N10 dual cat on an '85 IROC.
10-03-2022, 12:36 PM
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Car: 1989 IROC-Z. Original owner
Engine: LB9. Dual Cats. Big Cam
Transmission: World Class T-5
Axle/Gears: BW 3.45
N10 dual cat on an '85 IROC.
I've been patching up the original exhaust on my '85 IROC as long as I can.
I've got an '89 N10 dual cat exhaust,(Y- pipe, cats, hanger, heat shield). I also have a single cat, factory cat back exhaust from another '89.
Things to consider on such a swap. Modifying the airpump tubes and mating the N10 front with the non-N10 back.
Anything else I should consider???
I've got an '89 N10 dual cat exhaust,(Y- pipe, cats, hanger, heat shield). I also have a single cat, factory cat back exhaust from another '89.
Things to consider on such a swap. Modifying the airpump tubes and mating the N10 front with the non-N10 back.
Anything else I should consider???
04-22-2023, 09:22 PM
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Transmission: Sometimes
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Re: N10 dual cat on an '85 IROC.
The factory dual-cat setup isn't all that good.
Sure, better than the same-year single cat ones; sure, better than most earlier-year single-cat ones; butt ... SUPERIOR? not so much.
The 85 single-cat exhaust is pretty good. After the manifolds, the Y-pipe is probably the weakest link, followed by the I-pipe. The N10 won't fix the latter issue.
I just don't think there's alot of "there" there. If it's what you've got on hand, and you can bolt it up with a minimum of hassle, then yeah, sure; I don't think it's gonna be that much "better" though, if at all. The manifolds are still the weeeeeek point performance-wise, and will always be.
The air pump tubes are not that big of a deal. I've used water-heater/furnace gas lines from the hardware store to make those up in the past; they're stainless, and eeeeeezy to adapt to almost every kind of fitting out there. Compression, pipe thread, you name it. Dodges the ordeal of finding useable factory AIR cat lines.
What's failing on your existing system that makes you want to replace it?
Sure, better than the same-year single cat ones; sure, better than most earlier-year single-cat ones; butt ... SUPERIOR? not so much.
The 85 single-cat exhaust is pretty good. After the manifolds, the Y-pipe is probably the weakest link, followed by the I-pipe. The N10 won't fix the latter issue.
I just don't think there's alot of "there" there. If it's what you've got on hand, and you can bolt it up with a minimum of hassle, then yeah, sure; I don't think it's gonna be that much "better" though, if at all. The manifolds are still the weeeeeek point performance-wise, and will always be.
The air pump tubes are not that big of a deal. I've used water-heater/furnace gas lines from the hardware store to make those up in the past; they're stainless, and eeeeeezy to adapt to almost every kind of fitting out there. Compression, pipe thread, you name it. Dodges the ordeal of finding useable factory AIR cat lines.
What's failing on your existing system that makes you want to replace it?
Last edited by sofakingdom; 04-22-2023 at 09:25 PM.
04-23-2023, 11:36 AM
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Car: 1989 IROC-Z. Original owner
Engine: LB9. Dual Cats. Big Cam
Transmission: World Class T-5
Axle/Gears: BW 3.45
Re: N10 dual cat on an '85 IROC.
The factory dual-cat setup isn't all that good.
Sure, better than the same-year single cat ones; sure, better than most earlier-year single-cat ones; butt ... SUPERIOR? not so much.
The 85 single-cat exhaust is pretty good. After the manifolds, the Y-pipe is probably the weakest link, followed by the I-pipe. The N10 won't fix the latter issue.
I just don't think there's alot of "there" there. If it's what you've got on hand, and you can bolt it up with a minimum of hassle, then yeah, sure; I don't think it's gonna be that much "better" though, if at all. The manifolds are still the weeeeeek point performance-wise, and will always be.
The air pump tubes are not that big of a deal. I've used water-heater/furnace gas lines from the hardware store to make those up in the past; they're stainless, and eeeeeezy to adapt to almost every kind of fitting out there. Compression, pipe thread, you name it. Dodges the ordeal of finding useable factory AIR cat lines.
What's failing on your existing system that makes you want to replace it?
Sure, better than the same-year single cat ones; sure, better than most earlier-year single-cat ones; butt ... SUPERIOR? not so much.
The 85 single-cat exhaust is pretty good. After the manifolds, the Y-pipe is probably the weakest link, followed by the I-pipe. The N10 won't fix the latter issue.
I just don't think there's alot of "there" there. If it's what you've got on hand, and you can bolt it up with a minimum of hassle, then yeah, sure; I don't think it's gonna be that much "better" though, if at all. The manifolds are still the weeeeeek point performance-wise, and will always be.
The air pump tubes are not that big of a deal. I've used water-heater/furnace gas lines from the hardware store to make those up in the past; they're stainless, and eeeeeezy to adapt to almost every kind of fitting out there. Compression, pipe thread, you name it. Dodges the ordeal of finding useable factory AIR cat lines.
What's failing on your existing system that makes you want to replace it?
The shrapnel peppered my intermediate pipe. I did have a section repaired/replaced by an exhaust shop, the part which snakes over the axle. But now the rest of the intermediate pipe is giving up the ghost.
Regarding the N10. I feel the most restrictive part of our 190-220 hp cars is the super restrictive Y-pipe, or should I call it a T-pipe? Something addressed by the N10. With that said, I think I'm going to reserve my extra N10 set up for something else. My friend "found", (long story), a brand new, OEM, correct for my car, 4 bolt flange, L69/'85 LB9 cat, so I will use that to replace the leaky, banged up hollow one and have an exhaust shop bend me a new 2.75" or better IP, since no pipes bigger that 2.5" are currently available.
Last edited by chazman; 04-23-2023 at 12:43 PM.
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04-23-2023, 01:15 PM
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Re: N10 dual cat on an '85 IROC.
On my 83 L69 car (same 4-bolt flanges on the cat) I used one from Catco at the time although I don't know if they still make it; a 4-bolt to 3" slip-fit 45° angle sort of adapter from SLP, again I doubt it's still available but which could readily be duplicated; and the Hooker cat-back with the 3" I-pipe. Pretty sure you can still get that exhaust. It's not stainless though. The cat might still be available from others, maybe Walker or Magnaflow or somebody. I have the SLP 1¾" headers & Y-pipe, which is irrelevant as far as fitment (same as stock), but obviously has a better Y-pipe than stock. And of course gets rid of the weeeeekest part of the exhaust for performance, which is, the manifolds.
04-23-2023, 01:53 PM
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Car: 1989 IROC-Z. Original owner
Engine: LB9. Dual Cats. Big Cam
Transmission: World Class T-5
Axle/Gears: BW 3.45
Re: N10 dual cat on an '85 IROC.
On my 83 L69 car (same 4-bolt flanges on the cat) I used one from Catco at the time although I don't know if they still make it; a 4-bolt to 3" slip-fit 45° angle sort of adapter from SLP, again I doubt it's still available but which could readily be duplicated; and the Hooker cat-back with the 3" I-pipe. Pretty sure you can still get that exhaust. It's not stainless though. The cat might still be available from others, maybe Walker or Magnaflow or somebody. I have the SLP 1¾" headers & Y-pipe, which is irrelevant as far as fitment (same as stock), but obviously has a better Y-pipe than stock. And of course gets rid of the weeeeekest part of the exhaust for performance, which is, the manifolds.
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