Gutting your pre cats
08-02-2011, 12:47 PM
#121
Member
Join Date: Nov 2008
Location: Tampa
Posts: 192
Didn't drive the car for the last 3 days, however today I took it out for some errands... and I'm liking the new tone and the new grunt more and more.
At first blush, unrealistic expectations were there in the corners of my mind, even though I knew better... and so, the reality was kind of ho-hum. But a few days later, there is a gradual and growing appreciation for the subtle changes attributed to gutting the pre-cats in my config, and I like it.
I like it a lot.
At first blush, unrealistic expectations were there in the corners of my mind, even though I knew better... and so, the reality was kind of ho-hum. But a few days later, there is a gradual and growing appreciation for the subtle changes attributed to gutting the pre-cats in my config, and I like it.
I like it a lot.
i was thinking of doing this a few weeks ago when i had my cats off to see what type of condition they were in but i started reading about it and it seemed like a bad idea. One of the things i found out was that (at least here in florida dont know about anywhere else) a shop cant gut pre-cats as it is illegal! not sure if thats true or not, another i was that if your cats were gutted no shop would do anytype of work of the exhaust cause of the cats being gutted again not sure if this is true or not. Maybe someone with knowledge of this can set all that straight.
Rochester
I'm glad to here that you are loving that sound..i have a small request though. Would it be possible for you to get some good video of what it sounds like when you're in the car driving and maybe video of you driving but from the outside? so we can here how that is ?
08-02-2011, 05:30 PM
#122
well after talking with dallas at warpspend
he's says he will make 3' y-pipes( 2'' 1/2 at the flange so it will conncet to the pre catts) for are cars but they are made to order at 250.00 a pop in aluminized steel. little more for ss
and also has his standerd 2 1/2 y pipes at 199 plus shipping
Number for any body wanting one
1-479-246-9400
Since i pulled the custom maxima headers OFF (sold them in the matter of sec's) and put the stock set up back on.
Going to be gutting the pre cats and installing WarpSpeeds 2 1/2 to 3''y-pipe and going with a rear mount turbo set up like kevo911 is running.
he's says he will make 3' y-pipes( 2'' 1/2 at the flange so it will conncet to the pre catts) for are cars but they are made to order at 250.00 a pop in aluminized steel. little more for ss
and also has his standerd 2 1/2 y pipes at 199 plus shipping
Number for any body wanting one
1-479-246-9400
Since i pulled the custom maxima headers OFF (sold them in the matter of sec's) and put the stock set up back on.
Going to be gutting the pre cats and installing WarpSpeeds 2 1/2 to 3''y-pipe and going with a rear mount turbo set up like kevo911 is running.
Last edited by Clashez; 08-02-2011 at 05:59 PM.
08-02-2011, 07:26 PM
#124
Rochester
I'm glad to here that you are loving that sound..i have a small request though. Would it be possible for you to get some good video of what it sounds like when you're in the car driving and maybe video of you driving but from the outside? so we can here how that is ?
I'm glad to here that you are loving that sound..i have a small request though. Would it be possible for you to get some good video of what it sounds like when you're in the car driving and maybe video of you driving but from the outside? so we can here how that is ?
Besides, all this nuanced talk about exhaust tone just doesn't come across in video. Exhaust vids are a dime a dozen, and they all pretty much sound the same. The subtle differences I'm hearing are for me and my car... there's no way to represent that in some youtube video.
I might regret asking this... but why would you remove (shorty) headers and replace that setup with OEM manifolds, gutted cats and an aftermarket Y? Seems to me those two configurations are relatively equivalent.
Last edited by Rochester; 08-02-2011 at 07:38 PM.
08-02-2011, 07:41 PM
#125
Didn't drive the car for the last 3 days, however today I took it out for some errands... and I'm liking the new tone and the new grunt more and more.
