Went from 18-19psi to 25psi with no changes to the car, how the hell?

[MadrussianSVT]

I was replacing clutch for like a month so car was torn apart and battery disconnected. Finally got everything back together, and for the he'll of it took off my entire exhaust, so it's pretty much open down pipe. Besides that I did not do any other changes to the car itself or to the tune. Got on the road today and got on it in 2nd and 3rd, that bi*** spikes at 25psi now and stays around 23-24psi all the way till redline!!!! Car pulls much harder now and I love it but why the hell does it run 25psi now??? Does cool weather and open down pipe can gain another 7psi???? Another thing is that head studs are still oem and I'm afraid that with that much boost my head will start lifting off.

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[black91awdturbo]

What turbo is this, what do you have for fuel system etc? Yes running open DP will cause big boost spikes, it affects some turbos more than others.

 

[boosting_pwr]

You should turn it down for sure unless you have the supporting mods. My evo3 16g started to creep about 2psi once I installed a full 3" turbo back exhaust. Having an open exhaust could be a part of it.

 

[Boostinsideways]

Certain turbos will creep more on an open downpipe.

 

[MadrussianSVT]

What turbo is this, what do you have for fuel system etc? Yes running open DP will cause big boost spikes, it affects some turbos more than others.

It's a turbonetics 58 trim I believe, 3"down pipe, 255 walboro pump, 650cc injectors, Apexi SAFC and boost controller. and still, 7psi increase just from exhaust??? Crazy! I'm putting exhaust back on tomorrow.


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[JusMX141]

Finally got everything back together, and for the he'll of it took off my entire exhaust, so it's pretty much open down pipe.

That's a pretty significant change to me.

No backpressure = boost creep out the asshole on certain turbos.

 

[Vladimir]

im with the guy above me

 

[gsxeclipse97]

It seems that each turbo has a range it likes to be in where it no longer creeps. For example 14b likes 17psi I have not had mine creep past that, E316g, will creep 20-21 psi from 15.

Just from those examples, I know those are both relatively small turbos, but seem to find there way to where they are most comfortable. yours is likely doing the same thing. Knowing that turbos will creep maybe its best that we try to tune for where the turbo is most happiest on its map as a base line. and proceed on ward from that point.

 

[gusu]

Boost creep has to do with the port size of the turbo you are using and the size of your exhaust. If you port a 16g to match your exhaust you don't get creep.

 

[boosting_pwr]

My evo3 16g has an internal waste gate and I ported the hole a bit more and seemed to have helped me with controlling my boost.

 

[pj91gsx]

I have determine the main cause of boost creep is adding a 3" exhaust and not using a wastegate passage that will flow enough to keep up. If that is the case the air will be force threw the turbine because it cannot pass threw the Wastegate dump or stock o2 housing effiecient enough. I have cut the divider in o2 housings for 20g guys and they said it fixes the problem. Those guys went from o2 dumps to the ported stock o2 housing.

 

[spyder1219]

its a good thing you caught this before anything bad happened :/

 

[NOSLO2PT0]

Cold air = higher boost levels as well.

 

[JusMX141]

It seems that each turbo has a range it likes to be in where it no longer creeps. For example 14b likes 17psi I have not had mine creep past that, E316g, will creep 20-21 psi from 15.

14B's also have a smaller 6cm turbine housing which adds more restriction...making them less-prone to creep than 16G's using a 7cm turbine housing.

 

[syndr0me]

Cold air = higher boost levels as well.

?? ... A more dense charge, agreed. But more boost.. I don't know...

And who cares if the wastegate is fully open or not, bottom line is that it has to be less of a restriction. Air will take the path of less restriction just like many other things.

 

[95AWD6Bolt]

You state NO CHANGES but you took off your exhaust. THAT IS A CHANGE. There is your problem.

 

[MadrussianSVT]

Exhaust is back on the car, now it boosts at 20-21 psi, I guess cause of the temp drop I picked up 2-3 psi



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