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]

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:thumbsup:

[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. :mrgreen:

[zr-1assassin]

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. :mrgreen:12.7 sounds about right,(considering thats what chevy claims bone stock:icon_scra) 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:mrgreen:

[A26B]

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]

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?:thumbsup:

[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.

http://i190.photobucket.com/albums/z224/A26B/TQES20.jpg
http://i190.photobucket.com/albums/z224/A26B/TQES02.jpg

[zr-1assassin]

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.

http://i190.photobucket.com/albums/z224/A26B/TQES20.jpg
http://i190.photobucket.com/albums/z224/A26B/TQES02.jpgwhere 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!:thumbsup:

[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.

[zr-1assassin]

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.they are a bit irregular, and thats what makes them so awsome looking! i realy think the rear mount exhaust tips on yours are the best looking thing ive seen on a zr-1 azz! what did you do with the spare tire cover, remove it and put up a custom heat sheild on the back side? i always wondered if there would be a problem with the exhaust being up there by the gas tank (boooooom), but i guess not because you did it :mrgreen:. i seen one time in a magazine where they filled in the exhaust outlet spaces in the rear bumper of a c3. they just fiberglassed them in, or poly or what ever the rear is made of. i guess a guy could do that with a c4 bumper. i'm going to contact lingenfelter and see if the sell just the rear bumper. if not..... its customiztime.:thumbsup:

[WB9MCW]

THE GUY'S OVER AT CORVETTE VALLEY ACTUALLY THOUGHT THAT JERRY'S KEWL EXHAUST PHOTO OF THE "BEAST'S AZZ" WAS A FAKE---THE THOUGHT THE FUMES WERE PHOTOCHOPPED IN AND WERE FAKE! LOLOL

http://i126.photobucket.com/albums/p110/HAMMERHATE/JULY%2007/BeastAss.jpg

[zr-1assassin]

i guess just because they couldn't do work like that, they thought no one could. WRONG!

[Aurora40]

Just FYI since you are talking center exit, Callaway also made a center-exit version of their exhaust (and a center-exit version of the rear aerobody bumper)

http://gallery.viperclub.org/data/500/medium/100_0066.JPG

To your original question, if you look at the cat on the original exhaust, it's pretty huge. I suspect it's not the problem with the original manifolds. I imagine with no cats they wouldn't make much more power. Back in the day, Callaway reworked the primary tubes on the '90-92 style headers but kept the cat the same. They claimed about a 10hp improvement with them.

If you go to long-tubes, cats also don't seem to be much of a restriction, supposedly ~2hp on a 350. The main issue with them is fitment, the long tubes would otherwise bolt right up to the stock exhaust, but adding cats means you need to do a bit of work to the original pipes.

[zr-1assassin]

Just FYI since you are talking center exit, Callaway also made a center-exit version of their exhaust (and a center-exit version of the rear aerobody bumper)

http://gallery.viperclub.org/data/500/medium/100_0066.JPG

To your original question, if you look at the cat on the original exhaust, it's pretty huge. I suspect it's not the problem with the original manifolds. I imagine with no cats they wouldn't make much more power. Back in the day, Callaway reworked the primary tubes on the '90-92 style headers but kept the cat the same. They claimed about a 10hp improvement with them.

If you go to long-tubes, cats also don't seem to be much of a restriction, supposedly ~2hp on a 350. The main issue with them is fitment, the long tubes would otherwise bolt right up to the stock exhaust, but adding cats means you need to do a bit of work to the original pipes.do they still offer this rear lower shroud with the center exit port? or does anyone know if there is a company that still does? lingenfelter,drm,callaway....????

[Aurora40]

Callaway doesn't sell the aerobody parts separately. Also the lower part would wrap around to the rear wheels.

[GrayZ]

Assassin,
why don't you go ahead, and give in to the dark side.
buy yourself a honda civic, like all you young guys like.
you could then install one of those, beefy fart pipe mufflers.
Get yourself, a big frikkin wing, on the back.
maybe, add one of those, spiffy, under the car light kits.
then take a picture of it, and get yourself a tatoo.

[WB9MCW]

http://www.firebreathingfiats.com/Contribute/contact/images/Ricer-excuse-gaugeweb.jpg

http://www.streetracersonline.com/gallery/albums/userpics/14518/normal_ricer.jpg

http://www.speedguide.net/~brian/ricer.JPG

http://www.anti-rice.com/rice010/127200265924PM57221.jpg

http://www.accelrs.com/aero/1_1.jpg

[zr-1assassin]

Assassin,
why don't you go ahead, and give in to the dark side.
buy yourself a honda civic, like all you young guys like.
you could then install one of those, beefy fart pipe mufflers.
Get yourself, a big frikkin wing, on the back.
maybe, add one of those, spiffy, under the car light kits.
then take a picture of it, and get yourself a tatoo.not bad pizza man:mrgreen: but i think i will stay with the Z for now! but if you ever decide to sell that 1995 kia spectra you got,let me know. and keep it the way you have it now...i want those 28inch wheels you got on it and i love what you did with the 15 H.P. shot of NOS! i am still willing to give you the $350 for it we discussed in B.G. i still cant believe you trailered it all the way down there and it didnt sell:icon_scra

[zr-1assassin]

i forgot to tell you i got those pics back that we took down at your place keith:mrgreen: http://img2.freeimagehosting.net/uploads/74769eddd1.jpg (http://www.freeimagehosting.net/)

[GrayZ]

i forgot to tell you i got those pics back that we took down at your place keith:mrgreen: http://img2.freeimagehosting.net/uploads/74769eddd1.jpg (http://www.freeimagehosting.net/)

the diffenece between my post and yours, is that
mine really hits close to home, while yours is chopped to my home, which by the way, you'll never see

[zr-1assassin]

the diffenece between my post and yours, is that
mine really hits close to home, while yours is chopped to my home, which by the way, you'll never seeyes i will see it....B.G. 2008 baby! me and the travster are there:thumbsup: and i still think the center mount exhaust looks good....you know deep down so do you!

[GrayZ]

looks good on a callaway, or on Jerry's lingenfelter.
you and your boyfriend travis, are getting no where
near my little dog.

[petefias]

i forgot to tell you i got those pics back that we took down at your place keith:mrgreen: http://img2.freeimagehosting.net/uploads/74769eddd1.jpg (http://www.freeimagehosting.net/)

Oh well, I kind of like





















the color of that car!