logger 73
Active Member
Mild street 440 4bbl...question is should I run 2 1/2 or 3in exhaust? Tri-Y Schumacher headers is what I already have. Also should I install a "H-pipe" ? What does it do? I've heard both yes & no about a "H-pipe". Thanks
size & "H-pipe"
- Thread starter logger 73
- Start date
-
K.O. SWINGER
Meeting in the alley since 1976
H pipe will help remove drone and improve low end power it will smooth and equal out back pressure. depending on your RPM range and gearing would be my determining factors on piping size for me ...I would go 3 inch with 2.5 H pipe some will say that's to much but for me about right!!
Lonewolf3165
Living the Dream!
2-1/2" pipes with a 2-1/4" or 2-1/2" crossover("H") pipe. 3" pipe in a dual exhaust system is overkill for most streetable engines & will actuall hurt velocity.
chryslerman6772
Banned
i have a 440 in my dart with a 2.5 h-pipe exhaust system and tri-y schumaker headers. its works pretty nice
1968FormulaS340
Well-Known Member
demon seed
The Original Demon Seed
2 1/2" and X pipe (smoother flow than H) and yes 3" is overkill and a pain to route and install.
logger 73
Active Member
Thanks for all the info it really helps to have real life info from you all.Pics of the start of the project coming this weekend. 67 Cuda Fastback bought from original owner. Factory 273 automatic. Keeping all the original parts but switching to a 440
3 inch is what you need. And X pipes are useless. Get an H. I have 3 inch with Tail pipes. and tips with 2 1/2 H. Mine don't hang down or hit anywhere with a large solid roller. Sounds like a new Cadillac and flows like the Hudson river during a flood.
roccodart440
Well-Known Member
- Joined
- Apr 19, 2010
- Messages
- 6,800
- Reaction score
- 3,578
Schumacher's have a 2.5 collector. That si the size exhaust you should run. X pipe is best, H pipe is better than nothing.
Hyper-Performance
Late Apexer
H-Pipes inherently improve low-end torque by balancing exhaust gas pressures between the the sides. Most push-rod motors can benefit by using an H-Pipe.
X-Pipes tend to blance the flow between both sides and can increase horsepower on higher revving motors. The modern modular motors see benefit from the X-Pipe design.
Larger pipes are not always benficial to exhaust/horsepower/torque. It is all a matter of flow. It is possible to inhibit flow by using too large of a pipe. I would think the 2-1/2" would be more than adequate in your application.
X-Pipes tend to blance the flow between both sides and can increase horsepower on higher revving motors. The modern modular motors see benefit from the X-Pipe design.
Larger pipes are not always benficial to exhaust/horsepower/torque. It is all a matter of flow. It is possible to inhibit flow by using too large of a pipe. I would think the 2-1/2" would be more than adequate in your application.
famous bob
mopar misfit
I had dual 3" straight off the headers, to two 3" flowmasters, turned down in front of the rear wheels on my 92 GMC w/ a 406 sbc in it. it was a little too loud, but ran like a bat out of hell. high elevens - 1.50 sixty foots
350 turbo 10 street slicks, 3:73 gears.----yea I came back to mopar! bob:happy1:
I don't like any kinda crossover. I'd love to see independent testing on them. They make the exhaust sound less crisp, IMO. I spoke with Doug Thorley many years ago, and he said that in some instances, they actually lost HP and TQ and that he preferred exhaust systems without them.
The only information as far as testing and dyno specs I've seen on them are those from the companies that make them, or from magazines that those same companies sponsor. I would be really careful spending money on anything where the only evidence of benefit has a direct impact on sales.
The only information as far as testing and dyno specs I've seen on them are those from the companies that make them, or from magazines that those same companies sponsor. I would be really careful spending money on anything where the only evidence of benefit has a direct impact on sales.
i understand the concept of easier routing of the pipes keeping them smaller and the concept of not adding unecesary weight with pipes bigger than they need to be,go with whatever size the collectors are no point in building bigger or smaller and i still havent seen a prostock car with an X or H pipe.
64drtGt
Slant Six Lunatic
famous bob
mopar misfit
whatever the collector size is, is usually optimum,"open", w/ some collector tuning(length) if u ran the same size as the collector thru some configuration of pipe and the same size muffler, it still would be below optimum for full h.power for those headers. mine will be 3 1/2" , thru 3 1/2" turbo inserts, w/ a set of 3 1/2" straight thru shortys that only drop the decible level by about 2, figure both will be quieter than a 3 1/2" flowmaster, and flow way better, won`t have but a $120 tied up in all of it, not counting the headers. will be interesting!!-bob:burnout::burnout:
famous bob
mopar misfit
by the way, 68 hemi roadrunners came out w/ an h pipe "stock".
there must be some benefit , other than low end torque, because mine had more than than any tires could handle back then
ops:!---just sayin!--bob
"Mild street build" 440.
