How to tell if someone knows nothing about Automotives.

[bubblewhip]

100hp/liter is old news. It was a big deal when the S2000 was introduced as there were very few cars that could do it, let alone at a reasonable price. Where hp/liter does come into play is weight. A 2.0 making 200hp is(generally) going to weigh far less than a V6 of the same output. The new Scion FR-S makes 200hp out of a 2.0 boxer 4. That rivals the output of a mid 80's 911 carrera(a 3.2liter H6). Reducing the weight of the engine, while maintaining the power output allows for better weight distribution, and that is one of the biggest places to gain cornering performance. If you remember, the lowly Porsche 944 was dubbed the best handling car they had built up to that time. The reason was the almost perfect 50/50 weight bias due to a front mounted(lightweight) engine and rear mounted transaxle.

The unfortunate thing is that engine displacement = weight doesn't work all the time. Yes, generally speaking larger engine = more weight, but when you compare DOHC style engines from Europe to Pushrods in America, you find that America has much higher displacement than the European equivalents but more often then not the engines weigh more than the American counter parts.

Example: The 7.0 L LS7 weighs 70-80lbs less than the 5.0L V10 from BMW's M5, yet make similar horsepower with much more torque out of the LS7.

This all starts to get even more screwy when you add turbo's and superchargers in the mix which dramatically increases the weight of the engine in relation to it's capacity.

It would be much better if the actual dimensional size and weight of the engine was used instead of the capacity of the bore. An engine bhp/lbs would be a much better engineering goal than bhp/liter in motor racing.

[Aglifter]

Yeah, but hp/volume is a physical limit. HP/# for a car is an excellent metric for acceleration, but on an engine, it comes down to who is willing to pay for what, more than efficient skill in designing the motor.

[TheIrishman]

Yes, generally speaking larger engine = more weight, but when you compare DOHC style engines from Europe to Pushrods in America, you find that America has much higher displacement than the European equivalents but more often then not the engines weigh more than the American counter parts.
Example: The 7.0 L LS7 weighs 70-80lbs less than the 5.0L V10 from BMW's M5, yet make similar horsepower with much more torque out of the LS7.

But you could punch(and stroke, given enough deck height) that S85 V10 out to 7.0 and see where the LS7 stands. You also have to take into consideration, the use of the engine. The 7.0 LS engine is not a factory motor but rather a "crate" motor for racing applications, while the S85 is a production engine for a luxury car. BMW could certainly squeeze more CC's into that block. They don't, as european cars have a tradition of smaller displacement per cylinder. The 325i is a mere 2.5 liters matching the old GM "iron lung" 4 cylinder, but WILL run smoother at any matched RPM-power output. Now that M50B25 engine will weigh more than an iron block/aluminum head 4 cylinder of the same displacement, but has been taken to 3.0 liters by some and gains no weight. Taking a 4 cylinder to 3.0 or above makes for a very shaky running engine(think Cat diesel 4's).The actual displacement is not relative to weight, but the ability to fit more is. There were tall deck Chevy big blocks(in medium duty, 20-50k lb trucks) that were capable of FAR more displacement than the standard BB. They also weighed more. The same goes for the Ford windsor, you can only fit so much into a 5.0(baby windsor) before needing to move up to the 351W block adding more weight.

This all starts to get even more screwy when you add turbo's and superchargers in the mix which dramatically increases the weight of the engine in relation to it's capacity.

But any power gains from forced induction will be greater with more displacement.

It would be much better if the actual dimensional size and weight of the engine was used instead of the capacity of the bore. An engine bhp/lbs would be a much better engineering goal than bhp/liter in motor racing.

Yes, you can build a 450hp Caddy 425 wedge and a 450hp 425(pick your poison) stroker small block and give the advantage to the small block due to it's weight savings. Both would be mild motors in context. The caddy wedge however came factory up to 500ci and 425ci is pushing the boundaries of common small blocks. You could in turn, build a 450hp 4.0 liter V8 in a smaller package, giving you both they weight savings and higher HP/liter. There is only so much available space in an engine block for displacement. If (racing)rules regulated the exterior dimensions of a block, everyone would simply go as big as possible making their displacement equal. It would again be who could get more HP per liter. Yes a 100hp/liter engine is nothing special if it is only 1000cc's compared to a 700hp LS7(7.0), but it proves the efficiency of the design which is scalable to all engines.

ETA:I was kind of rambling. My point is that HP/liter really doesn't mean much in use, but does equate to smaller and more efficient designs which equals more performance.

[HTRN]

Example: The 7.0 L LS7 weighs 70-80lbs less than the 5.0L V10 from BMW's M5,

Tall Deck LS blocks from GM("LS-X") and Racing Head Service("LS Race") are both capable of going over 500CID/8.2L. The RHS block is also aluminum, so the weight differential between the LS-7(around 450lbs with all accessories) and it will be minimal. Add in a a big turbo and a set of big port heads, and you're talking upwards of 1500hp.

[SeekHer]

Had an 1964 Austin Mini Cooper "S" (with a Banshee Supercharger and bored out to 1,350 cc) for road rally back in the late sixties and a standard 1960 Mini Cooper for ice racing--which is sitting at the bottom of Lake Winnipeg when I skidded out and hit a patch of thin ice and it went through.

These were not race specific built, just my standard daily ride.

I did get a speeding ticket in the "S" at 138 mph from a RCMP radar trap one evening that I took to court claiming the speed was wrong on the radar machine...The judge looked at the speed, asked to confirm what kind of car I drove, looked back at the ticket and dismissed the case for faulty equipment--who would think that a Mini could go so fast.

As to "automotive", I can do the basics around a motor and suspension with the limited equipment we possess and anything requiring machinery or computer diagnostics I have to take to a mechanic...With today's motors doing the basics (oil, sparks, filters, etc.) is about all you can do.