Gsl-se

Hey fellas...gotta problem maybe someone can help me with here...am an 85 and 84 GSL-SE owner...have about 6 others for parts around yard. The 3 converters are bad and have been removed and thrown away....the premonolith, the seconday premonolith and the primary.
Now that i've thrown them away because of holes and cracks and so forth...and not having any on other parts cars, ive found the cost for replacement to be in excess of 1500.00. Can the car be straight piped? I know it can but is there any backpressure required and will it do any damage if in fact it was straight piped. Its not like theres an amount of valves to damage but there is a return feed line that runs back to intake that I can pinch or cap or something.....someone knowing answer please reply....car has been down for over 18 months. Poor white guy here with a love for the RX-7.

I don't see why running no cat would make a difference. A lot of FC guys are running without them, just using a presilencer in its place and a high flow muffler. Just as long as you don't run a huge exhaust like 3 inch or something your backpressure should be OK. But if you have emissions testing you won't be able to pass.

Running a straight pipe is fine. Depending on the rest of your exhaust, a straight pipe may even increase performance. Obviously if you're in an area with smog checks you'll fail them. Only thing to keep in mind is that with a straight pipe your exhaust will get a lot louder.

The rotary doesn't really need backpressure, per se. Of course back pressure is helpful for performance on NA engine, but it's not that necessary as on a piston engine.

The return line basically just pumps a small amount of exhaust gasses back into the chamber to reduce emissions. You can just block off the EGR with a plate.

Rotary engine does not need backpressure at all due to the powerful exhaust pulse from the engine exhaust port. Dumping off the cat on FCs is definitely a go as it does improve the acceleration of the car coz' you are actually making full use of the rotary exhaust pulse and it is not restricted at all but just a slightest of 2 hp gain.

A straight flow/piping exhaust system does make more hp on rotary than other systems. Especially the Apex'i systems.

If you thinking about performance, then sooner or later you are gonna throw off the cat.

Originally posted by FC3S
Rotary Rockets!
WE LOVE RE!!

1985 RX-7 GSL-SE
1990 RX-7 Turbo II
1993 RX-7 R1 Competition Yellow

I want your cars!! That's the exact combination of Rexes that I've always wanted. :D

Originally posted by Kaneto


I want your cars!! That's the exact combination of Rexes that I've always wanted. :D

Thanks. I really appreciate ppl who love RXs. You will have it all one day too. Well, i see you have 1987 RX-7 FC3S so it is a good start. The SA22C price is really affordable but most of them needs lots of work. But, sometimes u may find a good one so you gotta be super patient coz' it really takes time. The FD3S is still expensive in today's car market but i got mine in really mint condition in an auction :D

Originally posted by FC3S
Rotary engine does not need backpressure at all due to the powerful exhaust pulse from the engine exhaust port. Dumping off the cat on FCs is definitely a go as it does improve the acceleration of the car coz' you are actually making full use of the rotary exhaust pulse and it is not restricted at all but just a slightest of 2 hp gain.

A straight flow/piping exhaust system does make more hp on rotary than other systems. Especially the Apex'i systems.

If you thinking about performance, then sooner or later you are gonna throw off the cat.

i always thought on a N/A rotory you need some back pressure for it to run right.

what do I know i own a 87T2.
DP MP silencer

I ran my 85 RX-7 on straight exhaust and there is no problem to it plus there is also performance gains from that. :D

All I know is that all N/A cars needs backpressure but think....given that rotary possess such powerful exhaust pulse (in which is helpful in faster spooling for the turbo versions) then u should use it to our advantage.

Piston engines generally creates less powerful exhaust pulse compared to rotary maybe with the exceptional of Honda VTECs. I see many Honda are gaining more power by switching to straights but many others, straights will only give louder noises (in some cases lower acceleration) rather than good performance.

don't earlier 13bs have a 6 port intake that needs back pressure to open up the last 2 ports at higher rpms?

Originally posted by Big Guy
don't earlier 13bs have a 6 port intake that needs back pressure to open up the last 2 ports at higher rpms?

I don't think so. Even if they do a lot of guys wire their ports to stay open all the time anyways.

o

you can run straight pipes and still have your 6 ports work fine, as long as they worked fine anyway. Just be careful with a straight exhaust, N/A's are fooking LOUD! and will bring you even MORE attention from the less desireable local authorities than you already get.