340 dyno chart thoughts

fez440 said

i have a question about the ld4b that i have on the engine. this intake has smaller ports then the 340 intakes. is the full chamber smaller on the ld4b or is it just at the opening where it enters the heads? i ask because i was told he port matched the intake to the heads so would that not make it the same as the ld340 intake or no?

Click to expand...

You can port match it, but it is different. It will never be the LD340.

I know you won't like to hear it, but when the port is small, then you make it big at the flange, it's a pretty good flow loss. It's counterintuitive but, you are better off if the intake manifold is bigger than the port. Ideally the port at the plenum should be bigger than the port at the flange. And the port at the flange should should be the same size as the port. BUT, if you have to have a mismatch, the intake should be bigger than the cylinder head, without the hour glass shape from a port match.