Any "Power Gains" without cats? (off-road)

[fastglass95]

Just wondering if there is any power to be gained when using a C4 "off-road" where fedral laws do not apply,

By removing the cat. convertors and replacing with straight pipe sections to normal performance exhaust system (Corsa) still utilizing the O2 sensors before the cats and using O2 "sims" after the cats on Vettes so equipped (96 and up)

Would the decrease in backpressure adversly affect the torque output of the motor???
Anticipated RPM range of 2,500 to 6,000 rpm's

Anybody tried this?

Yes, I'm aware of Fedral Laws, this is an "OFF-ROAD VEHICLE"

 

[wookiebear]

Gutted Cats

I gutted my cats and and removed the resonators along with installing the Dynomax Turbos (LT 1) and picked up 21 HP at the rear wheels, its a cheap way to gain HP. It should be noted though that I lost 20 Lbs of torque. Go figure.

Wookiebear

 

[militant_x]

my friend has an 86 iroc-z, he had his cat cut off yesterday and replaced with a straight section of pipe. His car is pulling much harder.

If your car is old, the cat is probably somewhat clogged so replacing it or deleting it i think is a good idea.

-chris

 

[Da Hawaiian Punch]

If you have done the front mods first then you'll have some great increase in performence, I just did my straight pipe thing a couple of week's ago, and at first, I thought that I had made a big mistake in doing this mod, but, what was going on was the fact that my computer was learning what I had just done, and it took about a full day's driving around for it to finally put out some good power, remember though, port the front things like the plenum, runner's, and intake along with the cut airfilter lid thing and so on so the stright pipes can take advantage of the fully flow of air through your engine, from front out to the back.
I am running with a no muffler or cat set up, just pipes baby, from front to back.

 

[Remo]

Book'em Dan-o

Kalani,

Straight pipes - no mufflers? Your nieghbors must really enjoy that.

Remo :cool

 

[UB2 SLOW]

I run headers and cats, then straight pipes. My neighbors are always complaining about me waking them up at 4:30 when I go to work. :L

 

[Da Hawaiian Punch]

Re: Book'em Dan-o

Kalani,

Straight pipes - no mufflers? Your nieghbors must really enjoy that.

Remo :cool

I've got tollerable neighbor's. :L It doesnt seem that loud to me..........................of course I could just be used to it already.

 

[Mad-Mic]

i run the same setup on mine.

here is a few short vids of it so you can hear the sound. at idle it is very tolerable but once you hit 3500 rpm and above it's a whole different story


www.dsmetc.com/chris/mick1.mpg

www.dsmetc.com/chris/mick2.mpg

www.dsmetc.com/chris/mick3.mpg

windows up racing a turboed CRX
http://www.corvettekillstories.com/videos/87Vette_vs_Turboed_CRX.wmv

all mods listed below but with gutted cat

i noticed a Big Difference and dropped a few tenths from doing the gutted cat and new front Y pipe!

oh BTW Turn it UP! if you listen closely in clip 2 you can hear one guy say "Now thats what a Vette is suppose to sound like!"

 

[Da Hawaiian Punch]

i run the same setup on mine.

here is a few short vids of it so you can hear the sound. at idle it is very tolerable but once you hit 3500 rpm and above it's a whole different story


www.dsmetc.com/chris/mick1.mpg

www.dsmetc.com/chris/mick2.mpg

www.dsmetc.com/chris/mick3.mpg

windows up racing a turboed CRX
http://www.corvettekillstories.com/videos/87Vette_vs_Turboed_CRX.wmv

all mods listed below but with gutted cat

i noticed a Big Difference and dropped a few tenths from doing the gutted cat and new front Y pipe!

oh BTW Turn it UP! if you listen closely in clip 2 you can hear one guy say "Now thats what a Vette is suppose to sound like!"

Damn man!!! I swear if I close my eye's, it's as if I'm listening to my car while someone else is driving it, it sounds dead on like mine!!!!
On the 1/4, at what rpm's do you shift at for your best time?

 

[Mad-Mic]

Damn man!!! I swear if I close my eye's, it's as if I'm listening to my car while someone else is driving it, it sounds dead on like mine!!!!
On the 1/4, at what rpm's do you shift at for your best time?

5100 rpm and no more. seems like after i did the exhaust work she pulls alittle higher now. before i was shifting at 4900 rpm.

BTW i'm still running a bone stock TPI unit. no porting yet

 

[Mad-Mic]

the sick part is i can run 2nd gear to 5800 rpm and i'm at 101 mph

just wish she pulled past 5100 rpm......lol

 

[Da Hawaiian Punch]

the sick part is i can run 2nd gear to 5800 rpm and i'm at 101 mph

just wish she pulled past 5100 rpm......lol

Wow, my second gear only goes up to around 75-78 mph before I have to shift to 3rd and I have ported my front stuff.
I think that the ported stuff will raise your rpm level a good amount, I shift mine at around 5600-5800 rpm's, some where around there.

 

[Mad-Mic]

i took rrubel for a ride tonight (and let him drive since he's having withdrawals ) and i shifted at 5500 and we both said it doesn't feel like it falls off. i ment to shift at 5100 but overwound it some.

yeah when i do my headers and afpr i'm gonna port the upper plenum and runners to see if i can pull her alittle higher.

what gear are you running? i got the stock 2.59's still

 

[Da Hawaiian Punch]

i took rrubel for a ride tonight (and let him drive since he's having withdrawals ) and i shifted at 5500 and we both said it doesn't feel like it falls off. i ment to shift at 5100 but overwound it some.

yeah when i do my headers and afpr i'm gonna port the upper plenum and runners to see if i can pull her alittle higher.

what gear are you running? i got the stock 2.59's still

I now have the 3.07's, I had the 2.59's like your self at one time not to long ago, Hawaii 5-Lo helped me do the switcharoo.

 

[Mad-Mic]

i heard the 3.07's and 2.59's are like night and day. what did you think about the swap?

for now though i'm gonna stick with the 2.59's until i break them

 

[Da Hawaiian Punch]

i heard the 3.07's and 2.59's are like night and day. what did you think about the swap?

for now though i'm gonna stick with the 2.59's until i break them

It was pretty good, not that a dramatic difference, but was pretty good of a difference all the same.