Technical differences L/88 vs. ZL-1

[nuch_ss396]

Can anyone clarify for me the technical differences between
these two engines? Obviously, one had an iron block and the
other aluminum. I believe the camshafts were also different.
But what about the pistons, rods and '7115 crankshaft?
I would expect that both engines used a cross-drilled and
Tufftrided version of the '7115.

I believe early L/88's used '842 heads and a closed chamber
piston. By the time the ZL-1 came to be, the '074 heads
were in play. This would have required open chamber pistons
as well. Was this head/piston combination also used in the
L/88 during later '69 production?

Additionally, did both engines use the 4296 Holley? A couple of
years ago on this site, we learned that many, if not all
the ZL-1 Camaro's were delivered with 4346 carbs due to air
cleaner to secondary fuel accelerator pump interference.

Lastly was ignition and exhaust. The L-88 & ZL-1 Corvettes
had the Corvette only exhaust manifold design; where the ZL-1
Camaro's had the standard Camaro style exhaust manifolds.
What about the ingition systems for these two engines? Were
they different?

Nuch

[Canada George]

Nuch,

Sounds like you got all the facts nearly right… suffice it to say the late ’69 2nd design L88 engine was virtually identical its ZL1 aluminum block counterpart. This includes all internals (camshaft/crankshaft/pistons/rods) with the ZL1 having additional bosses for extra bolts to hold down the head. Most people believe the ZL1 was significantly different than the L88 in addition to its block material because it was indeed an improvement in many details from the earlier 1st design power plant.

Like the ZL1 the 2nd design L88 utilized the 4296 double-pumper; earlier L88s using the single-pump 3418 and 4054. The ZL1 also required the use of the K-66 transistorized ignition system (tach drive distributor), designed for the Corvette and borrowed for use with the Camaro. This was the only distributor dialed in for the full race camshaft.

Any other differences between the 2nd design L88 and the ZL1 are unknown to me; I’m sure someone will pipe up…

[PeteLeathersac]

Here's some info lifted off the net...more specific to Corvettes than Camaros and specs than part #'s but it includes some of the Can-Am block stuff too..


~ Pete


...
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.
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.

[Canada George]

Once again… MOST sources will speak of these differences between the ZL1 and the L88; this applies only to the 1st design L88. The 2nd design version was THE SAME , less the weight-saving aluminum block. And YES , the ZL1 did indeed make LESS power than the L88 (2nd design). This was due to the friction associated with the flexing of the aluminum, despite its cast iron sleeves.

[nuch_ss396]

So Ray, the 2nd design L-88 used the same cam as the ZL-1?
I thought they were actually different. I was actually of
the opinion that the ZL-1 made slightly more power than the
L-88. This clears things up a little.

I grew up believing the L-88 was the king of HP in the BBC
arena. I later learned about the ZL-1 like most of us did
and my opinion changed slightly. So it sounds like the L-88
was truly king.

Good stuff!

Nuch

[SBR]

I believe that the second design L88 camshaft and ZL1 camshafts were the same as well. I have asked several people in the know however and always got varing answers. As for output as stated earlier the L88 did in fact put out slightly more hp than a ZL1.