I Just bought a 1991 Turbo II, the motor was rebuilt about 5000 miles ago, but the mechanic at the dealership it came from told me the exhaust sytem needs to be replaced. I was just wondering what exhaust systems people are running and how they like them. I'm not necessarily looking for one that creates peak horespower, but more of one that creates usable horsepower all throughout the powerband. Please tell me what kind of Exhaust sytem you're running, piping diameter, and single dual exhausts. Also, if you've upgraded downpipes or cats. Thanks

 

Full RB

 

Yes, w/ a turbo the most usable power available is having they turbo able to spool very quickly-bigger is better here. Trust me, your turbo is providing plenty of backpressure; you don't need any in the exhaust system.

 

Definitely go with the Racing Beat Full Exhaust system. It will make a tremendous difference. Make sure you get the Fuel Cut Defender with it or your engine won't last long though.

 

and if you get an FCD and straight through exhaust, upgrade your fuel pump to a Walbro 255 liter per hour pump(~$130). It is a good upgrade anyways, as it will help prevent detonation.

 

wont he get boost creep if he just fits a full exhaust?

When it comes to Rx7 Turbo exhausts you will want a 3" system going to 2x2.5" then the tips are up to your discretion as it dose'nt realy alter the power.

If i was you i would get a Uprated Fuel pump,FCD and boost gauge before doing the Uprated Exhaust.

 

I've got the racing Beat 2.5" downpipe going to a straight 2.5" pipe and then to a single 2.5" Flowmaster Delta Series 40 muffler. It sounds great, not too loud and it definately helped power, and another good thing is that it was a lot less expensive than the Full Racing Beat exhaust.

Chris

 

Dual N1's

thats what I will be getting for mine eventually

 

Yeah.....I'm definitaley looking for a full 3" inch system. Apex'i makes a full 3" that is a single tip exhaust, and they also make the dual tip like Paul C was talking about, I think it starts out as 3" and then goes to 2.25 or something, which is perfect. Need to do a little more research on all the different exhaust systems though. Can anybody explain to me exactly what happens when the boost goes higher than stock, hence the reason that you need the FCD. I know so far that if boost exceeds the stock setting, the ecu will cut fuel to the rear rotor, but does it do anything else. That was a bad idea on Mazda's behalf since low or no fuel = lean = serious problems. They should have cut spark out instead, that seems to be a little safer, but I dunno.

 

Does anybody have any dyno plots on any exhaust systems from before it was installed to after it was installed. If you do...just tell me what exhaust system it was, hp and torque gains, and how much boost was increased. A dyno chart would be helpful too.

 

ok, on a 87 turbo II, racing beat catalog quotes horsepower increase of 32%-a 59 horsepower increase on a 87 Turbo II.

As for the FCD. Ok, this info is based on the 87-88 turbo II(I own a 88 with the full RB exhaust). Basicly, once you free up your exhaust, your turbo will boost higher, example, my car went from 5-6 psi stock, to 10-13psi with the exhaust and HKS intake. If you leave your stock air box on, you can lower this by 1 psi. The FCD basicly tells your ecu the max boost the motor is seeing is 8.5psi... (fuel cut out is 8.6psi to the second rotor). Can you drive without a FCD, yes, but the minute you put your foot into the gas and need power, your motor will cut out when hits fuel cut, and trust me the car is not drivable this way. So you need a FCD.

Please realize, now with a full RB exhaust and a FCD, you'll be boosting say 10psi, but your fuel supply to the motor will be based on 8.5psi.. thus you can easily lean the motor and boooom. This is why a upgraded fuel pump is a must. Also, boost creep is a problem, but on 89-91 RX-7's its not near as bad as 86-88's .. your turbo is much better. In your case, I would recommend the full RB exhaust, FCD, upgraded fuel pump, and leave your stock air box on.. this is a very safe and reliable set up. but trust me, once you feel the power of the exhaust hp increase you'll want more, more, more........ I need more HP...

 

ya with my full RB and stock intake I hit about 9psi in 4th. with a K&N cone I hit 11 so I took it off.

 

Check out corksport.com for exhaust ideas. Costs less than Racing Beat.

jerk_racer@hotmail.com