Exhaust

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rumblefish360 said:
Longer the tube, the more torque is made.
If the typical headers, the three tubes under the steering on the drivers side drag, chances are the car is just simply to low, regardless, header companies like Doug’s and tti offer a solution. They are not mid length headers.
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I'll run long tube headers then. Couldn't I raise the front end up via the torsion bars
 
rumblefish360 said:
Longer the tube, the more torque is made.
If the typical headers, the three tubes under the steering on the drivers side drag, chances are the car is just simply to low, regardless, header companies like Doug’s and tti offer a solution. They are not mid length headers.
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Is it true that 1 1/2" primary tube headers scavenge the combustion chamber faster than 1 5/8"?
 
Dan the man said:
I'll run long tube headers then. Couldn't I raise the front end up via the torsion bars
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Yes
Dan the man said:
Is it true that 1 1/2" primary tube headers scavenge the combustion chamber faster than 1 5/8"?
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Totally dependent on a list of variables. In short, engine size and ability and power. OR Every last part dependent.
 
Dan the man said:
Wouldn't 3" exhaust be over kill for my application?
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You asked:
Dan the man said:
wanting the best performance from the exhaust system.
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I answered;
AJ/FormS said:
I put a full-length dual 3"inch system on my car, with dynomax Muffs; no complaints
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You can do what you want.
A dual 3" Mandrel-bent system is as close to zero back-pressure as you are gonna get. And Zero back pressure is what your engine wants. Is it overkill? Probably. But you'll never have to change it out, and no matter what you do to your SBM,short of supercharging it, you will never have to wonder if it needs to be bigger, lol.
I even ran that same exhaust on my winter motor, a stock long-block, lo-compression 318LA with a BIG TQ on it and fresh-air; and she didn't complain about it either.
Besides all that, at the time I bought mine from TTI, the price was nearly the same as 2.5s, and I'm big on bargains, lol.
Put it this way, I've never been sorry, and I've never given the exhaust system a second thought, since 1999.
Yes it was a lil tight between the offset springs and the tank, but it's in there and it don't rub. I bought the ones with integral turn-downs and hung them out past the rear bumper ever so slightly.
If you buy headers that hang below the steering, over the next twenty years, you will likely replace them many times...... Unless you drive like an old man, watch the road like a hawk, never plow it around a turn, and never jump it.. And "trust me" with stock suspension; A-bodies plow....... until the back lets go, then they are sideways and probably still plowing. lol.
Yes TTIs or Dougs might be hard to install, but well worth it in the long haul. All it takes is just one time forced over a curb with stock suspension, and POW! you nailed it. Now you are making an appointment at the muffler shop, to spend Mo money.

BTW; if you have a torquey 360, equal-length long-tubes are not that big a deal. But since headers come that way............. it is what it is.
 
Dan the man said:
What is the best fitting headers for a "A" body? 318 with a 904 transmission. Mufflers? I'm not looking for the glass pack sound, wanting the best performance from the exhaust system.
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for a 67-up abody? tti or dougs headers will fit the best. mufflers are so subjective. everyone likes something different.. i like dynomax super turbos. friend has magnaflows that sound real good too.. may as well go 2 1/2" pipe while at it .
 
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A 2-1/2 open pipe can handle 600hp.
The muffler you choose to add might shorten that down a huge amount. Or not at all.

The best turbo mufflers are going to allow approximately 450hp before they become a restriction.
Then you have to look at the better chambered mufflers.
If your going to turn the screws on the engine for some serious power, look to the straight through mufflers like a Hooker Maxflow, Borla etc

A 2-1/2 is going to be quieter over a 3.
 
Dan the man said:
Wouldn't 3" exhaust be over kill for my application? 2 1/4" is just about right, 1 1/2" primary tube headers with the 2 1/4" exhaust system will scavenge the combustion chamber not only faster but more complete, doing this greatly reduces the chances of contaminating the fresh fuel mixture entering into the combustion chamber. I may have to use 1 5/8" primary tube headers. For the rpm range that my engine will be operating in I don't need big tube headers. Midlength headers may cost some low end torque from the research I've done and people that I've talked to. Is this correct or not?
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sounds like you're over thinking things....... again :poke: :thumbsup:
 
