In my search to find a endurance race car, I came across some 2nd Gen Rx-7's. I know nothing about these cars other then what I read on some other forums. I have a few questions on the reliability when tuning a NA? Why are the rebuild kits so expensive ($1500)? the engines themselves are just as expensive.
I love the RX-7 and am a complete sucker for the FC. That being said I found the 6-port NA to be a bit "limited" in potential and it required some work arounds to keep things working while I tinkered with it.
The early 6-port rotary (84-88) had actuators to open the 5th and 6th intake ports that fed off of exhaust back pressure (think something like VTEC). Installing a free flowing exhaust rendered mine inactive and it took me forever to figure out why my car was falling on its face at higher RPMs. I eventually removed the actuators and safety wired ports open, but the "correct" way of doing things is to install some sort of aquarium pump with an MSD RPM actuated switch... more here
The 89-91's used the smog pump to open those same intake actuators. So you don't have the restriction in the exhaust but you're stuck with the smog pump (if that bothers you)
After I changed the exhaust (headers, test pipe, and cat-back) and got things working right, I kind of ran out of things to do to the engine without investing $1500 in one lump (which to me was a lot). I guess I could have done a pod filter, but I didn't mind the stock air box with a K&N filter.
With the proposed $1500 "lump" I was looking at stand alone fuel management with the eventual goal of ITB's, or a porting job (where I would have bought a rebuild kit to go with). In the end I ended up fiddling with the suspension (tokicos and eibachs) and ended up always wanting more from the engine. It handled like it was on RAILS, but the suspension seemed to overpower the engine in really hard cornering. I hear you CAN make decent power from the NA's but they tend to have "peaky" powerbands.
One day I was horsing around with a turbo FC of similar vintage on some back roads and the guy just left me in the dust left and right (stock turbo, plus a few supporting mods). If I were to do it again, I'd get an 89-91 turbo II.
On the plus side:
the car suffered years of neglect and hard running from the previous owner and it still ran tip-top. The power is unbelievably smooth and I loved driving it. It was a bit slow in CSP autocross, but I always had a good time.
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