Exactly how restrictive are the LG4/LU5 exhaust manifolds?
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Exactly how restrictive are the LG4/LU5 exhaust manifolds?
Okay, afew years ago I had a free flowing exhaust made for my '83 Crossfire. 2.25" ---> 3" y-pipe, going into a high flow 3" cat, ---> 3" pipe into 2.5" tailpipes.
Anyway, I kept the stock, restrictive, LU5/LG4 exhaust manifolds on. Just wondering how big of a bottle neck they are now. I'm not interested in headers, but I do have a set of L69 HO manifolds. Any thoughts on whether it's worth my time to install the HO manifolds on my CFI? Will that extra 1/4 inch diameter give me much in the seat of my pants?
Anyway, I kept the stock, restrictive, LU5/LG4 exhaust manifolds on. Just wondering how big of a bottle neck they are now. I'm not interested in headers, but I do have a set of L69 HO manifolds. Any thoughts on whether it's worth my time to install the HO manifolds on my CFI? Will that extra 1/4 inch diameter give me much in the seat of my pants?
Last edited by chazman; 05-08-2011 at 11:55 PM.
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Re: Exactly how restrictive are the LG4/LU5 exhaust manifolds?
Anyway, I kept the stock, restrictive, LU5/LG4 exhaust manifolds on. Just wondering how big of a bottle neck they are now. I'm not interested in headers, but I do have a set of L69 HO manifolds. Any thoughts on whether it's worth my time to install the HO manifolds on my CFI? Will that extra 1/4 inch diameter give me much in the seat of my pants?
https://www.thirdgen.org/forums/exha...-question.html
BTW, note that the 2 1/4 aren't really 2 1/4:
https://www.thirdgen.org/forums/exha...manifolds.html
JamesC
Last edited by JamesC; 05-09-2011 at 09:52 AM.
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Re: Exactly how restrictive are the LG4/LU5 exhaust manifolds?
Thanks James. I guess the other question which only I can answer is, if it's worth the 300 bucks in labor.....
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Re: Exactly how restrictive are the LG4/LU5 exhaust manifolds?
I think I'll try to get them on by the end of the week and report back. I have to say that I expected more from my expensive, custom bent, free flow exhaust. Maybe the stock 2" exhaust manifolds are what's holding it back. We'll see.
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Re: Exactly how restrictive are the LG4/LU5 exhaust manifolds?
This seemed like as good a place to post this as any of the other threads. This is what the factory L69 pipe looks like when you sawzall it. About 2.125" I.D. I have a set of 14071200 lh and 1407xxxx rh I'll sell for $25 + shipping. no air tubes, includes EFE that needs to have butterfly tacked to shaft (seems to hold vacuum).
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Re: Exactly how restrictive are the LG4/LU5 exhaust manifolds?
Okay, got them on. I haven't driven it very much yet, but two observations:
1) When you get past 2500-3000 RPM you can really feel it pulling harder. It also seems to require a lighter throttle to maintain speed while cruising.
2) It sounds different. With the LU5/LG4 manifolds and the aforementioned exhaust, it had a sort of flatulent sound to it. Like small pipes dumping into larger pipes, which in fact was the case. It has a more pleasant burble to it now.
Two more items. The stovepipe on the driver's side was eliminated, and the butterfly valve on the passenger side was eliminated with a new pipe fabbed to take it's place. It really feels like I need to upgrade to 3.42 gears now.
1) When you get past 2500-3000 RPM you can really feel it pulling harder. It also seems to require a lighter throttle to maintain speed while cruising.
2) It sounds different. With the LU5/LG4 manifolds and the aforementioned exhaust, it had a sort of flatulent sound to it. Like small pipes dumping into larger pipes, which in fact was the case. It has a more pleasant burble to it now.
Two more items. The stovepipe on the driver's side was eliminated, and the butterfly valve on the passenger side was eliminated with a new pipe fabbed to take it's place. It really feels like I need to upgrade to 3.42 gears now.
Last edited by chazman; 05-27-2011 at 06:53 PM.
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Re: Exactly how restrictive are the LG4/LU5 exhaust manifolds?
Here's a picture of the "top of the line" L98 with dual converter setup.
Looking at it out of the car, it seems way more low performance than it would in the car. (Not my pics, I have the L98 manifolds with single cat, which is even less performance)
Cleaning up the stock manifolds.
Of course, like many, I want the Dyno Don headers.
I can't comment on the LG4 manifolds. Don't have any experience with them.
Looking at it out of the car, it seems way more low performance than it would in the car. (Not my pics, I have the L98 manifolds with single cat, which is even less performance)
Cleaning up the stock manifolds.
Of course, like many, I want the Dyno Don headers.
I can't comment on the LG4 manifolds. Don't have any experience with them.
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Re: Exactly how restrictive are the LG4/LU5 exhaust manifolds?
The N10 dual cat exhaust is what I really wanted. Mostly because of the way it sounds and how all the resonance and vibrations have been engineered out. Something that you can't say about some aftermarket setups.
After looking for a while, I of course found one locally one week after I had my shop custom bend a system from the manifolds back.
After looking for a while, I of course found one locally one week after I had my shop custom bend a system from the manifolds back.
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