i put a 89+ intake manifold and i don't have the vdi working yet and would that make the car any slower than if i had my inatake manifold 86-88 on and i have the 6 ports working

 

uhm, yes.

 

so that means that my car would be faster if i had the 86-88 intake manifold than having the 89+ on with out having the vdi working

 

uhm, yes.

 

I bought an 89 manifold once and was going to put it on my 88 GTU, and after looking at the logistics, and the minimal hp increase, it is just not worth it at all. Keep in mind the 89 has 14 more hp because of a SYSTEM of things.

~Jeremy

 

Higher compression, lighter weight rotors, intake design, revised AFM, revised ecu speed and maps.

 

You could wire it to the high RPM position until you get it working properly.You might lose alittle low end but it would be stronger on top.I keep mine set to high RPM all the time and it doesn't seem to be a problem.

 

i was thinking of seting at high rpm but have not had time to do it yet so i am going to have to do it this weekend

 

i have a 89 intake on my 88vert and i wired it open full time yes there is a noticable difference on perfomance but me speaking from experience your going to run into other probs.i have recently bought a Apexi S-AFC to control my fuel probs i have had since the 89 intake swap.

 

A fellow RX-7 owner had converted his 86' with an 89' intake. He wired his VDI via rpm switch. Initially, he felt the surge of power when the VDI opened up. Upon dynoing his car, he found that he actually lost 10hp and It wasn't until 7000rpm he had gained 8-9hp! He nolonger advocates It. He also has stated that, to his knowledge, many other RX-7 owners are dissapointed in this mod. Anybody have anything to add to this?

 

so what you are saying is that it is better to put the old intake back on

 

IF youre not gonna use the s5 operating sytsem(vacuum rail and solenoids) to operate the intake as it was meant to be, then yes, you shoudl put your old one back on...it responds better to being rigged and/or modifications such as internal porting than the s5 one does.

Like I said, the s5 works great in or near stock perameters, but once you get away from that, or go wiring stuff open, it loses a LOT.