Not another exhaust question!

B

benracin

New member
I'm doing the debate about going under or over the axle on my 1st gen. I already have the muffler (dynomax I believe) so I'm basically looking at how to get from header to muffler in the rear and since I'm a cheap DIY'er I'd like to do this with out visiting an exhaust shop.

If I were to order up some straight exhaust pipe to do the under the axle route can I make any bends I need basically with a mapp torch and some "gentle" persuasion?

I'm also looking at the ISC full set up and I may just fall back on that because of ease. But it sounds to me that a lot of people are just running straight pipes under the axle and getting good power. Can it be done cheaper? Somewhere I read that going over the axle might take a little power away but I'm not sure about that one.

I guess my main concern is cost, then ease. Sound doesn't matter too much to me. Quiet would be cool so that I could run it in my garage without feeling guilty, but these cars sure sound cool on the track!!!

Thanks folks. I know this topic has come up several times but I'm going for price conscious. I got a wedding to afford darn it!
 
Well, I would go with the ISC stuff. My 2nd gen car had a RB racing header and a fairly well designed 3" straight pipe on it...then I got the ISC header, mid and rear sections...

I found 5 hp and 1 ft/lb on the dyno. The key is the expansion chamber design (not just the EC but the POSITION of the EC). These are essentially 2-strokes ya know.

AB

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Andy Bettencourt
New England Region, R188967
www.flatout-motorsports.com
 
I currently have a RB header on the car so I was kind of considering just getting the mid and rear sections, not sure if they would bolt up the RB header. I also have a crack in that header and was kind of thinking about having that welded up. Is that really worth the cost savings or am I just going to end up with a re-cracked header? Of course if they don't all mount together I'm kind of loosing the point aren't I. I sort of feel like I'm going to end up just getting the ISC sections just like you did Andy.

Can we say, tax return? *gulp*
 
welding a cracked header got me thru one season only. these things run hot.

i started with a under axel system. i have since changed to over. i can now change springs without dropping exhaust. I also found exhaust acted like a droop liniter on the right rear under hard braking.

dick
 
You could buy "U"- Bends and "cut and paste" a system together (by welding) with your straight pipe.

I'm not sure whether the U-bends that are widely available are of sufficient wall thickness for a Rotary exhaust, however.

The last time I worked on a Rotary exhaust pipe, I think we used something like real PIPE.

Cheers.
 
I migged my collector using mandrel bends from RacingBeat and straight tubing that I bought from Dillsburg Aeroplaneworks. Wall thickness is 0.125, if I remember right. I went over the axle to avoid panhard/axle interference issues.

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Dave Youngren
NER ITA RX7 #61
 
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