I'm looking for a little more horsepower and at the same time trying to keep the mods pretty safe reliability-wise. Are there any problems I might run into by removing the catalytic converter center section with a straight pipe?

Are there any sensors on the mid section that will have to be removed?
Will it effect the computer in any way?
Will it make my car a lot louder or just a little?
Any guess on how much HP I might gain?


BTW: I'm not too worried about emissions here in Missouri. They don't do testing here (for 1995 and older) anymore. But I'll keep the cat just in case.

Thanks!
Scooter

 

what you have to worry about the most is boost creep unless you port the waste gate or put in restrictors you will get creep. IMO I would not mess with a midpipe unless you port your wastegate.

 

The Pettit ecu is not designed to support a mid pipe. You will also most likely experience boost creep. Putting in restrictors defeats the purpose of the midpipe. The car will also stink, polute, be much louder, and illegal so use your judgement.

 

That's not exactly true. Pettit supports full bolt-ons. The M2 was the rechipped ECU which they did not recommend/support midpipes.

 

Not saying you can't get away with it, but I have seen quite a few blow once going to a mid pipe. He asked about reliability.

 

I removed the cat, ran a mid-pipe, ported the wastegate and still had boost creep. Use a boost controller to keep in safe levels.

And yes, you will increase hp and it will be loud. It will also stink, but that's the problem for those in the back of the FD!

 

https://www.rx7club.com/showthread.php?p=5699718

 

Lots of people have blown their motors by going with midpipes without porting the wastegate and getting a boost controller.

Get a high-flow cat instead. You'll get a little boost creep from it, but should still be at safe levels(below 11.5PSI) and you'll get a bit of HP and save a lot of weight.

 

That's fine, but you did say "not designed" and it is a map for midpipes. It is splitting hairs, but I do want people to know that you can use midpipes with Pettit ECU's. The issue of controlling boost with a midpipe is the same no matter what ECU is being used.

 

+1, it also wont smell as bad as a straight-pipe.

 

Okay gang. You've convinced me that it's a bad idea. Thanks.

Perhaps I'll look into some reliability enhancement upgrades like a larger radiator or intercooler (does that one count?).

Oh, I still have the stock computer on my car. It's a pretty tame RX-7 going by the standard set in here! heh.

It's my baby and I plan to keep it for years to come.

Scooter

 

You'll have no problem with a large radiator, however be careful with your intercooler. The stock IC is very restrictive, and freeing up the intake path can also lead to boost creep issues, though it's not as much of a problem as it is with the midpipe.

 

I'd definitely keep a cat on there, either stock or high flow. Being that you have a stock ecu, I wouldnt mod past the usual intake/downpipe/catback, at least as far as power mods are concerned.