hp difference in crush bent vs. mandrel
hp difference in crush bent vs. mandrel well i have a set of qtp headers begging to be installed on my car, but i can't decide on the rest of the exhaust. i know that keeping the loudmouth won't sound good (i've heard it in person) so its either ory and some kind of muffler to replace the resonator or true duals. i know a guy who can do 2.5" td's out the back for just slightly more money as a qtp ory and replacing the resonator. but how well will crush bent duals flow? the guy has done this setup on a '94 Z28 and it is the nicest over axel setup i've seen. i'm planing on 2.5" orx and sweet thunders, i know that will sound hella sweet! but will i gain any hp over the lm setup?
Crush bends suck and will never find their way onto my car! A crush bent 2.5" true dual exhaust will flow worse than a 3" single exhaust. If the search button would pull up older posts, I'd show you dyno's of significant gains going from a crush bent TD, to a single y-pipe.
Originally Posted by Redneck Z
Crush bends suck and will never find their way onto my car! A crush bent 2.5" true dual exhaust will flow worse than a 3" single exhaust. If the search button would pull up older posts, I'd show you dyno's of significant gains going from a crush bent TD, to a single y-pipe.
+1.....mandrel bent all the way.
Originally Posted by Redneck Z
Crush bends suck and will never find their way onto my car! A crush bent 2.5" true dual exhaust will flow worse than a 3" single exhaust. If the search button would pull up older posts, I'd show you dyno's of significant gains going from a crush bent TD, to a single y-pipe.
Here are the calculated areas assuming a .065 wall thickness
Single 3" pipe has an area of 6.466 sq. in.
Mandrel 2.5 True duals have a combined area of 8.819 sq. in.
Crush bent 2.5 x 2" oval tubing True Duals have a combined area of 6.958 sq. in.
As you can see, crush bent true duals have a half sq. in. more area than a single 3" mandrel bent pipe, not to mention you still get the scavanging effect from the X or H pipe.
If you have the means, I still highly suggest mandrel bends, however, they wont choke you out as bad as it might seem.
thanks for the replies. some dyno comparisons would help, but guitsboy has some good info. i could try to buy some pre bent pipe and have it done with that, but i'm not sure if he would go for it, it might be harder to fab up like that. i'm sure it would be more expensive too. i want duals mainly for sound, but i don't want a dumped setup. if anybody else has any info or dyno numbers please let me know asap.
Originally Posted by GuitsBoy
Please substantiate this with evidence. As for the dyno comparisons, there may be another factor coming into play here. Perhaps the center of the X pipe narrows down to a single 2.5" pipe thus creating the restriction. If that were the case, its due to a faulty X pipe and it wouldnt matter if it were using mandrel bends.
Here are the calculated areas assuming a .065 wall thickness
Single 3" pipe has an area of 6.466 sq. in.
Mandrel 2.5 True duals have a combined area of 8.819 sq. in.
Crush bent 2.5 x 2" oval tubing True Duals have a combined area of 6.958 sq. in.
As you can see, crush bent true duals have a half sq. in. more area than a single 3" mandrel bent pipe, not to mention you still get the scavanging effect from the X or H pipe.
If you have the means, I still highly suggest mandrel bends, however, they wont choke you out as bad as it might seem.
Here are the calculated areas assuming a .065 wall thickness
Single 3" pipe has an area of 6.466 sq. in.
Mandrel 2.5 True duals have a combined area of 8.819 sq. in.
Crush bent 2.5 x 2" oval tubing True Duals have a combined area of 6.958 sq. in.
As you can see, crush bent true duals have a half sq. in. more area than a single 3" mandrel bent pipe, not to mention you still get the scavanging effect from the X or H pipe.
If you have the means, I still highly suggest mandrel bends, however, they wont choke you out as bad as it might seem.
Originally Posted by Redneck Z
Don't forget about the turbulance and associated energy/hp loss that crush bends cause.
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I started with crush bent 2.5" duals dumped when I put on my Pacesetters. I went from 13.62 @103 to 12.98 @ 107.7. My butt-meter told me I gained a lot as well. I think I did pretty good and I doubt I would have gained much more with mandrel bent. Now I have mandrel bent to the mufflers and crush bent behind. I'll fix it some day, but it works for now. And I can always take the pipes off behind the mufflers and run mandrel/dumped if I want to be really LOUD.
i don't think crush bent true duals would show a noticeable loss in performance compared to a mandrel bent setup. simply because there really aren't that many sharp bends in a GOOD true dual setup.
i think the only time you MIGHT see a difference would be a sloppy 3" crush bent true dual system (+ x pipe) vs. a mandrel bent 3" (+ x) over the axle comparison.
i think the only time you MIGHT see a difference would be a sloppy 3" crush bent true dual system (+ x pipe) vs. a mandrel bent 3" (+ x) over the axle comparison.
Originally Posted by MDoe8
do you think a larger diameter crush bent setup would equal that of a smaller mandrel bent setup tohugh? I'm thinking of going 2.75" crush bent vs. 2.5" mandrel bent
Tech Resident
Joined: Jan 2006
Posts: 5,117
Likes: 3
From: Philly
just buy a TSP true dual system with sweet thunders. that, i believe is mandrel bent and only costs $400. then, just have the exhaust shop cut off the turndowns, weld pipe onto it and bring it out the back. problem solved. prolly be a hella cheaper too.
mandrel bend maintains the perfect (for example) 2.5" diameter all the way through. A crush bent is just that, crushed. It's like taking a hose and putting a kink in it, only it just blocks off a minimum amount of diameter on our setups.
Anyone have any other input on the power difference between a 2.5 mandrel and a 2.75 crush?
-Mike
Anyone have any other input on the power difference between a 2.5 mandrel and a 2.75 crush?
-Mike
Well, my ecxhaust has to be custom made anyway. It's not going on an fbody. There is no such thing as true duals on my car that aren't custom. I know someone who can make it wth crush bends for dirt cheap, that's all.
-Mike
-Mike