whats the truth with the bleeding boost on our stock s5 turbos? we all know they bleed boost badly, BUT i have been reading recently that several people have installed many types of electronic boost controllers and FIXED the bleeding boost... now this doesnt make sense in my head because i KNOW the stock turbo compressor is not aggressive enough to push over 4-5psi above 6000 rpms. how could this be possible?

to those with electronic boost controllers: did the install of the EBC 'fix' your stock turbo boost bleeding problem?
i wish i could just borrow a solenoid boost controller just to see if this is really just a myth.

 

I wouldn't think that an ebc would fix the problem. Only something like a hybrid would fix it. Maybe it might get you higher boost in the midrange not tapering off as much in the higher rpm's because the turbo is spooled faster. I don't know just a guess

 

yes. thats why i made this post. because some people say that it fixes the problem but it doesnt make sense.

 

Theyre lying. Come over here and lets finish my install.

 

My S4 bleeds down to 8lbs by redline, peaking @ 13. I'm telling you, a good electronic boost controller will HOLD the pre-set boost level as long as it's above what the wastegate puts out on it's own. This is one of the main benefits over a manual controller. The stepper motor on an EBC should keep pressure on the wastegate and prevent it from closing. At SOME point it will bleed boost, but we're talking boost levels that you guys won't run with a stock turbo. An EBC should be able to hold 1 bar of boost on the stock FC turbos.

Any other EBC users that canverify this? My profec B spec II isnt in yet(need larger wastegate port, still creeping) but I'm sure it will hold 12 psi once it's in.

 

so you're speaking without any experience here....

 

anyone? anyone?

 

I was running an HKS evc with the stock turbo, and adding the boost controller did not hold boost much longer at all. I think it still bled off to 7-8 by redline, and thats with a turboback and 3" tid. Just having an EBC will NOT allow you to hold boost until redline, it will still start dropping after 5500-6000.

 

True story.


Just think about it Jacob. How could it make you hold boost til redline?

 

They're turbo rx7s, they bleed boost. DUH

 

The S5 electronic boost control system is programmed to lower boost towards redline. This is quite normal for factory electronic boost control. The point is to run higher boost in the mid-range to inprove driveability and response, and to use less boost at high rpm to avoid detonation, high temps, driveline stress, etc.

If you want to hold a certain amount of boost right through the rev range, an aftermarket EBC is best because their simple programming just tries to maintain a fixed amount of boost. But this doesn't necessarily mean you can get more that the turbo is capable of.

Most people don't understand that the "boost" we see on the gauge is simply a measure of high much harder the turbo is blowing compared to how hard the engine is sucking. As the turbo's compressor reaches its limit, it can't keep up with the increasing airflow demand of the engine, so boost drops. It doesn't necessarily mean something is wrong, it just means you're asking too much from the turbo . Intake and exhaust restrictions and undersized turbos will also cause boost to drop at high revs.