+1
Right on, not even mentioning that pipe diameter usually isnīt restriction, mufflers are...

 

^agreed, Adrian. That is a really cool exhaust system. I hope to replicate at least part of it.

 

https://www.rx7club.com/showpost.php...&postcount=197

 

lol ok I hope to replicate the part where it collects to 3". The rest will be a bit different.

 

well I've got my dyno appt tomorrow with the 3" collector back no more expansion chamber. Same dyno I did 189.65 on. lets see if it actually worked. Honestly I'm going to be pissed if I lost power removing the expansion chamber.

 

I hope you didn't loose any power. Thanks for wanting to get it dynoed to find out.

 

It will be interesting to see the result. If you lost power, it will mean you've found a setup that works better than this one which is very possible. At the very least you'll learn something and that's always a good thing!

 

Thanks for your reply, can anyone else please comment and give out some inputs please on the picture I posted??

The collector is different now and the car feels/sounds better!

Thanks.

 

I'll let the pic speak for itself make of it as you will.
Same timing, same jetting, 8* cooler, 39% more humidity today.
The blue line was the last time I was at Drift office. and the redline is today al the data is in the photo.

here's the problem. I just didn't take out the expansion chamber. I also changed the header. i was using an old rotary Engineering header painted with high heat paint and wrapped. The new header is an ISC header that has been ceramic coated. You can see the ISC header is straighter off the block and makes a better more gradual turn. I think that's where I picked up the extra 4 ft. lbs. of TQ. Plus you can touch the new header it's soo much cooler in the engine bay now. I think the header added the extra power. I think the expansion chamber was acting as an exhaust box in the same way that the 3" magnaflow that replaced it is...

 

I'd call that close enough as to make no effective difference, except for the burp between 5500-7000.

Interesting.

 

the burp is clearly from the better header. I think the 4" expansion chamber didn't do any better or worse than the 3" muffler that's there now. Actually i like it better w/o the chamber. the flatter TQ curve is much more driveable.

 

It would be interesting to see the expansion chamber on the new header.

 

Yea. It's too bad Mike only has 1 header left and he's not making anymore. And it's too bad my dynomax bullet was blown to ****. LOL!

 

I've always looked at his design and thought the bullet muffler would die in that location. I guess that answers that!