I posted this yesterday and got one response before the post mysteriously disappeared, due to server problems I assume. Emissions components aside, are there any other differences in the J-spec upper and lower intake manifolds? Someone is trying to sell both the upper and lower to a friend of mine saying they are larger in diameter. Are they indeed larger in diameter?

 

Extremely unlikely.

Kevin T. Wyum

 

The advantage of the lower is that it does not have the EGR valve mounted on it. So it might flow marginally better than the U.S. version, but it can fit a single turbo better. I doubt that the intake runners are larger. Besides you can just have the american version machined/and port matched instead of buying new ones.

eric

 

Please feel free to keep responding to my original question but let me add another. Are the factory ports on the J-spec motors larger? I'm doubting this as well but supposedly a buddy has a J-spec engine and claims the ports are larger and they have not been street ported.

 

NO FOR BOTH QUESTIONS... There are no differences
what so ever... UNLESS they had them bored out, that
would be the only way...

 

Also the 20B(3-rotor) has larger ports, but it looks different of course GREATLY