Increasing boost pressure

[williams.2277]

Hi all, I was wondering if anyone has used some sort of boost controller to hold the wastegate closed until higher pressures? I have seen more then one place advertise a maximum pressure of 20psi but have also read from many others that the digital boost gauge in the dash rarely if ever shows more then 16 lbs. Many have said they were going to do it, or wanted to do it. I was just looking to see if anyone has actually done it yet, and if so, if they knew what kind of gains they got, and how much pressure they were able to run before detonation began.

[Barry]

I have seen 19lbs on mine.

[SKYGAZR]

I have seen 19 & 20 on hard pulls....

[lbsky]

Originally Posted by williams.2277

Hi all, I was wondering if anyone has used some sort of boost controller to hold the wastegate closed until higher pressures? I have seen more then one place advertise a maximum pressure of 20psi but have also read from many others that the digital boost gauge in the dash rarely if ever shows more then 16 lbs. Many have said they were going to do it, or wanted to do it. I was just looking to see if anyone has actually done it yet, and if so, if they knew what kind of gains they got, and how much pressure they were able to run before detonation began.

there are a couple of companies coming out with ECM's for the RL, this should help. I think I would try checking the boost with a "better" gauge first, and remember, conditions affect boost pressure also. I put a carb spring on my waste gate arm on my pt turbo to help hold the boost.

[Robotech]

Originally Posted by lbsky

there are a couple of companies coming out with ECM's for the RL, this should help. I think I would try checking the boost with a "better" gauge first, and remember, conditions affect boost pressure also. I put a carb spring on my waste gate arm on my pt turbo to help hold the boost.

I'm assuming that boost reading is coming right off the MAP. Since it runs off manifold pressure just as any boost gauge would I'm not sure why a "better" gauge would be...well..."better".

[williams.2277]

Some cars use the signal coming from the mass air flow sensor to guess at what the boost pressure must be. The computer is programmed to know what pressure produces given airflows a different engine conditions in stock form. When the engine is changed from stock and air can flow more easily, the gauge would read higher pressures then actual. If the Sky’s gauge is run off a MAP sensor then this shouldn’t be a problem and a new one wouldn’t really seem necessary as long as the MAP sensor has the range to accommodate increased pressures over 20 PSI.

[williams.2277]

This is content from the Q&A with Steve Padilla the engineer at the National Solstice Meet.

What is the boost pressure setting for the turbo? How easy will it be to alter it?
The boost pressure varies according to conditions, from 14 psi on cold days to as high as 18-20 psi on warmer days. The engine control software is very well integrated, very complicated, and it will be difficult to alter the tuning.

[lbsky]

Originally Posted by Robotech

I'm assuming that boost reading is coming right off the MAP. Since it runs off manifold pressure just as any boost gauge would I'm not sure why a "better" gauge would be...well..."better".

same reason you check BP or temperature when you have a reading you do not think is right. Verification. Once you have verified that the gauge is reading correctly then you can look in to other issues that may be the problem if there is one.

[YellowSky]

yalll are seeing 20psi?? mine wont go above 16@ all..

[Robotech]

Originally Posted by williams.2277

Some cars use the signal coming from the mass air flow sensor to guess at what the boost pressure must be. The computer is programmed to know what pressure produces given airflows a different engine conditions in stock form. When the engine is changed from stock and air can flow more easily, the gauge would read higher pressures then actual. If the Sky’s gauge is run off a MAP sensor then this shouldn’t be a problem and a new one wouldn’t really seem necessary as long as the MAP sensor has the range to accommodate increased pressures over 20 PSI.

Would be interesting to see where the information comes from. If it is a MAP sensor then it should be fine up to about 27lbs of boost. MAP sensors use "bars" to measure the pressure. Usually a One Bar MAP will just measure vacuum. This is what a NA car would normally use. A Two Bar Map will measure vacuum (first bar) and boost up to 14.7 lbs (second bar). This is the kind of MAP I have in my Grand Prix and it posses a problem when I put the new SC on. A three bar MAP will have one bar for vacuum, the second for boost up to 14.7 lbs, and a third bar for boost from 14.8 lbs up to about 27 lbs. So if the Sky is reading off the MAP it HAS to have a three bar MAP already installed to read any level above 14.7.

I would think that having a boost reading off the MAF would stink...ewww...but I can see where they may consider that. If you have a scan tool you can scan MAP to and see if it reads above 14.7 lbs (can't remember what that is in KpH (?) which is usually what the PCM reads MAP as...but I do have a formula to translate a pure voltage reading from a 3 bar MAP to KpH to PSI. )

[RPIpower]

I agree, I would put a good mechanical boost gauge (even if its just temporary) to see how accurate the stock one is. I believe there is an electronic pressure sensor on the driver side of the motor where the DIC gets the readings from. The RLs still run off a MAF instead of a map sensor so thats kinda sucky. Our dyno measures boost as well as intake air temp so if anyone is interested I would be happy to check actual boost levels for you. As far boost is concerned, I wouldnt push the turbo more than 18psi. Running more boost on the small factory turbo could cause premature wear on the turbo's components. You could also try changing the bypass valve. On the EVO 8s, we found the stock valve to leak at anything more than 1.2 bar. Guys are changing to aftermarket bovs and bypass valves with stiffer springs to hold that pressure consistant on the top end.