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#1
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Guys,
I do not want to tell you guys how to cheat because I think that cheating only leads to hollow meaningless victories. The stock eliminator crowd has been messing with questionable modifications for decades now. Are you all allowed to "Extrudehone" exhaust manifolds? Are you allowed to acid port? Maybe speaking with a "guru" like Jere Stahl might help. Andrew |
#2
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Pete,
Congratulations on qualifying #1 at the PSMCDR (with a certified car no less)! I am not aware of any other track or dynamometer tests of ZL-1s or second design L-88s with the factory exhaust system installed during that time period. There was a 1995 dyno test of a ZL-1 engine that was published in Chevy High Performance that used the Camaro chambered exhaust, but I don't think there was anything done with the engine in stock configuration other than to establish a baseline for subsequent changes... They didn't spend a whole lot of time fine tuning the stock engine. I would imagine that you have seen that test already, but if not, let me know as I believe I saved the post for my files and can forward you a copy. To the best of my knowledge, the second design L-88 is identical to the ZL-1 in every way with the exception of the block. The actual option description for RPO ZL-1 (Corvette) reads "aluminum cylinder case" and, in fact, you had to first order the L-88 to get it. There were definitely changes between the the first design cam and the second design ZL-1 cam... I'm going from memory, but it went from something like .540/.560 to .560/.600 (I can verify this and repost along with the GM duration figures as well if you like). The primary reason for this was to take advantage of the new open chamber cylinder heads. In fact, the engineers determined that the new heads and cam were worth about 40 horsepower even with the loss of a half point of compression. By the way, are you planning on taking the ZL-1 to the PSMCDR next year or maybe leaning towards the LT-1 Nova? Regards, Stan |
#3
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Andrew:
Those types of mods are kind of frowned on by the majority of the Pure Stock racers, but they are out there. That's what was so great about Pete certifying...not only did he NOT build the engine to the extremes (per NHRA specs), but he chose not to even blueprint it to Chevrolet extremes (such as deck height, head cc's, etc.). Now, I'm sure there was a LOT of care put into the engine, but like JJ said, he could have done a LOT more. Just imagine what a blueprinted (just to GM specs!) ZL-1 would do! During the "Certified Stock", they had all of the runner specs, and checked everything out thoroughly. Believe me, they left no stone unturned! Extrude honing is going on, but at about $400 for a set of exhaust manifolds, you had better be pretty serious. Dave Dudek tested a set on the dyno on his Hemi Challenger, and picked up 12hp (I think) over his non-honed exhausts. I think Brewer had everything that could be honed gone thru, and that engine definitely makes the power. Stan: The test you are referring to is, I believe, the test where Bill Porterfield and Batten Performance spun up a ZL-1 on the dyno, trying to simulate the GM tests. But, like you stated, there isn't much info there on the exhaust manifolds ![]() |
#4
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Stan: Don't have that CHP issue handy. What month issue of 95 was it. If you remember, what hp fiqures did it make with manifolds.As far as next year....that's a long ways away. I still believe there is another tenth or three left in this ZL-1, so will likely play with it a little more. Original plans were to take the LT-1 Nova and try to be the first certified small block car in the 12's. If I do try and do that, Jimmy will be driving, so that still leaves me free to drive the ZL-1. But like I said, it's along ways away. Jimmy's car only ran some 12.6 to 12.8's. He ran three back to back 12.5's before we took it apart. He's not very happy with it, so it will likely be back. Thanks for your time!
Peter
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Pete Simpson 1962-2013 RIP Owen Simpson Eric Simpson |
#5
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Rob & Pete,
Rob, that's the article... As mentioned, not a lot of info on the stock setup, but interesting all the same. The following information was taken from the article and posted a while back (by Joe perhaps?). First off, the engine tested was supplied by Bill Porterfield, who at the time of the test, owned ZL-1s #1 and #3... Anyway, Bill supplied all the NOS parts, and tried to simulate the tests done in '68. So, here are the results: TEST 1: All accessories, production exhaust manifolds and Camaro chambered exhaust system; 36 degrees of timing; rev limiter set at 6750. Result: 375.7hp@6500 and 358.5lb-ft@4500 TEST 2: Exhaust manifolds were replaced with 2 1/8 inch headers. Result: 418.9@6500 and 404.4lb-ft@4000 TEST 3: The air cleaner, alternator and A.I.R. pump were removed. Result: 447.2hp@6500 and 408.0lb-ft@4000 TEST 4: The Holley carb was rejetted for a richer mixture, and the timing was set at 39 degrees. Result: 444.2hp@6500 and 410.7lb-ft@4000 TEST 5: The chambered exhaust system was removed. Result: 523.6hp@6500 and 469.7lb-ft@5000 Pete, I'll see if I can locate the actual issue tonight when I hunt for the camshaft information. Regards, Stan |
#6
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Stan, I had heard the chambered exhaust was restrictive, but never dreamed it would cost 80+ horsepower. Anyone would certainly think twice before using it.
[Edited by COPO (09-25-2001 at 07:38 PM).] |
#7
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See that Rob....you know, about chambered exhaust! Anyway thanks for your answer Andrew, it still brings a smile to my face,but it's not a option. And while I'm being a pain in the a$$, does anyone know anything about the story in High Performance Cars on the ZL-1? It's suppose to be the July 69 issue. And Stan, thanks for all your effort. I appreciate it!
Peter
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Pete Simpson 1962-2013 RIP Owen Simpson Eric Simpson |
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