IDI Exhaust.
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Junior User
Joined: Aug 2008
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IDI Exhaust.
Does any one know the best size exhaust for our IDI non turbo engines? Has anyone had any of there trucks on a chassis dyno. I know that bigger is better but is that always true. Im going to have my exhaust done tomorrow, iS 3" BIG enough. Also in a non turbo where is the proper place to put a pyro sensor? Also are flow masters the way to go, they are a chambered muffler, I assume they are also low back pressure, thrush has a new version too?
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From: Clarksburg WV
Exhaust manifold is where the pyrometer probe should go, whether n/a or turbo.
Also, for exhaust sizing...just treat it like you would a big block gas V8. 2.5" true duals are probably good, or you could do a 4" single like some people do.
There's lots of mufflers out there, so pick whatever you want. Flowmasters sound good but I've been told they don't flow as well as you'd think. I'd recommend trying Hooker Aerochambers...supposed to be really good. Or Hooker Maximum Flows, which are straight through.
Also, for exhaust sizing...just treat it like you would a big block gas V8. 2.5" true duals are probably good, or you could do a 4" single like some people do.
There's lots of mufflers out there, so pick whatever you want. Flowmasters sound good but I've been told they don't flow as well as you'd think. I'd recommend trying Hooker Aerochambers...supposed to be really good. Or Hooker Maximum Flows, which are straight through.
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Joined: Dec 2007
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Some people on here have argued that for a naturally aspirated IDI the largest exhaust you should have is about 3" to mitigate risk of a phenomena known as exhaust scavenging. I think if you search the forum for that term you will find more.
Postmaster
Joined: Mar 2008
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From: Sweet Home, OR
Jim Allen had a post, or answered a post, on here about the scavenging effects and correct size tubing. He DEFINITELY knows his stuff about this.
He also did a couple of magazine articles for $ Wheel Parts magazine (Off Road Adventures). You can get back issues from them @ there ORA Magazine site or just go look at the two articles on-line. They were in the April & May '08 issues.
You can also subscribe for FREE!
4Wheel Parts is about the only GIANT company I frequent and it's because they give me the magazine for free. I generally like to buy from the 'little guys". I also like to support the advertisers on here because they're the reason this site is here for me to come to. I don't think people pay enough attention to where they're bread's buttered, so to speak.
He also did a couple of magazine articles for $ Wheel Parts magazine (Off Road Adventures). You can get back issues from them @ there ORA Magazine site or just go look at the two articles on-line. They were in the April & May '08 issues.
You can also subscribe for FREE!
4Wheel Parts is about the only GIANT company I frequent and it's because they give me the magazine for free. I generally like to buy from the 'little guys". I also like to support the advertisers on here because they're the reason this site is here for me to come to. I don't think people pay enough attention to where they're bread's buttered, so to speak.
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This guy has been in the exhaust business for years I mean like 50. And his suggestions go right along with yours, he is going to do a 3 inch y-pipe and 3 inch back to a small resonator and then go up to 3.5 to the tail pipe. He said it will get rid of the raspy tone, that makes it sound like a gasser. One other question, Im going to turn up the IP tonight, what kind of EGT"S am I looking for, normal cruising and then loaded I tow a 28 foot enclosed loaded with a car. Around 8500 LBS.
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Postmaster
Joined: Oct 2005
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From: Clarksburg WV
I don't think you CAN get rid of the raspiness. Is he gonna run a muffler along with the resonator? I have a 3" downpipe on mine that steps up to 4", and then a 4" hooker maximum flow (as mentioned in my sig). It still sounds like a gas V8 once you get much above 2000 RPM.
Hell, for awhile I had a huge Magnaflow on there (7" round case, 30" long) and it STILL sounded like a gasser at higher RPM's when you were on the throttle.
Oh and by the way- I wouldn't really recommend turning the pump up more than one flat unless you live in an area that IS flat (no pun intended). I turned mine up 2 flats at first, and I couldn't even maintain speed on big hills on the highway because my EGT's were so high.
Hell, for awhile I had a huge Magnaflow on there (7" round case, 30" long) and it STILL sounded like a gasser at higher RPM's when you were on the throttle.
Oh and by the way- I wouldn't really recommend turning the pump up more than one flat unless you live in an area that IS flat (no pun intended). I turned mine up 2 flats at first, and I couldn't even maintain speed on big hills on the highway because my EGT's were so high.
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i turned the pump up a flat today and the smoke rolls out of them pretty freely
Posting Guru
Joined: Oct 2005
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From: Powell River B.C.
I have installed headers on my N/A truck with 3 inch cross over, to a y into a 4" aftermarket system from a 97 PS. I like the power my truck produces, fuel is turned up 1& 1/2 flats, EGT can get up to 1200 with a big load and up hill pulling.
Most dramatic difference I noticed with the bigger exhaust was much more responsive accelleration. More power actually only comes from burning more fuel. I have been able to acheive that by increasing the air in by ram air- big scoupe, and very efficient exhaust flow.
Most dramatic difference I noticed with the bigger exhaust was much more responsive accelleration. More power actually only comes from burning more fuel. I have been able to acheive that by increasing the air in by ram air- big scoupe, and very efficient exhaust flow.
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Joined: May 2007
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From: Troy MT
not really but before i put the exhaust on it it already had the same setup but the pipes were broke off at the back of the glasspacks, but it has great power with the pump turned up about .75-1 flat, did it the other day and its amazing the difference it makes.
i made it up a hill w/out trying at 60 that it normally struggles to do 55 up
i made it up a hill w/out trying at 60 that it normally struggles to do 55 up
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Joined: Feb 2007
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uhm... when i bought my '92 7.3 na the exahust was cut off just before the muffler. it was deafening so i took it to a shop and had a big muffler and single 2.5 inch pipe run out the back. i assumed that since it had 2.5 in it would be 2.5 out. it hasn't seemed to affect power or fuel economy. atleast not noticibly. it does bug me that it looks pretty small. it may be too small for it, i dunno. maybe next year i'll run bigger.
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