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Boosting Stock Turbo

SKYLINE SAMOA
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SKYLINE SAMOA Apprentice

SKYLINE SAMOA

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:ninja: Hi All,

Just boosted my stock turbo on a R34 RB25 DET with neo head, stock boost was around 7-8 psi, after installing a turbosmart boost T we have boosted pressure to 14 - 15psi, say 14psi. The problem we are having now is that on full stick the engine rpm winds to 5000 rpm, pauses for a while then winds out to 7000 rpm nicely. Any idea what might be causing this slight pause at 5k under hard , full acceleration??

The problem seem to be possibly heat related as on the 1st run it seems find but on the 2nd , 3rd and 4th run the problem occurs, possibly the timing adv., sorry no dyno in Samoa

Help apprecaited.

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snozzle Mentor

snozzle

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u need to get the car tuned, the revs will develop alot more smoothly and flat spots will be gone

does the boost stay 14psi across the whole rev range? no spiking?

wind the boost down to 10psi, u wont make much more power on anything more than this unless its tuned

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mad082 Grand Master

mad082

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there is a good chance you are getting close to, or hitting the ecu airflow protection. there are only 2 solutions to this. 1 is cheap, the other expensive. the cheap one is actually free. simply wind the boost down to 12 or 13psi. the other option is a new ecu.

the other thing is that (from what i am aware) the stock mapping of the r34 ecu's is somewhat.... what is the word i'm looking for here..... conservative through that part of the rev range.

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Hanaldo Grand Master

Hanaldo

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Are you telling me that more boost is not better?!?! :D

A car with 15psi will always beat a car with 10psi... :):D

Is that a serious comment lol? Because if so, i suggest you read this thread: http://www.skylinesaustralia.com/forums/Cl...on-t321471.html

Contrary to popular belief, psi does not equal power... Volume equals power

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The_AU_Viper Apprentice

The_AU_Viper

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as has been mentioned

R&R is being hit

Ohh and at that boost you will destory the turbo prettty quickly.

I got my nistune done at the same time as upping the boost. 11-12psi is plenty enough for the stock turbo, and on the neo motor should make over 200rwkw without too much trouble assuming proper supporting mods.

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mad082 Grand Master

mad082

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Is that a serious comment lol? Because if so, i suggest you read this thread: http://www.skylinesaustralia.com/forums/Cl...on-t321471.html

Contrary to popular belief, psi does not equal power... Volume equals power

it does to a large extent when talking about altering the boost on 1 turbo, but not if changing between 2 different sizes. on the stock turbo between 10psi and 14psi there is probably a 20 or 25kw difference in power. i know from what i have personally seen on a dyno with back to back runs the stock r33 turbo will make around 20kw more at 16psi than it does at 12psi. if it wasn't for the ceramic exhaust wheels on the skyline turbos everyone would be running them at 15psi, and there wouldn't be this mass of incorrect information about where the stock turbo runs out of power. people don't run them at 15psi because they are fragile (and because the stock ecu chucks the shits), not because they won't make any more power.

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Hanaldo Grand Master

Hanaldo

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it does to a large extent when talking about altering the boost on 1 turbo, but not if changing between 2 different sizes. on the stock turbo between 10psi and 14psi there is probably a 20 or 25kw difference in power. i know from what i have personally seen on a dyno with back to back runs the stock r33 turbo will make around 20kw more at 16psi than it does at 12psi. if it wasn't for the ceramic exhaust wheels on the skyline turbos everyone would be running them at 15psi, and there wouldn't be this mass of incorrect information about where the stock turbo runs out of power. people don't run them at 15psi because they are fragile (and because the stock ecu chucks the shits), not because they won't make any more power.

Ok let me rephrase that, psi is not the only thing to consider when making power. They may still be making power by 15psi, but run a stock turbo at 40psi and see how much more power you are creating. They simply don't flow enough. Flow is starting to run out by 14psi, and you won't see as much of a power increase anymore, which is why it is not worth the risk of blowing your turbo. The increase of power from 7psi to 10psi is greater than the increase of power from 14psi to 17psi. If psi is what produced power, then even a stock turbo run at 40psi should be making insane power, even if it blows up in the process.

Don't get me wrong, psi does obviously have something to do with power output, i'm just saying that it isn't the only thing to take into account. A car run at 15psi will not necessarily beat a car running 10psi.

Edited by Hanaldo
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3LGODZILA Proficient

3LGODZILA

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Ok let me rephrase that, psi is not the only thing to consider when making power. They may still be making power by 15psi, but run a stock turbo at 40psi and see how much more power you are creating. They simply don't flow enough. Flow is starting to run out by 14psi, and you won't see as much of a power increase anymore, which is why it is not worth the risk of blowing your turbo. The increase of power from 7psi to 10psi is greater than the increase of power from 14psi to 17psi. If psi is what produced power, then even a stock turbo run at 40psi should be making insane power, even if it blows up in the process.

Don't get me wrong, psi does obviously have something to do with power output, i'm just saying that it isn't the only thing to take into account. A car run at 15psi will not necessarily beat a car running 10psi.

you've either got it wrong yourself or you've just worded it wrong.

-a standard turbo wont run out of flow at 14psi

-id argue ur statement of 7-10psi making more of an increase in power then 14-17psi on a standard turbo giving in mind that the ecu isnt hitting R&R and the turbo doesnt blow. dont know exacly but id say the gains would be very similar.

-same 2 cars, same 2 turbos and setups. more psi = more power unless its already running out of puff then u further increase the boost which i dont think anyone would do anyways (not a 5psi increase anyway)

-u say a car @ 15psi wont beat a car @ 10psi, if they're identicle and not hitting boost cut or anything then it will. if its a different turbo then its a different story. 12 psi out of a standard turbo isnt the same as 12psi out of a 3076.

to the OP. wind the boost down. yes your car will run better at around 10psi rather then 15psi and u wont be hitting R&R

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Hanaldo Grand Master

Hanaldo

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you've either got it wrong yourself or you've just worded it wrong.

-a standard turbo wont run out of flow at 14psi

-id argue ur statement of 7-10psi making more of an increase in power then 14-17psi on a standard turbo giving in mind that the ecu isnt hitting R&R and the turbo doesnt blow. dont know exacly but id say the gains would be very similar.

-same 2 cars, same 2 turbos and setups. more psi = more power unless its already running out of puff then u further increase the boost which i dont think anyone would do anyways (not a 5psi increase anyway)

-u say a car @ 15psi wont beat a car @ 10psi, if they're identicle and not hitting boost cut or anything then it will. if its a different turbo then its a different story. 12 psi out of a standard turbo isnt the same as 12psi out of a 3076.

to the OP. wind the boost down. yes your car will run better at around 10psi rather then 15psi and u wont be hitting R&R

May have worded it wrong. I don't know the exact figure a stock turbo runs out of puff, but it does run out is what i am saying. Which is what i mean when i say psi is not everything you need to take into account. I didn't say anything about the exact same setups. Of course if the cars are identical then psi is going to make a difference, but that is because the turbos flow the same as well. Psi is psi, doesn't matter what turbo is making it. But 1L of air compared to 2L of air is different.

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