3" exhaust

[Superdave]

well, there is also the hard to find 2.75" pipe as well....


I just don't think 2.5" is enough, 3" may be excessive but it leaves room to grow.


I found sections of 2.75" on Summit for cheap....

[MidnightriderZ24]

either way dave its going to move. personally id just go with a 3'' because your going to keep modding like n20. 2.5'' choked the sh*t out my car. 32# injectors will be fun to tune.

[discostu]

Well knowing that your engine needs 2.2 cfm/hp of exhaust flow to not be a restriction, then it's easy after that...
350hp x 2.2 = 770cfm of exhaust flow for no restriction
We also know that straight pipe flows 115cfm per square inch of area...
770 / 115 = 6.70 square inches of exhaust area
And we know that the formula for area of a circle is pi * r * r
6.7 = 3.14 * r * r
6.7 / 3.14 = r * r
sqrt( 2.13 ) = r
r = 1.46" or the diameter of the pipe required is 2.92"...
3" pipe would be your best bet
Oh and don't forget to get a muffler to support 770 cfm of exhaust flow.
A Borla XR-1 would be your best bet, iirc the 3" flows in the 800cfm range...
Slowmasters are crap for flow, only like 400cfm. Magnaflows are better at around 650cfm.

http://www.thirdgen.org/techboard/exhaust/224858-muffler-use-poll.html#post1699808

Down about half way is a comparison of muffler flow rates.

Edit:
Just as a subnote to this, if you were still planning the dual exhaust route... Go get the necessary 6.7 square inches of exhaust area, you'd need dual 2,1/8" pipe, not 2".
And if you go dual exhaust, make sure you include an exhaust H-pipe or X-pipe. It lowers the decibels by 1-3db and increases power by 5-10hp on a v8. That's basically free power folks, no downside whatsoever.

READ: http://www.superchevy.com/technical/...xh/index1.html

[Arns85GT]

Thanks for that superchevy link. It is a good one.

Arn

[Superdave]

Well knowing that your engine needs 2.2 cfm/hp of exhaust flow to not be a restriction, then it's easy after that...
350hp x 2.2 = 770cfm of exhaust flow for no restriction
We also know that straight pipe flows 115cfm per square inch of area...
770 / 115 = 6.70 square inches of exhaust area
And we know that the formula for area of a circle is pi * r * r
6.7 = 3.14 * r * r
6.7 / 3.14 = r * r
sqrt( 2.13 ) = r
r = 1.46" or the diameter of the pipe required is 2.92"...
3" pipe would be your best bet
Oh and don't forget to get a muffler to support 770 cfm of exhaust flow.
A Borla XR-1 would be your best bet, iirc the 3" flows in the 800cfm range...
Slowmasters are crap for flow, only like 400cfm. Magnaflows are better at around 650cfm.

http://www.thirdgen.org/techboard/exhaust/224858-muffler-use-poll.html#post1699808

Down about half way is a comparison of muffler flow rates.

Edit:
Just as a subnote to this, if you were still planning the dual exhaust route... Go get the necessary 6.7 square inches of exhaust area, you'd need dual 2,1/8" pipe, not 2".
And if you go dual exhaust, make sure you include an exhaust H-pipe or X-pipe. It lowers the decibels by 1-3db and increases power by 5-10hp on a v8. That's basically free power folks, no downside whatsoever.

READ: http://www.superchevy.com/technical/...xh/index1.html

Good info!

However the '660 does not need an H pipe since it's an even fire engine. It may bennefit from an X pipe but i don't think anyone has tried one yet....

I'm using a Crossflow Hooker Aerochamber which should flow more than enough. The flow tests on the standard aerochamber showed it good for no loss on a 375HP engine. iirc they flow like 30% more than the best Flowmaster out there.

I'll be ordering the pipe and bends today. As soon as i get the engine in the car and started on this i'll post up pics...

Dave

[AaronGTR]

I'm pretty happy with my stainless 2.5" system, but yeah I think if I ever go turbo and started approaching the 400hp mark I'd probably go 3" with everything. Right now with the SC and the headers I've got have a 2.5" outlet so there's not much point going bigger.

[discostu]

I heard that the aerochamber was a pretty good muffler...
As for the H pipe, I think it would help even though it's on a even fire engine just because it would equalize the pressure between the two systems.
I don't have any facts to back this up, but I suppose it would be an interesting test to perform.
If I was going duals, I'd get an H or X pipe installed just for peace of mind. The extra cost would be... What 10 bux worth of pipe and time?
Up to you I suppose.

[Superdave]

Well, instead of the crossflow i'm going to run a standard Aerochamber. I ordered a 3"in/out Center/Center one last night. I'll be putting it where the cat would normally go, 3" pipe to the back and splitting into duals for the looks (since i have a custom rear bumper anyways).

This should help any velocity problems i may have had with the 3" pipe all the way back.. and sound cool too

[Superdave]

got my box of bends and pipe today, muffler came in last week and i have the 2:1 collectors on the shelf..



i'll start fabbing it this weekend...

[IsaacHayes]

What size pipe are you going with for the split? The straight through areochamber will flow better than a cross flow I'd say. It will be loud with the muffler up that close, because the exhaust will still be hot.

Get that thing running and tuned and get some video of it!! I wanna hear it

[RedBird]

Screw videos, i want a ride P.S. Dave i never got to drive the 3400 so....you owe me

[Superdave]

after the rear end it splits into dual 2.25".

I still need to pick out some tips but i'm broke.. haha

[IsaacHayes]

Just cut the tail pipe slashed at an angle :P

Dual tips look so sexy. I wish I had another Z26 tip on the other side. Maybe I should just put one there not hooked to anything? LOL Or maybe run smaller pipe before the muffler to it... So it'd be louder exhaust but the main flow would be straight through the muffler.... haha I wonder how that'd sound?

[Superdave]

Just cut the tail pipe slashed at an angle :P

Dual tips look so sexy. I wish I had another Z26 tip on the other side. Maybe I should just put one there not hooked to anything? LOL Or maybe run smaller pipe before the muffler to it... So it'd be louder exhaust but the main flow would be straight through the muffler.... haha I wonder how that'd sound?

Sounds funny.. i've done it

[ForcedFirebird]

Just cut the tail pipe slashed at an angle :P

Dual tips look so sexy. I wish I had another Z26 tip on the other side. Maybe I should just put one there not hooked to anything? LOL Or maybe run smaller pipe before the muffler to it... So it'd be louder exhaust but the main flow would be straight through the muffler.... haha I wonder how that'd sound?

That's how the 4th gen f-body's are. They have a y just before the muffler, so it is fairly quiet until you get on it .