OK.... first thankyou in advance.

I have a 1994 Rx7 with a single turbo conversion.

I went to go FINALLY have my RX7 tuned and the tuner told me that my motor had a S6 housing on the front and a S4 housing on the rear. He told me that my motor is UNtunable, because there is a timing variance between the spark plug position of a S4 vs. a S6. (apprx 8 degrees)

Is this true?

Am I going to have the tear out my whole install to rebiuld my motor with two S6 housings??

The setup I have is able to push 500Hp+, we were going to tune it to approx 440hp.

Thank you,

Please verify this and please send me your comments.

fulblown@gmail.com

 

free bump, because i have no clue whether the tuner is tellin you the truth or not, but why do you have a S6 housing in the front and a S4 housing on the rear? aren't S4 housings 4 port, and S5 and up are 6 port? i'd be interested in the flow characteristics between the two

 

So you are saying that your engine was built using a rotor housing from a 13B-REW and another rotor housing from a 13B n/a? Since you can't tune each housing individually, yes, it's very likely you are screwed.

Who the hell built your motor?

 

Hayes Rotary? I have witnessed such incedents.

 

Yeah, it wouldnt be half as bad if there were 2 of EITHER set of housing...2 s4's, though not recommended, would have worked no problem...just relocate the knock sensor to the INT iron and you're golden (like the s4 turbo engine has it stock). Though I have, in rare instances, did a housing swap like this (out of necessity, with prior clearance), I would never try and mix and match the housings like that.

You have 2 options. Go ahead and run it as-is, tune it as best as possible and hope for the best, or tear it down and replace both that s4 housing AND the seals that rode on it, unless it was in new condition with no grooving or wear patterns. Either way, you have to come out of pocket for a housing...if you wait, you might have to pay for a rotor as well. If the engine is tight at this point I'd be tempted to do a conservative tune and let it play out...you're only talking a couple or 3 hundred bucks difference at that point, between replacing it now while the rotor is still good, or waiting for it to tear up and tearing up the rotor in the process.