jaybird81

This may be a dumb question, but I am a little confused, what is the difference between an L88 and a ZL1? I know there were like 180 L88's made in 69 and like 3 (or some low number) ZL1's made.

es

ZL1 has aluminum block and heads, L88 has iron block w/ aluminum heads. I've heard there were only 2 ZL1s. One lives in Orlando at Roger's Corvette Center

LT1driver

Another major difference was the cam, much bigger than L-88 :yesnod:

MoMo

You sure about that? You better check.
The literature I read is that other than the aluminum block, the two were mechanically the same. Same cam, same crank, etc. They were both supposed to make the same power, but the lighter one of course had the better performance.

And I thought the L89 had the aluminum head option, and the L88 was all iron. Can anybody up on their history set this straight?

es

Now that you mention it, I think you're right - L89 = aluminum heads!

And yes, ZL1 was supposed to be the same internally as L88

67HEAVEN

:nono: L-88 definitely had aluminum heads, as did the L-89.

67HEAVEN

Camshafts:

L88 - p/n 3925535 - .540I/.560E Lift .262I/.269E Duration @ .050 lift

ZL-1 / LS-7 - p/n 3959180 - .560I/.600E Lift .262I/.273E Duration @ .050 lift





[Modified by 67HEAVEN, 1:21 PM 10/24/2002]

Chuck Harmon

MoMO,

Like the over the counter complete LS6 motors that came all iron, so did some of the complete L88's. You had to buy the aluminum heads on the side and stuff the pieces from the iron heads into them. But 67Heaven is right, the factory L88's had aluminum heads as they were installed in the cars.

The L89 was the aluminum head option for what was otherwise a L71 435 tri-power.

Chuck

Rowdy Rat

This is the first design L-88 camshaft which was used in all 1967-1968 L-88s as well as those 1969 L-88s equipped with closed chamber heads (in general those L-88s built prior to the strike).

This is the camshaft used for the second design L-88 as well as the ZL-1. The camshaft was also used for the service ("parts counter") engine that was referred to as the LS-7. The production LS-7 that was to be installed in the 1970 Corvette had lift values specified at .520" intake and .550" exhaust with identical duration.

By the way, I gather that your duration values are intended to read .050" rather than .50". :) The ramps on these cams were extremely long which accounts for the difference in the original GM duration figures (which were taken at somewhere around .004"-.008" off the base circle) and the figures which you presented (taken at .050" off the base circle - which is the current industry standard).

Regards,

fontking1a

More or less!

couldbefun

More than you will ever care to know

The L-88 was installed from the factory WITH aluminum heads. the ZL-1 was all aluminum. two ZL-1's were made, and yes one is at rogers'. i beleive they are "valued" if you can call it that at 500,000 US.
L-88:
5140 forged steel crankshaft
12.5:1 compression
Valves: 2.19" intake, 1.84" exhaust
850 CFM Holley Four-barrell
high rise aluminum intake
CAM:
solid lifter
.5365" lift on intake side, .5560 exhaust
duration: 337 intake, 340 exhaust

7/16" pushrod
"long-slot" stamped steel rocker arms
"chicken-wire" screen topping off the carb. those large gaps were to flow air not filter it.
95 motor octane minimum
1000 rpm idle, automatics were set to 2k commonly. please keep both feet firmly on the brake while shifting to drive. thank you

ZL-1
all aluminum, cast out of 356 T-6 alloy.. heads and block both. cast with a pair of extra bolt holes on each bank of cylinders. cast iron sleeves. dry sump oiling system

connecting rods, crank,pins, and valves were the same as used in the L-88
differences :
extra thick tops on TRW forged aluminum pistons
cam specs:
intake lift : .560 exhaust lift : .600
shorter duration, although I do not have the specs on that
reworked ports on the heads... which matched round headers that would be immediately installed by the new owner(we hope)
combustion chamber volume went to 118 cc, L-88 was at 106.8

L-89
the L-89 WAS not a version of the L-88. it was an aluminum headed version of the L-71 427. rated at 435 hp, it was designed to be the fastest corvette in street trim as the 435 hp was about right.....
the L-88 and ZL-1 were both rated at 430 hp which was a joke. both were tuned for wide open headers or race exhaust.. NOT for the restrictive stock system that was put on. even when tested the cars were built to underperform. they arrived for testing with an automatic tranny and 3.36:1 gears and stock exhausts. had chevrolet built the gears and tranny as they did the L-71/89 .. aka manual trans with 4:11's then the L-88 wouldve easily stomped the L-89 into the ground. the L-88 was never advertised as the high performance race car it was. people were expected to remove that exhaust, and race the car, since the L-88 and ZL-1 were both designed to never see trips to the grocery store. they were made to race, and were tuned to do so... no fan shroud, jet fuel as a minimum, no radio, no heater (except for 69) etc etc. with the headers on as they should be the L-88 out out approximately 600 hp. the ZL-1 was actually producing slightly less power but with some minor porting 600 was attainable. even with the less power the ZL-1 more than made up for it with the 200+lb weight savings. the L-88s actually were BB that weighed only 60 lbs more than a small block with their aluminum heads. after all was said and done the ZL-1 BB tipped the scales at 25 LBS LESS then a standard small block. imagine an LT-1 out there with 600 hp. and I do mean literally. the ZL-1 car weighed just a couple pounds over 2800.
again, internally the motors were NOT the same. with the ZL-1, the heads along with the specially cast aluminum block, had extra bolt holes to provide additional clamping force between the head and block surfaces. the intake also had an open plenum and some minor differences in the ports. the cam was also slightly different. as with the L-88 the ZL-1 had a HUGE cam that made idling a laborous task... they both sacraficed low end for all out high rpm racing.

