Zoomspeed

anyone ever try to ghetto rig a MP by just cuttin the cat off and replacing it with a short pipe? You would end up with a MP that is the diameter of teh stock piping.

I think it can be done with about ~$15 and maybe an hour of work.

Not as good as a real MP but much cheaper.

ttpowerd

Thought had occured to me....

Street King

Whats the width of the stock cat piping. If its 3 you can add a short section of 2.5'' pipping to control boost!!

Silex

I wonder why you peeps never htought of this in the first place lol. Just go to any shop and see what kinda stainless steel they have. Don't want that crap to melt on ya.

weaklink

uh, I thought that's what a mid pipe was...a piece of pipe instead of a cat, etc.

paw140

I know when I replaced my stock dp with a HKS dp, the diameter of the HKS pipe was quite a bit larger than the cat piping. That might be one of the downsides of cutting out the cat and welding in a pipe.

Moxeys93RX7

i did somehting similar to that on my dp. i tried punching it out but becasue of the bends i couldn't get at it well enough. so i cut it in half cleaned it out real good and then welded it back together. didn't notice much power gain but wouldn't have to worry about it clogging. on my fc i took the exhaust to a friend of mine and had him bend a new pipe. it isn't pretty (indents at the bends) but it works. he said he could do the exhaust for my Fd for ~$250 excpet i would need to find an elbow and a flange where the DP goes into the turbo. if i do it is about $1000 cheaper than buying even a used exhaust system. if i wanted i could have it made out or larger or rectangle pipe (to gain ground clearance).

Street King

Thats my point. To control boost have the diameter of the pipping a little smaller. But keep the same connecting pieces to your cat back and down pipe.

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Sorta like my high technology graphics design.

Street King

How come it wont post the pic like i drew it? But the top part is fine, just think identical!!

weaklink

i think racing beat sells flanges...

Flybye

You could save urself the $15 and aggrevation of the fitting and cutting and just gut the main cat

ptrhahn

iTrader: (9)

Jeez you can pic up a proper mandrel-bent MP used for like $100-$150. If you ever need a cat again (for emissions test) it will cost you more than that to replace the one you ruined.

Either way, it'll probably cost you WAY more than that to port the wategate which you will want to do unless you want to spend WAY more on a new motor.

If you're gonna use smaller piping or restrictors in the Ghetto MP, the flow is likely ruined so you may as well use the stock or a Hiflo cat instead. No offense to anyone, just sounds penny wise, pound foolish.

Zoomspeed

well, not really, a 3" MP would have the entire section that inlcuding the cat replaced with 3" piping, this ghetto way would only be replaceing the cat and leaving the rest of the stock piping intact.

cuz that sounds like more trouble then the ghetto MP, I would have to take off the cat section then open it out and get all the inners scraped out. sounds kinda tedious to me

Where as I can just rent an exhaust pipe cutter, cut off the whole cat, use an exhuast pipe expander and expand the ends and shove in a peice of pipe with a couple of exhaust clamps.

I don't need to worry about emissions around here. I don't really intend this as a replacement for a true mendrel ben 3" MP, more as a cheap ***'s (me ) temporary MP.

About this I was thinkin along the lines of street king. If you get boost creep with a 3" MP, but you don't get boost creep with a 3" MP when used with a restrictor plate; then surely in a MP in which the entire thing is the stock diameter then boost creep wouldn't bee a problem. ya know wut I'm sayin?

So your sayin that a little turbulance in the exhuast flow of a stright pipe would cause my to loose more HP then if I had a stock cat i there? I' sorry but that doens't make too much sense to me. I understand the the power increase won't be as much with a real MP but surely it has to be more then with a stock cat.

Flybye

Not really. I personally never did it but have spoken to plenty of people that have and they have all said it's easy. Simple shove a stick in it and start pounding away and it all comes crumbling out. I think the interior of the main cat is made out of a ceramic material. The precat is different, though. The precat's insides are actually made out of metal, and that DOES require you opening up the precat.

Want2race

The rx-7 crew has gone ghetto!

$100 isnt that much.. spend the money and get real, descent parts!

Crash

The precat I just took off Has welds on it where some one cut it open and took all of the guts out and welded it back together. They should have spent the extra dough and bought a downpipe but maybe they were trying to cheat in the stock class auto-x them b@st@rds.

spyfish007

One reason is probably because the cat section is really so large. There are only short little connecting pieces on the end. Might as well just make a new pipe at that point!

GoRacer

iTrader: (2)

Is the Cat' mild steel? I was thinking of welding a Borla XR-1 in the section where the cat is cut out but it's stainless steel. Can you weld mild steel with stainless steel?

rotorbrain

gutting a cat isnt hard. just shove a stick into it and grab a beer. not very hard at all. not tedious either. how tedious can ramming a rod into a hole be. it has never been tedious to me. haha. just a little inuendo in there. haha. if you want to gut your cat then just do it. it is more tedious to try and come up with these ways to make an mp out of doodoo material. if you dont have any emissions testing in your county then just save the money you would have to spend on an emissions check and inspection and eventually youll have enough to get a mid-pipe. im not trying to bash at all. i just dont understand why it is so hard to gut a cat. i gutted mine and the performance is okay. not due to the gutting, but due to other stuff. the gutted cat should be a safety mod IMO. haha. just like the downpipe. im sorry, im ranting.

paul

rx7speed811

yeah... what he asked. i wanna know too please.

right now i have the true ghetto midpipe (hint: looks like a cat ) but it is pretty loud, and i want to know if it is necessary to buy a brand new midpipe and chop it up to put in the xr-1 or if i can use the stock flanges.

Zoomspeed

I'm pretty sure u can weld stanless steel ro mild steel. I could be wrong though.

Well, if u try to use the stock piping and put in an xr-1, you'll have to get an xr1 that has inlet/outlet daimters the same as the stock piping, so you would be getting less power then using a 3" MP with a 3" inlet/outlet xr1. You know what I'm saying?

any other thoughts on the "ghetto MP"?

pp13bnos

iTrader: (1)

I payed $200 for a brand new SS pettit down pipe, and $100 for a SS Pettit mid pipe. Bolth on group buys. Maybe someone should start up anouther GB for the combo? CJ