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Early Mpi Cooper S Conversion Inlet Manifolds

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#1 Alice Dooper

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Posted 07 June 2019 - 10:14 PM

The early kits had a few things different than the later / current kits. For example the janspeed exhaust instead of the manifold and the ‘crimped with a set of pliers modified’ fuel pressure regulator instead of the power boost valve.

But the early kits came with a modified inlet manifold, I think it involved some minor grinding back of a radius inside and stamping some letters somewhere on the outside. Anyone know what it was they done?

I know that there was a modification sometimes done to throttle bodies to allow the butterfly to fully open - they just ground the end stop back a bit.

Was there any other differences apart from the air filter?

#2 Fast Ivan

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Posted 08 June 2019 - 06:39 AM

The inlet manifold was opened up a bit so that it matched the now larger ports on the worked cylinder head (I have one somewhere)
The mod to the throttle body was, as you say quite simply the removal of the restrictor that stopped the butterfly from opening up fully, I also have one of those somewhere. I’m not convinced this mod produced any additional power though

Edited by Fast Ivan, 08 June 2019 - 06:49 AM.

#3 FlyingScot


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Posted 09 June 2019 - 03:55 PM

One of our club members removed the restrictor that prevents the butterfly opening. It had zero effect on power. Modifying the air box however did make a difference.


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