What would you like to know about engines?
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From: Chester
Yeah, I can remember bits and pieces about them but struggling to find real details.
Things that strike me are that the crank must be mounted relatively high in the engine which isn't exactly desirable, the plate has to be a fairly hefty bit of metal which wouldn't lend itself well to quick engine response and the bearings would have to be very high end to avoid friction losses.
I'm not necissarily saying they would be but they'd be things I was looking at
Things that strike me are that the crank must be mounted relatively high in the engine which isn't exactly desirable, the plate has to be a fairly hefty bit of metal which wouldn't lend itself well to quick engine response and the bearings would have to be very high end to avoid friction losses.
I'm not necissarily saying they would be but they'd be things I was looking at
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From: Market Harborough, Leics.
I'd be interested in a discussion of why diesel engines are able to be more efficient that petrol engines.
On the face of it Petrol is a more calorific fuel so why can an engine not be designed to take advantage of that? I know some of the answers to that question, but it would be very interesting to know more.
On the face of it Petrol is a more calorific fuel so why can an engine not be designed to take advantage of that? I know some of the answers to that question, but it would be very interesting to know more.
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Diesel requires no throttling, which is a big power loss, can sustain higher compression ratios, which leads to higher efficiency, and the flame front spread isn't much of an issue on account of it being self igniting, even with the low FF speed.
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From: Hertford
...which in turn, leads to a horrible, slow-turning, torque-biased long-stroke design.
Great for efficiency, but not much fun.
The probability is, that Ottos & Diesels may well converge into a middle-pressure engine which combines the advantages (hopefully) of both.
Great for efficiency, but not much fun.
The probability is, that Ottos & Diesels may well converge into a middle-pressure engine which combines the advantages (hopefully) of both.
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From: Market Harborough, Leics.
I'm sure a petrol engine could be made that could cope with the lean running conditions that you'd have with no throttle.
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From: Hertford
It needs to be run close to stochiometric, otherwise it won't start and run.
Diseasels can run lean most of the time, being CI.
You can dispense with a throttle valve by using variable valve lift, but the inertia in the valve drive causes big problems and aren't worth the ~10% gain. That's why A-VTEC was binned in the end.
With direct injection, it may be possible to run a spark ignition like a CI, but it's problematical.
Hence the middle-pressure engine may be some years away just yet.
Diseasels can run lean most of the time, being CI.
You can dispense with a throttle valve by using variable valve lift, but the inertia in the valve drive causes big problems and aren't worth the ~10% gain. That's why A-VTEC was binned in the end.
With direct injection, it may be possible to run a spark ignition like a CI, but it's problematical.
Hence the middle-pressure engine may be some years away just yet.
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From: Chester
Originally Posted by BuggyofMildDiscomfort' timestamp='1378215429' post='22758598
Diesel requires no throttling, which is a big power loss, can sustain higher compression ratios, which leads to higher efficiency, and the flame front spread isn't much of an issue on account of it being self igniting, even with the low FF speed.
I'm sure a petrol engine could be made that could cope with the lean running conditions that you'd have with no throttle.
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From: Chester
