Is 3 inch exhaust too much?

fasttback · Dec 19, 2005

Just another vote for 2.5"exhaust. Three inch is too big for most small block setups. As mentioned, look at your expected flows, existing setups, and drivability to help guide your decision. Also I think 3" exhaust would be hard to fit over the rear end if you plan to run out of the rear.

If you're as picky as me and can handle some welding just buy a kit and fit it exactly as you like. I made the Summit 2.25" exhaust kit with x-pipe fit in my '66 through the valance.

Max Power · Dec 19, 2005

Well, if you already have to replace it, 2.5" probably wouldn't hurt much. Since the bends will probably reduce down to 2-1/4" anyway, you won't really notice a difference. I went with 2.5" mandrel bent all the way back for my 393. I bought the Flowmaster tailpipes as it saves a lot of money at the exhaust shop.

Keep in mind that your exhaust is only as big as its smallest restriction. Many custom shops, when building tailpipes actually bend them far enough that they are down to 2". Many people who think they are running 2.5" really aren't.

steel1212 · Dec 19, 2005

I vote for the kit. Put it on yourself and if you can't weld it up take it to a shop and have them do it. Thats if you want it. I just use band clamps and haven't had a problem so far.

66Dave · Dec 19, 2005

66stangmeister said:
thats for the tip Tim

i'm just looking ahead to the future so that I won't have to get a new exhaust when i make modifications to my motor.

right now it is just a 1968? 302 with a mild cam...probably stock, and stock heads and stock intake. I plan on getting a new intake (probably a weiend or edelbrock), a new cam and finally new heads down the road.

would 2.5" hurt it while i have the stock parts on my motor? i don't really do a lot of performance running of any kind.

what other kits are there? besides flowmaster? dr. gas?

PM sent

blown65 · Dec 19, 2005

Personally Id do 3", heres why.

My Caddy is the LS6 with 400hp, 2 1/2" kit gained 10hp at the wheels and a 3" kit gained 23hp at the wheels. I doubt your going to hurt performance with a 3" kit, and if you ever hop it up you will have the exhuast to go with it. I know on my stang with the blower the 2 1/2 was WAY to small.

D.Hearne · Dec 19, 2005

How much you want to bet, that you'll find NO difference between your present 2.25" system and a 2.5" system? Spend your money on something worthwhile. If anything just add some kind of equalizer in the system ahead of the mufflers. Anything like a simple crossover pipe, an "X" pipe or what I did, build a 4"(dia). x 12"(long) chamber , will do wonders for what you have now. Mainly it smooths out the pulses and quietened it down on the system on my Ranger.

LMan · Dec 20, 2005

3-inch is fine. For your PowerStroke.

blown65 · Dec 20, 2005

and stupidity is for internet forums I guess. :/

06cobra · Dec 20, 2005

LMan said:
3-inch is fine. For your PowerStroke.

Nope, on the power stroke you need at least 4" LOL

D.Hearne · Dec 20, 2005

blown65 said:
and stupidity is for internet forums I guess. :/

Who you callin stupid ?

06cobra · Dec 20, 2005

double post, stupid net LOL

D.Hearne · Dec 20, 2005

blown65 said:
Personally Id do 3", heres why.

My Caddy is the LS6 with 400hp, 2 1/2" kit gained 10hp at the wheels and a 3" kit gained 23hp at the wheels. I doubt your going to hurt performance with a 3" kit, and if you ever hop it up you will have the exhuast to go with it. I know on my stang with the blower the 2 1/2 was WAY to small.

You've neglected to tell us how much you paid for that 2-1/2" kit ? And then also neglected to say how much more you shelled out for the 3" kit And THEN do the math and tell us how many dollars per horsepower you ended up with PLUS, just where in the powerband were those extra ponies found ?

66stangmeister · Dec 20, 2005

i found an article somewhere online where the 3 inch helped with horsepower...like 58 ponies it said, but that was wayyyy at the top end like 5600 or 5800 rpm. i think it was for a dodge anyway

D.Hearne · Dec 20, 2005

66stangmeister said:
i found an article somewhere online where the 3 inch helped with horsepower...like 58 ponies it said, but that was wayyyy at the top end like 5600 or 5800 rpm. i think it was for a dodge anyway

I see you live just down the road from me in Lafayette. I live in Opelousas, and work out of Breaux Bridge. If you want to see what even a somewhat constricted 2.25" system ( locally bent) will do behind a 331-six pack Ranger, just let me know, and I'll arrange to let you test drive it.

mdjay · Dec 20, 2005

It would probably make more power at the top end. But you will loose torque on the bottom end.

The L6 has nice low end torque so it is not apples to apples.

66stangmeister · Dec 20, 2005

D.Hearne said:
I see you live just down the road from me in Lafayette. I live in Opelousas, and work out of Breaux Bridge. If you want to see what even a somewhat constricted 2.25" system ( locally bent) will do behind a 331-six pack Ranger, just let me know, and I'll arrange to let you test drive it.

Opelousas haha do i really want to test drive it?

On another note, i appreciate all the replies from you guys thanks for the help with this somewhat confusing decision.

57fairlane · Dec 20, 2005

D.Hearne said:
If you want to see what even a somewhat constricted 2.25" system ( locally bent) will do behind a 331-six pack Ranger, just let me know, and I'll arrange to let you test drive it.

No one wants to drive that z-cammed slow ranger.

06cobra · Dec 20, 2005

^^^Blahaha, I'm glad someone posted that!

Edbert · Dec 20, 2005

mdjay said:
It would probably make more power at the top end. But you will loose torque on the bottom end.

This is very important and often overlooked in bench racing discussions. For a street car, average HP/TQ figures are more important than peak HP/TQ figures. It is quite possible to gain 10-20rwhp yet lose power from idle to 5,000RPM.

gp001 · Dec 20, 2005

I vote 8" dual exhaust

Is 3 inch exhaust too much?

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