Straight Pipe
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Trailering
Joined: Nov 2008
Posts: 24
Likes: 0
Straight Pipe
I am considering a straight pipe for my truck. I was told by a local exhaust shop that i cannot run straight on my truck because i will not have enough back pressure for the turbo. Correct? BS?
Truck is a 1994 f250 7.3 idi turbo, 4x4 auto.
Thanks
Truck is a 1994 f250 7.3 idi turbo, 4x4 auto.
Thanks
More Turbo
Joined: Jan 2008
Posts: 679
Likes: 2
From: Vancouver B.C.
I have read that a straight pipe and or exhaust thats too big can hurt your low end performance as scavanging is at work when your turbo is not spolled up... but tjc transport is rite, a turbo diesel doesn't require backpressure or the scavanging efect it suplies under boost or ful throttle... atleast thats what I heard
i ain't rite
Joined: Mar 2005
Posts: 65,450
Likes: 5,520
From: Marlboro Mental Hospital.
small exhaust pipe and muffler equals slow turbo spool-up.
large pipe and no muffler equals free-spooling turbo.
free-spooling turbo equals more power.
with the 2 1/2 inch pipes out of the turbo to the muffler, and 2 1/2 out to the rear of the truck i only got 210 hp on the dyno. it ran this way for 3 days.
with 26 inches of 3 inch pipe from the turbo to the splitter, then 3 inch pipe to each of the 4 inch stacks with no mufflers, i had 325 hp. it ran this way for 17 years.
with the current setup, 3 inch out of the turbo to a 3 inch flowmaster delta 50 series into the splitter to the stacks is 255 hp. it has been in this configuration for 4 years now.
large pipe and no muffler equals free-spooling turbo.
free-spooling turbo equals more power.
with the 2 1/2 inch pipes out of the turbo to the muffler, and 2 1/2 out to the rear of the truck i only got 210 hp on the dyno. it ran this way for 3 days.
with 26 inches of 3 inch pipe from the turbo to the splitter, then 3 inch pipe to each of the 4 inch stacks with no mufflers, i had 325 hp. it ran this way for 17 years.
with the current setup, 3 inch out of the turbo to a 3 inch flowmaster delta 50 series into the splitter to the stacks is 255 hp. it has been in this configuration for 4 years now.
i ain't rite
Joined: Mar 2005
Posts: 65,450
Likes: 5,520
From: Marlboro Mental Hospital.
it is not so much a just a pipe deal, you also need to turn up the fuel delivery some, and modify the air intake also. without a larger intake air supply and more fuel, a large exhaust will only flow as much as it can get into the engine.
then you will need a pyrometer to monitor the exhaust temps so you don't melt down the engine.
it is a vicious cycle. you add one thing, and need to add 2 more to get it to work properly.
then you will need a pyrometer to monitor the exhaust temps so you don't melt down the engine.
it is a vicious cycle. you add one thing, and need to add 2 more to get it to work properly.
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Trailering
Joined: Nov 2008
Posts: 24
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the pump is turned up and it has a turbo, the factory for turbo. i'm planning on a pyrometer and boost gauge soon. I'm not planning on sled pulls or diesel drags just a little more power to tow every once in a while.
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i ain't rite
Joined: Mar 2005
Posts: 65,450
Likes: 5,520
From: Marlboro Mental Hospital.
with a stock turbo,setup the down-pipe looks like it was run over by the truck before it was put on. i don't think you will see any difference in the way it runs with a 4 inch pipe. if you were to replace the down-pipe with an aftermarket ATS 3 inch pipe, you will notice a big improvement in the way it runs, and probably see a 20-30 hp increase with no muffler and a straight pipe exhaust.
Dave Sponaugle knows alot more about the ATS systems, and has pictures of the stock down-pipe and the ATS pipe.
i will see if i can direct him over here to answer your questions on the ATS system better than i can.
Dave Sponaugle knows alot more about the ATS systems, and has pictures of the stock down-pipe and the ATS pipe.
i will see if i can direct him over here to answer your questions on the ATS system better than i can.
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Post Fiend
Joined: Nov 2003
Posts: 21,285
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From: Nutter Fort, WV
Here are two pictures.
ATS turbo outlet left, stock Ford right
ATS down pipe left, stock Ford right
As for back pressure, the less back pressure you have, the faster the turbo will spool and the more heat you get out of the engine which lowers EGT considerably.
A muffler is not really needed on a turbo equipped engine.
The turbo does a rather good job of chopping up the exhaust pulses, which is what a muffler does.
So all a muffler is good for on a turbo equipped truck is more weight and less performance.
Some states require a muffler to pass inspection, so the best option there is run a muffler you can see straight through.
ATS turbo outlet left, stock Ford right
ATS down pipe left, stock Ford right
As for back pressure, the less back pressure you have, the faster the turbo will spool and the more heat you get out of the engine which lowers EGT considerably.
A muffler is not really needed on a turbo equipped engine.
The turbo does a rather good job of chopping up the exhaust pulses, which is what a muffler does.
So all a muffler is good for on a turbo equipped truck is more weight and less performance.
Some states require a muffler to pass inspection, so the best option there is run a muffler you can see straight through.
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