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Turbo Lag

gillies2001
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gillies2001 Collaborator

gillies2001

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Posted

Hi there

I have just fitted a series 1 RB25 turbo to my 89 GTST/4 RB20

Every thing was ok with the RB20 turbo, but now nothing much happens until 4000rpm +

The car has a front mount, dump pipe, manual boost control (set at 14lb)

When it does come on boost it really goes hard but below 4000rpm its a pig, real laggy

The engine is healthy, good compression (about 165lb x 6 ) Also the new turbo is smooth and spins free.

I read the forums, and it would appear that lag should not be a problem doing this conversion.

Any help would be appreciated

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Cheddle Enthusiast

Cheddle

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Posted

i would point a finger at the wastegate actuator...

there is virtually no noticible difference in response between these turbos on an rb20...

make sure that the wastegate arm is as tight as possible, i remember when i changed my turbo on my r32 last time the bolts were ever so slightly loose on the actuator bracket and ti caused epic wastegate leakage

for what its worth i think that running the RB20 turbo actuator on the RB25 turbo results in more boost... i think, could be the other way around tho lol...

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lachlanw Veteran

lachlanw

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Posted

rb20det + anythign = laggy

flat mate has a rb20det with a neo turbo on it(bigger rear housing ) that reaches full boost at 4100 on the dyno graphs .

do you have a boost gauge

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  • 5 years later...
Cassbo Grand Master

Cassbo

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Posted
I've got this problem with my rb25det and stock turbo boost don't come on till 4000rpm would it be same problem?

I brought a aftermarket turbo if I just do change over will that fix it 2?



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