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555HP at 6300 rpm.
Mostly NOS parts...but...
they tamed the cam down 14 degrees.
The cam they used is 6 & 12 degrees larger (@ .050") than the L72 /LS6 cam.
Comp Cams (PN 11-773-8). With duration of 248/254 and lift of 0.653- and 0.660-inches of lift, with 110 LSA
vs 262/273 for a real ZL-1 cam.
Last edited by leigh1322; Jan 3, 2025 at 12:03 AM.
Yeah, not stock so it doesn't tell the story of what the originals were actually capable of across the curve.. As soon as I read "roller cam" the hopes of seeing an actual historically accurate numbers was lost. Still pretty cool though. Roller Cam profiles are usually good for more power across the curve but by at least attempting to mimic the original cam somewhat closely this is still likely "in the ball park" for the peak power numbers vs the originals.
Do any of you remember the Gulf OilRacing Corvette (a 1969??) that used to show up at Corvettes@Carlisle? That Corvette was equipped from the factory with a ZL1 and painted the Gulf Oil's racing colors according to the owner of the car.
The sound of that ZL1 engine was just awesome, it was "music" to my ears. That Gulf Oil Racing Corvette sure was a "hit" with the crowds whenever he would start the engine up. It sounded ferocious just idling there and when he would "blip" the throttle you could "Feel" the engine's power.
Unfortunately there were not enough of the ZL1's made and people have been trying to "copy" one ever since. I have heard so many stories about how their Dad bought them a real ZL1 while they were in high school....
Thank you for taking the time to share this with us! I really appreciate it!
Yes they used a mechanical roller, but 14 degrees smaller.
So the question is would a 14 degree larger cam actually be any stronger?
Normally yes - maybe 30-50HP worth. And at say 700-1000 rpm more.
But doesn't going from an old school solid cam to a mechanical roller also make up a similar increase?
So would going backwards to a solid flat lobe profile, even with more duration, actually make any more power? Maybe some? Maybe none?
For sure it would rpm better.
With the old cam, I would guess 560-580 HP at closer to 7000 rpm.
But maybe not.
Any other opinions? Or L88 Experience?
One thing is for sure, it is lighter than an all iron small block. And a powerhouse. 56 years ago!
Complete engine weights: (dry, flywheel/WP/oil pan/dist) (based on the sum of component parts) All iron BBC: 646# BB AL heads, intake, wp: 554# All iron SBC: 516# SB AL heads, intake, wp: 450# ZL1 AL heads, block, intake, wp: 474#
Last edited by leigh1322; Jan 3, 2025 at 11:05 AM.
Way back in the early 80s, I ran a Chevy ZL1, flat tappet, solid lifter cam in 69 Camaro, bracket racer. Engine was a 427 plus .060, so 438 cubic inches. Iron block and heads.
The car ran 10.70 at 127 in good air. I guess car weight was around 3,400 (all steel) plus 200 for me equals 3,600. Plugging that weight and MPH in Wallace calculator yields 568 hp. Similar to your thinking.
Do any of you remember the Gulf OilRacing Corvette (a 1969??) that used to show up at Corvettes@Carlisle? That Corvette was equipped from the factory with a ZL1 and painted the Gulf Oil's racing colors according to the owner of the car.
The sound of that ZL1 engine was just awesome, it was "music" to my ears. That Gulf Oil Racing Corvette sure was a "hit" with the crowds whenever he would start the engine up. It sounded ferocious just idling there and when he would "blip" the throttle you could "Feel" the engine's power.
Unfortunately there were not enough of the ZL1's made and people have been trying to "copy" one ever since. I have heard so many stories about how their Dad bought them a real ZL1 while they were in high school....
Thank you for taking the time to share this with us! I really appreciate it!
Best regards,
Chris
Yes I remember this car very well. He was at many Carlisle's with it and everyone thought it was fake because of the automatic. It was really cool to find out that was car 2.
Yeah, not stock so it doesn't tell the story of what the originals were actually capable of across the curve.. As soon as I read "roller cam" the hopes of seeing an actual historically accurate numbers was lost. Still pretty cool though. Roller Cam profiles are usually good for more power across the curve but by at least attempting to mimic the original cam somewhat closely this is still likely "in the ball park" for the peak power numbers vs the originals.