At first blush, unrealistic expectations were there in the corners of my mind, even though I knew better... and so, the reality was kind of ho-hum. But a few days later, there is a gradual and growing appreciation for the subtle changes attributed to gutting the pre-cats in my config, and I like it.
I like it a lot.
At first blush, unrealistic expectations were there in the corners of my mind, even though I knew better... and so, the reality was kind of ho-hum. But a few days later, there is a gradual and growing appreciation for the subtle changes attributed to gutting the pre-cats in my config, and I like it.
I like it a lot.
08-03-2011, 12:24 PM
#126
Well he said sure i can do it i been making them for a while now, he doesn't keep them in stock they are made to order and no need for goup buys or any thing .....ect
To make a long story short, I think more power can be had with gutted cats and a 3'' y-pipe then the shorty headers.
So i will be placing my order this friday after i figuar out my buget.
Last edited by Clashez; 08-03-2011 at 12:27 PM.
08-03-2011, 01:07 PM
#128
Banned
Join Date: Jul 2011
Location: Worcester, MA
Posts: 133
Just a thought: With 3'' y, 3'' straight pipe, and 3'' catback to a rmt will that not effect how fast you spool? I would have thought 2.5'' would be the max you would want to go with...then again i'm not an expert on RMTs...I always thought the best place would be to put the turbo where the cat is but it would have to be a small turbo as there is not much space...
08-03-2011, 01:16 PM
#129
08-03-2011, 03:52 PM
#130
08-03-2011, 03:59 PM
#131
08-03-2011, 04:03 PM
#132
I'm not really into HP numbers, but this post at the beginning of this thread is pretty impressive considering there are no headers, and there's no phenolic under the IM.
It's fun.
Man, I love driving my car.
Last edited by Rochester; 08-03-2011 at 04:08 PM.
08-03-2011, 04:10 PM
#133
http://forums.maxima.org/8143635-post10.html
http://forums.maxima.org/8087097-post29.html
Either way, like anything and everything else, it be nice to have a comparison of before and after.
Last edited by NmexMAX; 08-03-2011 at 04:12 PM.
08-03-2011, 04:16 PM
#134
The only true comparison would be a run on the same machine with the same car, with headers on, then again with gutted cats. And even then, there would be a variance.
08-03-2011, 07:09 PM
#135
08-03-2011, 07:26 PM
#138
My thoughts are sporadic.... .. . But the headers is one unit not headers + y-pipe it's just headers /end
08-04-2011, 02:11 AM
#139
The latter of which, as Rochester once pointed out, I don't have - but my girl is hella good in bed. (That is a very rough paraphrase from the "pretty engine" thread.)
Last edited by tcb_02_max; 08-04-2011 at 02:13 AM.
08-04-2011, 02:40 PM
#140
figured I would offer up a little experience comparison to this thread ie dyno numbers
with gutted pre-cats and a WS y-pipe, I dyno'd ~240 WHP
with OBX V3 headers (and their y-pipe) I dyno'd ~253 WHP.
No changes between the two runs besides the manifold and y-pipe change. Runs were even done on the same dyno and similar atmospheric conditions.
I was probably one of the first people to gut their precats (at least for a 5.5 gen) when I did it back in 2008. I drove like that for almost 2 years before I got headers. After installing the headers, there was a significant butt dyno difference throughout RPM range and especially at the track where I knocked 3 tenths off my best 1/4 pass with only this change
with gutted pre-cats and a WS y-pipe, I dyno'd ~240 WHP
with OBX V3 headers (and their y-pipe) I dyno'd ~253 WHP.
No changes between the two runs besides the manifold and y-pipe change. Runs were even done on the same dyno and similar atmospheric conditions.
I was probably one of the first people to gut their precats (at least for a 5.5 gen) when I did it back in 2008. I drove like that for almost 2 years before I got headers. After installing the headers, there was a significant butt dyno difference throughout RPM range and especially at the track where I knocked 3 tenths off my best 1/4 pass with only this change
Last edited by Gemner; 08-04-2011 at 02:44 PM.
