Rebuilt G40 engine but no boost

ant1-gl · October 16, 2008, 03:33:27 PM

Hi
just rebuilt my G40 engine and got it started lastnite.
I drove it up the road (1/4 mile) under 2.5 rpm but there was no boost. At the moment it's only timed manually to just to get the car engine running, could this be why there's no boost? I've checked all the boost hoses which are all fine.
p.s i got boost return mod.
any ideas?

regards Anton

hayesey · October 16, 2008, 04:18:40 PM

no boost as in the boost gauge never goes above 0bar at any point? Is the charger connected? Does the charger work? Is the boost return valve connected properly? Can you hear air hissing out?

ant1-gl · October 16, 2008, 05:04:25 PM

the charger was working fine before so no probs there and it's all connected up. i'll check the boost return valve but I reckon that's ok too. I don't have a boost gauge so not sure if there's little or no boost. I have found something which may be the problem, on the underside of the inlet manifold there are two "threaded holes" which don't have any bolts in them, should there be? At idle there is not obvious hissing sound.

hayesey · October 16, 2008, 06:25:15 PM

yeah those holes are normally empty.

I mean can you hear any hissing when driving when you would expect there to be boost.

If you don't have a boost gauge then it maybe something else such a overfuelling which is just causing the car to be well down on power and just "feel" like there is no boost?

But definitely check the boost return valve is working properly, get someone to press the accelerator while you watch it with the engine off.

ant1-gl · October 16, 2008, 06:27:47 PM

ok i'll check that tonight and give an update 2morrow!

samg40 · October 16, 2008, 09:57:25 PM

It could just be down to timing possibly? I know when I adjusted mine with a duff timing light it was well out and there was no power there at all. If you've done the boost return mod can you feel the air coming out of the end of the throttle body? Its quite a lot of air out of there even on idle if all is well with the charger.

NeilG40 · October 17, 2008, 06:48:56 AM

I'd agree with Sam, I set the timing on mine using a light with the car at 2000rpm and there was no power there at all but setting it at idle speed it was fine.

ant1-gl · October 17, 2008, 10:02:32 AM

thanks guys,
i'll get it timed up properly then take it from there.