Hi all,

I need to build 4" for my 88. I know I can get that Sinister kit but for 400$ (plus shipping to canada,plus taxes) I'l be over 550+CAD when it gets here.

I can goto the truck store, buy some bends and pipe and make my own for 1/3 of the price.

Question :

Who has made 4" over the axle and what radius bends did you use to make the tight bend up and over ? Pics would be awsome as well.

Maybe to simplify things I can do a bullet muffler under the car and dump the exhuaust before the axle. How is gnd clearance for something like that ?

Either way I need 4" out the back with no muffler OR end it under the car with a bullet muffler.

thanks.

 

No offense, but it's almost useless running a single 4" at how much it's going to cost..
You could do dual 2 1/2" for that much.

 

Don't have to run it over the axle, you can run it sraight and under it giving better flow. Plenty of other stuff that hangs that low.

I run it that way, then up and out the center back.

 

why do you feel the need for a 4 inch exhaust? just curious.....

 

Several members have installed 4" over the axle. It's a tight fit going over the Pan Hard Bar brace but it's been done. I have thought about this myself and I think I would modify the brace to clear the pipe. Some guys take the brace out but I don't recommend that. I've run the exhaust out before the axle for customers who wanted big exhaust on the cheap. That works too. I just prefer to keep my IROC looking clean and my ride height is too low for side outlets anyway. I'll soon go dual 3".

If you have the old exhaust system, use it as a pattern and tack up the 4" from bends and pipe. Set it in place over the axle to test for fit. You can cut the tacks and make adjustments as needed.

 

And about that, you cut the end of the Y pipe back so it not pointing towards the center of the car, so it shoots down the right side, in that valley area between floor and sides I got a bullet CherryBomb, exhaust runs down the side in that valley, then takes a lazy turn in, under the axle then shoots up to the center of the rear bumper. Keeps it a nice straight shot as much as possiable.

reason for the axle loop over top is that where the movement is, going under, only going rock crawling could hit the pipe. And plenty of room for even a 4in setup. lots of stuff hangs that low.

 

Thanks guys.

I am in the process of building a turbo 6 and am shooting for 500+HP, larger exhuast is needed.

Dual 2.5" doesn't flow as much as single 4". Plus I only have one turbo so single is all I need.

There is a local guy selling a complete bullydog 4" kit for a cummins for 145$, I might pick that up and just hack it up...

Right now I have 3" off the turbo, no muffler to a side exit behind the front tire. it is too LOUD.

 

to the cat area, and with a single dump before the driverside bumper, i used 5 90's, cut a few of them to the angles i needed, and welded them up, took me 3 tries to get everything the way i wanted it, but i just cut and reused the bends i already had. you need a short piece of straight pipe too, 4' is plenty.

Its all a bit tight, but with careful planning, it all fits. Mine is tucked up in the tunnel, and i lost no ground clearance at all.

plan to make a slip fit connection behind the rear seat, before you go over the axle. It will make life a lot easier. I put a slip fit after the muffler too, just because that stuff is a bit heavy and working with small parts without a bunch of bends makes fitting it all in the much easier.

I dont really have any good pics of it right now

single 3.5 would probably be enough for you (3" would probably work too FWIW).

 

Why do we even have a Search Feature on TGO, if nobody uses it?

Here is just 1 thread about a 4" cat-back.
https://www.thirdgen.org/forums/exha...h-exhaust.html

 

Dude, I already read that thread 3 days ago and saved the pics, but my question was more about the type of bend (radius) required to make the bend over the axle.

You can get 4" mandrel bends with 5 or 6 different radiuses, from very tight to larger radius... I was wondering which one works... I can't really eyeball it that well unless someone that has already built one chimes in with what they bought....

 

I just built one...it will work. It is very tight but possible. I used another bend section right where it goes over the upper panhard brace.

https://www.thirdgen.org/forums/exha...4-exhaust.html

No offense to the true dual crowd...dumping the exhaust under the car sucks! It is too loud, the interior noise will give you a headache and they hang so low that they drag on every bump or dip.

 

Oh one more thing...check Summit Racings site...they are blowing out some Edelbrock bends. These are the ones I used and you can't beat the price.

 

yeah i noticed that, they want an arm and a leg to ship across to canada....

 

Hehehehe how mine ended up like that, at first it was a "side pipe" exhaust that dumped before the rear tire and I then got sick of the noise

 

Blame it on Canada & their Import Fees, not on Summit.

I've shipped to Canada & it is ridiculous! I've shipped to Canadians friends in the states, because it is cheaper for them to cross the border & got get it, than get it delivered to their address in Canada!

 

Actually I blame UPS those guys are crooks, USPS is a much friendlier company to deal with when it comes to shipping to Canada.

If you really want to make your own 4" over the axle just use 2 90* like they have in thier sinister kit, it's the same as my mufflex kit but without the muffler and that's pretty much what they use.