Reward if found: My new FB RX-7 project.

Awesome fine especially for the price! Does it currently run?

Since its a GSL-SE it will be easier to keep it fuel injected. Keep us updated.

Does not currently run. Previous-previous owner put in a fresh 13B, got a plan to go carb'd turbo, ran out of money and care. PO bought it as a father-son project, decided to go another route.

Might as well ask while I've got your attention: do you think it's worth the effort to swap over the S5 manifold I've got?

Ive never run the S5 intake but I had planned to. It is reportedly worth about 10hp if you make the VDI functional. It is pretty much a bolt on to my understanding. Getting the VDI to work takes a little wiring though.

I would certainly recommend keeping the 5th & 6th ports working if possible. I removed mine and while it was fun to drive full throttle but I missed the low end I gave up. Really there is no benefit aside from simplicity to removing them. I had planned on reinstalling them when I did the S5 intake swap.

Then I sold the motor and bought an LS1 which I am bringing to LS6 specs now.

Osterkraut wrote: Winner, myself. A longtime GRM reader noticed this thread and emailed me. 1985 GSL-SE, extra engine, extra bumper. Needs a paintjob. Less than .3 Challenge Units. Not that I was going to Challenge it, but with 13B values in the toliet, it might just work...

I hope you can tell me that car didn't come from PA- I've been trying to buy one identical to that from my dad for YEARS, and I know it'd go right about the price you paid on that one.... same color too. If he sold that car out from under me.......

Build thread or ban!

Javelin wrote: Build thread or ban!

Give me a week, mang! I've got to prep my garage for real work.

Car is not from PA. Keep bugging your father.

The 6 port is operated by pressure from the smog pump, which makes pump removal a pain since you now lose the needed pressure. The same pressure is used to operate the variable runner valve. That means if you use the S5 intake it's possible to trigger the variable runner system by using an RPM switch. It will also operate in a purely mechanical way by running the pressure hoses to all three, they will do their thing somewhere between idle and roughly 3500 RPM that way. Not as elegant as the original S5 programming which used vacuum/pressure solenoids to control all that but it will work.

I'm not running a smog pump on my motor, so I use a RPM switch to trigger a cheapie pressure pump which pops the 6 ports open at 3500 RPM. It has to also dump the pressure via a solenoid valve so the 6 port will close. There is definitely a noticeable difference with this in place.

You don't want to use the S5 ECU because it's set up to run an electronic oil metering pump. If the ECU does not 'see' the pump it kills the trailing ignition and drops the fuel pressure to put the engine in 'limp mode'. The S4 ECU is probably your best bet.

Caution: GSL-SE's and early S4's came with high impedance (square connector) injectors, later S4's and all S5's had low impedance (oval connector) injectors so make sure to match your ECU to your injectors.

The plan is to use the GSL-SE ECU and just put it's bits on the S5 manifold, with the 6 ports and VDI operated by exhaust backpressure.

I was debating just using the S5 ECU, I had forgotten about the limp mode issue.

S4 6 port works from exhaust back pressure, S5 from the air pump. I haven't tried to adapt S4 stuff to an S5 intake, so I don't know if it will work. The S4 exhaust passages are in the intake. I have never tried it, but maybe the S5 upper can be used with the S4 lower? That way you might be able to have a hybrid setup.

S5 6PI actuator diagram:

On the S5 the ECM decides when to open the solenoid valves to let air pump pressure through. The variable runner setup was only on S5's and was also run by the air pump so I'm not sure the actuator is compatible with hot exhaust gases. It's supposed to do its thing over 5K RPM but I see no reason it couldn't be triggered at the same time as the 6PI, that way you use only 1 solenoid valve and RPM switch. From what I understand, it's possible to leave the air pump in place if you aren't running headers etc so that it can work the 6PI and variable intake.

I don't think the upper and lower intakes mix and match between the S4 and S5. RB had a pressure tube plumbed into their first presilencer to actuate the S4 secondary ports when dumping the air pump.

Curmudgeon wrote: S4 6 port works from exhaust back pressure, S5 from the air pump.

Fortunately the actuators won't know the difference between 2-3 PSI from exhaust backpressure and 2-3 PSI from the air pump, and the general construction of the parts (and this link)seems to check out ok for exhaust I'm hoping a restriction in a line (like a manual boost controller) going to the VDI will enable it to open a bit later. We'll see. If not, I'll just have to turbocharge it.