Christmas present for me

[Infidel67]

Originally Posted by mlee

I love this^^^

I was thinking the same thing

[Little Walter]

Originally Posted by bsn

Its been proven on a blown car a cutout can add HP if the exhaust system is somewhat restrictive, on a N/A car there is little or no gain. With the valve closed they generally rob a few HP due to reversion, that is why I am trying a reverse Y it will act as an expansion chamber when closed and blow off excess back pressure when open. I am pretty sure I will pick up a measurable bit of HP open and not lose and maybe even pick up a minute amount of HP closed.

Respectfully I do not want to change the narrative of the OP post, but I have a blown car ZL1 making 782whp no cats x-pipe into stock NPP mufflers and only gained 2 hp or nothing with cutouts since no two dyno pulls seem be the exact, removed them and got rid of the extra weight, was money wasted for me ended up having to get another x-pipe to prevent ugly welds.

[bsn]

They have to be placed in the right spot if you placed them on the factory 2-1/2" pipe your after the restriction so you wont have as big of a benefit as you would tying it in to where its 3" off the headers. My setup weighs about the same as the high flow cats its replacing since its mechanical and welded. The main reason I am doing this is because I am worried about the cats failing and causing engine damage during a pull, these won't hurt anything and hopefully there will be some gain. Since they are mechanical and will open anytime they see positive pressure I can tune the car accordingly. With electric cutouts you cant do that plus they take a few seconds to open where a mechanical valve is instant.

Engine Masters season 7 episode 13 (I think) did an episode on cutouts with a blown engine and saw a considerable gain.

[Little Walter]

Originally Posted by bsn

They have to be placed in the right spot if you placed them on the factory 2-1/2" pipe your after the restriction so you wont have as big of a benefit as you would tying it in to where its 3" off the headers. My setup weighs about the same as the high flow cats its replacing since its mechanical and welded. The main reason I am doing this is because I am worried about the cats failing and causing engine damage during a pull, these won't hurt anything and hopefully there will be some gain. Since they are mechanical and will open anytime they see positive pressure I can tune the car accordingly. With electric cutouts you cant do that plus they take a few seconds to open where a mechanical valve is instant.

Engine Masters season 7 episode 13 (I think) did an episode on cutouts with a blown engine and saw a considerable gain.

Hopefully you will see a greater gain, I have 2 inch headers into 3 inch exhaust all the way to the stock NPP mufflers, 103 throttle body, Ported supercharger, 5 inch cold air intake, cam, cnc ported heads finished off with hand porting clean up, fore fuel system. Just did not see any gains, however two identical cars are different so hopefully yours will be, please let me know your outcome.