Mandrel bends

I need to remove the rusty exhaust under my CRX and we have no good exhaust shops in the area. The cheapest quote I got was $200.00+ for crimp bends. The shops around here have a reputation for screws thru the floor pan for hangers, low hanging pipes and mufflers, etc.

Any good sources for inexpensive mandrel bends? The last ones I got were about 5 years ago for my Spitfire build. The cheapest I found was thru JC Whitney. I dont need Stainless that I could'nt weld anyway. Im thinking 2- 2 1/2".

On a related matter- any suggestions for a performance muffler thats not too loud for the above?

My local muffler shop has mandrel bends in stock for about the same price as the online stores - and if I need just one more, I can have it in hand 15 minutes later. Worth asking.

If the local shops don't have them, check Jeg's or Summit. The problem is not the cost of the pipes, it's the shipping charges. But if the local clowns can't supply them then that's what you will need to do. The Walker Dynomax has been my go to muffler for the best balance between noise and HP.

http://www.stans-headers.com/ i buy some stuff from them from time to time when i need to do dwarf car headers. they'll even bend it to the angle i need.

also http://www.coneeng.com/

http://www.mandrelbendingsolutions.com/servlet/StoreFront

Local shop to me. Check out the "builders kits". Good stuff.

Check out www.mandrel-bends.com You can sign up for his B stock list that gets emailed out about once a week. His B stock mild steel bends are 50% off. On the B stock page is an explanation of what constitutes B stock.

i bought a set of 8 mandrel bends, 2x U, 4x 90, 2x 45 i think, in aluminized steel 2" off ebay for around $75 shipped or something close to that. thick enough to weld easily, i think they were around .065" or so, just helps to wire wheel off the 1/4" of coating for a cleaner weld.

Why can't you weld stainless? Stainless wire in a 120V MIG works just fine for exhausts!

93gsxturbo wrote: Why can't you weld stainless? Stainless wire in a 120V MIG works just fine for exhausts!

I only have oxy / acetylene. I'll have to check the place with B bends.

I have used (and still get wholesale) vibrant brand u-j bends. for 1 low price you get a 180 degree bend & a 45 degree. I can't hotline from my phone easily, but Google vibrant u-j

Kendall

umm hate to bring this up but have any of you ever actually tested mandrel bends on a car as opposed to a flow bench. because of the nature of an exhaust system normally there is no to lil gain. as in a 700 hp mustang 414 ci windsor. 3 inch mandrel versus huth style bends 10 hp on back to back runs... 10 hp on a 700 hp vehicle is ummmm nothing......

What year is your CRX? If it's a second gen, why don't you just buy one of the pre-bend systems that are available? If you were closer, I have a 2" mandrel bent B-pipe that is otherwise identical to stock I don't need, and an HKS system that needs the muffler replaced. But I'm thinking shipping would be prohibitive. BTW, 2-1/2" won't provide any benefit over 2" in your case.

KATYB wrote: umm hate to bring this up but have any of you ever actually tested mandrel bends on a car as opposed to a flow bench. because of the nature of an exhaust system normally there is no to lil gain. as in a 700 hp mustang 414 ci windsor. 3 inch mandrel versus huth style bends 10 hp on back to back runs... 10 hp on a 700 hp vehicle is ummmm nothing......

Yeah, but he doesn't have a 700hp mustang, he has a CRX and any small gain IS noticeable.

We bought all the bends for our Formula SAE exhaust from these guys:magnum force for pretty cheap.

porksboy wrote:

93gsxturbo wrote: Why can't you weld stainless? Stainless wire in a 120V MIG works just fine for exhausts!

I only have oxy / acetylene. I'll have to check the place with B bends.

Stainless welds no different than mild steel. Braze it. It works fine.

In reply to mblommel:

what im saying it is is less than 1 percent. on the intake side of things and headers yes it makes a difference but on the overall exhaust system not so much. reason being, exhaust is not a constant flow its pulsed thus doesnt make that much of a difference if any.

KATYB wrote: In reply to mblommel: what im saying it is is less than 1 percent.

10HP is 1.4% of 700HP which is actually not less than 1 at all.

It is 7.7% of the 130HP a CRX has.

I previously worked for a sister company to Supertrapp, and we were located next door to them. They sponsored my race car for a couple seasons, which was a close to stock '89 Civic si. We dyno'd the car with quite a few different setups, but using mandrel bent 2" exhaust in place of 1-7/8" crimped exhaust (everything else unchanged) provided an increase of 2hp. That's huge on a car that was dynoing around 112hp. Overall, we gained 8hp over the stock setup. And another 3hp switching to Redline oil, believe it or not.

In reply to bravenrace:

Gah! That's so close to being directly applicable... But 2" has >12% more cross sectional area than 1 7/8"... That had to make up for some/most of the difference, no?

At the very least, it makes it hard to draw a conclusion...

An exhaust made with madrel bends but welded then polished down to be in visible to the naked eye just looks cool when I roll underneath to change my oil.

Bravenrace, it is a 90 year model. Any chance you are coming to the Mitty? Any suggestions on what prebent one wouldnt make the car sound like a consipated bumble bee with gas?

ransom wrote: In reply to bravenrace: Gah! That's so close to being directly applicable... But 2" has >12% more cross sectional area than 1 7/8"... That had to make up for some/most of the difference, no? At the very least, it makes it hard to draw a conclusion...

Don't forget he said the original pipe was crimped 1 7/8", so in the crimped areas they would be less than the full 1 7/8" diameter straight sections.

Giant Purple Snorklewacker wrote:

KATYB wrote: In reply to mblommel: what im saying it is is less than 1 percent.

10HP is 1.4% of 700HP which is actually not less than 1 at all. It is 7.7% of the 130HP a CRX has.

I think what KatyB is pointing out is that going to mandrel bent on a 700hp engine got 10hp or about 1%, so don't expect to get 10hp on a 130hp car but more like 1-2hp. Bravenrace backed this up with his experience of gaining 2hp on a 112hp car (at the wheels, I assume) when upsizing the exhaust and switching to mandrel bent, so duplicating the existing design but just switching to mandrel bends won't get you much.

Bob

Giant Purple Snorklewacker wrote:

KATYB wrote: In reply to mblommel: what im saying it is is less than 1 percent.

10HP is 1.4% of 700HP which is actually not less than 1 at all. It is 7.7% of the 130HP a CRX has.

While I am strongly opposed to arithmetic errors, I think you are missing her point. She's saying that, even in a very powerful car with few other power "bottlenecks," the benefit is very small (1/70th in her example.)

In a car that is at a much lower state of tune and has a much lower power output it is not reasonable to assume that the power "boost" will be the same 10 horsepower. The relationship here is likely to be roughly proportional, not a simple 10 HP boost regardless of input. It is much more reasonable to expect that "boost" to be around 1/70th of the CRX motor's output.

If the right bends give the 700 hp engine 10 hp, and you guys are saying they give a CRX the same 10 hp, will they give my lawnmower 10 hp?

edit: what shmidlap said. I type slow

Well, the muffler fell off in traffic on my way home this evening. Gotta do something this weekend.

Buy earplugs?

Got the ear plugs.