What size exhaust best on all all motor ZE

[RobertoCarlos]

I am running a ZE with a 2 1/4 inch exhaust now and am wondering if upgrading to 2 1/2 will ney me any more hp or torque with an all motor setup. I may be going wiht nitrous later in the summer so I know it would help wiht that. Thanks in advance

[rebel2k4]

I would just leave it as is. It is mandrel bent correct? even if its not I'm sure its fine.

I'm running stock exhaust and I'll be hitting 250-300 whp in my car, just wait and see.

I know 2.5" can support around 500 whp, so 2.25" shouldnt be much less.

[babyblueMX3]

Originally posted by rebel2k4:
I would just leave it as is. It is mandrel bent correct? even if its not I'm sure its fine.

I'm running stock exhaust and I'll be hitting 250-300 whp in my car, just wait and see.

I know 2.5" can support around 500 whp, so 2.25" shouldnt be much less.

300whp with stock exhaust...it'll be tpp restricitve..according to Corky Bell's book...you shouldn't be running under 2.25" and for that kind of power I would be running 2.5...just my 2 cents..and Corky's

[RobertoCarlos]

I am hoping to be running about 250 hp wiht nitrous so I figured 2.5 inch would be a bit better flow. I read somewhere that you are only supposed to go about .25 inches bigger wihtout forced induction and wiht F/I you should go at minimum .5-1 inch bigger.

[RobertoCarlos]

Oh yeah by the way its crush bent not mandrel bent. Where I am located there is no one who does mandrel bent exhausts.

[bubbaflaat]

that sucks, you can't get mandrel bent exhaust!! Crush bent looks so ghetto! I'd try and find a place that will mandrel bend the piping. Alot smoother flowing. I bet 2 1/4 mandrel flows just as much as 2 1/2 crush bent, just because the velocity would be slower on the crush bent. I have 2 1/4 mandrel bent piping, and a high flow cat.

[RobertoCarlos]

It is almost impossible for me to get mandrel bent piping unless I can find a place in the next province over which is like 6-7 hours away. There used to be a place an hour away from me but when I went to get it done there was a note on their dooer saying " Went out of business". That sucked.

[Gro Harlem]

When I get my headers, I'm going with 2.5" crush-bent tubing on my KLZE. I'm going with hotshot headers, a 2.5" freeflow Carsound cat, 2.5" resonator and a 2.5" JUN titanium muffler for my exhaust setup.

When all that is done, it should dyno between 170-185 at the wheels & 155-170 torque. I plan on dyno'ing it in July sometime when there is another dyno meet.

[Taras]

Can't you get pre-bent mandrel pipe pieces and then get someone to weld your exhaust for you. I know that it is not as good as a whole pipe, but does the trick. I beleive some online places might have it.

[RobertoCarlos]

Thanks for the tip JDM but what is to say that you can find the right pieces already bent for our cars. I will give it a try though.

[RobertoCarlos]

Gro how come you are getting hot shot headers instead of those hot shot knock offs online. I want to get hot shots too but they ar e too expensive to bring into Canada. The last time iasked they were going to be like 825 dollars. Would ne nice though.

[ikarus1]

Originally posted by RobertoCarlos:
Gro how come you are getting hot shot headers instead of those hot shot knock offs online. I want to get hot shots too but they ar e too expensive to bring into Canada. The last time iasked they were going to be like 825 dollars. Would ne nice though.

Probably because the knockoffs don't exist in great quantity yet.....

[Gro Harlem]

Buying seperate mandrel bent peices is soooo expensive. I tried that before and ended up spending about $150 in tubing alone. Then another couple hundred to have a shop cut and weld it all together.

IMO a 2.25" mandrel bent would work well. A 2.5" crush bent would also work well. Crush bent may/maynot promote scavenging of the exhaust gases (this is a good thing) due to the restriction in the bends. THere are only 2 90 degree and 1 45 degree bend in the exhaust system on the MX3, I don't think those bends are going to hinder the flow too much.

[RobertoCarlos]

I figured the crush bent was not going to have a huge effect on performance. I think I am going to go with 2.5 inch and see how it goes. You are right though in saying that it is expensive to get mandrel bent. I could understand if you had like 1000 hp in your car and you were trying to squeeze out an extra few ponies then I could merit spending that much money on exhaust work. Thanks for all your replies.

[TsiMiata]

99% of the people who think they are getting mandrel bent exhausts are not getting it. There are four common ways to bend tubing.

The first is crush- You take a shoe with the bend you want and ram into the side of tube to make the bend. Here is a cheap one from harbor freight-
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=35336

The most common type, which most people refer to as crush but it isn't, is this type-
http://www.exhaustbenders.
com/automotive-shop-equipment.html
I'm not sure what the technical name of this type is. They are pretty much mandrel benders minus the mandrel. They dont reduce the ID as much as a crush bender but still arent as good as a true mandrel type bender.

Another type is a roll bender. I've never seen these used anywhere but in manufacturing-
http://www.thomasregisterdirectory.com/tubing/tubing_list.html?display=listing&az=73500662&pn=04990602&search_type=product&search_string=Tubing&seq=1&uuid=THezsrch&ezlocation=http: //www.thomasregisterdirectory.com/tubing/pipe_tube_machines_benders_0041026_1.html

A mandrel bender is a VERY expensice piece of equipment. A good new one costs upwards of $20k. I have yet to see an exhaust shop with a true mandrel bender. A mandrel bender looks almost like a machine an exhaust shop would have with abig difference. They are usually much longer and have the ever coveted MANDREL. The mandrel is just apiece that goes inside the pipe and keeps it from collapsing whe nthe tube is bent. The mandrel is hooked to a hydraulic ram so it can be pulled out of the tube after the bend. I wish I could find a good pic of one right now but I can't.

It just annoys me to see people talk about having a custom mnadrel bent exhaust. In reality they really don't.

<small>[ June 07, 2004, 06:39 PM: Message edited by: TsiMiata ]</small>