I am trying to find answers for my exhaust. right now I have a 3 inch edelbrock catback. I just bought a set of slp 1 3/4 headers with the y pipe. My idea would be to keep the 3 inch exhaust and put a cut out for when I go racing. I dont have a cat, and hopefully this will flow enough for my engine. Any comments or what works?

 

single 3inch will choke that motor, but use a good flowing muffler and you will minimize the losses. I'm not sure how good flowing the edelbrock stuff is.

The slp's have a 2.5" collector. You could use a 2 3/4 or 3 inch collector and 2 3/4 or 3inch ypipe too but if you run a cutout in the right spot, probly 2 cutouts, one on each piece of y pipe, you will make up for the losses

 

Which muffler would you recommend for most free flowing. If I put a cut out on each side of the y pipe would that flow enough, and what size cut out would be correct. 2 inch or 2.5

 

Dynomax and Magnaflow make good straight through mufflers. For max power gains from your situation you need to put the cutouts in the right spot. Maybe 18" inches from the collectors.

 

how high does your 383 rev to? anywhere around 17-19 inches total collector length seems to work well for cars witha peak between 5800-6300 rpms range. thats doable on a y pipe setup

I'm not sure what the y pipe is, proby 2.5 inch but measure it to be sure

I agree, a magnaflow would probly be a good flowing muffler. A good flowing stock style crossflow muffler i'm not sure what would be the best. If you dont mind a single exit, you can run a single UltraFlo or magnaflow Round. else you can have dual exits fabbed up over the rear axle like i did, and run the muffler behind the cat.

 

So I put the cut-outs on the y 17-19 inches from the cut out. I am still looking for a high flow muffler and have come up with these two from summit. Any ideas?


http://store.summitracing.com/partde...5&autoview=sku
http://store.summitracing.com/partde...5&autoview=sku

 

Here ya go man.... I went out and did some research before getting my Magnaflow muffler....I havent heard the Flowtech muffler but it is right there with Magnaflow....but ALOT cheaper....
Also, if you want the Magnaflow muffler DONT get it from Summit unless you want the polished version.....go to your local muffler shop/performance shop and order it there. I paid $90 shipped to my door for the same magnaflow muffler you see in summit but without the polish and for alot less.
anyways here is the dyno that i found on ls1 forum


The results in HP order:
1.Flowtech Warlock (open) 374.2 hp/ 333.1 tq
2.Bassani Real Street 373.7 hp/ 333.8 tq
3.Hooker Maxflow 373.5 hp/ 333 tq
4.Borla XS 373.3 hp/ 332.6 tq
5.Magnaflow 372.8 / 332.5 tq
6.MAC 372.3 hp / 331.5 tq
7.Flowtech Afterburner 372.3 hp/ 330.1 tq
8.Hooker Aerochamber 372.1 hp/ 330.4 tq
9.Bassani 372 hp/ 333.5 tq
10.Spintech 371.6 hp/ 332.2 tq
11.Edelbrock Performer RPM 370.9 hp / 331.3 tq
12.Borla XR1 370 hp/ 334 tq
13.Flowtech Terminator 369.5 hp / 331.3 tq
14.Dynomax Ultra Flo 369.4 / 333.2 tq
15.Flowmaster 369.4 hp / 331.8 tq
16.Flowtech Warlock 366.3 hp / 325.3 tq
17.No muffs 365.2 hp / 330.1 tq

Sound Off in Quietest to Loudest (Decibels):

1.Borla XS, 80db at idle, 90db at 2,000 rpm, 110db at WOT.
2.Hooker Maxflow, 80db at idle, 90db at 2,000 rpm, 120db at WOT.
3.Magnaflow, 82db at idle, 91 at 2,000 rpm, 114db at WOT.
4.Flowmaster, 82db at idle, 93 at 2,000 rpm, 115db at WOT.
5.Flowtech Warlock, 83db at idle, 92 at 2,000 rpm, 112db at WOT.
6.Dynomax UltraFlo, 83db at idle, 94 at 2,000 rpm, 113db at WOT.
7.Borla XR1, 83db at idle, 96db at 2,000 rpm, 118db at WOT.
8.Bassani Street, 83db at idle, 96db at 2,000 rpm, 120db at WOT.
9.Edelbrock RPM, 84db at idle, 93db at 2,000 rpm, 118db at WOT.
10.Bassani Real Street, 84db at idle, 96db at 2,000 rpm, MAX. (120+db).
11.Flowtech Afterburner, 86db at idle, 94db at 2,000 rpm, 115db at WOT.
12.Flowtech Terminator, 86db at idle, 94db at 2,000 rpm, 119db at WOT.
13.Hooker Aerochamber, 87db at idle, 94db at 2,000 rpm, 114db at WOT.
14.SpinTech, 87db at idle, 97db at 2,000 rpm, 116db at WOT.
15.MAC, 87db at idle, 98db at 2,000 rpm, 119db at WOT.
16.No Muffler, 91db at idle, 103db at 2,000 rpm, MAX. (120+db).
----------
http://www.ls1tech.com/forums/showthread.php?t=113572 try this one too

 

what size cutout would be correct for the 2.5 y pipe

 

Cutouts are sections of pipe for the exhaust. They come in the same sizes as the pipe.

so if you have a 2.5" pipe, you need the 2.5" pipe cutout

 

Joe - I had a 383 set up pretty similar to yours. My exhaust was Hooker 2210 Super Comps, 3" Y pipe with dual 3" converters into a 4" Mufflex with Flowmaster muffler and single exit.

I was able to get the car down to 11.61@118 mph with that exhaust right off the street. The motor made peak power at 6500 on the dyno.

 

I just bought some 1 3/4 shorties and i really wanted to use them along with the y pipe and my 3 inch catback. Wondering if I use this setup with you 2 2.5 cutouts 18 inches from the collector, would that flow enough. I don't have a cat.

 

Joe, I know you said you dont have cats, but did you get the dual cat y pipe?

 

nope

 

the cutouts will definately flow enough..its an open pipe at that point

 

I'm going the same route Joe....hopefully we will have matching times

 

Sounds good, how far you going to put the cutouts on the y-pipe?

 

around 18 inches give or take an inch....but i HAVE to run cats.....or at least have the shells

 

Anybody ever tried making a 3 inch y-pipe without have clearance issues around the oil pan.

 

Yes, we have looked into it and there are clearance problems without the pipe hanging low. You can either modify your oil pan (I did) or get a tubular K-member.

 

Would there be any difference in performance with a 3 inch catback with a 3 inch cutout after the y pipe, as compared to a 3.5 mufflex with a ultra flow muffler and no cutout?

 

just wondering what HP and ET gains I would get from going with a Cut Out. My exhaust is SLP 1 3/4" into a 2 1/2" Y pipe into 3" Banks-no cats... I know the 3" prob is choking my 385 cu. in. but I dont plan on changing it out anytime soon... So I was thinking of seeing if I'll get any gains with a cut out install under the passenger seat....mods in sig.

 

I have my 3.5 inch cutout right after the y pipe. When I leave it on I can only go as fast as 12.20 in the 1/4. With the cutout off, I have ran as fast as a 11.64 in the 1/4. So I know that my 3 inch catback is a huge restriction

 

Ok, just ordered 3" electric cut out. I'll post dyno results with it open and closed in the next few weeks.