MSefi.com read only forum (Jan.15,2018)

I have a 77 Datsun 280Z that came factory with Multiport injection. From what I've read, the intake runners are too small to support over 200 hp so I'm wanting to switch over to the older SU manifold (bigger runners). I have two options. Option 1: mate the two manifolds together so I have MPI and I'm able to use factory style plumbing. Option 2: slap on the SU manifold and convert the SU's to TBI. If I was ambitious I could bo both and fade to the TBI at higher RPM's. From a performance standpoint, which is better.

I'm hunting down a cheap SU manifold on Ebay to get the measurements. Do you have the formula to calculate the length and diameter the runners need to be? I love to play with the numbers.

I'm definitly having head work done by either Rousch motorsports or Rebello Racing. They do phenominal work and have LOADS of experience with Z heads. But that's going to set me back some serious cash If money were no object I'd like to go with the Individual Throttle Body setup from TWM Induction. That runs close to 3 grand, computer not included! So needless to say I'll hold off on those for a while. The triple weber carb setup also runs for nearly $1800.

I've read about the old SU carb'd 2.4 pushing the 240Z into low 10 second 1/4 mile times (even lower on race only engines). I haven't heard much from the factory fuel injected Z's unless they go turbo.

TABrin wrote:I'm hunting down a cheap SU manifold on Ebay to get the measurements. Do you have the formula to calculate the length and diameter the runners need to be? I love to play with the numbers.

Then you'll love this:
http://www.not2fast.com/gasflow/Lecture08.ppt

(Or if you don't have powerpoint, I've converted it to html: http://www.not2fast.com/gasflow/Lecture ... cument.htm )