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Engine Specific Info and Questions => IDI Engine => Topic started by: watsongs on April 27, 2005, 09:18:18 pm
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My cat converter has a large hole in the bottom, probably from sitting in tall wet grass for 3 years. I'd like to replace it with a straight piece of pipe - does anyone know the pipe diameter? Looks to be about 2", but I'm not sure, and I don't have the best way to jack up the car yet, so I only want to go under 1 time.
By the way, cherry bomb mufflers are kind of cheap; anyone ever put one in?
Thanks for the help
Greg
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How about the size?
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How about the size?
for diesels... the bigger the better, tho I doubt if a 1.5l needs 4", 2-2.5 is likely optimum, since they do rev higher than the 1.6/1.9's
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How about the size?
for diesels... the bigger the better, tho I doubt if a 1.5l needs 4", 2-2.5 is likely optimum, since they do rev higher than the 1.6/1.9's
The bigger the better on turbo diesels. I don't think you're going to see much gain, possibly only torque loss on an NA diesel if you go much larger. 2" would probably be very generous.
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The 1.5L diesels had either 1 1/2" or 1 5/8" exhaust. If you're replacing the whole system, go with 1 3/4" or maybe 1 7/8" on that engine. Anything bigger won't help power much, might hurt midrage torque and will just weigh more.
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No overlap on the cam means no scavenging effect from 'tuning' the exhaust. Therefore, no real downside to a bigger pipe. Two inch pipe is real cheap, but unless you plan to turbocharge the engine, going bigger than that won't help with only 50-60 hp on tap. If you do plan to boost it, then 2.5" would work great - and it's still cheap.
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I'm just tring to replace the resonator for now -
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No overlap on the cam means no scavenging effect from 'tuning' the exhaust. Therefore, no real downside to a bigger pipe. Two inch pipe is real cheap, but unless you plan to turbocharge the engine, going bigger than that won't help with only 50-60 hp on tap. If you do plan to boost it, then 2.5" would work great - and it's still cheap.
Exhaust tuning doesn't come from overlap scavenging, it comes from the pulses that happen when the exhaust valve opens and shuts, so a diesel can benefit from that just like a gas engine. This is really only to do with the header or manifold and downpipe design, though.
The exhaust tubing diameter (after the header/downpipe) aren't dictated by scavenging, more from displacement and hp production potential. Oh, I have never seen/felt a loss in midrange or low-end response on a diesel from using a 2" exhaust. Fabricating a smaller mandrel bent one wouldn't be worth the cost over simply buying a Techtonics 2" setup off the shelf.