GM 8.1 replacement

[DonavonP]

HERE is a horsepower/torque chart for the 2 liter GM engine in the Pontiac Solstice. Notice how the torque comes in at about 1500 rpm and notice the horsepower where the lines intersect. Now multiply that times 3 for a 6 liter small block V8 engine. At cruising speed of about 2500 rpm you'd have about 450 HP but even more impressive is you'd have over 750 ft. lbs. of torque (with a turbo charger). That torque is pushing the diesel engines.

I'm not a wrench, not much in the engine/car world so I'd like to hear what's wrong with my idea that a 6 liter small block could easily replace the 8.1 large block in our Workhorse.

The turbo charger seems to be what's really needed along with variable valve timing and the new direct injection. Love to hear comments.

[DonavonP]

HERE is a horsepower/torque chart for the 2 liter GM engine in the Pontiac Solstice. Notice how the torque comes in at about 1500 rpm and notice the horsepower where the lines intersect. Now multiply that times 3 for a 6 liter small block V8 engine. At cruising speed of about 2500 rpm you'd have about 450 HP but even more impressive is you'd have over 750 ft. lbs. of torque (with a turbo charger). That torque is pushing the diesel engines.

I'm not a wrench, not much in the engine/car world so I'd like to hear what's wrong with my idea that a 6 liter small block could easily replace the 8.1 large block in our Workhorse.

The turbo charger seems to be what's really needed along with variable valve timing and the new direct injection. Love to hear comments.

[DriVer]

For the immediate time being I was told that there would be enough 8.1s in the pipeline for model year 2009. Going into 2010 and beyond is certainly going to be interesting.

I am currently running the Ecotech 2.4L engine in my Vue. It's not a rocket ship but for such a dinky engine in moves us along just fine. I wish the MPGs were better, I was expecting more but it's better than the Honda V-6 it replaced.

The series of engines that we are going to see in Workhorse chassis going forward are going to be in the "LS" family. I believe it's going to be a V-8 in the 5.3L range with 6 bolt mains and it most likely will be augmented by a Supercharger and not a Turbo. The engine will be a cast iron variant of the aluminum blocks that we see in the LS family which can range as high as 600+ horsepower.

[ron55]

There is no substitute for cubic inches!

[DriVer]

.... and a liberal amount of long stroke!

[Fred and Bonnie]

I am concerned the upheaval at GM will change the game after half-time. GM just shut down it's various large SUV lines; for good. The news out of GM indicates a mad scramble to "Small"; which will eliminate the need for "Big Iron".

Just food for thought.

Fred

[DonavonP]

Here's the chart for over twice as many cubic inches.

To me, it takes turbo charging or super charging combined with "direct injection" to provide torque (and HP).

I've always liked cubic inches too but the torque/hp charts don't lie (GM uses an independent lab to test where some competitors use their marketing department).

Thanks to ALL that have responded.

Now I have to read about LS engines.

[oemtech]

Donavon,

I think you making a wrong assumption in the 3X theory. It doesn't work that way. I think there are the laws of physics that get in the way.

Back in the day it was easy to add 100HP to a 327CI Chevy with a few mods. But, if you wanted another 100HP it will cost you a bunch of money and work.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by oemtech:
Back in the day it was easy to add 100HP to a 327CI Chevy with a few mods. But, if you wanted another 100HP it will cost you a bunch of money and work. </div></BLOCKQUOTE>Dale, I remember when I was working at our local Chevy dealer, the 1969 Chevrolet Corvette with a 327. If I am not mistaken this engine cranked out 375HP but I have a hard time remembering that far back.

Then again it might have been the early 350s.

[oemtech]

The L84 327/375 was done in 1965 with fuel injection.

[angelman]

Prior to 1972 hp ratings were taken @ the engine. After 1972 the hp ratings were taken @ the rear wheel. A 1971 mustang with a 351 had 295 hp. In 1972 the same engine was rated @ 177hp. The 8.1 is rated @ 340hp @ the rear tires. I would say this motor is making about 485 to 500hp @ the engine.

[tderonne]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by DonavonP:
(GM uses an independent lab to test where some competitors use their marketing department). </div></BLOCKQUOTE>

Actually we do the testing in house to the SAE standards. We do have a third party witness present to verify that it's all done correctly. I'm doing one the week we get back for the 3.0 liter direct-injected V6 that just hit the press last week.

[Davel]

DonavonP,

You're on the right track, but frictional and pumping losses will keep it from being 3 times the power at 3 times the size. One of the car magazines I subscribe to, can't remember which one, pulled a stock 5.3 LS engine out of a Chevy truck, added a cam, new heads and a supercharger and got 600 HP with matching torque. While this engine was built to run higher rpm's than a motorhome would like, a milder engine in the 6.0 range would match the torque at a much lower rpm. I've also read on several turbo websites that at cruising speeds a turbo will slightly improve gas mileage. It would seem that a smaller turbocharged or supercharged engine would get better mileage at crusing speeds than a similar horepower larger motor because of reduced friction.

At any rate it will be interesting to see what they do. Who would have thought back in '66 that a Z06 Corvette would have 505 HP and get 24 mpg on the highway and a ZR1 Vette would come stock with 638 HP. Makes my old 340 HP '62 Corvette that got 8-10 mpg seem kind of puny.....

Dave

[oemtech]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">The 8.1 is rated @ 340hp @ the rear tires. I would say this motor is making about 485 to 500hp @ the engine. </div></BLOCKQUOTE>

I am not sure where you got this info... But, the L18 8.1L is rated t 340HP at the crankshaft. Brazel's chassis dyno proves this to be true. The drive line loss (tranny, drive shaft, rear axle) is about 75HP. But with UltraPower we gain almost all of that back. A buddy had his 39' W24 Gulf Stream dyno'd and saw 334HP at the rear wheels.