT gauge and see whats up, just out of curiosity. On a side note, after running kinda hard... when I got out, the oil line on my turbo was smoking I defintaly need a fmic, So, my setup is in my profile, and my next question might not be answerable, but:

Say I was going to get a Extreme Psi Street FMIC (thats the one I want), A) how much more boost would I be able to run on pump gas? B) Also, would a race FMIC make that much of a difference, I really dont want to have to mod the visual's of my bumper... the supports are already gone, C) So would I be able to run a race FMIC without cutting the bumper cover away?

Thanks for all of the help, and sorry for the stupid questions.

 

[NOSLO2PT0]

I understand detonation and all, plus I am still running a SMIC. So, I guess that answers my questions... Ill get a EGT gauge and see whats up, just out of curiosity. On a side note, after running kinda hard... when I got out, the oil line on my turbo was smoking I defintaly need a fmic, So, my setup is in my profile, and my next question might not be answerable, but:

I wouldn't say an EGT is a necessity. Lots of people swear by them. However, I don't. That's one more gauge I don't have time to look at. I simply tuned via datalogger, watching timing/knock. Only two factors that concerned me. Now, I concentrate on the wideband as well, since I added one. The smoking oil line is probably due to a leaky crush washer or something.

Say I was going to get a Extreme Psi Street FMIC (thats the one I want), A) how much more boost would I be able to run on pump gas? B) Also, would a race FMIC make that much of a difference, I really dont want to have to mod the visual's of my bumper... the supports are already gone, C) So would I be able to run a race FMIC without cutting the bumper cover away?

Thanks for all of the help, and sorry for the stupid questions.

Each FMIC core is diff. and has diff. cooling properties. I don't know what core they use, or how efficient it or your turbo is. A smaller turbo will not allow you to run big boost #'s on pump gas alone, even with a very good fmic. As for that "race" fmic, it all depends on what core you use and what endtanks are on it. Shouldn't be a lot of cutting on the plastic bumper cover. Very minimal at most.

 

[shleppy]

I've been running 24 psi all this winter(last 5 months) on 93 pump with the evo3 turbo, 650's, tuning with dsmlink and just the big greddy frontmount without any knock or retard at all. So far in the midrange I have to run a little rich, and still can have my timing advanced around 3 degrees for increased power(still tuning). My egt's never get past 1600 even on a long highway pull to 8000 in third gear. I also have made my own cold air kit which I'm sure helps some, but even with all that I'm sure I would have to turn down the boost some as outdoor temps heat up this summer. I hope this gives you a general idea of what the evo 3 can do with a frontmount. Get that front mount and see what you can do

 

[NOSLO2PT0]

So far in the midrange I have to run a little rich, and still can have my timing advanced around 3 degrees for increased power(still tuning).

I'm curious as to how much power you are making with that little timing advance. The LOWEST advance I see at 25psi is 15 deg, for a total of 20 deg. advance. Having only 8 deg. total advance, I can't see the car making much power. Sure, you are running 24psi on pump gas with that turbo, but your advance is so small, i really wonder if you are actually making power that high up. Look at your airflow, then drop the boost and add in some timing. See if your #s go up.

 

[nine5raptor]

I think shleppy meant an additional 3 degrees (via dsmlink) on top of the 17 or so.

Shleppy-- What is the total advance you are seeing?

 

[shleppy]

I never saw less than 18 degees total either, Thats actually +3 on top of the normal advance the ecu gave me when I datalogged it, although I havent logged it for months to see if I'm losing any timing with the warmer weather(Its my friends laptop). I guess the combination is working well. I was also getting over 40 lbs of air this winter when the air was real cold, but I don't know what I'm getting now. The most timing total I would see would be 21-23 degrees. I figured add timing to make power and run it rich(10.1 approx) to supress knock

 

[NOSLO2PT0]

I think shleppy meant an additional 3 degrees (via dsmlink) on top of the 17 or so.

Shleppy-- What is the total advance you are seeing?

Where did he mention 17 deg. of timing?

 

[NOSLO2PT0]

Hmm...maybe I should just order DSMLink and run 30psi on pump gas. See if I can make some good #'s or run lo 11's on 93 octane! That would ROOL! Damn DSMLink gets more and more enticing each day. C'mon lottery!!

 

[shleppy]

Its more doing logging runs at night in the winter when its 25 degrees out than the dsm link.