Greddy Plenum Loud Howl?

[skeg_man]

Hi all,

Recently did the greddy front plenum change on a R33 gtst and I seem to have come across a problem. When the car gets up to around 7-8 psi of boost (upgraded turbo) there is a loud howl from the intake plenum...

Ive done a vacuum leak test with a compressor and cant seem to fund any leaks???

Is this sound caused from a higher rate of air flow due to being a front facing plenum or something more to it?

The car doesnt idle funny or anything. Seems to build boost fine. Altho I havent been going above the 8 psi at all.

Any info would be great.

Cheers

[bubba]

Probably something opening up on boost..

[GTSBoy]

I'm guessing you have a boost leak rather than a vacuum leak. Same thing of course, except in this case it's something that's opening up when it gets pressure inside it. Not necessarily the gasket faces or anything, could just be a hose clamp. Need to get it on a dyno perhaps so you can see it / hear it leaking under load.

--edit -- beaten to it.

Edited July 25, 2011 by GTSBoy

[skeg_man]

Oh ok. No real way of checking for the boost leak at home?

Im fearing having to take the plenum off. Lol. Was a pain in the arse to get it on. If it has to be done tho. Better off doing it sooner then later i guess.

Cheers guys

[TiTAN]

friends landcruiser had the same problem, drove fine idled fine but whistled on boost, turned out one of the gaskets on the intake manifold wasnt sealing quite right under boost.

pull them all off and go over them with some hylomar then put it back together.

[skeg_man]

Thinking i might have to do that. Looks like next weekends project.

Ive pressurised the plenum to around 10psi but i couldnt seem to hear anything.

Cheers again guys

[boostn0199]

Check all your cooler piping espcially the new one you would have made for the plenum. Check simple things cause last thing you want is to take it off And find it was something simplr.

[skeg_man]

Yeh, I've gone over the whole system. Double hose clamped some connections too.

Really don't want to remove it again. Like I said before, pain in the !

I'm just kinda confused. I thought if you put pressure in the plenum you could find the leak like that?

[GTScotT]

Is it a GReddy or a FReddy?

If its a copy you might need to machine the flange surface... It wouldnt be the first time one showed up bowed.

[skeg_man]

yeh, its FReddy. Think ill just take it off.

[skeg_man]

Can anyone confirm this please?

Putting pressure in the plenum you could find the leak like this?

[skeg_man]

Anyone?

[Adriano]

From what i have seen, all the Freddy manifolds needed machining to get the flange flat, however if you were able to get the piping up to 10 psi, it should have shown up. Try spraying some carby cleaner around the gaskets when it idling to see if there are any leaks, the idle will go up or down.

Edited July 25, 2011 by Adriano

[STATUS]

If its a copy, they can have all sorts of dramas, pinholes, warped flanges etc...