hi all, i have a 1974 Comet with a swapped 302 and t5. it has long tube headers. i want to make an exhaust system for it but i don't have much to go off of it. basically i want 3 inch pipes going down to good flowy dual chamber mufflers or equivalent and i want it to dump out right before the rear tire. does anyone have photos of there cars with a similar setup? it would be a lot easier for me to mock it up if i know what one looks like lol. thanks to all in advance!
You're not going to be able to do this with 3" pipe.(likely don't need 3" either) You're better off with 2.5" as a max size pipe. To fit the mufflers where they're intended to fit (under the rear seat) you'd need to use a muffler with the inlet and outlet at the same end to be able to fab pipe with a bend to end at the location you're talking about. I'm running 2.5" pipe on my 331. And there's no restriction.
Not unless it's a diesel. I think the 64-1/2 427 Galaxie with 2 four's had either 2" or 2.25" exhaust. They designed this car to run in the Stock Car circuit (Nascar) back when "Win on Sunday...Sell on Monday" meant something
i did a 3" exhaust on mashoris car. i dont have pics of it. we used hooker headers with this exhaust kit http://www.jegs.com/i/Flowtech/387/53631/10002/-1 we then put 2.5" mufflers and tail pipes on. the car was definitely faster when the cut outs were uncorked. this car has a 400hp 331 motor in it. so with enough motor a 3" exhaust will work. on my car i used the same system except it was the 2.5" version.
He's talking about the whole system. You built a system with 3" intermediate pipe and 2.5" mufflers and tailpipes, then uncorked the 2.5" portion to make the gains. So with enough motor and enough noise, the 3" will work ? That's not being realistic.
he asked if any body had any pics of a 3" exhaust system. i didnt but had experience with putting one in. i qualified the 3" exhaust system with the link to the system that was used and fit in the car, and a description of motor and use of the system. the cut outs let the advantage of the 3" system to used when it was desired. the 2.5" mufflers back made for more efficient low rpm cruising. he did not say how built up his motor was. i provided experienced options to help him to decide on what he wanted to do. that is very realistic.
On a little 302 inch "street motor"(smaller flat tappet/small intake tract/small headers)?.. you'll most definately give up low and mid-range torque(+ off-idle throttle response) for that slight post 5,000 rpm surge. Might be worth 5-7 horses at most. If you want to do a nice exhaust system and have the basic skills to mig weld(flux cored wire is decent enough for most jobs).. look into mandrel bent piping to keep a consistent 2.5 inch through all the bends. That system will outpower a typical compression bent 3" system without a doubt. Unless of course my assumptions above were off and this thing is built more radically(runs high compression over 10.5/1) and rev's WELL past 7k. Even then.. a good 3" will need lots of gear to avoid the average losses on this size motor. Hope that helps any little bit.
yeah its definitely not a super built motor. 306 with a rollin thunder cam, decent intake and a Holley carb, long tubes, e7 heads. forged pistons and rods. probably categorized as a good street screamer.
so 2 1/2 it is! thats okay cuz 2 1/2 mandrels are cheaper then 3 inch lol... also I've done a little research on mufflers and i came to the conclusion that i want the magna flow race series mufflers (the 4 inch round ones) because i want it to really be heard but i want it a little more street friendly then my current setup (stock 2 1/4 or whatever pipe cut at the flange and angled to fit. no mufflers) anyone want to add to that? anyone have a better muffler for what i want? i don't want flow masters or a chambered muffler.... they don't flow very well
The 2.5 oval magna flows will fit under the car better. I ran them on my big block 62 F100 and they were plenty loud.
Ever seen a NASCAR stocker with a stock exhaust system??? Didn't think so as as stock system robs at least 75Hp(yes they were lying about the car having 425Hp, at least with the exhaust system)... Hp was rated with open exhaust and no accessories,and is the reason HP took a nose dive in '72... That's when requirements changed to all accessories and full exhaust for net Hp... BTW the factory exhaust on a Thunderbolt was a single 2" system...
If you're asking if it will fit, the answer is definitely yes. I have long tube headers with 3" pipe and all mandrel bends. I also have oval magnaflows and it goes over the rear and out between the leaf springs and trunk drop offs. It's all 3" from front to back. I didn't like the way it would look with the tailpipes exiting under the rear valance. My exits aren't really too visible from behind the car. I built the whole system myself.
