sealing stock turbo inlet

[duratothemax]

I finally got around to testing the twins for boost leaks...WOW. MASSIVE air leaks around where the stock turbo inlet seals into the stock LLY turbo. I could hear air rushing through even with the radio on in the shop. The twins must move some serious air if they could make 40psi with that big a leak.

Im looking into buying opie's inlet, but until then, any ideas how to get it to seal better? Throw some RTV on the mating surfaces??

I know its not designed to hold boost, but before opie made his cast intake, the twins kits just used that stock piece and it seemed to work OK...

ben

 

[JoshH]

Maybe cut a piece of rubber to clamp between the surfaces?

 

[LarryJewell]

Opies piece uses a rubber O ring, I have several

 

[duratothemax]

well I tried doing another boost leak test... basically got a plug to fit in the inlet of the big turbo, and mounted a schreader valve in it, hooked it up to the air compressor, and it still doesnt hold pressure. I listend closely and could hear quiet bubbling?

Opened the oil fill cap and when I pressurize the intake system I can hear the bubbling coming from the crank case? Is leakdown on these engines really supposed to be that bad???

Obviously theres no crankcase pressure or cooling system pressure when the engine is running, no blowby no nothing...the engine is literally as smooth and quiet as a stock LBZ. Am I just being stupid and this is completely normal????

 

[stacks04]

why would your leak inlet side pre compressor affect boost. if anything it is adding air to the system, but i'd be more concerned about the fact that it is sucking dirty air. maybe i read you wrong

 

[duratothemax]

I did it that way because it would pressurize the entire intake "tract" no?

Im only making 43psi manifold pressure or so, as I understand it with the twins I should see more. Nathan was seeing 55+ with his LMM twins setup.

waitt I think you misunderstood me. I got a PVC end cap thats the same size as the inducer on the big turbo, sealed that in there so I could pressurize everything from the big turbo right to the cylinders themselves.

 

[JoshH]

You're right Ben. Leaking where you are/were is bad. I had a massive leak there on mine when I pressure tested it last weekend. My o ring was totally f'ed up. On Nathan's LMM, you have to remember that he is running a much larger primary turbo than what you or I have.

 

[duratothemax]

but is the cylinder leakdown bad? (bubbling coming from the crankcase)

 

[whitetrash21]

probably worse with a cold engine than with a hot engine. heated motor is gonna have all moving metal mass expanded to its largest size (rings, guides etc) so there is less blowby..........everything will be seated a fraction tighter. just my take on it....

 

[WolfLMM]

I think your okay... Was the engine warm?

 

[duratothemax]

I think your okay... Was the engine warm?

no it was cold

 

[Killerbee]

but is the cylinder leakdown bad? (bubbling coming from the crankcase)

Personally, I think you showed that the induction system is sound, since you pressurized the CAC and all the pipes, and no noise from them. This is the first I have heard of anyone doing this, and I always wondered how to pull it off.

What you reported is what i would have predicted if everything was normal.

You could always fill the crankcase with oil and then see where it comes out.:rofl:

Just kidding...good test.

 

[duratothemax]

ok good

thanks everyone