True Duals or keep it single
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From: Grapevine, TX
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Nice to see someone actually knowledgeable about exhaust sizing. (Jim)
In the old days, carbs, the factories set the engines a bit rich, so when getting rid of the stock exhaust, adding headers, duals what have you, the engines picked up decent power. Freeing the exhaust allowed a better A/F ratio = more power.
With todays FI and computer control, the motors are pretty much dead on with the stock restrictive exhaust. The real gains in freeing up the exit will come with a custom tune.
Exhaust tube size also applies to headers. Most commercial headers are too big for street driving, and I have never seen an off the shelf set of equal length tubes.
In the old days, carbs, the factories set the engines a bit rich, so when getting rid of the stock exhaust, adding headers, duals what have you, the engines picked up decent power. Freeing the exhaust allowed a better A/F ratio = more power.
With todays FI and computer control, the motors are pretty much dead on with the stock restrictive exhaust. The real gains in freeing up the exit will come with a custom tune.
Exhaust tube size also applies to headers. Most commercial headers are too big for street driving, and I have never seen an off the shelf set of equal length tubes.
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Joined: Feb 2004
Posts: 10,390
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Nice to see someone actually knowledgeable about exhaust sizing. (Jim)
In the old days, carbs, the factories set the engines a bit rich, so when getting rid of the stock exhaust, adding headers, duals what have you, the engines picked up decent power. Freeing the exhaust allowed a better A/F ratio = more power.
With todays FI and computer control, the motors are pretty much dead on with the stock restrictive exhaust. The real gains in freeing up the exit will come with a custom tune.
Exhaust tube size also applies to headers. Most commercial headers are too big for street driving, and I have never seen an off the shelf set of equal length tubes.
In the old days, carbs, the factories set the engines a bit rich, so when getting rid of the stock exhaust, adding headers, duals what have you, the engines picked up decent power. Freeing the exhaust allowed a better A/F ratio = more power.
With todays FI and computer control, the motors are pretty much dead on with the stock restrictive exhaust. The real gains in freeing up the exit will come with a custom tune.
Exhaust tube size also applies to headers. Most commercial headers are too big for street driving, and I have never seen an off the shelf set of equal length tubes.
In addition, the commanded A/F's don't always result in actual A/F's for some calibrations (and there are hundreds of those).
To add insult to injury, even the stock shifting calibrations cripple the engine's ability by shifting too early ( resulting in the engine dropping into the next gear too low in the powerband) and too slowly (excess heat & slippage), poor TC algorithms etc, etc.
All in all - great 'soccer Mom' driveability - that twittering idiot Sarah would be proud.
So - almost ALL of the gains come from revised calibrations. Exhaust is not really a factor at all. Same applies to intakes. Caveat is a full-zoot long-tube/hi-flow/x-pipe true-dual replacement - for which tuning correction for O2 transport delay and large scavenging changes will likely be required anyway for best results.
Tons of corroborating data on this site - you need only go look for it. OR call one of the tuning shops listed in my siggie.
MGD
Last edited by MGDfan; Feb 12, 2011 at 01:40 PM.
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From: Schenectady, NY
Ok I got a new muffler and had it installed Saturday. I decided on a Dynomax Super Turbo muffler because I I liked what I read about it having good flow and being quiet. I was debating over muffler only or cat-back system, and I thought of a way to have the benefits of a cat-back without the extra expense. What I did was have the muffler shop install the muffler and a pipe going out the side before the rear tire..turned out pretty good. I'll put on pictures when I can.
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From: North Huntingdon,Pa.
no tuning changes done or NEEDED after i went back on dyno after having my true 2.25" setup installed, dismisses this theory
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If you didn't , then it's not a full system replacement; hence not enough to require correction.
IIRC, the stock exhaust manifolds are still yer largest bottleneck. Have you changed them?
