hulling out the cats

[zr-1assassin]

im sure some one on here has tried the old trick of hulling out the cats on your z. or even removing the converters all together. i'm thinking of it and was wondering what your outcome was? i have heard a car needs some back pressure and you can lose power? what did you guys who have done it come up with? thanks

[GrayZ]

Leave you're cats alone. most you'll get is one or two
ponies, but the smell isn't worth it.

[zr-1assassin]

Originally Posted by ITLGO2

Leave you're cats alone. most you'll get is one or two
ponies, but the smell isn't worth it.

how about with headers? are yours still there or removed.....you got jeals dont ya? also what times did you see down at B.G. this year with your mods? i ask because getting ready to do headers and prob 4:10's. thanks dude

[GrayZ]

i have watson headers, 410's and a haibeck chip
my best time was 12.74 @113 mph at Beech Bend,
Jeff and Uly also ran very similiar times driving my car.
but thank god, i had the lowest E.T. so i didn't have
to listen to the rhetoric.

[zr-1assassin]

Originally Posted by ITLGO2

i have watson headers, 410's and a haibeck chip
my best time was 12.74 @113 mph at Beech Bend,
Jeff and Uly also ran very similiar times driving my car.
but thank god, i had the lowest E.T. so i didn't have
to listen to the rhetoric.

12.7 sounds about right,(considering thats what chevy claims bone stock) have you ever had it dyno'd? thanks for the info! see....i told the guys that stuff about you being a homosexual probably wasnt true

[A26B]

Originally Posted by zr-1assassin

im sure some one on here has tried the old trick of hulling out the cats on your z. or even removing the converters all together. i'm thinking of it and was wondering what your outcome was? i have heard a car needs some back pressure and you can lose power? what did you guys who have done it come up with? thanks

Hp gains from headers are well documented. They reduce backpressure. Cat back aftermarket exhaust systems are beneficial as well, for the same reason. Only gutting your cats will be an insignificant reduction in back pressure.

I have 415, headers, no cats & only a single, custom muffler where the resonator used to be, and no mufflers, all with a 3" system. I dynoed it both with open headers and with the described exhaust system in place. I actually lost about 7 hp with open headers.

In summary, I do believe slight back pressure may be beneficial, but you gotta get way out on the lunatic fringe before a drop in power is noticible.

[zr-1assassin]

Originally Posted by A26B

Hp gains from headers are well documented. They reduce backpressure. Cat back aftermarket exhaust systems are beneficial as well, for the same reason. Only gutting your cats will be an insignificant reduction in back pressure.

I have 415, headers, no cats & only a single, custom muffler where the resonator used to be, and no mufflers, all with a 3" system. I dynoed it both with open headers and with the described exhaust system in place. I actually lost about 7 hp with open headers.

In summary, I do believe slight back pressure may be beneficial, but you gotta get way out on the lunatic fringe before a drop in power is noticible.

i was just looking at your z pics on here....nice! did you custom that exhaust or is it part of the body package? and one muffler? is it 2-in & 2-out or did you go down to one 3" pipe? very nice and thanks for the info on the cats. i had an 84 years ago and i hulled out the cats on it and it sounded like a $2000 exhaust system and felt like you put nos on it.i fuigered it might work on the old Z. i'v heard that over half the backpressure is in the cats on these?

[A26B]

Picture are how it USED to be. Now, there is an x-pipe where the muffler used to be, no mufflers at all. It's all 3" mandrel bent from header collectors back. The exhaust is all custom built and was necessitated by the LPE Aerobody center outlet.

As far as the backpressure in the ZR-1 cat system.....I recall, possibly wrongly, that Marc Haibeck dyno tested and found that only eliminating the cats made no noticable difference in rwhp. Not sure about this, but if it's so, I think it's reasonable to infer that the cats do not create appreciable backpressure to the exhaust system on a ZR-1.

[zr-1assassin]

Originally Posted by A26B

Picture are how it USED to be. Now, there is an x-pipe where the muffler used to be, no mufflers at all. It's all 3" mandrel bent from header collectors back. The exhaust is all custom built and was necessitated by the LPE Aerobody center outlet.

As far as the backpressure in the ZR-1 cat system.....I recall, possibly wrongly, that Marc Haibeck dyno tested and found that only eliminating the cats made no noticable difference in rwhp. Not sure about this, but if it's so, I think it's reasonable to infer that the cats do not create appreciable backpressure to the exhaust system on a ZR-1.

where did you get the center cut out bumper for the back? i have been wanting a center mount exhaust for some time. and where did you get the tips? they look great!

[A26B]

The rear bumper is part of the Lingenfelter Aerobody. I don't know if they will sell only the rear bumper.

http://www.lingenfelter.com/pack_cor_c4bk.htm

John Lingenfelter's yellow 95 ZR-1 had only the rear bumper installed. I understand he wanted more downforce from the bigger spoiler during his 225 mph run.

The tips were hand made by Texas Quality Exhaust in Houston. That's why they are just a bit irregular.