But most cars are driven with insufficient use of the gearbox. Whereas on a bike the gearbox is a natural extension of the driving style. So the engine types work for their intended uses.
Mark Rand RTFM
Conversely, you can hang a V8 block from the end of a lever and produce 1200 ft lbs of torque - it will move the go-cart a couple of feet when you let it drop. No speed - no power.
That 5 HP 25000 RPM engine is producing just a hair over 1 ft lb of torque at that RPM, and may produce 2 ft lbs at 12,500 for 4.6 HP. It MIGHT even produce 3.5 ft lbs at 6000 RPM for 3.9HP
It will still be rated as a 5HP engine, when in reality, it is a real nice 3.5 HP engine. The rating will be; A, accurate, and B, Misleading, at the same time.
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Difference was not so much SAE vs DIN as gross vs Net.
All American (sae) rated automotive engines today are NET rated - and they are still turning out higher REAL numbers than engines of the same displacement turned out gross in the sixties.
And there is FAST, and there is QUICK. A friend's modified MGA TwinCam (1800cc MGB block grafted to the twincam A head) used to routinely wipe the smile off the face of Boss Mustang and Z28 Camaro drivers on the twisties, while having trouble with a good slant six on the straights ---- More fun per pound in the MG fer sure.
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Particularly when most American iron today turns less than 2000 RPM at the legal speed limit in top gear. Where it's producing something like
75 HP at full load, or more likely closer to 35 or 40HP at cruise.The engines, in most cases, ARE capable op putting out 80% power for hours on end at the rated RPM though - which IS rather incredible. A smallblock 8 cranking 6000 RPM for several hours at a time - with virtually the same geometry a sicties or seventies engine had trouble staying together at 4000 for a few minutes, or 6000 for 1/4 mile.
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OK, maybe we're mechanically minded, but I'll bet you can't find car owners cheaper than this bunch. From reading the posts, I'd guess the average transportation for this group has about 150-300,000 mi. and is old enough for vintage tags.
Pete Keillor
And then there was the friend of my former b-i-l who shoehorned a high compression 283 into a Sprite. It was a farmboy job, no firewall, solid rear end, but it would scoot. From the outside, the only noticeable mod was the cut out wheel wells and larger rear tires.
Pete Keillor
Gasoline? We don't want no skinkin' gasoline... It falls right off the shovel and runs right through the bars of the grate.
Mark Rand RTFM
My Toyota only has 140,000 on it. Almost broken in!
Fred
Uh huh. The SAE standards were revised to eliminate such practices something like 20 years ago.
If it is a typical liquid cooled engine then whether it will overheat or not depends on components external to the engine, so as posed it's an unanswerable question.
They also raise the temperature from 60 degrees to 77 degrees to which you correct HP and torque. At the same time dropping Barometric Pressure from 29.92 to 29.23. In other words lower HP ratings from the same engine. Old SAE J816 new SAE J1349. Stan Stan
Aircraft engines typically redline at 2700 RPM or so; a few geared versions will redline at around 3300. The engines have somewhat longer strokes than auto engines, producing useable torque at lower RPMs. The propeller is the limiting factor with airplanes; it can't operate efficiently when the tips are above about 600 MPH and the centrifugal forces on the prop get too large. The Subaru is having some success, but it can't be operated at or near its redline for long periods, as most aircraft engines can be. The engine normally has a redrive to allow the engine to run up to
5600 or so while the prop turns at about 2500, the high engine RPM increases fuel burn enormously (loss of VE), and the light valves burn too easily if the engine is run lean. Consequently, the engine is cruised at about 4700, sacrificing HP and cruise speed. It's not an "equivalent" replacement for an aircraft engine. I put a Subaru in an airplane, had lots of fun doing it, and it flew OK except for the lower cruise. Very noisy, since there was no room in the cowl for mufflers of any significance, and I had used the full-size Subaru rad with some fancy ductwork to make it cool properly. Not easy. Lots of bugs to work out.Dan
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