08-04-2011, 02:52 PM
#141
and a 3''id cat back.... ..
08-04-2011, 03:19 PM
#142
figured I would offer up a little experience comparison to this thread ie dyno numbers
with gutted pre-cats and a WS y-pipe, I dyno'd ~240 WHP
with OBX V3 headers (and their y-pipe) I dyno'd ~253 WHP.
No changes between the two runs besides the manifold and y-pipe change. Runs were even done on the same dyno and similar atmospheric conditions.
I was probably one of the first people to gut their precats (at least for a 5.5 gen) when I did it back in 2008. I drove like that for almost 2 years before I got headers. After installing the headers, there was a significant butt dyno difference throughout RPM range and especially at the track where I knocked 3 tenths off my best 1/4 pass with only this change
with gutted pre-cats and a WS y-pipe, I dyno'd ~240 WHP
with OBX V3 headers (and their y-pipe) I dyno'd ~253 WHP.
No changes between the two runs besides the manifold and y-pipe change. Runs were even done on the same dyno and similar atmospheric conditions.
I was probably one of the first people to gut their precats (at least for a 5.5 gen) when I did it back in 2008. I drove like that for almost 2 years before I got headers. After installing the headers, there was a significant butt dyno difference throughout RPM range and especially at the track where I knocked 3 tenths off my best 1/4 pass with only this change
IIRC, this was on a DJ too.
Runfiles?
08-04-2011, 08:35 PM
#143
+1 can we see those files gemner?
Clashez, any way you can do obx, gutted cats w/ stock y pipe, and gutted cats w/ WS y pipe? Might be interesting to see what difference the ypipe makes.
Clashez, any way you can do obx, gutted cats w/ stock y pipe, and gutted cats w/ WS y pipe? Might be interesting to see what difference the ypipe makes.
08-05-2011, 12:40 AM
#144
his 3rd run hp247.6@6126 tq248.5@3964 just gutted pre-cat no y-pipe, i would say they put out just about the same power. Now i wonder what numbers will be had with a warpspeed 3'' y-pipe with gutted cats and a 3''id cat back.... ..
and a 3''id cat back.... ..
08-05-2011, 05:00 AM
#145
his 3rd run hp247.6@6126 tq248.5@3964 just gutted pre-cat no y-pipe, i would say they put out just about the same power. Now i wonder what numbers will be had with a warpspeed 3'' y-pipe with gutted cats and a 3''id cat back.... ..
and a 3''id cat back.... ..
08-05-2011, 05:54 AM
#146
figured I would offer up a little experience comparison to this thread ie dyno numbers
with gutted pre-cats and a WS y-pipe, I dyno'd ~240 WHP
with OBX V3 headers (and their y-pipe) I dyno'd ~253 WHP.
No changes between the two runs besides the manifold and y-pipe change. Runs were even done on the same dyno and similar atmospheric conditions.
I was probably one of the first people to gut their precats (at least for a 5.5 gen) when I did it back in 2008. I drove like that for almost 2 years before I got headers. After installing the headers, there was a significant butt dyno difference throughout RPM range and especially at the track where I knocked 3 tenths off my best 1/4 pass with only this change
with gutted pre-cats and a WS y-pipe, I dyno'd ~240 WHP
with OBX V3 headers (and their y-pipe) I dyno'd ~253 WHP.
No changes between the two runs besides the manifold and y-pipe change. Runs were even done on the same dyno and similar atmospheric conditions.