They always screw up these retro dyno tests in some way. On this one, they changed the camshaft and pistons from stock. For what it’s worth, the 180 cam is tough to find and brings $900 - $1,000 if you can find one for sale. The pistons have been unavailable for many years (either standard, .030, or .060) and offered 12.00 to 1 compression ratio (not 12.50 to 1 used in the first design L-88 as stated). They were originally made by TRW; first with a GM part number, then as a TRW part (L2308), and finally Speed-Pro (when they bought out TRW) under the same part number. It is really VERY difficult to put a factory correct engine together these days as many of the parts are no longer available.
If I recall correctly there were two tests in the late 1980s or early 1990s… One was a ZL-1, the other was a second design L-88 (which was basically the same engine without the aluminum block). Those engines were both relatively stock and; output was something in the range of 525hp - 535hp which is pretty darn good. Some cylinder head work would add a bit more to those numbers. I’m putting together a second design L-88 that will be completely stock. I’ve been toying with the idea of having it dynoed just to know what I’m working with. If I do, I’ll post the results (I’m probably a year out).
Originally Posted by J.Abbott
It was really cool to find out that was car 2.
Based on what I have seen, my opinion is that there is no direct proof that ties that car (#10209) to being a ZL-1. There IS direct proof that shows it as the third L-88/M-40 built. The games played with the dealer invoice(S), the tank sticker(S), and the attempt to verify the tank sticker through NCRS are well documented on this forum.
They always screw up these retro dyno tests in some way. On this one, they changed the camshaft and pistons from stock. For what it’s worth, the 180 cam is tough to find and brings $900 - $1,000 if you can find one for sale. The pistons have been unavailable for many years (either standard, .030, or .060) and offered 12.00 to 1 compression ratio (not 12.50 to 1 used in the first design L-88 as stated). They were originally made by TRW; first with a GM part number, then as a TRW part (L2308), and finally Speed-Pro (when they bought out TRW) under the same part number. It is really VERY difficult to put a factory correct engine together these days as many of the parts are no longer available.
If I recall correctly there were two tests in the late 1980s or early 1990s… One was a ZL-1, the other was a second design L-88 (which was basically the same engine without the aluminum block). Those engines were both relatively stock and; output was something in the range of 525hp - 535hp which is pretty darn good. Some cylinder head work would add a bit more to those numbers. I’m putting together a second design L-88 that will be completely stock. I’ve been toying with the idea of having it dynoed just to know what I’m working with. If I do, I’ll post the results (I’m probably a year out).
Based on what I have seen, my opinion is that there is no direct proof that ties that car (#10209) to being a ZL-1. There IS direct proof that shows it as the third L-88/M-40 built. The games played with the dealer invoice(S), the tank sticker(S), and the attempt to verify the tank sticker through NCRS are well documented on this forum.
Regards,
Stan Falenski
Stan,
Not really aware of all that. I always thought of the car as an L88 or clone of either until the magazine article that came out about the car. It stated that GULF oil had written a letter asking GM for the ZL1 TH400 combo and that is how it was delivered. I know of no details on it other than seeing the car for years in Carlisle. I do know car number 1 though as it came through VA and was restored by Wayne Walker.
Justin
Stan,
Not really aware of all that. I always thought of the car as an L88 or clone of either until the magazine article that came out about the car. It stated that GULF oil had written a letter asking GM for the ZL1 TH400 combo and that is how it was delivered. I know of no details on it other than seeing the car for years in Carlisle. I do know car number 1 though as it came through VA and was restored by Wayne Walker.
Justin
Justin,
Thanks for your response and my apology if my initial answer was a bit terse.
I’ve known about the orange car (#10209) since the early 1980s and I’ve been involved with it (off and on) since that time. I’ve heard all the stories and seen the various versions of paperwork associated with it… After a while, it gets old trying to keep the story straight. In any case, the car is a real L-88/M-40 car; I’m not willing to go any farther than that.
As you mentioned, the yellow car (#29219) is well documented and is the only 1969 ZL-1 Corvette that I am aware of that is, without question, real.
Yes I remember this car very well. He was at many Carlisle's with it and everyone thought it was fake because of the automatic. It was really cool to find out that was car 2.
Spoke to the original owner John M on a few occasions and he told me the engine was a transplant. Then the story changed. Lots of controversy surrounding the authenticity of it being real. I for one don’t think it’s legit regardless of how much it sold for recently. Plenty of threads on it so no reason to go into it here. Still, a very interesting car with history none the less.
With the limited numbers of L88's and ZL1's ever made people would naturally try and copy them. I hope it becomes harder and harder for them to make illegal copies of these Corvettes. The sounds and actions of the L88's has led many people to making a clone of the engine. I loved the sound of those big beasts idling along and the power numbers so I too decided to build a L88 engine clone.
