Better exhaust or new cam?

[saltshaker]

Which is a better way to get more hp....a bigger cam or different mufflers for the side pipes or maybe exhaust under the car with low restrictive mufflers....fe headers are available to run the exhaust under the car, they look like Sanderson Headers but made by Hurricane at a reasonable price. Which would be the bigger gain? Any suggestions on the mufflers or cam? Currently using a Comp 282s ....

Jon

[Dwight]

we need more details on the motor. Have you had the car dyno'ed?

Sidepipe typical lose 40 to 100 hp on a Cobra.

You can install better sidepipe mufflers for $150 plus the welding and the cost of the coating. Are your pipe ceramic or paint?

Cam change alone may not increase your hp. Your intake, carb, heads and cam work together. Your exhaust system is part of the puzzel also.

Air in Air out

If money is not a problem then you can changes parts out till you get the hp you want. But I'm always on a budget so I have to plan everything so it will work together and produce the max hp for the dollar.

Dwight

[undy]

Poor eshaust will kill a heavier cam and in a lot of cases the engine will yield LESS HP.

[Ant]

[quote=Dwight;1092160]we need more details on the motor. Have you had the car dyno'ed?

Sidepipe typical lose 40 to 100 hp on a Cobra.

I agree with most of what you have said, but I am wondering how sidepipes typically loose 40 to 100hp on a cobra?
We made a set of headers for my KC Ford Yates 358 based engine which dynoed at well over 600bhp, my headers are stepped and go into Chris Hills merge collectors and back to 3" perf mufflers that I am in the process of making, maybe I should go bigger with 3.5" core mufflers, I have read where too big slows the air flow or just doesnt make a difference!

[vector1]

if you have a little air cleaner that could be your restriction so it wouldn't matter..

[Dwight]

vector1 is correct
you need to check (auto math calculators) to determine if you have the correct size air cleaner.


air in air out

air cleaners and sidepipes are the two largest hp killers on a Cobra


Dwight

[Rare Iron]

If you are running "standard fare" sidepipe mufflers, U losing a LOT of HP probably. The stockers I've seen are absolutely ridiculous. I wouldn't run them on a 1966 Mustang with a 289-2bbl.

[saltshaker]

The motor is 428, .40 over,10.5 comp, C4 heads w/cj valves...ported 285 cfm l .600 & 195 cfm @ .600, MR 2x4 w/600's vac carbs & comp 282s cam....So which mufflers are better?

[Rick Parker]

Good points made on efficient exhaust being necessary. Often the original collectors utilized on a 427 car are duplicated in an attempt to maintain originality, but here in lies the problem, they create a huge amount of turbulence where the primary pipes join. Investigate a correctly designed set of Merge Collectors connected to a well sized muffler blank, and you'll have more horsepower to show for it.

[vector1]

if i was to look at sidepipes here is what i would consider

http://www.coastfab.com/index.html

[xlr8tr]

Originally Posted by vector1

if i was to look at sidepipes here is what i would consider

http://www.coastfab.com/index.html

These look interesting- do you have any pics? I didnt see anything on their website.

[Dwight]

I had Lone Star sidepipes with 2 1/2" core and 24" long mufflers. The louvers were facing so they did not catch air. This would give max air exiting the muffler. I replaced them with Cobra Pack 3" x 28" mufflers. I installed them so the louvers would scoop the air into the muffler. Four inches longer gave more volume.

Before you could heard me from 1 1/2 miles away. I've got witnesses. Lots of them including one police office, pictures in my gallery. No ticket.

After I changed the mufflers, it's a "lot" quieter and I "think" it makes more HP. I made other changes between dyno runs so I don't know what the muffler change gained me. But I feel very confident the new sidepipes help.
I now have a quieter exhaust system with a deep health rumble. I like it.

It's that air in - air out thing. I have larger mufflers to handle the same amount of air, so it should be quieter.

A muffler is a place to store air till it can sloooowly exit the muffler. The reduced speed of the air exiting the chamber reduces the noise.

IMHO

Dwight

[Dwight]

this is a pic of the core out of Unique's sidepides. Note the louvers.

Dwight

[CobraEd]

Originally Posted by Dwight

A muffler is a place to store air till it can sloooowly exit the muffler. The reduced speed of the air exiting the chamber reduces the noise.

Dwight

I don't believe this is correct, . . . . Uhhhhh, . . This is 100% wrong.

Exhaust gas and sound waves are two completely different things. You never want to make an effort to slow or reduce the exhaust velocity. You will lose power (backpressure). The mufflers job is to absorb and/or cancel out sound waves. The better it can absorb/cancel sound waves relative to maintaining a free flow, the better it is at its job.

Mufflers like glasspacks absorb sound waves and mufflers like Flowmasters cancel out the sound waves inside small resonance chambers within the muffler.

(just as an aside, . . . . good backpressure is like good cancer)

.

[vector1]

Originally Posted by xlr8tr

These look interesting- do you have any pics? I didnt see anything on their website.

i haven't used these, just brought over from another site, thought they looked interesting. i've read the guys will make anything you want, they also have a discounted list of stuff.

[Dwight]

I removed the fiberglass and re-installed them.
It was a friends Cobra.
Dwight

[Dwight]

CobraEd, I think you use the word absorb and I used the term "place to store air till it can sloooowly exit the muffler" to describe the same thing.
All the air that enters a muffler has to exit. Nothing is absorbed. A large muffler is quieter than a small muffler on the same car.

Stock vs glasspacks (Cherry Bombs).

The large muffler has more room to store the air till it exits the muffler.
Glasspacks have fiberglass in them and Flow Master uses metal baffles to slow down the air.

This same theory is used to build/design suppressors for firearms.

I don't design or build mufflers for a living, but this is what I think happens inside a muffler.
Dwight

[RestoCreations]

Originally Posted by Dwight

I removed the fiberglass and re-installed them.
It was a friends Cobra.
Dwight

Why? Did he want them louder? Eventually the fiberglass builds up with so much carbon/exhaust gunk that it doesnt absorb the noise anymore anyway.

[vector1]

dbl post it sticky

[RICK LAKE]

saltshaker Jon Here's the issue, How the hearing in your left ear and are you happy with it. Side pipes for street kill power. 10-50 hp is about the norm. Race pipes no power loss with about a 15-25 increase in loadness. Ringing sound in your ear after a ride will happen. The trick with side pipes is to have a quiet one without too much back pressure and noise. Ideal back pressure numbers are in the 1-2.5 pound of pressure at WOT. The newer you go the more power lost. I have found that having 2 sets of pipes works the best. 1 set for cruising and one for racing.
If you have the money and time, a dual exhaust system can be built with a splitter valve. Side pipes for making noise and a complete rear exhaust system for cruising and talking. Not Cheap but very doable. Stormin Norman runs a car with dual setup.
Which everyway you go, do only 1 part swap at a time as to not cause the tune to go way out of range. IMO I would stay with the exhaust you have and leave the motor alone and enjoy it. The more power and abuse it makes and takes, the shorter the life of the motor. You have a motor with a .040" overbore. You are running small valve heads. Getting a set of KCR heads stage 3 with 2.19 intake valves will wake up that motor alot. I wouldn't push this motor too hard with thin walls. Build another motor if you want to get crazy.
As far as aircleaners I am running the small one without the inner filter. between the throttlebody running with and without the filter I picked up 3-5 hp with it on. It helps bend the air and keeps a smooth flow to the throttlebody. Same would apply to a carb setup with keeping a smooth flow to the carbs. Other airfilters do kill power. You also want a low striction setup to improve throttle responce. Rick L.