BTW - it's not theory - it fact (w.r.t long-tubes as part of the system upgrade):
http://www.troyerperformance.com/cgi...no=122-622100s
^^^ "No tuning changes are required from using these longtube headers in 99% of the trucks we have installed them on, unlike some other longtubes."
Also: http://www.vmptuning.com/forum/showp...12&postcount=2
MGD
Last edited by MGDfan; Feb 17, 2011 at 07:21 AM.
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From: North Huntingdon,Pa.
that horrible oem y was the bottle neck, i tested back pressure at 2nd set of o2 sensors in cab with magnahelic up to 5400 rpms while driving - the stock cats and manifolds are not bottlenecks, testing proved it...
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BTW - This yours?
first off i'd like to thank mike,anita,crystal and dad-for just getting into the building-it is a top notch operation-mike is truly a consimate profeesional in his trade and the passion and analism? he has in his field is second to none.
first off ,after some pulls ,some things are obvious in my application,possibly a camshaft variation,the intake tract is restrictive as hell[dad is working on that,also the exhaust manifolds aren't meant for breating-one thing is duals = loss of tq-i know first hand they don't as i tow 6000lbs with it-i didn't have ud pullies on-just 93 tune-[no adaptive strategy obviously,true duals and and exit side of air cleaner opened up-my peak hp was 207.2 @ at a LOW 4200 rpms,tq was 279.68 @ 2500 rpms-ashame dyno doesn't show lower-most likely around 300 at that rpms.i've already preached about mikes part throttle tq results-i made 279 @2500 and it stayed high up till 4200 where it was 252-this just reinforces why it tows so well-i'll post forms when my scanner is working- here are some numbers of sweet spots-remember with it onl being a 2 valve and the bad things i mentioned -hopefully once pullies are on and air intake addresed-i feel 10-15rwhp and 15-25 ftlbs of tq are available
4000-201.51
4100-205.46
4200-207.20
4300-206.77
4400-207.14
4500-206.64
4600-205.05
4700-204.14
4800-202.77
5100-makes 192 then falls big time
2500-279.68
2600-273.36
2700-263.05
2800-257.31
2900-256.70
3000-257.1
3100-257.59
3200-262.42
3300-265.88
3400-264.08
3500-265.78
3600-268.38
3700-271.31
3800-270.2
3900-266.8
4000-264.6
4100-263.2
4200-252.57
on aclosing note- i can't emphasize the importance of data logging- if the air fuel#'s are off it could be not only detrimental to the engine but also could be more power there-mikes tune of tims was dead nuts on- no adjustments needed- 2wd 5.4 -air force 1,excalibur,sido magnaflow-2wd-263hp-326 tq-i beklieve rockpicks was 252 and 325-phil
first off ,after some pulls ,some things are obvious in my application,possibly a camshaft variation,the intake tract is restrictive as hell[dad is working on that,also the exhaust manifolds aren't meant for breating-one thing is duals = loss of tq-i know first hand they don't as i tow 6000lbs with it-i didn't have ud pullies on-just 93 tune-[no adaptive strategy obviously,true duals and and exit side of air cleaner opened up-my peak hp was 207.2 @ at a LOW 4200 rpms,tq was 279.68 @ 2500 rpms-ashame dyno doesn't show lower-most likely around 300 at that rpms.i've already preached about mikes part throttle tq results-i made 279 @2500 and it stayed high up till 4200 where it was 252-this just reinforces why it tows so well-i'll post forms when my scanner is working- here are some numbers of sweet spots-remember with it onl being a 2 valve and the bad things i mentioned -hopefully once pullies are on and air intake addresed-i feel 10-15rwhp and 15-25 ftlbs of tq are available
4000-201.51
4100-205.46
4200-207.20
4300-206.77
4400-207.14
4500-206.64
4600-205.05
4700-204.14
4800-202.77
5100-makes 192 then falls big time
2500-279.68
2600-273.36
2700-263.05
2800-257.31
2900-256.70
3000-257.1
3100-257.59
3200-262.42
3300-265.88
3400-264.08
3500-265.78
3600-268.38
3700-271.31
3800-270.2
3900-266.8
4000-264.6
4100-263.2
4200-252.57
on aclosing note- i can't emphasize the importance of data logging- if the air fuel#'s are off it could be not only detrimental to the engine but also could be more power there-mikes tune of tims was dead nuts on- no adjustments needed- 2wd 5.4 -air force 1,excalibur,sido magnaflow-2wd-263hp-326 tq-i beklieve rockpicks was 252 and 325-phil
Thanks for your posts, Phil & Brad.
