AbusiveWombat

I thought that this was some interesting information. You see, I used to be a person who saw Honda's hp/L figures and thought that they produced the best engines in the world. I always thought that our American V8's were low tech and if given the LS6 5.7L V8 Honda could ring out 684 hp (120 hp/L). Well, my thoughts have changed and I thought that I would share this information.

You see a car doesn't care about your cylinder size. It cares about horsepower and weight. So let's compare the LS6 (Z06) to the S2000 (F20C?).

Z06 LS6
engine weight: 497 lbs
power: 405 hp
torque: 400 ft-lbs
hp/#: 0.81 hp/#
Miles Per Gallon: 19/28

S2000:
engine weight: 326 lbs
power: 240 hp
torque: 153 ft-lbs
hp/#: 0.74 hp/#
Miles Per Gallon: 20/28

As you can see, the Z06 engine is awesome and is truely one of the best engines out there today. Not only does it best the S2000 in hp/# but it matches the highway economy and is 1mpg behind in city. And this is an engine that has 165 more horses and 247 ft-lbs more torque.

Don't get caught up in the hp/L hype. It's BS. What really matters is power, weight, and economy.

I don't want this to turn into a bash the Z06 or S2000. This is only a comparison of the engine and I wrote this to open up some eyes.

FooF

but we have better traction

Patdeisa

I believe people look at hp/L not as a performance measure, but more of a technology measure. It's harder to make better hp/L than hp/#. A person doesn't buy an S2k or RSX to brag about the best performing car, but one that is more cutting edge, economical, environmentally friendly, and with high strung fun. I'm not knocking domestics, as they definitely have their good qualities, but I find it more fun to see how much I can do with less (displacement).

topcat7111

The weight of engine got noting to do with the HP/L rating!! Yeah the zo6 has more h/p, it also has four more cylinder. You see when a mfr build a new engine you have choice to use cast iron block or cast aluminum block or you could have cast iron block and aluminum head or vice versa. Depending on the material, some will weight more. The weight of engine has noting to do with HP/L rating. When it comes to performance, it's the complete weight of the whole car not just the weight of the engine. Remember it's hp in relation to the size of the engine not hp to weight of the engine. When it come to engine i rather have the strongest and the most durable material then try to save weight and use inferior parts. Just my .02 cents. I rather

Mr Payne

[QUOTE]Originally posted by Patdeisa
I believe people look at hp/L not as a performance measure, but more of a technology measure.

Penforhire

I have to admit around town I don't get that magic 19 MPG out of my Z06. I average 14-16 MPG in mostly city driving (too much right foot?). Highway number, cruising at 80 MPH, is almost dead-on though. I did get better city mileage from the S2000 (18-22 MPG average).

I agree the specific output (HP/displacement) is a technology thing. I think it has bragging value, just like having the highest reving production motor has value. I don't know if it makes a car "better" if it is higher tech. I always thought winning the race is what counted, dinosaur tech or not, but I'm a gadget geek like many of you so tech has appeal.

The S2000 motor is 170-odd pounds lighter. That's a big deal too. I don't have the numbers but I the RX7TT motor may have even better power-to-engine-weight.

I figure saving weight while not suffering reliability problems is worth it. That aluminum block is a good example of a winner, at least for normally aspirated applications. Iron is ultimately a more durable block but the longevity difference is not significant in a stock application (e.g. iron sleeving where it counts).

And Foof, sorry, you're just wrong.

Patdeisa

[QUOTE]Originally posted by Penforhire
I agree the specific output (HP/displacement) is a technology thing.

ejis

Manufacturer published fuel economy numbers depends on everything from gearing to useage, and there's a "standard test method" to determine the mfg's number. It's the car and the method that determines fuel economy. Not just the engine.

If you want to measure engine efficiency, you need to look at specific fuel consumption. I have no idea if this data is available anywhere though...nor do I know which engine it would favor.

ultimate lurker

While I think that GM is one of the best powertrain companies in the world (they just can't do much else right in the auto marketplace), this is a dangerous comparison.

1. There are efficiencies of scale as you go larger. A V8 engine, while it may have twice the cylinders and 3 times the displacement of a 2.0 liter I4, doesn't need two crankcases, or two cranks. Not even two throttle bodies or two alternators, or anything else. Up to a point, larger displacement engines will be more power/weight efficient - especially if you are comparing inline engines vs. V-configuration engines, which allow a very short crank.

2. Packaging and materials choices. GM has admirably done a number of things to keep the weight down on the LS series engines and especially the LS6. In particular, the use of composites in certain areas, especially the intake manifold. This allows a significant weight savings vs. cast aluminum. Honda has not taken such steps on the F20C. I don't know why (the engine was light enough?), but that does play a role in overall weight. Its not a high tech thing (some Honda engines have composite manifolds), but a matter of choice.

3. Valvetrain technology. GM, despite criticism from many, stuck with pushrods for the LS generation motors. In retrospect, it was a smart move. Given the power goals for the engines and their target displacements, the required rpm did not require a more modern valvetrain configuration. Pushrods work just fine and are very reliable up into the 6000-7000 rpm range. Above that you may have to start getting extra creative if you expect to maintain long engine life. By comparison, Honda had to choose the heavier, more complex DOHC, 4valve per cylinder configuration to get the target power out of a 2.0 liter. Horses for courses. A pushrod 2 valve motor will not in the forseeable future produce 100+ hp/liter in a OEM warrantied application, let alone 120 hp/liter. But if you have the displacement, who cares?

4. Gearing - as someone pointed out, gearing plays a big role in fuel economy, as does aerodynamics. The S2000 is geared super tight. Fewer than 19 mph/1000 rpm in top gear. But, it will outaccelerate your typical LS V8 engined car if both cars are 6th gear. Gear the S2000 down to a similar accel level and fuel mileage will go up, it'll just be a super slug in top gear instead of a slug. Also, the aerodynamics on an S2000 are horrible. The Cd is approximately 15% higher than a Z06. Frontal area probably isn't much smaller either. That means for a given speed (say 80 mph), the S2000 requires 15% more thrust to maintain a given speed. That means 15% more power. Even if the engine is more efficient (BSFC), I doubt its 15% more efficient.

Always lots of factors to consider in making comparisons, aren't there?

UL

basscase

I think many S2K owners could never see themselves in a Corvette, Viper, Saleen Mustang, etc, regardless of those vehicles' remarkable performance.

While a Z06 or Saleen may devour many foreign-made comeptitors in terms of track numbers, and while they can be plenty of fun to drive, they arguably lack the aura of sophistication and style endemic to an M3, 911, or even the comparatively "humble" S2K.

If you want simplicity, go pushrod, it's proven and powerful. If you want sophistication, try to extract 100+ hp/liter naturally aspirated. I don't know why, but personally I'll always be drawn to the latter.