my turbo in quetion..

[krush]

hey all,

after driving the car for a bit, ive come across a few things that dont seem too good.

theres a sound that im sure is coming from the turbo when it spools up, which sounds like a screaming screeching sound (almost like tyres screeching). i know what a spool'ed turbo sounds like, but this is a louder, higher pitch sound. any suggestions on what it could be?

secondly, the car drops boost as it goes towards redline. on take off, it makes 0.5bar by 2500rpm, 0.8bar by 3200rpm, starts dropping at around 5800rpm and hits back to 0.5bar at 7000rpm.

my first thoughts would be the turbo is too small and cant provide, but ive read on here rb20 turbos are capable of running 12psi all the way to redline? although, looking under the car the turbo did look rather small.. do those turbo actions sound like anyone elses stock rb20?

any thoughts would be appreciated.

thanks, shaun.

[cameron]

Tyre screeching sound :uhh: depends what you mean if its metal scraping metal thats not good! But if not its proberly just the way the turbo spools.

Boost drop off can be a number of things.

Stock RB20 with usual pod and boost. You need the other bits & pieces to go with it, exhaust, dumpipe, FMIC. - If you havn't already got them.

The turbo carn't be running out of efficency already because its only stock boost, so sounds like a restriction problem at high RPM.

Jun

[TTT]

Both your problems are caused by the one fault.

Turbo to manifold gasket.

You are probably missing a bolt/nut that is holding the turbo to the manifold.

if they are all there, then you will probably find that one or more are loose.

the above 2 problems cause HOT HOT exhaust gases to escape from the nearest opening, and this is obviously between the turbo and exhaust manifold.

this burns the gasket and then you eventually start hearing the high pitch squeel when you come on boost. obviously because this is when there is more pressure going through there..

if you leave it, you will eventually start hearing the car run like a lawn mower on cold starts..

sort of a ch ch ch ch sound as air escapes through there..

now.

the boost drop at high revs.. again, the leaking gasket is to blame cause it is taking the easiest exit out of the system here..

it just can't hold that pressure when there is a leak.

GCG turbo's in Sydney sell the nissan exhaust gasket kits for $27 I think.

then it's a matter of spending the time doing it yourself or paying like $200 for a mechanic to do it for you.

I'd take the mechanic option as this will mean that when he brakes a manifold stud (and he will and so will you if you try it), he can just drill it out and tap a new one in.

[cameron]

GTST,

Good point,

If you had a manifold leak it will sound like a tractor, not lawn mower tractor's are better :wassup:

Curious to know why R33 GTST's always loose manifold bolts usual on cylinder's 1 & 6 ?

Jun

[TTT]

tractor... lawn mower.. eother way, some sort of farm machinery rather than a smooth straight 6

[krush]

heh, ok, ill have to take a look at that then tomorrow while the engines cool..

thanks for the tip!

s.