Dan the man said:
I'll run long tube headers then. Couldn't I raise the front end up via the torsion bars
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yes you could but the further you get from stock, the harder it will be to get the alignment in, and the alignment is only gonna be close in the straight ahead position. As soon as you turn the wheel or the suspension changes with bumps or dips, the alignment is gone. So you kindof want to keep her at least close to the factory spec, as to height. So, what I did was increase the T-bar diameter and increase the shock damping and installed a bigger Sway-bar all in an attempt to keep the suspension in the best operating window.
You could use taller tires....... but this messes with the scrub radius and is counter to handling. If the scrub radius gets to be too far from stock, the car will hunt with every ripple in the road , wandering from side to side and you will tear you hair out trying everything you can think of to correct this, and cannot. Only when the scrub radius returns to stock, will it become acceptable. Power-steering will exacerbate this.
Plus if you raise the front, you kindof have to raise the rear. And in the end you get a straight-line machine, that has to slow for the turns, and slow for bumps, and is all-the-time nervous, following every rut in the road.
Ok, mine was like that; maybe yours won't be, lol.
 
Dan the man said:
the 2 1/4" exhaust system will scavenge the combustion chamber not only faster but more complete, doing this greatly reduces the chances of contaminating the fresh fuel mixture entering into the combustion chamber.
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Um I don't think so.
>only the headers scavenge and only when operating at or near zero back-pressure.
The exhaust system into which the headers work, at whatever size they might be, will immediately affect scavenging.
>Scavenging is happening during the overlap period, when both valves are open just a small amount. If the header is working right, then;
at low rpm it will be trying to yank the Fresh fuel charge out of the plenum and straight across the piston, and into the primary pipe. And it will succeed, if the headpipes are adequate.
This is normal at low rpm, and is what helps to make hi-rpm power. If you don't need hi-rpm power, then you can either; give up the headers, or buy a different cam.
The step header is a good solution for a street car.
> Reversion is a function of when the intake valves close. During "reversion" the A/F charge is always polluted. Reversion ends about the time that the vacuum peaks. For typical street cams, this will be between 1800 and 2200. It is best to chose a cruise rpm that is above this rpm.
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IMO, the 3inch front pipes on my car serve a second function. They have 33% more heat-radiating area per foot than 2.25s. Those pipes are about 5 or so ft long, before they enter the mufflers. This helps the exhaust cool before it gets there, where the honking big 3"in/3"out 3-pass muffs cool it even more. Cooler exhaust is denser exhaust, occupying less space, and it is slowing down. It loses it's harsh tone and at Part Throttle, trickles out the 3" tailpipes nonchalantly....lol. The turn-downs finish the job, directing the sound downwards; and nobody complains about my exhaust volume.
At full-song, while the headers are doing their thing, it does get louder; but I have never been pulled over for a loud exhaust.
>I think of it this way;
>on every two revolutions, my engine has the capacity to fire, at WOT, 367 cubic inches of very hot exhaust, times whatever the expansion ratio might be, into the dual 3"system. At say 5:1, that is ~1.1 cubic foot@ 2rpm .... At 5000 rpm, and 90%VE, that maths to ~2400 cubic feet of expanded gasses, per minute. My engine has to cram all of that into a total of 14 square inches of dual 3" pipes.
>Or how about this; My throttle blade area might total 8.95 square inches. And they are passing air at ambient temp, and at 1 atmosphere. The exhaust at 14sq inches, is about 56% bigger.
Your pair of 2.25 headpipes total 7.95 square inches; already smaller than the 4bbl; and that air is now about 5 times expanded. So your pistons are gonna have to pump some to all of that hot air down to the end. That is work that could have been used to propel the vehicle.
I'm not saying that you have to have dual 3s.
What I am saying, is what my thinking was that led to my car having dual 3s. All-in-all, I gotta say, the dual 3" mandrel-bent system is the best that I have ever had. I got no complaints.
 
I'm not saying it's correct, or that you can trust anything a magazine says, but I remember reading an article in the late 80's in one of the big mags talking about exhaust scavenging. I was 18 or 19 at the time so I believed everything they said!

Basically, the article said to go to smaller diameter tail pipe to help scavenging. 2.5" main then 2.25" tail, etc. Something about the exhaust cooling so therefore exhaust velocity would drop and the smaller tail pipe from the muffler would help maintain velocity and this somehow helped. Wish I could find the article for reference.
 
Yeah I have read that too.
But here's my thinking;
after the muffler, the exhaust has already cooled and contracted, so maybe you don't need the bigger tailpipe. Is this true for all loads and rpms?
I doubt it.
 
Seems my 2.5 is just fine dumping out the rear of the car. 340 w/ 2.02 J heads to TTI headers with 3 in collectors, with TTI H pipe extension, to moroso spiral cores under back seat, to over axel TTI pipes.

if I didn’t hate wearing ear plugs all the time, I’d run open headers…
 
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