Hi,

I just found an article here on a diesel engine that revs to 10,000 rpm. Yes that's 10 thousand rpm. Although it's for an aircraft I can see the technology being transferred to bikes then cars.

Any comments?

John

"Record-breaking diesel's developer promotes return to pushrods

AVL Inc. will unveil a world record-breaking diesel engine at the SAE Small Engine Technology Conference in Madison, Wisconsin this week. Schrick, Inc., a subsidiary of AVL, has created a prototype diesel engine that weighs 53 pounds but produces 47 bhp, a new record for four-stroke (aircraft) diesel power density. The engine is designed for high-altitude unmanned aircraft. The team designed a pushrod-type valve train that, in combination with Schrick's advanced camshaft profiles, enabled the engine to sustain engine speeds of 10,000 rpm. AVL believes the project demonstrates the extended use of pushrod- type valve trains for all diesel-powered vehicles, including automotive. The discoveries could lead to OHC performance with a lower-cost pushrod system".

I dont think it will ever make it into cars.... the current "rev" issue with diesels is more a physical limitation than anything else, mainly because diesel fuel takes longer to burn with it being compression combustion.. which is why they loose their efficency (torque) the higher they rev... thats the main "difficult" issue, others are the weight of engines, pistons etc.

Hi, please escuse my ignorance but whats the difference between attaining 10,000rpm in an diesel aircraft engine compare to a car?

John

Hi' date=' please escuse my ignorance but whats the difference between attaining 10,000rpm in an diesel aircraft engine compare to a car?

John[/quote']

Well the engine was built to be small and used in small applications.. so it can rev high. but a aircraft engine doesnt need much torque.. just lots of BHP.

Diesel technology has been ignored for years, and slowly the units are revving higher with each subsequent development. Give it a few years and we'll see higher revving diesel units or some other technology that gives massive improvements in power. As little as 10 years ago 5krpm was the norm for petrol engines, at the same time a diesel with a 5k redline was unthinkable (BMW diesel anyone?).

When Honda launched their new diesel engine one jurno asked why it didin't rev like a Honda petrol. Honda said it was enitrely possible to build a diesel that reved like one of their pertol engines, but in doing so you would lose the primary advantages to the diesel in the first place (efficiency, torque & economy) and if you were to lose those you may as well hve the pertol engine as it would have more power and probably weigh less.

I drove a 118d about 250 miles a couple of weeks ago, and they rev much more like a petrol, but as Martin states, they've lost the diesel advantage - 40mpg, not that quick, no torque lump. Obviously the 120d (and the forthcoming 130d) will be quicker, but they've gotta be revved, it's the revving that disappoints me - if you're missing the mid-range thrust of a diesel and getting not much better fuel economy, what's the point?

So fundementally a car will always have a long stroke, whereas a motorcyle will primarily have a short stroke?

John

IIRC limiter on a PD engine is 5200... with NO reason to rev that high at all LOL

John. its all down to size.

As above, with the technical advancements on petrol engines, they are currently again reaching a platau for how high they rev, due to the valvetrain... go much higher and you risk valves kissing pistons and valve bounce.. the "future" is allegedly in a 42v car power system, and electric solenoid valves and variable compression engines... Saabs prototype 1.3l is as economical as a 1.3l and also has 225bhp

the inherant problem with diesels. im not sure how to explain this.. is a "chemical" thing... in that the diesel takes longer to burn than petrol- showing why diesels have big torque... which if its a tiny engine.. like the 10k revvy one.. not much fuel to burn, but efficency at that rpm wouldnt be great. if you redline a diesel, it has a "soft" limiter, which isnt much of a limiter at all, its just the combustion cant keep up with the RPM.. they only go that high anyway because of the heavy engines components momentum to assist.

Who Cares All I Want To Have A Shot In Is The World Record Holder For A Diesel 1/4 Mile Of 7.6 Sec Now That Impresive