1973 l-82 roadster engine refresh
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2nd Gear
Joined: Apr 2014
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1973 l-82 roadster engine refresh
Am doing an engine refresh on my 1973 l-82 roadster. Am installing a comp cam high energy 274 cam, brodix k-180 aluminum heads, weiand dual plane intake etc. My question is are 2 and a half inch exhaust adequate or should i switch to headers, not sure. Thanks for any insights
Le Mans Master
Joined: Oct 2010
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
headers will allow everything to work together much better. the more power an engine makes the more headers will help. so yes, you would be leaving a fair amount on the table without headers .
Le Mans Master
Joined: Oct 2007
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From: RI, Now Franklin/Nashville TN
Unless you plan to race the engine, 2.5 inch ram horn exhaust manifolds will be fine with a good flowing 2.5 inch dual exhaust with free flowing mufflers for a normal street car.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
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From: Fremont CA
Headers will give a 20HP or larger increase in performance. Since you went with aluminum heads, I'll take it your not interested in keeping the car in original condition. Going from a set of highly ported early C2 fuel injected 2.5" rams horn manifolds to a set of 1.75" headers on my LT-1 dropped the drag times by 4 tenths of a second and added 4 MPH to the trap speeds with the same mufflers and exhaust system being used. You would definitely feel the difference!
Le Mans Master
Joined: Oct 2007
Posts: 7,453
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From: RI, Now Franklin/Nashville TN
Here is the dilemma: I achieved 233 RWHP with a totally stock L-82 except 2.5 duals, free flowing mufflers, shorty headers-Thee engine was rated at 220 Net HP (OEM stock) with 2-1-2, 2.5 exhaust, restrictive mufflers, big restrictive cat which is about 180-185 RWHP when totally stock. Removing the RAM horns, cat, and adding 2.5 duals, with free flowing mufflers, shorty Headers added roughly 45-50 hp, roughly 180-185 RWHP to 233 RWHP. I have a very hard time thinking that LTH's would have added much beyond that improvement on a stock type engine. Maybe on a big build HP engine >450 HP but I am not convinced it would be over 10-15 HP-just not so sure....
Last edited by jb78L-82; Dec 4, 2014 at 05:05 PM.
Le Mans Master
Joined: Aug 2008
Posts: 5,578
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From: Austin TX
Here is the dilemma: I achieved 233 RWHP with a totally stock L-82 except 2.5 duals, free flowing mufflers, shorty headers-Thee engine was rated at 220 Net HP (OEM stock) with 2-1-2, 2.5 exhaust, restrictive mufflers, big restrictive cat which is about 180-185 RWHP when totally stock. Removing the RAM horns, cat, and adding 2.5 duals, with free flowing mufflers, shorty Headers added roughly 45-50 hp, roughly 180-185 RWHP to 233 RWHP. I have a very hard time thinking that LTH's would have added much beyond that improvement on a stock type engine. Maybe on a big build HP engine >450 HP but I am not convinced it would be over 10-15 HP-just not so sure....
