Busy weekend
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From: Kent WA
SO, Spectramac, do you think there would be NO benefits to the 4-inch "expansion chamber" and reducing it to 3" right at the entrance to the muffler. You think I'll get just as much improved flow if I reduce it down to 3 inches just after the y-pipe?
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From: Quesnel, BC, Canada
not IDI relative...but I remember a couple years ago I read an article in a mustang mag where they ran 3" off the collectors into a 3" x-pipe and 3" into the mufflers, then ran 2.5" out for the tail pipes. They made more power than open headers and the with the same set up in all 2.5".
So remember as exhuast cools it travells slower, and its definately going to be hotter at the y pipe than it will be at the end of the muffler. I think the 4" off the y-pipe into a 3" muffler/tailpipe will make it sound pretty good. Youll get a deeper tone for sure, and Ill bet that 4" section is better than a 3" section.
So remember as exhuast cools it travells slower, and its definately going to be hotter at the y pipe than it will be at the end of the muffler. I think the 4" off the y-pipe into a 3" muffler/tailpipe will make it sound pretty good. Youll get a deeper tone for sure, and Ill bet that 4" section is better than a 3" section.
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From: Monroe, WA
I'm just saying that they will run so much better going from 2.5" with a horribly restrictive muffler to a 3" with a free flowing resonator that you'd never feel the difference going up to 4". I just took a 4" pipe out of a dodge and replaced it with 3" the other day and the guy couldn't tell the difference. I just can't bring myself to put a downsize in a pipe, no matter what the dyno told me. 
If you made it with nice flowing tapers and such like a motorcycle pipe, that could be cool.
If you made it with nice flowing tapers and such like a motorcycle pipe, that could be cool.
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From: Kent WA
Originally Posted by pud
not IDI relative...but I remember a couple years ago I read an article in a mustang mag where they ran 3" off the collectors into a 3" x-pipe and 3" into the mufflers, then ran 2.5" out for the tail pipes. They made more power than open headers and the with the same set up in all 2.5".
So remember as exhuast cools it travells slower, and its definately going to be hotter at the y pipe than it will be at the end of the muffler. I think the 4" off the y-pipe into a 3" muffler/tailpipe will make it sound pretty good. Youll get a deeper tone for sure, and Ill bet that 4" section is better than a 3" section.
So remember as exhuast cools it travells slower, and its definately going to be hotter at the y pipe than it will be at the end of the muffler. I think the 4" off the y-pipe into a 3" muffler/tailpipe will make it sound pretty good. Youll get a deeper tone for sure, and Ill bet that 4" section is better than a 3" section.
https://www.ford-trucks.com/forums/5...installed.html
I don't expect the difference to be dramatic, compared to just doing the 3" pipe all the way. But either way, I am going to have to buy a 4" to 3" reducer - whether I use it as the collector for my 2.5" downpipes, or as the reducer right before my muffler, and collect the downpipes into a straight section of 4" pipe. I will NOT be laying out the cash for a 4" muffler and tail pipe when I already have the brand new 3" ATS parts already bought and paid for.
Basically I'm trying to decide whether the performance/sound difference between the two options is worth the few bucks it will cost for about a 6' section of 4" pipe.......
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Cheaper, I have agree with Spectramatic, you will not feel the difference on the mods you're describing...I'm not an engineer and I know dragsters have fine tuned their engines by legthening or shortening the the tubes on headers but your comparing results of a high reving gas engine on a light wieght car to a low reving diesel on a truck. Please correct me if I'm wrong....
-IDI max tourqe @ approx 1800 RPM
-IDI max hp @ approx 2700 RPM
These engines were made to work under load not for horse power. Well thats my 2 cents.
-IDI max tourqe @ approx 1800 RPM
-IDI max hp @ approx 2700 RPM
These engines were made to work under load not for horse power. Well thats my 2 cents.
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From: Kent WA
Originally Posted by bc6.9
Cheaper, I have agree with Spectramatic, you will not feel the difference on the mods you're describing...I'm not an engineer and I know dragsters have fine tuned their engines by legthening or shortening the the tubes on headers but your comparing results of a high reving gas engine on a light wieght car to a low reving diesel on a truck. Please correct me if I'm wrong....
-IDI max tourqe @ approx 1800 RPM
-IDI max hp @ approx 2700 RPM
These engines were made to work under load not for horse power. Well thats my 2 cents.
-IDI max tourqe @ approx 1800 RPM
-IDI max hp @ approx 2700 RPM
These engines were made to work under load not for horse power. Well thats my 2 cents.
FWIW, the 4.0 liter Jeep motor is not a high revving engine in a lightweight vehicle. They are an I-6 and although they are a gasser, they are more like a smaller version of IDI in terms of designed performance parameters. Their torque figures are higher than their HP figures, and at lower RPMs because they are made for low end grunt - not so much for pulling as for slow speed crawling.
The principles of gas flow, temperature, pressure, and speed are pretty universally applicable. I'm just wondering if there would be enough difference to be worth spending a few extra bucks to do it this way. You guys are probably right. The gain from the stock to the 3" system will probably be 95% of what it would be to go from the stock to the 4" to the 3" and the difference might not even be noticeable. Just a thought......
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From: Kent WA
Yeah, well, you know how it is. Thinkin', thinkin', - always thinkin' 
I just have to wonder what that number is. Like I said, in the last post, I'll probably get 95% of the potential gains just from the 3"...... but I can't help wondering, is it really 95%.... or is it actually only 90%..... or could it even be as much as 99%....?
Just hate the idea of possibly leaving an appreciable amount of performance "on the table" when the cost is small....
I just have to wonder what that number is. Like I said, in the last post, I'll probably get 95% of the potential gains just from the 3"...... but I can't help wondering, is it really 95%.... or is it actually only 90%..... or could it even be as much as 99%....?
Just hate the idea of possibly leaving an appreciable amount of performance "on the table" when the cost is small....
Last edited by CheaperJeeper; Oct 26, 2006 at 07:49 PM.
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From: Kent WA
Originally Posted by Spectramac
Bad part is you'll never know unless you do them both.
Last edited by CheaperJeeper; Oct 26, 2006 at 09:08 PM.
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From: florida
all this posting about the advantages and dis-advantages of a K & N air filter reminds me of my situation. for years i only run K & N filters on motorcycles, never a problem and i don't go crazy on maintenance on them. for the last two summers my 91 ford IDI has been in ruidoso, nm. the elevation there is 7000 ft. this old truck has been smoking and running bad. i got fed up and put a K & N filter on it, and what a difference it made. everything else pales in comparison. i do plan to put the dual air intake on the truck too. i currently have something like dave sponagle has. my truck has no turbo.
