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11-12-2020
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#1 |
 Join Date: May 2018
Location: VA
Posts: 209
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Factory Exhaust Manifold horsepower data
I found an advertisement from Lingenfelter showing the 368 ci LT-5 at 530 hp. Is that number before the factory exhaust manifolds and cats are installed? The add has an EPA number for this configuration. How much horsepower do the stock exhaust manifolds with cats support?
Thanks for any opinions and insights. http://lingenfelter.managecontent.co...hp-368-cid-lt5 |
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11-12-2020
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#2 |
Join Date: May 2013
Location: Chicago
Posts: 982
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Re: Factory Exhaust Manifold horsepower data
Since it has a carb # and no description of headers I am going to say the engine is advertised with factory exhaust manifolds.
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11-12-2020
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#3 | |
 
Join Date: Nov 2007
Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri
Posts: 6,466
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Re: Factory Exhaust Manifold horsepower data
Quote:
 tgonyaw: Based on my 350 cid LT5, I picked up 20-25 over top-end porting and a canned tune by switching to LT headers, no cats, and flow thru mufflers (with a 2.5" choke on the inlet. So, based on that, it would be an estimate at best, but the stock manifolds and cats, etc. are prolly costing you ~ 30 hp or maybe more. Marc Haibec's site can give you some more info, far as mix and match goes (headers, a tune, aluminum FW, etc.) With his treatment including exhaust, porting and tuning shows 540 HP. So, if you're getting ~ 530 w/ stock exhaust manifolds and cats, I'd say your right in the ball park with a typically well tuned 368 with stock exhaust manifolds and cats, etc.! |
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11-13-2020
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#4 |
 Join Date: Nov 2011
Location: Dunbarton NH
Posts: 7,580
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Re: Factory Exhaust Manifold horsepower data
But why would you build a 368 with stock exhaust?
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11-13-2020
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#5 | |
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Join Date: May 2013
Location: Chicago
Posts: 982
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Re: Factory Exhaust Manifold horsepower data
Quote:
That is something not seen today. Building a 500 - 600+ hp car with a tuner warranty. |
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11-13-2020
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#6 |
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Join Date: May 2018
Location: VA
Posts: 209
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Re: Factory Exhaust Manifold horsepower data
Thanks for the replies.
My car is emissions exempt here in Virginia. It still must pass a visual test for the safety inspection each year. It has a ported top end with Corsa exhaust and deleted secondaries. The shop replaced everything under the plenum except the AC compressor. Ran well for about 400 miles after new fuel pumps and 2nd tune completed. It now acts like an old carb car with a faulty accelerator pump. I will contact Marc after the holidays to craft a plan. His 510 package makes the most sense because I would get new head gaskets and could add all new hoses while fixing 2 oil trips, etc. while the engine is out. This sight has 100?s of years of data and knowledge. Can not be duplicated. |
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11-13-2020
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#7 | |
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Join Date: Nov 2014
Location: Brooklyn ny
Posts: 1,044
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Re: Factory Exhaust Manifold horsepower data
Quote:
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11-13-2020
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#8 |
  
Join Date: Aug 2005
Location: Northridge, CA
Posts: 1,457
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Re: Factory Exhaust Manifold horsepower data
__________________
1995 ZR-1 #106 Blk/ Blk Owned by me since 2000. 93K miles, but not on motor :-) Mods the way I want it, Not afraid to drive it! Last edited by tf95ZR1; 11-13-2020 at 03:29 PM. Reason: Wanted 2 |
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11-13-2020
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#9 |
Join Date: Nov 2007
Location: Sunshine State
Posts: 1,061
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Re: Factory Exhaust Manifold horsepower data
I think with the new "political climate" those of us not having to worry about it will not have too long to enjoy "emissions exempt".... just sayin'
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11-13-2020
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#10 | |
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Join Date: May 2013
Location: Chicago
Posts: 982
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Re: Factory Exhaust Manifold horsepower data
Quote:
I was talking with Pete about his 391 and if the factory crankshaft is offset grind from 3.66" to 3.76" you will get a 402. So tempting!!!!! Last edited by Karl; 11-13-2020 at 07:23 PM. |
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