Calling All Mechanical Geniuses

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thats what my dad did with his 440 challenger


but he got pulled over turns out the cop just wanted to look at the car

no joke



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Even with just headers and tailpipes you have a phenomina called 'reversion' where a high pressure pulse is present in the headers when the exaust valve opens contaminating the incomming charge. The tuned aspect of headers minimizes the effect by scavenging but does not iliminate it.

18" individual upturned pipes through the hood might work but the guy at the inspection station will have a fit8)
andrew
 
My old 73 Camaro I had a built 327 in it, headers with a pair of hollowed out glass packs bolted to them and that was it. If I got pulled over I would show the cop the "new" (fresh red paint :snakeman: ) glass pack mufflers and tell him that they were just loud mufflers.
 
Hey J.R. You bring back the memories of Bellevue in the late 70's early 80's.

I remeber the cops used to be down on cars with glass packs back then. I did the same trick with my 65 880, it had a 383 with a mild cam in it, i hollowed out a set of new glass pack too.

The thing had a wicked reverb at about 2500-3000 rpm, with poping etc, i pissed so many cops off, never got a ticket.

Do you remember Officer Hershey of the Bellvue PD, Motorcycle cop? He was my nemisis.
 
the only way i know of to eliminate exh. sys. backpressure is to remove the exh.. 8 individual straight pipes will work though.
 
You don't want to eliminate all back pressure. Some is good, the key is flow velocity, thats why there are so many different tests out there. Be cautious of claims by muffler companies for backpressure and flow. You don't want to eliminate it all.
 
rp23g7 said:
Hey J.R. You bring back the memories of Bellevue in the late 70's early 80's. Do you remember Officer Hershey of the Bellvue PD, Motorcycle cop? He was my nemisis.
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Nope, I was born in 78 and was raised in Port Orchard. We has Officer Williams, he was an asshole!
 
Gotcha, Hershey was a overweight Motorcycle cop.

I think he was assigned to be the hot rod/muscle/classic car driven by a teen high schooler nemisis.

Go 1 MPH over the speed limit driving your 80 Firebird and he would stop you, and harass you.

I had backed into a post in my 64 Custom 880 and cracked a tail light lens.

If you havent seen one, it kind of bends around the side of the car. Real hard to find and in the early 80s, impossible. I knew of a 2 dr at Whiteside in Clearview, i had scavenged most of the parts off of.

Anyway, he stopped me for a cracked tail light. I said I knew it was cracked and was planning to go get a replacement that weekend.

He says hmm, let me look if its safe to drive that long. He goes back and "tests" it, breaking it. Needless to say, he gave me a ticket for defective equipment and a fix it ticket.

Nice guy huh?
 
Flyboy,
the more i research this the less there is to back the keeping of any back pressure in the system.
Please explain the physics of why you state dont get rid of it all.
Then we can discuss how.
Andrew
 
There is a way to attach individual exhaust tubes with 'Y's connected to other cylinders. Proper flow angles will create a vacuum at each individual exhaust valve . Its almost like a natural turbo using the physical properties of atmospheric pressures.
Only drawback is the gosh aweful web of tubing required.
I'm no genius and this isn't an original idea.
It's been done before.
There is no way to get absolute zero pressure though. It'll have to be either positive or negative pressure.
 
I think anyone that says the motor needs back pressure doesn't understand what's happening or why. Back pressure is a by product of a properly designed exhaust system. When the exhaust valve opens, the pressure in the cylinder moves into the lower pressure area of the exhaust system. As the pressure drops, and the piston starts moving up, the pressure in the cylinder resists the piston's upward travel, reducing net HP. Less back pressure would reduce this, but there is also an intake charge about to happen next, and it starts while the piston is still moving up in the cylinder. The exhaust gasses have mass, therefore they have momentum. When the exhaust gasses travel down the pipe, they want to keep moving in that direction. This phenomenon is used to create a lower pressure area in the exhaust system, and that lower pressure area travels backward toward the exhaust valves. Exhaust manifolds have primary runners that are too small, too short, and of varying lengths, to be of any benefit as far as tuning goes. The only thing they have is back pressure. With a header, the tubes can be of a large enough size, and long enough length to cause the backwards moving pressure wave to hit the exhaust valve when it opens at a realistic RPM. Velocity has a greater affect on inertia than mass, so whereas the same amount of exhaust is moving through the exhaust system, the one with a faster moving exhaust will have more inertia. This is where primary tube diameter comes into play. A smaller tube causes the exhaust to move faster, have more inertia, and create a larger negative pressure wave to be created. As RPMs increase, more and more exhaust moves through the primary pipe, increasing back pressure to a point where it cancels out the benefits of the negative pressure wave. The length of the primary pipe has the affect of boosting power before or after the torque peak, which was determined by the primary pipe diameter and CID of the motor. A slower running motor has more time between exhaust pulses, so a longer tube gives the pressure pulse more time to reach the exhaust valve. A shorter tube gives the pulse a shorter distance to travel, so it would be tuned to a higher RPM. Velocity is the key, and is controlled by the tube diameter. A smaller tube has higher velocity, but adds pressure to the system. The back pressure itself is of no use. That's as much as I understand. Could someone explain collector size?
 
I do not desire to debate anyone, but the easiest way to remove ALL the backpressure on an engine is to:

(eight) Adequate Sized (for the air flow) Individual pipes, non-baffled, exiting as close to the head as possible.

A properly designed and sized exhaust system with an X pipe has been proven to make more power than open headers....I can't remember which magazine did the power comparison, but it was clear as day after reading that article.

A properly setup X pipe system scavenges (pulls) the exhaust flow from each bank and is not choked down with too small diameter pipes.

For a lumpity 360, I would use headers or good manifolds, Dual 3" with X pipe and straight through design mufflers...made of T304 Stainless for longevity and durability.

just IMHO (in my honest opinion).....

:cheers:
 
Collecter size is not about pressure but volume. It takes four 1 inch pipes to move the same about of volume as one 2 inch pipe.
During my 10 years in plant maintainance I learned all sorts of crap.
We has a cummins diesel engine powered fire pump on the mill pond.
With a 12 inch header off the pump can you guess how many 3 inch gate valves were on there for fire hose hook ups ? I go ahaed and tell you.. Ten.
These were more for annual pump testing that use. There was another 12 inch line underground tied to the sprinkler system. I wont get into how those gate valves were configured on that header and why to avoid a hyjack here.
I built my own vacuum for our above ground pool that is power by my air compressor. The Y pipe velosity pressure principals make it work. Very well too :)
 
375,
All that I researched confirms all that you have said.
Illiminating the back pressure in the system will greatly increase velocity.Yeah it will get louder as well even with a muffler, but the benifits to effeciency and power would be worth the effort. IMHO.
Andrew
 
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