Hi Rob,
I try not to get involved with the Politics but had to add my two cents to this one. The post above you mention X and H pipes what you dont mention is the size/diameter of the exhaust. Please correct me if I'm wrong here I'm going off of old reads and Concourse repo exhaust systems that list the ZL1 exhaust diameter is 2-1/4" headpipe into 2" inch tailpipes, the L88 Headpipe is 2-1/2 into 2"tailpipes. The PSMCDR is allowing an upgrade all Vehicles that dont have 2-1/2 and also allowing an H or X Pipe again UPGRADE! Mopars came with the 2-1/2 and H so No upgrade here!
Interesting read here from Bill Porterfield (ZL1 pioneer)regarding his dnyo testing.
http://www.camaros.org/copo.shtmlHow much real power?
Although rated at 430 horsepower by the old method, Chevrolet never released actual power figures for the as-installed production ZL-1 engine. Numbers were tossed around for years until Bill Porterfield decided to find out. Bill had acquired an original block from one of the cars and enough NOS parts to complete another engine. The engine was subjected to 5 levels of test. RPM was limited to 6750.
Engine Test
Configuration Result
---------------------------- --------
#1 All accessories, production 375.7 HP
exhaust manifolds, Camaro
chambered exhaust system,
36 degrees timing
#2 As above with 2-1/8" headers 418.9 HP
replacing the manifolds
#3 Air cleaner, alternator, AIR 447.2 HP
pump removed
#4 Carb re-jetted, timing set 444.2 HP
to 39 degrees
#5 Chambered exhaust system 523.6 HP
removed
The ZL-1 was a legitimate 500+ horsepower engine.
Others have recently built ZL-1's with similiar or higher results. Several have dynoed in the 540-550 HP range. Modern components like piston rings may be the cause of the slightly higher performance.
The ZL1's and L88's were some of the most wicked Iron to come out of the Motor City No Doubt but without the Upgrade given to them by the PSMCDR rules they would be down how much horsepower with factory exhaust??? 147.9 Horsepower gain with Headers goes to show you how bad this combo was corked up from the factory? The UPGRADE that was given didnt apply to the Mopars that came stock with 2-1/2 exhaust with H. So how much horsepower was GIVEN to any brand that could benifit from the UPGRADE? Bill Porterfield did a nice job of Documenting.
Also to quote Bill Porterfield who has been restoring ZL1's since the 70's " All ZL-1 cars were equipped with AIR pumps and Gibbs' cars were produced with standard N10 dual exhaust."
Seems like every Reference resto I see has a Smog Pump, Yenkos,Copo's L88's, 435's I've been looking at the L88's for the last 6-7 years and every survivor car I've seen has a smog pump the Fields survivor car with 700 original miles has a smog pump. Its not just the weight of the Pump on the front of the motor the belt drag there also.Hit or Miss on the Smog Pump??? I'm calling it Smog Pump Delete must be an RPO code for that one.
All Muscle cars were not created equal the Olds got the W27 alum rear, everybody didnt get the upgrade, Studes got a Supercharger No upgrade to everyone else, ZL1's got an Alum block no one else got the upgrade, Maxies, Ford 427's L88's Some Hemi's got solid lifters but everybody didnt get the Upgrade, Lift Off Six Packs got the Hood, intake and carbs everybody didnt get that Upgrade. Smog pumps everybody didnt get that but sure deleted it quick."(RPO Smog Pump Delete).
So how much of a Horsepower Bonus is it to get the UPGRADE to 2-1/2 exhaust with an H? Could be Huge according to Porterfields webpage listed above unless your a Mopar no UPGRADE at all.
The Rules of the PSMCDR are as written I dont expect any changes and dont have a problem accepting them But the Exhaust UPGRADE is a huge Horsepower gain to those that have been given that BONUS. No Denying it, just smile and know it is an "UPGRADE".
Rob Please correct me if I'm wrong on the Exhaust diameter I'm sure you have forgotten more about Yenkos,Copo's,L88,ZL1's ect... than I'll ever know. Hope to see you at Martin!!!
Paul M Petcou
440 SixPack Challenger
