probabilist

When the LT1 came out in 1992 Car Craft did a comparison net to net and gross to gross. The 92 LT1 made 330 HP gross vs 370 for the 1970 LT1. This is the GM gross method(pressure and temp correction)

So has anyone seen what our ls7s do in a gross dyno test? not RWHP.
The L88 was reputed to make roughly 560-580 at near 7000 rpm.
And the zl1 over 600HP. The l88 had more compression(12.5/1) and much more duration in the cam but probably inferior cylinder heads( my guess). It is so cool that in 2008 we can buy a street car that exceeds the l88 by a huge margin. In net form
the l88 was in trouble --typically only 420 - 440 HP.

carcrazyandbroke

The new technology is awsome; we have the power and the driveability.

yanniz

540, maybe?

GMuffley

Weren't the gross HP ratings of yore about 25% higher than SAE net?

slwhite

There are a number of postings on this which you can quickly find. There will be endless arguments over this which are caused by 2 things:

1. Gross measurement compared to net measurement (apples and oranges)
2. Many rumors but almost nothing published about L88 power back in the 1960s

Add to that the fact that back in the 60s, even the gross measurements were frequently exaggerated or measured using "ringer" cars from the factory. There was also no industry standard of how to conduct a gross power measurement as there is today with SAE net measurement methods. For example, some testers attached tuned headers for a gross measurement and some did not.

The one certain thing that can be said is that, when the LS7 came out in 2006, GM stated that the LS7 was the most powerful production engine that they had ever produced.

redzone

this.....

Les

As we all know, our LS7 is an amazing engine. Without doing a prolonged technical breakdown about why I just want to make one point for now- I think the R & D that went into the LS7 exhaust manifold and pipes is very significant in comparing these two legendary engines. With the LS7 there's little to be gained with headers unless you start modding other aspects of the engine to take advantage of the increased flow capacity of headers.

The same could not be said about the L88. The stock exhaust manifolds and pipes didn't flow nearly well enough for the mild versions of the 427 let alone for the L88. Putting a set of headers on that motor and tuning the carb accordingly gained gobs of power.

What I'd love to see is a dyno test on an L88 set up as described above and then compare it to our LS7. Now that would be interesting. Comparing stock to stock I think the LS7 distances itself comfortably from the L88. This doesn't begin to address the comparative drivability, which even the most ardent L88 fan would have to admit, isn't even close to the LS7.

I love both motors but technological advances gained during 40 years should and do give the newer motor some big advantages.

66L72

as i understand it the L88 was 430 hp at a somewhat lower RPM.
the generally accepted horsepower rating is 560 HP at the higher RPM and i believe that is with the stock headers.
i will post this on the C2 section to see if anyone pipes up over there.

AZDoug

What sort of RWHP numbers do you LS7 guys get?

Thanks,
Doug

Les

You're correct about the 430 HP at a lower RPM- Chevy didn't want to show what it really made, so they stopped the chart well below peak HP. I found some info on Wikipedia about the L88. Let me first say that I'm posting it only to put some info out there, but I'm not claiming it's entirely accurate or valid. Also, if you look at my sig you'll see that my 69 has heads and a solid lifter cam that are fairly comparable to the L88 but my motor has alot milder compression ratio. My point is, I truly love the older 427 motors too and am not trying to put anything out that is biased in favor of the LS7. Here it is:

