I put my headers on today and went to Midas to have the y-pipe welded on and for them to put my cutout in. The guy said that he highly recommends NOT putting the cutout in cause I lose all the backpressure and probably loses 20-30 hp because of it. He said its only good for duals and long tubes. So I told him I could just leave it capped, but he said then it would create a lot of turbulance. Any info here? Has anyone put a cutout on a y-pipe (before the cat) and lost HP? Thanks in advance.

 

i know many people who sware by the cut out. got any pics of the headers installed?

 

from what ive read over and over and over and over again backpressure is pretty much bad. lower backpressure = yay

 

if backpressure were good wouldnt there be some sort of restriction of the exhaust on top fuel? so what the guy at midas said was

less back pressure = more power

 

Where did the guy work again? Midas? thought so, question answered

 

As F-BIRD'88 would say......

Back

pressure

is

BAD!!!!

 

I'm getting red x's.

 

Yeah, I know what you mean. I kept blowing out collector donut gaskets on my TES headers and the muffler shop told me I probably didn't have enough back pressure. Turns to find out I was actually flexing the pipes enough to weaken them... how did I find this out? hehe I noticed when I put new gaskets in then I broke the cat back pipe behind the weld (crack all the way around it).

Having a little back pressure helps with making some extra tq though, but I don't see any reason for not running cut outs. It's not like it's perm. mod. I hope to get an electric one in the future.

 

No backpressure = crappy throttle response and slower, at least on my car.

 

How did you achieve 0 backpressure, what you know is worth fortunes to drag racers, IIRC it is impossible to get 0 backpressure.

 

I just cut my cats out of my exhaust and it feels like i gained some power. really loud also

a cutout is basically the same thing right.

 

Backpressure sucks. Or blows. Or something...

 

I know your not built. But this kid has a 96 z28 here putting out 350 at the wheels. With an open cutout he gained 20 hp on the butt dyno.

 

Yeah Mark, he works at Midas, which is why I'm coming here to ask some people who may know more about this. But I don't know why he'd want to talk me out of it, its more labor for him to make money on ya know? I'm just gonna get it put on. If it hurts, I can keep it capped and uncap it for sound. I have the power plate anyway.

As for pics of the headers, tomorrow I will get them posted. I have to reduce the size of the pictures and upload them all. I also have some short video clips.

Thanks guys

 

The only thing I have noticed with my cutout is that.....when it's WIDE open...there isn't much low end torque....so...I just have to close it up...(McCord Power Plate) I just use it for sound anyway.....the best of both worlds....

 

I would love to know how you managed that also
less backpressure is better. makes the motor work less to get the exhusat out.
if you know how to create a vaccume on the exhuast please let me know that aslo that way I can have the exhuast sucked out and pull in even more a/f


fireturd350
how would it help?
it just makes the motor work harder to get the same affect
that would be like me saying if I stand in front of you while your trying to run you will run faster

 

could be partly because of too much area inside your pipes (two areas to flow) that the exhuast gas slows down enough that they back up on themself

 

Don't listen to that guy at Midas. He don't know what he's talking about. I put my cutout before the cat, its Edelbrock TES headers and Y pipe....I cut a oval shape hole in the corner of the Y pipe, and welded the straight part of the cutout on.

I have some Spohn SFC's (just need to install them) and they should fit with a little tinkering.

Here's the picture -




As you can see in the picture, I kind of "flared" out the Y pipe...so I could have a good amount of metal to weld onto. It's kinda hard to explain...but if you look inside the cutout, you can see it.

 

Or his engine is not tuned for the extra airflow.

I switched from Edelbrock TES & 3" Dynomax Ultra Flow to Hooker 2210 longtubes & 3" dual. The car picked up a solid 4mph in the 1/4 mile. So much for backpressure being good.

 

Hahaha, tell the guy he's a fuggin moron

Lose 30 hp...

I personally think you should kick him in the head for that one.

 

well I had my cut out installed and went from a 15.4 to a 14.8, and it is much torqeur(if thats a word)..

 

I lost 12hp and 20ftlbs torque on the dyno. I have mine after the cat though and I also have stock manifolds also.

 

even not being tuned for extra flow shouldn't make that much of a difference

just the effect of not making the motor work as hard to push that stuff out I think would be good all in it's own


big reason a cutout might make for lower power is they can create turbulance which would induce backpressure.
another thing is that low pressure zone that follows an exhuast pulse will only really last while the pulse that created it is still inside the piping

once that exhuast pulse leaves it starts to fill back in with high pressure again......... loss of scavaging

 

True, but it can cause an off idle stumble or flat spot that could be construed by the old butt dyno as loss of torque.

 

Where they at?!

 

DP

 

mine had no loss what so ever, but I also put on headers,y-pipe, and 2 3/4 inch piping, and a high flow cat(my cut out is after the cat.

 

I posted them in another thread I think, a while ago. They're up on my webpage if you still wanna see the pics. The sound clips didn't turn out very well though.