After putting the L88 Hood on my 1968 C3 convertible, the paint was done to match the rest of the Corvette. At this point I made sure that everyone who saw it, knew it is a CLONE and not a real L88. The only time I was not near hovering near the C3 was when the SpeedVision people saw it and were filming a short segment on my Corvette. I stepped in and made sure that it was noted that this was a "Clone" and NOT an original. The speaker was asking the viewers why a Virginia resident would drive it up to PA? It was obvious that it was not trailer-ed as it was still dirty from the ride up. I saw the segment on SpeedVision and they did not mention that it was a clone.
If you ever watch a speed vision show about Corvettes@Carlisle and they have a segment with a bright, Daytona Yellow, 1968 C3 wearing a L88 hood from Virginia, you will have seen my C3. I have a radio and a heater which should be dead give-a-ways for anybody who knows Corvettes.
Honor the originals, but drive the clones like you stole them! The L88 power is intoxicating and very addictive to boot. I keep the tail lights clean for the followers to appreciate them..... Thank you Zora!!!
The media has the tendency to do that. I never followed the car that much just remember seeing it every year and I still believe it was one of the loudest Corvettes in Carlisle. I always thought of the car as an L88 or clone until the magazine article. I don't know anything else about it though.
With the limited numbers of L88's and ZL1's ever made people would naturally try and copy them. I hope it becomes harder and harder for them to make illegal copies of these Corvettes. The sounds and actions of the L88's has led many people to making a clone of the engine. I loved the sound of those big beasts idling along and the power numbers so I too decided to build a L88 engine clone.
After putting the L88 Hood on my 1968 C3 convertible, the paint was done to match the rest of the Corvette. At this point I made sure that everyone who saw it, knew it is a CLONE and not a real L88. The only time I was not near hovering near the C3 was when the SpeedVision people saw it and were filming a short segment on my Corvette. I stepped in and made sure that it was noted that this was a "Clone" and NOT an original. The speaker was asking the viewers why a Virginia resident would drive it up to PA? It was obvious that it was not trailer-ed as it was still dirty from the ride up. I saw the segment on SpeedVision and they did not mention that it was a clone.
If you ever watch a speed vision show about Corvettes@Carlisle and they have a segment with a bright, Daytona Yellow, 1968 C3 wearing a L88 hood from Virginia, you will have seen my C3. I have a radio and a heater which should be dead give-a-ways for anybody who knows Corvettes.
Honor the originals, but drive the clones like you stole them! The L88 power is intoxicating and very addictive to boot. I keep the tail lights clean for the followers to appreciate them..... Thank you Zora!!!
Only the 1967's were Heater Delete. By 1968 the Feds required that all cars sold needed to have a defroster.
I just could not help myself.
I had to compare the power curves!
LT-1 vs ZL-1
(Since I now had dyno tests on both engines)
What struck me the most was the very similar RPMs at which the peak HP and peak TQ are made.
The cams are pretty similar, and of course they both rev like crazy!
That BB revs like a rev-happy small block.
(Of course a real ZL-1 had a little bigger cam, but so did the DZ 302. Kind of similar cams, again.)
Engine: 1970 LT-1 vs ZL-1 (Hot Rod Version)
Block: SBC vs BBC
Cu In: 350 vs 427
Block: Iron vs Aluminum
Block Weight: 165# vs 120#
Engine Weight: 502# vs 554# HP Peak RPM: 6100 vs 6200
TQ Peak RPM: 4700 vs 4200
In Cam dur @ .050": 242* vs 248*
HP/Cu In: 1.05 vs 1.23
TQ: 372 vs 526
HP: 367 vs 555
But the extra 154 TQ and 188 HP is just irresistible!
From only 77 extra cubes.
Back in the late 70's I had a 68 L-88 roadster that I lucked up on that a scca racer that was going through a nasty divorce had. Over almost 5 years I put almost 10k miles on it. It had the stahl side pipes on it and I couldn't get very many people to street race it. But driving it through the mountains of Virginia is something that stays with me. Do I wish I still had it? No I don't, because today it would just sit in a garage too valuable to drive. I love my 79 L-82 it ain't stock and I can drive it anywhere any time and it's pretty nasty in its own right.
My cousin is Jerry Hanson he at one time owned and raced the old Owens corning vette, that was a very cool car.
I got my very first autocross ride in Pittsburgh at North Park in an L88 around '73, and it is an experience I will never forget!
That glorious noise!
It ruined me for life!
427 ZL-1 Dyno Test