The most legendary version of the 427 was undoubtedly the 1969 ZL1 engine. It was developed primarily for Can-Am racing, where it was very successful in cars like the Chaparrel 2F and McLaren M8B. The ZL1 had specifications nearly identical to the production L88 version of the 427, but featured an all-aluminum cylinder block and cylinder heads, which dropped total engine weight into small block Chevy territory (approx. 575 pounds dressed). The engine was also fitted with the new open combustion chamber cylinder heads, a light weight aluminum water pump, a camshaft that was slightly "hotter" than the L88's and a specially tuned aluminum intake manifold. Like the L88, the ZL1 required 103 octane RON (minimum) fuel, which made both engines largely unsuitable for street use in an era where 102 octane RON (Sunoco 260) represented the highest octane gasoline sold at common retail stations. Impressive as the ZL1 was in its day and despite the "larger than life legends" surrounding it, actual engine dyno tests of a certified production line stock ZL1 revealed 376 SAE net HP, with output swelling to 524 Gross HP with the help of optimal carb. and ignition tuning, open long tube racing headers and with no power sapping engine accessories or air cleaner in place. ZL1 DYNO TEST - COPO CAMARO WEBSITE A second engine dyno test conducted on a second production line stock (but recently rebuilt and partially blueprinted) ZL1 revealed nearly identical figures for the various "Gross" conditions. 2nd ZL1 DYNO TEST Magazine tests of the ZL1 were quite rare due to the rarity of the engine itself. "High Performance Cars" tested a production line stock version and recorded a 13.1 second/110 MPH quarter mile, which correlates quite well with the previously referenced 376 Net HP figure. "Super Stock and Drag Racing Magazine" recorded an 11.62 second/122.15 MPH quarter mile in a ZL1 Camaro that was professionally tuned and driven by drag racing legend Dick Harrell, although that car was equipped with open long tube S&S equal length headers, drag slicks and minor suspension modifications. The 122.15 MPH trap speed indicated very low 11 second ET potential (e.g. with larger drag slicks) and suggested something on the order of 495 "as installed" HP in that modified configuration. This large difference in power suggests that the OEM exhaust manifolds and exhaust system were very restrictive in the ZL1 application, as was also the case with the similar L88.

Les

Doug,
The LS7s typically come out around 450 RWHP when stock.

AtlBlkZ06

According to the infamous Wiki the L88 made 524 Gross HP. This could be fact, or someone's opinion.

I think 435-445 is a good range for a stock LS7.

redzone

My 06 dynoed 462RWHP before tuning.....472RWHP after.
Have'nt dynoed the 07 but I assume it's similar.

TRR

This from a book by Mike Mueller

The ZL-1 427's solid-lifter cam was even more redical than the L88, at least as far as lift was concerned. Intake valve lift was 0.560 inch, exhaust was 0.600. Seven grand on the tach was no problem, and Chevrolet engineers claimed short bursts to 7,600 were within reason. Keeping the juices flowing during those high-rpm trips was a huge 850-cfm Holley four-barrel.

As was the case with the L88, the ZL-1 was given a bogus output rating of 430 horsepower. Reportedly, 525 horsepower was more like it, and engineers claimed 600 horses were possible with only a little tweaking.

Not until the new Z06 was unleashed in 2006 has Chevrolet dared deliver so much raw power to the people.

I don't think this answers the question. If Chevrolet gave the L88 a bogus rating of 430 HP and the engineers claimed a lot more, it was still gross HP.


TRR

Donny Brass

I have personally seen a 'Pure Stock" L88 Corvette run 11.36 @ 122 mph on a F70-15 bias ply tire through untouched heads, intake, and exhaust manifolds

sure, the machine work in the engine is more precise than it was 40 years ago, but the l88 is one heck of motor..........

TRR

According to Motor Trend in 1969, a ZL-1 test mule managed a 10.89/130 mile pass. They stated that "Anybody that knows how to drive could jump in and duplicate this run".

Keep in mind that it was a test mule.

TRR

AtlBlkZ06

Wow thats nuts. The ZL-1 apparently weighed around 3100 pounds so given higher efficiency losses it looks like 540 is a good number to start with.

I bet it didnt claim 26mpg on the sticker though

Power and efficiency - quite a package!

TRR

Are you kidding. Back then gas milage was not an issue. You'd just pull up to the pump and tell the attendant to "Fill it up with Ethyl"


TRR

Donny Brass

it's amazing that a L88 can even be in the conversation after 40 years...

the cell phone in your pocket has more computer power than NASA used to get to the moon in 1969......

the new cars are so much more refined.

AZDoug

What RPM?

What torque at some select RPMs?, say , 2000, 3000, 4000 , 5000 etc RPM?

Thanks,
Doug