running without a tune
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yuhtinkyuhslick
Spectator
7psi on a t25 is not the same as 7psi on a larger frame turbo. The larger will push more volume of air (CFMs). But you should be fine if you install the larger turbo as long as you stay out of boost until you get the rest of your setup installed and tuned. Don't change your injectors or maf because you will need a tune.
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crayZwhiteboy
Spectator
A turbo engine is a pressurized system.the larger turbo CAN push more air because it can boost higher but as a pressurized system your boost psi measures how much air is going into your engine.
Maybe I'm being an uneducated devils advocate but the quick research I've done supports my theory.
At the same psi a small turbo and big turbo push the same amount of air into the engine. The bigger turbo is just at a lower capacity.
Someone prove me wrong I'm trying to learn just like the op and ill delete these posts if I'm wrong.
Maybe I'm being an uneducated devils advocate but the quick research I've done supports my theory.
At the same psi a small turbo and big turbo push the same amount of air into the engine. The bigger turbo is just at a lower capacity.
Someone prove me wrong I'm trying to learn just like the op and ill delete these posts if I'm wrong.
BiG MiKE
Driver
Fixed
---------- Post added at 01:10 PM ---------- Previous post was at 01:09 PM ----------
My ass dyno cant be wrong
crayZwhiteboy
Spectator
You always help me out big mike.
crayZwhiteboy
Spectator
No need for the attitude there buddy. Op was asking for info. I'm am as well.
If what your saying is true I'm fucked cuz my t25 was seized so I got an s15 t28 bb on and I didn't get shit tuned and I run it hard all day everyday for my job. About 100 hard miles a day.
Is what I'm doing wrong and should I never go into boost?
Again, asking for information. Give an attitude just to sound hard over the internet won't make anyone understand.
crayZwhiteboy
Spectator
Lol...stock....no boost controller
BiG MiKE
Driver
S15 Turbo is about the same as a T25 as far as CFM is concerned... Sure it runs... but do you know if your running lean? Got a wideband? Be careful pushing it too hard without proper tune and fuel is all Im saying
crayZwhiteboy
Spectator
Black bumper says rich. Following behind my vehicle running hard after each quick shift a little puff of black also puffs out which also says a little rich. No wideband that's not my first priority. But I run the car hard.
So your saying I need a tune also? You usually have good advice and help so I take what you say with much respect.
So your saying I need a tune also? You usually have good advice and help so I take what you say with much respect.
yuhtinkyuhslick
Spectator
Just check out your spark plugs and look for any signs of detonation. Remember, the SR uses a maf sensor so it will adjust to the increased volume of air to a certain extent.
The s15 is not that much bigger than the t25. Putting on a t3/t4(much larger frame) for a car that is tuned for a little t25 isn't safe. That's why running it hard will definitely lean out the motor and most likely blow the headgasket.
crayZwhiteboy
Spectator
Thank you.
BiG MiKE
Driver
Id recommend a tune with atleast an SAFC II but thats just me. Like someone mentioned yes the car will try and compensate for the increased air/boost but only to a certain extent
booster seat
Spectator
I have a metal head gasket.. listen to what i am saying. MY CAR SMOKES DUE TO T25 HAVNG BAD SEAL. I CANT AFFORD THE TUNE yet. I NEED TO PUT IN NEW TURBO MEANWHILE TO STOP SMOKING.
I am asking if i put in the turbo (36 cfm) and run low low boost like 3 or 4 pounds, will it be ok for like a month till i can finish the set up?
I am not planning on even getting on the gas and letting it spool. I just need to get rid of the smoking issue because i have been pulled over for the same problem in my old s14.
I am asking if i put in the turbo (36 cfm) and run low low boost like 3 or 4 pounds, will it be ok for like a month till i can finish the set up?
I am not planning on even getting on the gas and letting it spool. I just need to get rid of the smoking issue because i have been pulled over for the same problem in my old s14.
booster seat
Spectator
i know but that was directed towards all the others that cant read lol sorry
^i beg to differ.
psi is the measurement of pressure
cfm is the measurement of flow, albeit volumetric flow.
nothing flows without pressure differentials. basic thermodynamics. more specifically, given the same restriction(ie valve lift), the flow value is solely related to the pressure difference before and after the valves. the greater the difference, the greater the flow. so psi does have something to do with cfm.
^i almost completely agree with you crzywhiteboi. you've done your research and your intuition does not entirely fail you. i was in the same position a year or two ago right here on this same forum. you've got theory and they've got experience. but so far you've been unable to marry your theory with their experience. and i hope i can clear it up for you.
7psi is 7psi of inlet pressure regardless of the size of the inducer. but you only have enough to tell half of the story of our lead character: mr. flow. as you've probably have already begun to realize mr. flow is a total couch potato. he doesnt move his lazy ass unless he is being pushed AND pulled. so if pressure was equal on either side of the valve then no flow occurs. i think we can all agree that there exists a strong positive correlation between the amount of flow and the power made. their experience says 7psi of a small turbo doesnt make the same power as 7psi of a comparably larger turbo even though inlet pressures are the same. now you may be thinking, how can this be true? well given what we know about mr. flow this could only lead us to conclude that, with the smaller turbo, there is greater preexisting pressure in the chamber on the intake stroke. using further reasoning it is safe to assume that on the exhaust stroke the engine was not able to evacuate as much air. right about now a light bulb should be going on in your head and its easy to see(given the same inlet pressure) that the decreased power output is caused by the greater back pressure of the smaller exducer housing thus reducing flow/power.
and in this succinct thought experiment i firmly believe i've wed your theory with their experience. you may now kiss the bride.
If any person here can show cause why these two should not be joined in holy matrimony, speak now or forever hold your peace.
so you see, you are not completely wrong, and they are not completely right.
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booster seat
Spectator
^i beg to differ.
psi is the measurement of pressure
cfm is the measurement of flow, albeit volumetric flow.
nothing flows without pressure differentials. basic thermodynamics. more specifically, given the same restriction(ie valve lift), the flow value is solely related to the pressure difference before and after the valves. the greater the difference, the greater the flow. so psi does have something to do with cfm.
^i almost completely agree with you crzywhiteboi. you've done your research and your intuition does not entirely fail you. i was in the same position a year or two ago right here on this same forum. you've got theory and they've got experience. but so far you've been unable to marry your theory with their experience. and i hope i can clear it up for you.
7psi is 7psi of inlet pressure regardless of the size of the inducer. but you only have enough to tell half of the story of our lead character: mr. flow. as you've probably have already begun to realize mr. flow is a total couch potato. he doesnt move his lazy ass unless he is being pushed AND pulled. so if pressure was equal on either side of the valve then no flow occurs. i think we can all agree that there exists a strong positive correlation between the amount of flow and the power made. their experience says 7psi of a small turbo doesnt make the same power as 7psi of a comparably larger turbo even though inlet pressures are the same. now you may be thinking, how can this be true? well given what we know about mr. flow this could only lead us to conclude that, with the smaller turbo, there is greater preexisting pressure in the chamber on the intake stroke. using further reasoning it is safe to assume that on the exhaust stroke the engine was not able to evacuate as much air. right about now a light bulb should be going on in your head and its easy to see(given the same inlet pressure) that the decreased power output is caused by the greater back pressure of the smaller exducer housing thus reducing flow/power.
and in this succinct thought experiment i firmly believe i've wed your theory with their experience. you may now kiss the bride.
If any person here can show cause why these two should not be joined in holy matrimony, speak now or forever hold your peace.
so you see, you are not completely wrong, and they are not completely right.
well then.. know we know