Hey guy's,
I'm building an exhaust for my truck using Ram horns and a set of glass packs that exit in front of the rear tires.

My question is what size pipe should I use for my 292 with holley 4 barrel?

There is another factor involved. I want to eventually put a built 351w in the truck and not have to redue the whole exhaust. So I would like the pipes to be a good size for that motor as well to save me a little money when I do the swap. I plan on making 350-375 hp with the 351.

I'm thinking 2.25 would be a good size for both motor's. What do you guys think?

Thanks,
Mike

 

2.25 or 2.50 at the most would suit both engines well.

 

I agree with Kens64. Anything bigger might rob you of the needed back-pressure.


vernon

 

Have a 302 with 4bbl and used the 2.50. Posted simular question in another FTE forum and majority agreed with Kens64 and Vernon. Have the flareside (stepside) exhausting front of rear tire under the step. The only issue may want to consider is muffler selection. With the exhaust just rear of the cab too loud of mufflers can be anoying, at least i found this to be the case. The glass packs should be okay. If considering doing yourself, i have a 65 F100 with headers and found the 'offset extention', if recall made by Hedman, very helpful in dealing with crossmembers.

dave

 

If you Want sound and better gas miles id say ya go dual exhust with glass packs but if you want stock stay dubd single exhast you get better compression. But i have a question i have a 1966 250 and i just got it and it came with dual exhust coming out in front of the rear tires do i leave it or change it?

 

You guys raise a question.

I have 3" Stainless from the headers back about 4 feet that drop into a Y pipe into a single 3" stainless muffler than over the rear axel out behind the right rear tire. It sounds great and runs well 352 4v.

The question is how do you know if you don't have enough back pressure?
Or how do you check for back pressure?
How much back pressure should you have?

 

I have a 292 with the ford-o-matic trans after checking around most people said to go with a 2.50 exhaust however after I was given two flowmaters with three in and three out, I went with the 3.00 inch from front all the way out the rear see my gallery for pic's. I'm not a racer so the sound of flowmasters sounds great and looks great. I put an awsome set of tips that makes it look real koool from behind. But the question being raised about back preasure and how much you should have is a good one. How much and how do you tell what's right for your application?Staing low for now
Robert

 

"The question is how do you know if you don't have enough back pressure?"
You want as little as possible. You cant get rid of it completely though because even a straight pipe system will have some due to the bends in the pipe. Backpressure=restriction. Velocity=good exhaust scavenging=power.

"Or how do you check for back pressure?"
Welding in an 02 sensor bung and screwing in a pressure gauge and plumbing it into the cab can tell you what you have.

"How much back pressure should you have?"
See question 1.

 

Dual vs single- it doesnt really matter. If both are designed right, one will offer no benifits over the other, except the single system could weigh less and probably be cheaper. There are WAY better choices than glasspacks if you want good exhaust flow. I admit they do sound good though if done right.

Neither has anything to do with better compression. Bore, combustion chamber size cam profile and some other things determine that.

Whether you keep what you have or not depends on opinion. In my opinion I would extend it out to under the bumper. The longer the total pipe length is, the more mellow the exhaust will sound.

 

Three inch pipes would be called overkill especially for a stock 292. My Cougar, with a modified 302 at 340hp, uses 1 5/8 in. headers and pipes at 2.25 in. which we researched quite a bit. I know people with Cougar GTE's (427 or 428) and they use 2.50 in. pipes. Same thing happens with pipes as does with carb CFM. Ford put a 4100 1.08 venturi on many small blocks for a reason and yet people think they know better and try to put on bigger (is better???). At low speeds a smaller venturi will flow air better than large and give you better response and not screw up the idle circuits. That is what you want unless you intend to run at Daytona. Exhaust pipes are the same way when it comes to flow. Too big and the flow at low speeds will cost you scavenging ability and torque. Example, take a small diameter straw and a large on and just try blowing through them. Velocity in the small diameter is much greater and that is what you want. My Cougar is only running at speeds from 35-70 mph and so I want my power to be in that range.

Oh, and pipes out in front of the rear tires. Not on my truck and that is the first thing that went along with the glasspaks.

 

you mean it has a lower growl sound when the longer the pipes are? LONGER PIPES=LOWER SHORT=HIGHER GROWL ?

 

I had straight exhasut that came out behind the cab, with almost no bends from the headers and it was very load and seemed very sharp. and i would liek to say it almost sounded liek it was cracking.

I then finished off the exhaust and made it go all the way back over the rear axle and the kicked out the side behind the rear wheel. It sounds alot deeper, it doesent sound as sharp. and it is also quieter than the shorter exhaust.

so yes it has a lower growl with longer exhaust , it is also a little more quieter (very bad gammer)

 

O.K. thanks i thout that I should take it out the back and its dual it comes out the both sides in front of the rear tires and should i put turbo mufflers or just normal mufflers but i don't want to get rid of dual exhust.

 

I cant say whether to use turbo or not. ive only used glasspacks and straightpipes ever. so i really cant help there. im sure soemone will be here shortly to tell you which is best

 

If you want to swap out a differing engine combo use Heddder flanges as couplings near the transmission. this will allow you to only have to fabricate a short section of exhaust to meet the new conditions of a non Y block motor. Seeing as a small block chevy is the only other user of rams horns........

GArbz