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-   -   cutouts question(sweet ass pic attached) (http://www.njfboa.org/forums/showthread.php?t=52554)

jts98z28 08-02-2010 11:14 PM

cutouts question(sweet ass pic attached)
 
1 Attachment(s)
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...
http://speed-eng.com/store/images/QT...d%20Y-Pipe.jpg

crainholio 08-10-2010 10:39 AM

Quote:

Originally Posted by jts98z28 (Post 720189)
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 (Post 721712)
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 (Post 721785)
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 (Post 720224)

Fixed

crainholio 08-11-2010 08:24 PM

Quote:

Originally Posted by LTs1ow (Post 721785)
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" :D

1994lt1 08-23-2010 11:36 AM

Quote:

Originally Posted by 98tadriver (Post 722147)
im waiting for someone to say something like "open headers will kill your bottom end torque" "or youll lose power" :D

I guess it doenst? :-?

crainholio 08-23-2010 05:33 PM

Quote:

Originally Posted by 1994lt1 (Post 724229)
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.


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