Thats my delima....


I here that the long primary is the best... but what would happen if I ran dual all the way out without collecting???


Thanx,Laterz, Andrew

 

Not sure, but the '86-92 mazdatrix system is uncollected for the 6port engine. They claim it is 20%better torque from 2000rpm I think, and more highend also. Forget the full figures, but must have a highflow intake also ofcourse. I run long tube custom made headers for my bridgeport. Made highend much better. But it really hurt lowend too, probably had something to do with the fact its a bridgeport??

 

If you run it all the way out your exhaust will sound like a little machine gun. (each individual pulse creating it's own noise, instead of being homogenized into a more steady hum)

You'll also lose stable backpressure which could have adverse effects on the 5th & 6th ports if you're running a 13B.

 

12a not worring about sound...


I will doit this way.. dual all the way out...


now I just need a header.. then I am ALL set...ALLL set!!!!!

 

If you're running a stock motor, I'd go with the short primary setup. Better torque curve for street driving, and quieter, too. The long primary systems are most effective on street-ported motors, and even then, the gain is all top-end. I have run both on stock port motors, and I like the short primary system better as it is also cheaper and lighter. I have a long-primary setup right now, minus the header and muffler. It has two presilencers and the collector pipe at the rear, all set up with hangers to fit stock rx7 mounts. All that's needed is a Racing Bleat "road race" (uncollected) header, and a muffler will need to be welded aft of the collector section, or flanged. It's a bit rusty, but perfectly servicable. I've been thinking about selling it, but I'd rather not ship it, too heavy! So someone would need to come get it in Springfield, Oregon. I would trade it for a Racing Bleat '80 RX7 header and mini presilencer, in decent condition. In fact, if someone came up here, I could probably make it worth their while if they were looking for pre-RX7 rotary parts. Just a wild thought.

 

I've got a dual all the way out on my REPU except for a little mini 'H' pipe where the header would normally collect in a short primary system. It's also got six Rotary Performance glass packs (they went our of bussisness years ago). It sounds very good and has lots of bass at idle. The closest thing I'd say it sounds like is RB's street port exhaust. Pretty cool! However, it's extremely heavy and doesn't bend over the axle very well (it has wear marks where it hits the axle housing and the shock). I'm going to redo the exhaust someday and delete one run of three glass packs and install them on my Cosmo as it needs an exhaust too. I'll also smooth the bend over the axle. I suspect my REPU will get a little quieter and a lot lighter. It should have more power too since its engine is currently in my MG Midget project and it actually revs more freely with a short primary exhaust system (I can't drive the MG yet, but things are looking up!).

So that's my opinion of a full dual pipe exhaust system that was poorly made some 11 years ago for an REPU that hasn't been on the road since '96. At least its parts live on in others.

 

So what every one is saying, is the earlier the exhaust collects, the earlier there is torqe?


So if it was uncollected, it would have power WAY WAY WAY high!!! So thats why the "street port" system is collected infront of the axle. Because RB thought that would best suite the rev range of a SP.......





hmm......... so since its a stock port, I will go with a short primary system...... but when I half bridge, and have street it, I will go with dual all the way over the axle, then collect before leaving...


Thanx, Laterz, Andrew

 

Mine used to collect right before leaving too. I cut off the Y pipe and ran two pipes straight out under the bumper. It didn't get any louder and still sounded the same. Probably because of the 'H' pipe.

 

i use the rb header andi think it's a long primary?? got it used. ahaha, i dunno, the collector is like almost halfway to the back of my car. must be. anyways, from there i am running a straight pipe (no cats) 2 1/4" to a huge tsudo muffler. sounds nice and deep at idle, but holy crap when i'm hittin 8000 rpm's people say it sounds like an airplane going by hahahah, REDICULOUSLY LOUD!!!! great great great HP GAINS, although i don't feel it till about 3500 rpms. doesnt bother me. i still own up on some honda ***!

-zac

pm me and i'll get a pic of it for you, my whole setup so you can see what i'm talking about. only cost me 70 bucks to get it all welded and bent on.

 

Currently I'm running a short primary header system (no name header, kind of homemade, 2.5" no cat, no presilencer to a greedy S.P. stainless steel muffler. Not too loud but it's way louder than stock. This in my opinion is the most streetable yet powerful combo possible besides a racing beat heavy exhaust system on a stockported engine. I have designed plenty of systems and they are all noisy compared to the racing beat system. The trick is the stainless steel presilencers from racing beat...that's the only way it will be quiet enough.

Next week I'm getting a mindtrain stage III header, should free up some high end HP but I think it will be a bit louder than now.

 

well since my other name some how stoped working, here is my new name



i also have a nameless header, but im going to run dual all the way until right before the axle, where im going to(if i can find one, sigh, help me out here) put a dual inlet, single outlet flowmaster right there, and then single over te axle, and then it will Y out the harley tips i have, since they have this silencer things in them...


anyways, Thanx, Laterz, Andrew

 

I don't think there is going to be space for a flowmaster before the bend over the axle. Unless it's close to the header.