outside of the difference in motors... it should be noted that the ZL-1 was the closest duntov ever got to shaping his baby into a world class car. he had wanted mid engine design for years to compete with the ferraris and such overseas, and had numerous test cars designed so. none made it to production obviously. he also had an affection for small cube high revving motors but felt it unfair to have the chevrolet flagship sporting anything but the most power in the factory. the ZL-1 gave him close to the midengine weight distribution he had dreamed of.. 43/57 front to rear ratio. and with all that power in a package that took 25 lbs more off the front than a small block, it handled better than any other that had come before it.... Duntov had always been motivated to make a car to run with the european cars,... small light and quick, enabling them to be nimble in the corners as well. the power was there for the corvettes, but all that iron on the front wheels hurt corning ablility badly. in the 69 may edition of motor trend, and I quote.... "They said Detroit could never build anything like a Ferrari because some product planning committee or cost accounting group would pinpoint the economic folly of such low volume-madness, compromise it and send it on to the world as just another gimmicked-up cop out" this was said about the ZL-1, proving "they" wrong. the same writer stated that it was the best handling corvette ever built (meaning it was the best handling american car ever built) he stated that the car could run with the ferraris at one-third the price... ZL-1 sold for 9 grand.
as a last note, from the years of 68 to 71, McLaren racers powered their cars with the ZL-1, and obliterated everything out on the playing field... they won 32 out of 37 events.



[Modified by couldbefun, 8:15 PM 10/24/2002]

jonstr

By the way, the second ZL-1 lives here:
http://www.corvettes-musclecars.com/Home.htm

Chuck Harmon

It feels so good to be understood and appreciated (even if I do drive a clone)!

Thanks,

Chuck :cheers:

joe58

McLaren and Chaparral and other Can Am race cars did not use the ZL1 block. It was not strong enough withstand the HP and RPM abuse. They used the Can AM block which looked similar to the ZL1 block but was a completely different casting. The top Pro Stock drag racers were also replacing the ZL1 block with Can Am block.
The Corvette road racers were using the ZL1 block at Daytona, Sebring, LeMans etc.
In my opinion the King of the Big Blocks was the Chevy 4.44 inch bore alu. Cam-Am motor (not the same motor as the ZL1). In 1969 it was 430 cu. in. making about 650hp. It grew over 500 cu. in. and made over 750 hp. normally aspirated on gas in road racing trim. Bill Grumpy Jenkins was making over 800hp with his Can Am Pro Stock motor in 1970. Most of the Can Am components were available from the Chevy HD parts list. Chevy stopped selling it and allowed Don Yenko to take over marketing the Can Am block. The CanAm BB Chevy motor dominated CamAm racing beating Ferrari, Porsche, and Ford, who all had more expensive exotic engines, until Porsche went insane and built their duel turbo 1100hp 12cyl. but that's another story.

Rowdy Rat

Chuck,

Over on the Supercar forum, they refer to cars like yours as "tribute cars"... That always sounded a lot better than "clone" to me. :)

Clones make me think of scientists doing unspeakable things to sheep in secret laboratories...

In any case Chuck, heck of a nice car!

Regards,

67HEAVEN

I posted the story of this amazing engine back in May, 2002 as [REPRINT] Our Corvette Heritage #36.....


Rest of story here..... http://forums.corvetteforum.com/zerothread?id=298341

joe58

That article refers to the 430 BB Chevy as a ZL1 which was a common mistake back in the day. The ZL1 was the production Corvette/Camaro block with 4.250 bore. The 430 CanAm engine was a different block with 4.440 bore and destroked crank.

kdealkev

This is a great post by the way. Theoretically speaking, would it be possible to do a modern build for not a huge amount of money that had the same feel and sound of the ZL1 & L88 Motors? Something about the lumpiness and loudness of those motors gives me butterflies.

redvetracr

yea considering it`s only 13 years old...

Alan 71

Hi,
AND, since the original post 840 more L-88 cars have been discovered!!!!
Regards,
Alan

Wait, make that 841, one more was found (in a barn of course) while I was typing!