Would need more on the cam to plug into 'pipemax' but from past experience I can tell you that discplacement plus power band rpms are primary factors in determining the sizes needed. Guessing that the rpms of interest and peak Hp is below 6000, probably below 5500, would favor a smaller diameter (like 2.5"). 3" is a big jump up in terms of cross sectional area. I'd not do that without more data or as an experiment. If so, I'd test it from the collector to the first interuption (H- pipe, X pipe or muffler).
H-pipes and x pipes are somewhat useful for 'sharing' the mufflers, but measurable value seems to depend on placing in the right location to create harmonics that help in the rpm range of interest.
My guess is the factory either found a performance advantage with H-pipe and/or used it to break up a drone resonance.
Would need more on the cam to plug into 'pipemax' but from past experience I can tell you that discplacement plus power band rpms are primary factors in determining the sizes needed. Guessing that the rpms of interest and peak Hp is below 6000, probably below 5500, would favor a smaller diameter (like 2.5"). 3" is a big jump up in terms of cross sectional area. I'd not do that without more data or as an experiment. If so, I'd test it from the collector to the first interuption (H- pipe, X pipe or muffler).
H-pipes and x pipes are somewhat useful for 'sharing' the mufflers, but measurable value seems to depend on placing in the right location to create harmonics that help in the rpm range of interest.
My guess is the factory either found a performance advantage with H-pipe and/or used it to break up a drone resonance.
i would bet the factory used the H-Pipe for soundtuning in one way or another,most probably to break up a pipelength to stop unwanted frequensys from forming and keaping the hated droning sound inside the car away.
my previous post about crossovers and prostock was more directed towards the crowd that thinks a crossover of some sort is needed to make the most power.
roccodart440
Well-Known Member
- Joined
- Apr 19, 2010
- Messages
- 6,800
- Reaction score
- 3,578
Originally Posted by 1Fast340
i understand the concept of easier routing of the pipes keeping them smaller and the concept of not adding unecesary weight with pipes bigger than they need to be,go with whatever size the collectors are no point in building bigger or smaller and
i still havent seen a prostock car with an X or H pipe.
Agree with the collector coment
Every prostock i've seen runs opwn headers with evac tubes. Kind of need to compare apples to apples here.
ir3333
Well-Known Member
..the factory installed an H pipe to reduce noise,this allowed them to use a less restricted muffler.
Larry Sheppard AKA mopar Direct Connection head engineer says there is no performance gain but an H pipe will reduce sound and should be placed 12 - 14" behind the collector.
Me..i don't know.
Larry Sheppard AKA mopar Direct Connection head engineer says there is no performance gain but an H pipe will reduce sound and should be placed 12 - 14" behind the collector.
Me..i don't know.
Lonewolf3165
Living the Dream!
Velocity is what you want to achieve through the system. The fact is that too large of a pipe diameter will actuall hurt velocity. Remember that we have to blow all the exhaust through a set of pipes nearly the whole length of the car through 2 at least partailly restrictive mufflers. Too big of a pipe causes the velocity to drop. Another thing is in an efficeint exhaust system the exhaust gases need to be kept hot all the way through the system until they exit. Hot exhaust gases move faster. Smaller pipes keep the heat in better & therefore the gasses move faster than a larger diameter pipe would. The natural movement is from a hotter area to a cooler area- heat disipation helps flow. That why racing headers are thermal coated on the inside & the outside. To keep the heat in the gases longer & keep it flowing. What you don't want to happen is the gasses expand & lose their heat before they exit the system, then the velocity stalls & you just have a wall of exhaust that has to be pushed out of the system.
Any body ever run or seen at the track guys running Torque Tubes on their open headers to run quicker? Same theory.
Unless you are running a fire breathing dragon on the street, 2-1/2" exhaust should be plenty in a dual system. If it were a single system then 3" is good.
Any body ever run or seen at the track guys running Torque Tubes on their open headers to run quicker? Same theory.
Unless you are running a fire breathing dragon on the street, 2-1/2" exhaust should be plenty in a dual system. If it were a single system then 3" is good.
velocity is important for primary tubes on the headers,collector sizing is also important but after the correct collector lenght has been achieved all you want is minimum restriction.
383Duster
Well-Known Member
2 1/2 pipes with a 21/4 H pipe with Schumacher headers on my 383. I had the H put in, it solved noise issues and made the sound more balanced with my turbo mufflers. I really couldn't tell any performance difference, my motor is stock.
Lonewolf3165
Living the Dream!
The system with the highest velocity would be the system with the least restriction. What changes in air flow in the header collector that doesn't happen in the rest of the system?
famous bob
mopar misfit
disagree on 2 1/2" pipe. had 3" on a stout 406 sbc,had tail pipes put on it, out behind the rear wheel wells. wasn`t mandrell bent. ( BENDS CAME OUT ABOUT 2 1/2"). I could tell the diff. when I started it and backed it out of the muffler shop. put about a hundred miles on it, pulled them off, went w/ two 3" into 3' flowmasters, then dumped before the rear wheels. get this, those tailpipes made almost 3 tenths diff. on the dragstrip!
if anyone wants 3" dual tailpipes for an 88-98 chev-gmc pick up, (mufflers back, (will have to move gas tank to runem) I gotem layin in the barn, not even rusty yet>-------------bob
-
