scv8

Has anyone seen a loss of power in an exhaust system when adding cutouts when they're closed? I was wondering if the extra path of the cutout pipe creates any disturbance, by the exhaust flowing down the closed pipe.

ryle

iTrader: (19)

Just a guess, but I would think the air would swirl in the closed cutout like it does in the bed of a truck when you are going down the road. For the truck it is beneficial and actually provides for better airflow, but no so sure it would be a benefit in a closed system like exhaust. I would think it would cause more turbulance and hurt your power.

But realistically, who runs with their cutouts closed anyway


This is kinda off subject, but I had a 18rwhp difference between open cutouts and closed cutouts. You probably wouldn't notice as substantial of a gain being that you are running dual exhaust. Mine was a complete Edelbrock exhaust system. Edelbrock headers, ORY, Cat-Back.

scv8

Thanks Ryle!

Wow, that's a good gain you saw.

libertyforall1776

iTrader: (2)

Seems like the better choice is a double butterfly cutout, lessening the chance of this issue:

RAMPANT

iTrader: (17)

With my 412, it made 512 rwhp with a full exhaust and no cats. I added Random Tech cats and cutouts behind the cats. Cutouts closed it only made 478rwhp, cut out open it made 511 rwhp.

Cutouts closed made for a huge drop in HP and made it run very rich as it was tuned for open.

This is the reason I do not even bother with them. I like having more hp all the time.

bww3588

iTrader: (49)

Libertyforall, them are some pretty sweet looking cut outs. Any idea where they can be bought?

Cumbias

Those cutouts look overly complicated. Remember, more moving parts=more wear and tear and a bigger chance of a part failing. Keep it simple.

Regular cutout will do the job, might add a little turbulence when closed but when they're opened the problem goes away. Isn't that the purpose of a cutout??? To bypass all the twists and turns and make it an "easy-fast" exit for the exhaust gasses when open for maximum power.

I wouldn't worry about the HP drop when the cutouts are closed. Open them when you need the extra power. In RAMPANT's case his car was tuned to run open so it made a considerable difference in O2 levels behind the cats when it was running closed.

libertyforall1776

iTrader: (2)

noweeds.net

CamaroSS27

iTrader: (6)

Dang how much do those run??

RAMPANT

iTrader: (17)

How else would you tune it? Tune for it closed then go lean when you open them? Much higher chance of damage then.


Anyway, I think they are a waste of money and the electric ones seem to have a life of less than a year if mounted closer to the front of the car like mine where. I have heard of dozens failing, including my own. I used 2 different makers and both died.

If you hadn't noticed I think you are throwing money away. Get the best flowing cat back you can afford and enjoy your car all the time. I know in a number of states they are illegal like they are here too. Electric anyway.

Having to stop and change tune seems like a PITA, if you are tuned for 13:1 with them closed.

Cumbias

True, I agree with you. The only way I could think of would be after the O2s with enough length of pipe to prevent this, but IDK what this would be. Anyways I would also go with your suggestion of not using them. best flowing pipes for your application and mufflers (if you want).