cutouts question(sweet ass pic attached) - NJFBOA - Home of New Jersey's Camaros and Firebirds

jts98z28 · 08-02-2010, 11:14 PM

why dont cutouts go straight from the headers instead of going off to the side? doesnt a lot of the exhaust gasses travel through the exhaust that way?would you gain power if it was the other way?
thanks

Green_Phoenix_LT1 · 08-02-2010, 11:19 PM

If the cut out were to be placed where you state in the picture than it wouldnt be a cutout. Its called a cutout because it cuts out the normal flow of exhaust and reroutes it. It relieves almost all the back pressure from the cats/muffler(s) depending on where you place it. When placed right after the headers pointed down or to the side it is basically like running open headers. I'm just a noob but i hope that helps you.

BarneyMobile · 08-02-2010, 11:55 PM

The exhaust flow will take the path of least resistance.

jts98z28 · 08-03-2010, 07:37 AM

thanks guys

LTb1ow · 08-03-2010, 08:34 AM

Go go go...

crainholio · 08-10-2010, 10:39 AM

Quote:

Originally Posted by jts98z28

why dont cutouts go straight from the headers instead of going off to the side? doesnt a lot of the exhaust gasses travel through the exhaust that way?would you gain power if it was the other way?
thanks

Because there is such a thing as too little backpressure. You can actually under-fill the cylinders as the intake charge is blown out the still-open exhaust valve, causing the engine to run lean.

LTb1ow · 08-10-2010, 03:14 PM

Quote:

Originally Posted by crainholio

Because there is such a thing as too little backpressure. You can actually under-fill the cylinders as the intake charge is blown out the still-open exhaust valve, causing the engine to run lean.

So race cars with open headers are doing it wrong?

Back pressure is cool and all if you have a carb, EFI, not so much.

BonzoHansen · 08-10-2010, 03:17 PM

Quote:

Originally Posted by LTs1ow

So race cars with open headers are doing it wrong?

Back pressure is cool and all if you have a carb, EFI, not so much.

why does it impact carbs and not efi? aren’t we talking about air flow in & out of the cylinder?

LTb1ow · 08-10-2010, 03:50 PM

Applies to more older carbs, and mainly bikes, but the lack of back pressure causes more air flow to come through the carb and since a carb cannot adjust itself like an EFI system can. So air will become double loaded with fuel and make all sorts of nonsense.

Further more, although many will say dated, David Vizard claims that about .2psi is needed for a no hp loss exhaust system. But what do I know.

ar0ck · 08-10-2010, 04:28 PM

Quote:

Originally Posted by LTs1ow

Trash, Trash, Trash...

Fixed

crainholio · 08-11-2010, 08:24 PM

Quote:

Originally Posted by LTs1ow

So race cars with open headers are doing it wrong?

Where did your John Force imagination invent that I was talking about "race cars"?

LTb1ow · 08-11-2010, 09:10 PM

Yea you are right, nevermind, backpressure ftw, ill go away now

98tadriver · 08-12-2010, 12:37 AM

im waiting for someone to say something like "open headers will kill your bottom end torque" "or youll lose power"

1994lt1 · 08-23-2010, 11:36 AM

Quote:

Originally Posted by 98tadriver

im waiting for someone to say something like "open headers will kill your bottom end torque" "or youll lose power"

I guess it doenst?

crainholio · 08-23-2010, 05:33 PM

Quote:

Originally Posted by 1994lt1

I guess it doenst?

Nope, open headers and 0.2psi FTW like the rase carz!!11!1!

I'd never argue against David Vizard and have no doubt that what you read is fact, but it's possible you skipped the part where Vizard covered all the compromises that come with that zero-loss setup.

And I'm pretty sure Vizard didn't say to slap open headers on an engine without also updating the induction and cam to match it.