exhaust cutout setup or not?
 

I'm thinking about adding exhaust cutouts to my car this winter but I'm not sure how much I'll gain for the price (remote opening). My current exhaust is headers with 1 5/8" primary's into 3" collectors. The collectors feed into a y pipe setup with a high flow cat and a single inlet dual outlet flowmaster muffler. The entire system is 3" pipe all the way from the headers back.

What I'm wondering is if I'll gain much power from adding the cutouts. Also I was wondering if I would get the same results from a cutout after each collector or just adding one at the y pipe before the cat. I'm just not sure how much more flow I would get. I guess any horsepower gain is good but spending $150 for 1 or $300 for a dual setup, for only a few HP just doesn't seem worth it.

If it helps to know, I'm running 10:1 compression with a 150 shot of NOS, ported aluminum L98 heads (not d port), and a 750 cfm holley carb.

bump

I would buy a pair of regular cutouts first... a pair of 3" cutouts with just the cover plate would be about $50 at Summit. Install them, try them out and see what you think, then if you like it, spend the money for the electric cover plates (they just replace the cap on a normal cutout anyway).

BTW - longtube or shorty headers?

I'm running short headman headers. I was thinking about changing over to long tube headers, and true duals, but figured cutouts would be more efficient. Thats a good idea. I didn't think about doing that. Sometimes you just need another point of view. Thanks.

I'm running a set of hooker shortys into a single 3"cat, a single 3" elecricly operated cut out, and then into a sinle 3" in dual outlet Flowmaster 40-series.

When I open the cut out, I can feel the difference, and thats after going through a the cat first. Besides the fact that you'll probably scare away most potential racers.

The only complaint I have about the electric butterfy valve is that after a while it leaks. It comes with red RTV lined edges, but mine got blown off after about 3 months. I peeled off the excess and reapplied some black RTV, and it lasted about the same, so plan on getting a metallic rattle coming from underneath after about 3 months.

Where can you get the electric plates at?

Not sure where you get them, as I don't have one, but thats how all electric cutouts work.. they just go on in place of the cap on a regular cutout.

All the units I have seen, that come without the tubes, are just as or more expensive than the units including the tubes. It's rediculous. I think hawk's sells them both ways but I can't remember. I know you can get them on ebay and summit.

I have the Headman shorties and modded the Y pipe to 3 inch with an electric cutout where the cat would normally be.
I picked up 6 hp at the wheels with it open. $200 for a 6 hp gain isn't great but it is a fun toy to have on the car.

Hi you can get the electric cutouts from summit racing heres the link http://store.summitracing.com/defaul...egnsearch.asp. (In the seach box just type in cutouts) I wouldnt put 2 and weld them on after your headers though, most engines normaly aspriated needs some kind of backpressure if you loose that you will actually loose HP I did anyway I bought 2 of the wingnut style ones and put them on after my headers and it was a noticable loss in preformance although it sounded increadable believe me, you would scare anyone that pulls next to you. The other thing now I was only told this is you need to have stainless steel exhaust valves because of the extra heat that is generated I was only told that i dont know if its true or not. However this was just me case it could be diffrent for others I wanted to have a BADDDD sound for rolling around SAT nights but during the week keep it to a normal tone. Good luck with it

for someone who's running such a badass engine I would expect you to know something about the tuned length of exhaust. You don't lose power when you open up cutouts, the tuned length changes and the power moves higher up in the RPM band.

I've written an interesting FAQ on this, it's in my sig.

i got mine from http://www.mccordcg.com/mpp/mpp.htm

I knew that the power band changes but the loss that I felt it the low end didnt seem like it was made back up in the upper RPM range. My 1/4 time went from 14.34 to 15.03. It was pretty much a stock 350 though anyway I just read your post ill tell you there was alot of info in there I didnt know. Thanks for the correction

I figure running a 150 shot of nitrous I won't notice the rpm band change as much. That's also one of the reasons I wanted the cutouts. The better the exhaust flow the better the nitrous works!

1989GTABlown632- how the hell did u get a blown 632 in ur firebird?

So you buy a cable type exhaust cut-out then put the Gear Motor w/circuitry & mounting plate kit thingy on it and you have an electric exhaust cut-out? That would be nice b/c the cheapest I have found an electric one for was $117 from the link you sent me.

632 is just a tall deck big block... not really any different than swapping in a 427 or 454 big block, except the valve covers sit a bit higher.

with a big prybar! :D

That's odd that you would lose .7. Sounds like something went wrong on that run. Everytime I've ever seen a car run with a cutout they've only done better.

yes faulball6, get some cutouts and you'll be doing well. Enjoy the nitrous.

It actuall will bolt right it you just need to change the engine mounts. With the cam thats in there it created very low vacuum so for the brakes I got rid of the brake booster and replaced it with a hydraulic set that gets rid of the whole brake assembly and runs off the power steering pump. On the other side I had to remove the A/C and just put in the stander heaterbox. Up front I had to replace the fans on to the front of the radiator to push air through because of the blower cog. The exhaust was easy 3 inch custom zommies right through the hood. But in the end and alot of money later we got it in. The cars still not finished I want to have it done by this summer. I just got the air suspension on. Oh just so everyone knows this car was built for me Im not looking to drag it everyday or street drive it its more of a show car I pulled this car bare and and just about replaced everything in it. I will be a complete bottom up restoration. Ill post some picks as I go.

The motor you see in this pic it not the 632 its a 502 HO motor I bought and sold a year ago, long story.... anyway it gives you an idea of size

2nd I know its just the waterpump I got the superchiller intercooler and wanted to see what it looked like so i layed the now short belt on

scoop

and nitrous plate anyway

I have a 3" cutout and lobe it, i got mine for just under 150$ shipped to my door from Quick Time Performance, there's an add in the back of Chevy High Performance too.

Brett

I wish I could afford to build up a big block like that! So It's blown and you're shooting nitrous? Crazy! What boost level are you running and how big a shot of nitrous? Can you even get that thing to hook up at the track?

Thus far the project hasnt been cheap I could have bought a new WS6 fully loaded 02 T/A with all the bells and wistles with what iv spent so far. The compression is 8.5:1 and the current pulley setup is 9 lbs as for the nitrous the kit goes up to a 500 HP shot I havent yet decided on what shot im gonna run im thinking maybe a 150 I only droped the motor in 2 months ago and the car still needs work before its road worthy or track worthy so I havent run it yet. Im hopeing to have around 1000 hp without the nitrous. I was also playing around and talking with some guys about installing 4 jets above the nitrous plate to inject a small amount of alcohol at WOT never seen it done before just trying somthing different.

I just had a custom mandrel bend 3"Y-pipe installed with cutouts that I bought from Summit. here is how the setup looks, I was able to drive arouind town this week without dragging the ground, plus when I put it on my trailer I had no problems.

thats where i got mine from.

him or QTP are the only places to get quality ones.... you can get a couple crappy ones elsewhere.

Early in the summer, I had a problem with my car slowing down with an open cutout VS closed exhaust. Turns out, its because with the cutout open, the airflow through the exhaust improved enough to lean out the engine enough to slow it down. I richened it up a little bit, and that fixed it.

something i noticed that wasnt posted here is this. i have a cutout on my car but have never ran it closed at the track so i cant PROVE a difference ut ill say with my bassani catback, i feel no difference open or closed.

if you get a cutout, only get one. i like a more streetable car and thats why i say that. if you just want all out performance then get two. but one in the i pipe should be fine. ive seen modded cars pick up 30+rwhp with a cutout over a flowstopper catback.:eek: