00Vette04GTO

Hey guys,
I have a 2000 Corvette with a 6.0 and a good bit of work done to the motor. Finally swapping out my bbk short tube headers for some long tubes and wanted to get some opinions on the mid-pipe diameter.

I have the Billy Boat Quad system, which is 3". My long tubes' collectors are 3". Should I stick with a 2.5" mid-pipe for back pressure - or will the 6.0 respond nicely being opened up even more?

No catalytic converters... And I don't know if you call what Billy Boat does as mufflers.

Already very loud and "open toned" which I am ok with.

Thoughts?

I assume some people have gone to 3" the whole way?... What kind of results did you get?

Thanks,
Mike

SSCamaro99_3

iTrader: (1)

I would say that 3in all the way will not hurt anything, and will only help if you do more work. Short of open ports, less backpressure is good.

00Vette04GTO

That's pretty much my thinking, and always has been. More is better.

But the deeper I get into engines the more I am trying to think ahead. Seems to cost less and a less headache that way.

Will I loose a lot of torque to only gain a horse or two? That is my main concern.

Or will the engine just eat it up?

By any chance does anyone have any experience running 2.5 and 3" midpipes? What was your seat of the pants feeling on the difference?

Of course if someone ran across this post that dynoed it on a 5.7 or 6.0 with both that would be awesome.

00Vette04GTO

Anyone else? Where is the point that 3" will not cause a loss of torque? Calculated by rwhp, motor hp, displacement, cam, etc???? I am sure someone has been in this spot and decided where the line for the 3" wide open exhaust was. I assume there is a place it will hurt, and a place it will start helping. Anyone care to shed light? You could save me a good bit of time and money!

I am not looking to go 3", then realize I am loosing torque, and go back to 2.5

00Vette04GTO

Since this seems to not be a hot topic that I am going to receive too much info on:

I'll respond to myself to help anyone else in the future with this question.

Been talking to some LS guys elsewhere.

I was told only one (i thought a few - but he said one) company made cat back for C5s that was 3" (which I guess is the Billy Boat i have - since its 3")

That is one reason Header companies include 2.5" midpipes. Another is just cheapness on the header manufacturer's end.

As far as loss of torque. Seems I might loose a little - but with my stall and such - the gain up top will make it worth it to go 3" the whole way.

Supposedly, sub 500 horsepower - 2.5 would be fine. But if you are at or near 500 go with 3"

I assume with cats you could go 3" and not notice any difference at a lower HP. But my concern was without cats and very little muffler or restriction.

All I can do at this point is do it - and see what the results are.

But there's more info than I was able to get from one forum post. So maybe putting it here in one will help someone with an oddball question like this that most will pass over because they haven't worried about such a trivial matter - or because it seems silly to think that deeply into your build - or because it's just a stupid question - or whatever.

Thanks guys! Happy motoring!

SSCamaro99_3

iTrader: (1)

I think you are way over thinking it. Most people on here go with as much exhaust flow as possible. If by chance you loose any torque, it will be more shifted up than lost, your stall will cover it up. Most of us have trouble hooking up the power we have, any wheelspin any your torque value instantly becomes immaterial.

00Vette04GTO

I can pretty much guarantee I am over thinking it. And I do apologize.


My reasoning was - once you're in so deep, you want to do things right - even if it seems stupid - give it a second of thought.

I know guys have dynotested different primary diameters to death to figure things like this out. And I was confused on why almost all manufactures give 2.5 midpipes with their longtubes. So I figured I'd dig a little deeper.