jagone

I have a 91 rs that the I pipe has rusted out on and I am going to get a complete catback. I know most people will say go with the hooker system but I already have a 90 rs w/ flows and I am going to go that route again on the 91. My question is will a 2.5" mandrel bend flow more than a non mandrel bend 3" I-pipe. Will I even be able to tell much difference with the stock setup? This car only has 27k miles so all I plan on adding, other than the exhaust, is an open element breather.

Mark A Shields

If you don't plan on building the motor up the 2.5" will be fine for that engine, actually 3" would be a little big. Plus the fact if you get a 3" that isn't mandrel bent, it could really hurt the flow.

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AJ_92RS

I would guess, since I never measured a 3" non-mandrel bend, that the most it'll dent it is 1/2". That's probably being nice. It's probably more than that.

Well if it is only 1/2", that 3" pipe will then flow as much as a 2 1/2" mandrel bent. Mandrel bends are the way to go. Even if you only run a 2" pipe, get the mandrel bends.

If you run a 3" pipe into a non-mandrel bend, then all your gonna have is the performance of a 2.5" exhaust, with the cost and added weight of a 3" pipe.

Make sense?
AJ

jagone

yeah it makes sense. I guess then if you think they will flow roughly the same then it becomes a matter of cost. I have priced the cat-back system I want and it is $328 from Jegs or Summitt (american thunder system), or I can have it done locally with the 3" non mandrel bends for $220, and I don't have to do the work. Decisions decisions...

deadbird

To bad you can't weld,, you could compromise between pinch bends & mandrel using conduit.

Yes,, i said conduit,, the same crap they use for electrical applications.

Pinch bends really don't shrink that much unless you're bending something past 90°

If you could weld (or had a buddy that could), a "3in." catback would cost $40 plus whatever muffler you decided to buy

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[This message has been edited by deadbird (edited December 13, 2001).]

Z28 Boy

this may be a little nit-picky, but will the fact that a non-mandrel bent pipe has those ridges hurt performance?

we can assume that a 3" non mandrel bent pipe will only lose 1/2" then it will effectively be the flow of a 2-1/2" pipe.

BUT..if you consider the interuption in flow of the ridged (and we arent talking ridged for her comfort here....) part, is it possible that they could mess up teh flow even further?

just an idea...

-brian

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[This message has been edited by Z28 Boy (edited December 14, 2001).]