I was probably one of the first people to gut their precats (at least for a 5.5 gen) when I did it back in 2008. I drove like that for almost 2 years before I got headers. After installing the headers, there was a significant butt dyno difference throughout RPM range and especially at the track where I knocked 3 tenths off my best 1/4 pass with only this change
08-05-2011, 02:58 PM
#147
his 3rd run hp247.6@6126 tq248.5@3964 just gutted pre-cat no y-pipe, i would say they put out just about the same power. Now i wonder what numbers will be had with a warpspeed 3'' y-pipe with gutted cats and a 3''id cat back.... ..
and a 3''id cat back.... ..If you properly read my post, you would see that the gain was 100% the result of changing from gutted precats to "real" headers. comparing my numbers to someone else's is meaningless as the comparison is much better between my car/same dyno than comparing mine with someone else's and different dyno types
Oh, I dont have the files any longer. I am working on getting them back but theyre hiding on a crashed laptop right now
Last edited by Gemner; 08-05-2011 at 03:02 PM.
08-05-2011, 04:05 PM
#148
Gutted cats for FTW..Im going to see how much hp i can pull without headers.ssim/spacers/portmatched,lr maf,350z injectors and a utec and i think ill be 270 ish give or take a few
08-05-2011, 09:04 PM
#150
So I'm figuring out how to upload to youtube (drag, drop, done).
Here's the car, very gently starting up and rolling out of the garage with the two front windows open. In reminder: VQ, gutted pre-cats, Cattman y-pipe, OEM main cat, Cattman 2.5" cat-back.
Quite the little rumble the car has now.
More videos to follow as I play with my new camera.
Here's the car, very gently starting up and rolling out of the garage with the two front windows open. In reminder: VQ, gutted pre-cats, Cattman y-pipe, OEM main cat, Cattman 2.5" cat-back.
Quite the little rumble the car has now.
More videos to follow as I play with my new camera.
08-06-2011, 05:54 AM
#152
Now that I've figured out a simple way to mount the miniature video camera, I'm intending to take two more videos with the same 0-60 run, one with windows up and one with windows down. Nothing breakneck, just spirited enough to get a good sense of how noisy things are.
08-06-2011, 10:24 AM
#153
If you don't mind sharing your creativity, how did you manage to mount the camera? On the passenger seat below the headrest? It's a great angle - which is, I'm sure, why you chose it 
Would you take a picture, pretty please? (Maybe I'll get lucky and get the spoon-fed baby, too!)
btw. what model is your cam?
Would you take a picture, pretty please? (Maybe I'll get lucky and get the spoon-fed baby, too!)btw. what model is your cam?
Last edited by tcb_02_max; 08-06-2011 at 10:27 AM.
08-06-2011, 10:56 AM
#154
Anyway, it's a Kodak Zi8.
I used a pocket tripod, (like this one below) where the legs were simply tucked between the seat and the headrest on the passenger side. Not sure how well that will hold up to actual driving, or spirited driving, vs. simply pulling the car out of the garage. I guess I'll find out soon enough.
What... what?
Last edited by Rochester; 08-06-2011 at 11:11 AM.
08-06-2011, 01:36 PM
#156
If you lean the seat back, the camera angle is spot-on perfect: dashboard, windshield, shifter, etc. But it's so shaky that it's unwatchable. Granted, you guys are interested in sound, but I still can't post that video.
Bouncy Bouncy.
08-07-2011, 10:36 AM
#159
Ha ha. 
Yeah, I suppose it is. Sorry.
It seems I have to get someone's help to video from the backseat in a way that I'm satisfied. I think I know just the right 11 year old girl who could help with that. Although she can be illogically disagreeable sometimes... in which case, I have a 7 year old girl who would love to help.
Working on it.
Yeah, I suppose it is. Sorry.It seems I have to get someone's help to video from the backseat in a way that I'm satisfied. I think I know just the right 11 year old girl who could help with that. Although she can be illogically disagreeable sometimes... in which case, I have a 7 year old girl who would love to help.
Working on it.
08-07-2011, 12:45 PM
#160
I highly doubt 270 NA is impossible. It's gonna be hard and I don't know if it's achievable with just bolt-ons (no internal work) but there are definitely 270 whp n/a vq35 maximas running around