It was a blast having Phil around, he was non-stop trying to figure out what would make that van produce more power - it did very well, but the mostly stock intake & factory pancake exhaust manifolds just cannot breathe worth squat in those vans. So it made excellent power numbers up until it just couldn't breathe any more, and was fun to have something WAY different on the dyno.
And yes, we gave Phil all of the first-vehicle-on-the-dyno "heart attacks" - such as when I pulled a bone-headed stunt and loaded up a set of files I had last been looking at (instead of his actual tunes) and promptly got an initial no-start - which of course, we quickly remedied and had a good laugh about. The first vehicle on these dyno events usually gives us some surprises of some kind, no matter what they may be, & I think we gave Phil a couple of extras before we were thru with it.
All in all, it was a lot of fun - though when it turns into a 3-day event it is always grueling on us here at Troyer Performance, and to a certain extent, those who hang around for more than a day as well. But thanks to everyone, great results and a good time were had, and we thank you all for coming!
It was a blast having Phil around, he was non-stop trying to figure out what would make that van produce more power - it did very well, but the mostly stock intake & factory pancake exhaust manifolds just cannot breathe worth squat in those vans. So it made excellent power numbers up until it just couldn't breathe any more, and was fun to have something WAY different on the dyno.
And yes, we gave Phil all of the first-vehicle-on-the-dyno "heart attacks" - such as when I pulled a bone-headed stunt and loaded up a set of files I had last been looking at (instead of his actual tunes) and promptly got an initial no-start - which of course, we quickly remedied and had a good laugh about. The first vehicle on these dyno events usually gives us some surprises of some kind, no matter what they may be, & I think we gave Phil a couple of extras before we were thru with it.
All in all, it was a lot of fun - though when it turns into a 3-day event it is always grueling on us here at Troyer Performance, and to a certain extent, those who hang around for more than a day as well. But thanks to everyone, great results and a good time were had, and we thank you all for coming!
^^^ https://www.f150online.com/forums/ch...ml#post2104515
So - have you changed anything since then as that suggests the 'pancake' exhaust manifolds are still a factor ...
MGD
Last edited by MGDfan; Feb 17, 2011 at 07:59 AM.
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MGD, I must not have made myself clear. I agree with what you said. I was referring to long tubes VS manifolds. The factories do tune for the stock exhaust. Although it is a complete compromise.
So for headers to have the most impact, you need a custom tune.
Primary tube diameter and length affect the torque curve.
So for headers to have the most impact, you need a custom tune.
Primary tube diameter and length affect the torque curve.
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Joined: Feb 2004
Posts: 10,390
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MGD, I must not have made myself clear. I agree with what you said. I was referring to long tubes VS manifolds. The factories do tune for the stock exhaust. Although it is a complete compromise.
So for headers to have the most impact, you need a custom tune.
Primary tube diameter and length affect the torque curve.
So for headers to have the most impact, you need a custom tune.
Primary tube diameter and length affect the torque curve.
Thanks.
MGD
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From: Schenectady, NY
Does anyone know approximately how much horsepower/torque can be freed up from replacing that y pipe? Is it more restrictive than the factory muffler? From the research I've done the factory muffler is restricted down to 1.75". One side of the factory y from what I've heard is about an inch, but the other side is 2.5? it seems to me it would flow better than the factory muffler because it has both sections of the y for air to flow through..did I interpret this wrong?