TeamCapri
Tech, Repairs, Upgrades => Capri XR-2 89-94 => Topic started by: Surfnut on November 09, 2010, 03:09:00 PM
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I'll be fabbing my entire exhaust system relatively soon...will a 3" exhaust pipe fit right under the turbo dump or is 2.5" the largest diameter I can go at the motor?
Thanks,
Dave
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The corksport downpipe is 2.5", and all the custom ones I've seen are 2.25 or 2.5". I think on a stock motor 3" will have a very tough time fitting. I run a 2.5" on my BPT.
If you're still running a stock turbo then there is no benefit to going that big.
-Rocket
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Rocket, I went to the Corksport.com website and I don't see a downpipe listed for XR-2's or 323's. I do see this one :
http://www.corksport.com/corksport-power-series-bp-downpipe-bp-turbo-only.html (http://www.corksport.com/corksport-power-series-bp-downpipe-bp-turbo-only.html)
Is that the right one ? It doesn't look right to me...but regardless, that is for a car with no A/C and although my A/C is off the engine right now, I will be adding a new system down the road.
Is there another downpipe that would work ? If you know of one, would you mind sending me a link if it's not too much trouble ?
My plans were to build a 3" mandrel-bent pipe with a flange to bolt to the turbo. It would then go to an electric exhaust cutout.
The valve'd side of the cutout would go to a 3" pipe, no cat, no muffler and straight out the back.
The regular side of the exhaust will go to a 2.5" cat with muffler, road-legal exhaust.
I know that's probably overkill but in the future, when I build this engine up, at least the exhaust will be finished with.
Does that sound good to you ?
I didn't know if I could fit a 3" pipe at the turbo's exhaust side.
If this engine conversion works out as well as I'm hoping it will, in the future I will probably be upgrading the turbo and building the snot out of an engine.
Thank you,
Dave
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This is the 3" exhaust cutout I was looking at :
http://www.youtube.com/watch?v=PeVQJ8HwEss (http://www.youtube.com/watch?v=PeVQJ8HwEss)
and installed :
http://www.youtube.com/watch?v=PeVQJ8HwEss (http://www.youtube.com/watch?v=PeVQJ8HwEss)
Any thoughts ?
Dave
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Yes thats the downpipe in question. There's a few pictures around here of it installed, it requires some minor modding to fit as it is intended for the BP. I actually just got ahold of a used one myself, they're a really nice piece (2.5" right off the turbo, divorced wastegate, and mandrel bent all the way) If you can afford it - it'd save a lot of work. I'm unaware of any other aftermarket downpipes. (I heard at one time Midco had one? but 2.25" comes to mind?)
I'm not sure that the oil pan has enough clearance for a 3" pipe. You'll have to grab some measurements, my concern is oilpan to subframe clearance. I've seen a 3" downpipe on a GTX before, but it was a full custom turbo setup.
I mean, the stock turbine housing's outlet is less than 2" in diameter, the turbo itself is a massive restriction for big power. 3" is overkill and I honestly think you'll see major boost creep with it, be sure to port the hell out of the wastegate.
I enjoy having the active exhaust on my car, but at the same time its not too often that I touch it. Its not my daily driver anymore so I guess I don't drive it as much. I've driven Russ's Super Roo a lot and he has Magnaflow mufflers, which are quiet-ish at idle but loud, and oooooh so sexy under throttle. I'm seriously considering one or a set of those in the future, with no cutout.
I see a 2.5" cutout on their site too. Looks like a nice piece, and inexpensive...hmmm. I enjoy my converted throttlebody but I'll keep this in mind for future projects...
My $.02 anyways
-Rocket
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No turbo that bolts to the stock manifold and has the stock style downpipe flange is gonna take advantage of anything bigger than 2.5".
You would have to have something at least as big as a full T3.
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Rocketman, your two cents is worth a LOT more than that.
So basically, don't bother with the 3" ?
2.5" is good enough - I mean, realistically ?
I just figured that if I'm going to fab the whole thing, it's just as easy to do 3" as it is to do 2.5".......
Thank you very much,
Dave
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Dave-
I concur with Matt- 2.5" is fine. Anything more, and boost creep becomes an issue. The Super Roo runs a full 2.5", and I have no problems.
--Russ
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That's all I need to hear..
Thanks very much !
2.5" it shall be.
Dave
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Yep 2.5 Is just right on these cars!
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Next dumb question :
If I get one of those 2.5" exhaust cutouts and install it in front of the cat, what bad stuff is going to happen to my engine with the oxygen sensor sending whatever goofy readings to the engine and then the engine richening the mixture or whatever ?
Any idea of what kind of repercussions am I going to have by bypassing the cat ?
For what it's worth, I wouldn't want this thing to run with the exhaust dumping out in front of the cat for a long time but it'd be neat to do every now and then..
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Nothing, this isnt OBD II.
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You need your 02 sensor or your car will do goofy things(biased on my own experience). There is no 02 sensor in the cat, at-least there wasn't one on my 91. The stock location is on the header. (above the turbo). Keep it. You'll miss it when you car sputters under load and your gas mileage sucks. There's a reason mazda engineers used o2 sensors. Even if the ECU in the car IS a dinosaur.
Just my .02
Greg.
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It should run fine without the o2 sensor. It will just run open loop all the time and rely on fuel maps. Maybe a bit of an MPG hit but no o2 is way better than a bad o2 in my experience. I was only managing 32 mpg with a bad one and 38-40 with it unplugged. Havent been able to check it yet with the new sensor. Im hoping for 40+ consistently.
If it runs like crap with the o2 unplugged something else is wrong.
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there was no way to do a 3" on mine just not enough room to make the bends, 2.5 works wonderfully, then take the extra pieces from the FMIC and refab the intake. Take out the unnessassary bends, make the flow as straight as possible... the little engines like to breath in... then breath out!!!!!
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Kelly, thanks for the info on breathing. its good to know. Hey i just got a blow off valve, nothing special just a knock off, but know it will work. where is the best place ton install.
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If you plan on doing a FMIC, then wait to install it because what ever you do now will be changed more than likely.
Photo of it and flange would help. there are several style of flanges and adapters made to make them fit
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I need to get a blow off valve too. If you're happy with yours, could you please send me a link when you have a chance ?
And, of course, I'd appreciate you posting about how you install it so I can copy that too (http://smile.gif) !
The less my brain has to work the better !!
Thank you,
Dave
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Not saying to buy this one but the adapter is what i wanted to show you.
if you have no plans to upgrade the intercooler anytime soon then this is what you want.
just add the hose and cap the other side. easy!
http://cgi.ebay.com/ebaymotors/HKS-UNIVERSAL-BLOW-OFF-VALVE-BOV-SQV-SSQV-BLACK-LIMITED-/180586006370?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a0bc3c762 (http://cgi.ebay.com/ebaymotors/HKS-UNIVERSAL-BLOW-OFF-VALVE-BOV-SQV-SSQV-BLACK-LIMITED-/180586006370?pt=Motors_Car_Truck_Parts_Accessories&hash=item2a0bc3c762)
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You can get a knockoff version of that BOV for $50 shipped or better. Those adapters are kinda hard to find though, most of those are 1" and we need 3/4" or 19mm for it to be a bolt-on. I think mine was at least $20...
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I found my 3/4 or 19mm adapter on ebay, look for rx 7 parts too. Mine is a type rs and the adapter was on the rx 7 site.Rocky
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YEP