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how restrictive is a press bend?

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Old Sep 14, 2010 | 01:50 PM
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Default how restrictive is a press bend?

I'm looking into a hooker aerospace chamber. A local guy I know owns a shop and said if I buy the muffler he can put it in cheap with his bender. I doubt its mandrel so guessing its a press bender. How restrictive is press bends? Is it worth $300 more to get the mandrel pipes with the muffler? All I have done so far is LTH, ory, and a lid
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Old Sep 14, 2010 | 01:52 PM
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Why not just buy the $80 muffler & have him just install it in place of the factory muffler. Thats what I did. Saved a bunch of cash & it still sounds great.
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Old Sep 14, 2010 | 02:08 PM
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Well that was my plan. But he was going to bend me new pipe for like an extra 50. So altogether it will be around 125-150. I know the guy thru a guy I work with so we give each other side work til our jobs pick back up. So he's giving me labor free. So I'd rather get new pipes but don't know if press bends are restrictive to the point where I don't want them
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Old Sep 14, 2010 | 04:40 PM
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Not with the power your making, there is a small power loss, but nothing to spend $300 on to get back at this point. Wait and spend the $300 on other parts for now. As long as he is a competant exhaust fabricator, you'll be fine.
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Old Sep 14, 2010 | 04:59 PM
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Well I haven't spent anything yet. Didn't know if it was worth spending more to get the mandrel bends. How much of a power drop should I expect?
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Old Sep 14, 2010 | 09:13 PM
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Depends on how bad your exhaust guy is, it all depends on how far the crush bends restrict/compress the overall tubing diameter, and disrupt flow. On a street car that isn't seeing alot of track time, mandrel bends are not entirely necessary. I would have to ask my exhaust guy, but it would obviously vary based upon construction/fabrication quality..i expect 5hp or less on a stock street car. On a modified FI car exhaust flow becomes more critical....on a car with no cats, not as big of a deal as there is very little restriction at that point, so a little backpressure wouldn't hurt torque any.
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Old Sep 14, 2010 | 09:37 PM
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With the mods you have, and with just swapping a muffler, I don't think you'd see any power difference between mandrel and non-mandrel exhaust bends.
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Old Sep 14, 2010 | 10:30 PM
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They sell prebent mandrel sections at summit. I have used these to fab a bunch of complete exhausts from the headers back.
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Old Sep 14, 2010 | 11:13 PM
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just have them cut and weld, unless your stock exhaust is falling apart there is no need to get new piping bent
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Old Sep 15, 2010 | 01:00 AM
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You can semi mandrel small bends by filling the exhaust pipe with sand and using the press bender. There are videos on youtube explaining this.
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Old Sep 15, 2010 | 08:25 AM
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Well its not "falling apart" but I think it will just look better to redo the piping. Thanks for all your input guys. I am thinking to look into the madrel elbow bends on summit. Do you know how many I would need? And the welds won't restrict airflow will it? I think the elbows is the cheapest way to get the mandrel bends. I figure if possible I want it to be done right from the beginning.

Last edited by bwilde86; Sep 15, 2010 at 08:40 AM.
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