Over boosting

[hicks]

surely there got to be a cheaper way. maybe add a restrictor ring. my downpipe came with one but i havent fitted it yet. will see what hapens once i have sorted out clearence of wastegate round exhaust flange.

[Al-sw20]

Tried an EBC? I have a 3" aussie dp, 3" mandrel bent exhaust with single 3" inlet muffler, ct20b and get 0 overboost, boost control using a greddy profec b.

[mr2haz]

My next mod is going to be and ebc anyway, hope this will do the trick.

[mr2haz]

Since deciding the decat was the likely cause of the mister over boosting I replaced the decat pipe with the gutted cat that was fitted before which I had no over boosting problem with.

Even though i have replaced this the car is still over boosting, going upto 1.2 bar. and i now have two gauges in the car which are both measuring the same amount of boost.

Please help someone

[Century Motorsport]

I have had a de cat & mongoose for a while now and everything was fine until a couple of weeks ago. It is now overboosting like mad. I have wound the grainger valve out as far as it will go but it still is making no difference!!

I have now purchased an uprated actuator to see if that cures the problem - i will keep you posted!!!

Nathan

[Rambo73]

DUMB QUESTION OF THE DAY

How do you know when you're overboosting? ie symptoms.
I have Apexi induction, 3 inch downpipe and HKS exhaust, yes the boost has gone up a couple of psi but is that a bad thing? More boost = more power doesn't it or am I missing something?

[hicks]

overboosting is when your creating more boost than you want. i was overboosting because i dont feel its safe for my engine to run more than 1bar with the standard intercooler and was hitting fuel cut at an idicated 1.2bar.

[THE DUKE]

Oh the subject of crap downpipes....

My cars boost is very laggy! full kick is about 3750,4000 rpm!!

I have been told that the fact i have a "crap" downpipe might hinder the wastegate from opening fully..

The car was fine until i changed the downpipe and turbo (CT20B stage 3)
Its either the fact that the turbo exhaust wheel is too big and takes a long time to spool or something like the wastegate.. any ideas??

Cheers!

[[SiG]]

Is your car mapped Duke? If not that'll help a LOT with your turbo

[THE DUKE]

Nah it's a lowly rev1!!

Im guessing mapping would be the best route, in fact i have today emailed thor about this.

Going to play with the actuator tomorrow see if its getting stuck

I must say tho at 4k rpm i get an almighty kick and me thinks the old injectors might be maxing, its got a 1bar actuator on it! So with a bit of over boost and the fact that its a 20b not a 26 im getting pushed to the redline very quickly. It feels as if it wants to go through the redline..

I dunno!! Its a one off turbo rated at 370-380bhp....

[The Morris]

the downpipe shouldnt make the boost come on later, it it was affecting the wastegate it wiuld increase boost.

you wont be maxing your injectors at 1 bar.

Was your turbo new or did you buy it 2nd hand

[THE DUKE]

It was second hand, good condition, i have had it tested and its ok.

When driving it i can hear it spool from about 2-2.5k but the power waits till 4..

I have tried remove TVIS, MAF sensor, Boost sensor.. I have tried everything really?? Just stumped!

[jimGTS]

mate, bigger turbo means big lag, no getting away from it...

[THE DUKE]

Yeah i thought that might eb the answer, its just lost lots of drivability.. oh well more money!!

[jimGTS]

im sure bits like flywheel, and an ecu will give you alot of driveabilty back...
even the stock ct20b dont hit max boost til 3-3.5k rpm (i heard), 4k rpm is ok.
then again i bet id miss my low down torque with a bigger turbo, im full boosting at like 2.5-3k...

[THE DUKE]

Already have flywheel.. Im looking at getting a rev1 -> rev3 ecu conversion and a rev3 intake cam to try and iron out the flat spot.. Also then if i like i can fun a power fc etc

[The Morris]

dont know when CT20b kick in, but my 300+bhp ct26 hits full boost just after 3000rpm

[splashnatz]

i've had overboosting problem for a while now. overboosted on std CT20b and also on the hybrid CT20b i've got on now. Blamed downpipe first, so swapped it for an Aussie. No change. Actuator would slowly leak, so tried new actuator. Still did it. Put the bung that you get with Nur Spec back into the tail-pipe, and it seems to have cured the problem so far ... was going over 1.4 bar, since putting restriction in the exhaust, hasn't gone over 1.04 bar (except for a single spike to 1.2 for a split second).

Asked about this on the Owners Club, and Hellboy reckoned that the restriction wouldn't really help, so i';m unsure if it is the "bung" that has sorted this, or if another factor came into play.

[The Morris]

i've had overboosting problem for a while now. overboosted on std CT20b and also on the hybrid CT20b i've got on now. Blamed downpipe first, so swapped it for an Aussie. No change. Actuator would slowly leak, so tried new actuator. Still did it. Put the bung that you get with Nur Spec back into the tail-pipe, and it seems to have cured the problem so far ... was going over 1.4 bar, since putting restriction in the exhaust, hasn't gone over 1.04 bar (except for a single spike to 1.2 for a split second).

Asked about this on the Owners Club, and Hellboy reckoned that the restriction wouldn't really help, so i';m unsure if it is the "bung" that has sorted this, or if another factor came into play.

Well hes obviously wrong as the bung has helped. Its down to a lack of backpressure from the free flowing exhaust. When i put my downpipe on i got 22 psi.