Better exhaust or new cam?
 

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

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

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

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

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

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.

Info on motor
 

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?

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.

Better exhaust or new cam?
 

[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!

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

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

dbl post it sticky

How's your hearing
 

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.

I run side pipes that are bolted to the collector with four bolts. On track day it's quick to simply unbolt and remove them and run open headers. I bolt on a short extension with a turn out to direct the "flames" away from the body.

The more horse power and flow you have the greater loss of horse power you will have from restrictive exhaust. In my case, 427 with 428 crank and solid roller cam that would turn up to 7,000 rpm, the side pipe loss was 97 horse power.

At the track I don't run air cleaners (2X4 intake) and also run bigger jets in the carb. With no air cleaners and open exhaust you need to increase the jet size to compensate for the additional air flow in and out. On the street, smaller jets, air cleaners, side pipes and I STILL can seldom go to wide open throttle due to traction issues. On the track, road race slicks are a must have for my setup.

Jon,
Often, the key to getting the best answer is to ask the right question. You asked, "Which is a better way to get more hp....a bigger cam or different mufflers ...." I'm not certain that is the question you really want answered. Perhaps the question should have been, "What is the most cost effective way to make my car feel more powerful in street driving without giving up much comfort or drivability?" The answers to those two questions would be very different. For example, opening the exhaust would likely be the best answer to the first question if you were planning to use the car only on the track, but it wouldn't fare well as an answer to the second question. Perhaps you can refine your question and expand on why you are asking. I think that will get you better answers.

I recently changed carbs from 450 mech to 600 vac and there was a hudge difference....no bog vs tires that broke loose, but I still felt the motor could be more responsive. I also have driven the car on several trips of over 200 plus miles a day and the noise can be a problem( my ears ring all the time)... So when I thought about a motor that could be more responsive and had read about how restrictive the side pipes were I also thought that maybe a under the car exhaust might be less restrictive and give me more hp and move the noise from below my ears. With a muffler change in the side pipes maybe I could accomplish the same thing! As for air cleaners, I'm using Stelling & Helling....no room to go up!
Jon

I have a 390fe which had a very dissapointing dyno run. After learning my side pipes and intake manifold were of the restrictive type thats all I changed. First the intake and the car ran very bad with my sidepipes. Then after changing the sidepipes to rare irons 2.5 dia mufflers the car picked up 70 hp on the dyno. My cam is about the same as yours. I also use stock iron heads D2TEA. I'm a believer in what has been said. It's important to get the A/F mixture correct too.

John

depends which one is more restrictive

Cobra pack mufflers
 

Anyone using them and how did they change the sound and the noise level of your motor(FE)....has anyone done a dyno comparison to see the gain?
Jon

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

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