exhaust advice

[corvettejim1968]

i have a 65c10 with the stock 230 six. i wanted to upgrade the exhaust to something like a 3in pipe from the manifold back with a nice but not too loud muffler. should i keep the old exhaust for a person that wants a bone stock truck or is it not worth keeping and tell the installer to throw it away?

[jocko]

no need to hang onto it in my book unless it's "like" new - which, if it was, you probably wouldn't replace it. Take a few pics, take a few measurements, then toss it if it's rusted. If someone ever wanted to replace, I would say pics would be most important - especially pics of it ON the truck so they can duplicate it with a new system that is stock-like if they want.

On another note, 3" seems way too big in my mind for a 230 six. 2.25, 2.5 max I would think. But let others chime in on that one.

[corvettejim1968]

Originally Posted by jocko

no need to hang onto it in my book unless it's "like" new - which, if it was, you probably wouldn't replace it. Take a few pics, take a few measurements, then toss it if it's rusted. If someone ever wanted to replace, I would say pics would be most important - especially pics of it ON the truck so they can duplicate it with a new system that is stock-like if they want.

On another note, 3" seems way too big in my mind for a 230 six. 2.25, 2.5 max I would think. But let others chime in on that one.

okay thanks and i will take heed on the size too.

[Fred T]

Originally Posted by jocko

On another note, 3" seems way too big in my mind for a 230 six. 2.25, 2.5 max I would think. But let others chime in on that one.

The bigger the exhaust, the lower the torque. Unless you have done work on the head and cam, I wouldn't go over 2.5. My 235 (earlier series engine) has 2" exhaust with a 3/4 race cam and has turned just short of 5,000 rpm. The newer 230 head flows better.

Air flow is relative to area. 2.0" diameter has 3.1 sq in. 2.25" has 4.0 sq in, 2.5" has 4.9 sq in, 3" has 7.1 sq in area. The 2.5" gives over 1.5 times the air flow, which is huge, with a corresponding loss in low end torque, which is what is needed to move a heavy pickup.

[corvettejim1968]

Originally Posted by Fred T

The bigger the exhaust, the lower the torque. Unless you have done work on the head and cam, I wouldn't go over 2.5. My 235 (earlier series engine) has 2" exhaust with a 3/4 race cam and has turned just short of 5,000 rpm. The newer 230 head flows better.

Air flow is relative to area. 2.0" diameter has 3.1 sq in. 2.25" has 4.0 sq in, 2.5" has 4.9 sq in, 3" has 7.1 sq in area. The 2.5" gives over 1.5 times the air flow, which is huge, with a corresponding loss in low end torque, which is what is needed to move a heavy pickup.

so given thats its a stock 230 what do you think i should go with the 2.25 or the 2.5in?

[jocko]

get a few more inputs on exh dia before you decide, I'm no expert - that just caught my attention, that's all. Good luck!

[corvettejim1968]

here are some pics i just took of the old exhaust

[markeb01]

I'd be inclined to go 2.25" unless the show off value of 2.5" is more important or you’re going really wild on engine modifications.

If your next door neighbor could use the current exhaust system I'd think it might be worth saving because they’re wouldn’t be any storage or transportation issues. Removing the system intact however is going to be more difficult for the installer compared to just slicing it up, and that might add to the cost.