Diesel Engines

[G.90]

I've heard a few rumors that some competitions may be allowed to run a diesel engine without a restrictor.

namely the English competition, and i think that the american competition mentioned that they may be thinking of introducing it, but nothing has eventuated.

Does anybody know if there has been any significant development in this area?

[RenM]

this is purely academic. Show me a lightweight, fast running 600ccm Diesel engine available.

[G.90]

haha there a none that i know of which would be suitable for sae.

i was toying with the idea of developing one from scratch to use in a few years.

There are a few commercially available, small capacity diesel engines which are found in agricultural equipment. From which a diesel engine suitable for sae could be built.

[PatClarke]

The only place a diesel engine is permitted is in the 'alternate' UK comp as a hybrid.

There is currently no chance of a diesel being accepted for FSAE, primarily because they are not throttled.
Power adjustment is done by varying the fuel being injected which makes diesels susceptible to running away should a valvestem, piston ring or turbo seal leak oil into the combustion chamber.

To get competitive power from a diesel, one would probably need to use the 'common rail' type technology with electronic injectors. These engines run at up to 25,000psi fuel pressure, something that would worry me in a student developed engine.

Finally, there needs to be some sort of cutoff valve in the intake to stop the engine if it runs away, runs on or generates power not according to the drivers demand. (They are 'fly by wire' controls). This would constitute a 'throttling device' not controlled by the driver and the effectiveness would have to be proven.

Diesels have been discussed at Rules Committee level before and believe me, they ain't going to happen any time soon!

Pat

[ed_pratt]

What about their use in a power generation capacity?
A small diesel running at a steady rpm to produce power for electric motors/topping up a capacitor bank could be interesting.
Is this effectively what FSUK had in mind for the hybrid solution?

Ed

[BMEP]

Almost meets the cc limit:
http://www.dieselpowermag.com/...is_fusion/index.html (http://www.dieselpowermag.com/features/0909dp_2005_polaris_fusion/index.html)

[Z]

Originally posted by G.90:
I've heard a few rumors that some competitions may be allowed to run a diesel engine without a restrictor.


Without a restrictor???

Consider the 2011 Le Mans winning Audi with a 3.7l V6 diesel. This breathed through a 17.65 sq cm restrictor and was "estimated" at well in excess of 600hp. So a single cylinder of 616cc, breathing through 2.94 sq cm (cf. FSAE = 3.14 sq cm) giving well in excess of 100hp! (And running for 24+ hours at ~80% WOT, compared with FSAE 1 hour(?) at ~20% WOT... And, admittedly, 3 bar absolute plenum pressure, and 2600 bar injection, and steel pistons, etc., etc. But it is R&D that is likely to appear on Audi road cars.)

Diesels = The Future.
Electric = Dead End.
FSAE Rules Committee = Head-In-Sand!

Z

[PatClarke]

Electric = Dead End.

The one point many people miss Erik, is EVs must carry all their energy mass on board, usually very condensed and often pretty dangerous.

IC engines, on the other hand, only have to carry about 1/15 of their fuel mass. The rest comes from the air we drive through.

Personally, I loathed diesels, but since the advent of low sulpher fuel in Aus (about 2001) which allowed the introduction of CRD engines, I am a fan! Fantastic things!

The car company I work for have made several efforts to justify a hybrid. Series and parallel, petrol and LPG, but they never stack up to the life of vehicle common sense of a little CRD turbo engine!.. Much to the dispair of the marketing people http://fsae.com/groupee_common/emoticons/icon_smile.gif

Pat

[PatClarke]

A small diesel running at a steady rpm to produce power for electric motors/topping up a capacitor bank could be interesting.
Is this effectively what FSUK had in mind for the hybrid solution?

Exactly Ed.

Pat

[spierson]

What about their use in a power generation capacity?
A small diesel running at a steady rpm to produce power for electric motors/topping up a capacitor bank could be interesting.
Is this effectively what FSUK had in mind for the hybrid solution?

We used to have a Hybrid SAE car that did exactly this. It was interesting to see the concepts, but was painfully slow. I think weighing 800lbs had something to do with it though. Originally it was supposed to be a diesel motor charging the caps, but the diesel conversion they tried to do didn't work. So they used a 250cc Ninja motor that held a constant 8000RPM throughout an entire run.

[Simon Dingle]

I spotted this rule a few years back while working for a diesel fuel systems manufacturer. I've always wanted to build one, but the cost of the project and the fact that you could only enter 1 competition were too big a problem.

However, I did recently get into a conversation about it again with the idea of building a dual-fuel engine (diesel and E85) to allow you to compete at multiple events. But it will probably remain a pipe-dream http://fsae.com/groupee_common/emoticons/icon_frown.gif

[RenM]

Originally posted by Z:
Without a restrictor???

Consider the 2011 Le Mans winning Audi with a 3.7l V6 diesel. This breathed through a 17.65 sq cm restrictor and was "estimated" at well in excess of 600hp. So a single cylinder of 616cc, breathing through 2.94 sq cm (cf. FSAE = 3.14 sq cm) giving well in excess of 100hp!

Those Figures are very exaggerated. A Diesel can only run lean with a limit of 1.1 or 1.15 lambda. So unless it has a much higher efficiency then a comparable gasoline engine it will always produce less power running with the same restrictor.

Then you would also have to run a high boost pressure to reach a high power output because you are very limited on your engine speed. This however is something you wont want in FSAE because you need a fast throttle respond which contradicts high boost pressure.

[Adambomb]

Ooh, this talk of diesel conversions is giving me the heeby jeebies. Does anyone remember all the gas engines GM converted to diesel in the early '80s? I'm pretty sure that's a huge reason why Americans don't like diesel cars...

[Z]

Originally posted by RenM:
Those Figures are very exaggerated. A Diesel can only run lean with a limit of 1.1 or 1.15 lambda. So unless it has a much higher efficiency then a comparable gasoline engine it will always produce less power running with the same restrictor.
Not exaggerated. Diesels ARE more efficient that gasoline SI engines, but the artificial ACO smoke limit pulls them back to about the same as SI engines. The rule of thumb is 30kW or 40hp per square centimeter of restrictor.


... in FSAE ... you need a fast throttle respond which contradicts high boost pressure.
So are you suggesting that you do NOT need good throttle response at Le Mans? With all the traffic, etc.? Hmmm, those Audis and Peugeots must have been dogs to drive...

Z

[Z]

Originally posted by PatClarke:
IC engines, on the other hand, only have to carry about 1/15 of their fuel mass. The rest comes from the air we drive through.
Pat, Yes, 100% agree. And that is the killer for battery powered EVs. It doesn't matter how much you flog them, those poor little atoms can only hold so much chemical energy. Best to breathe in 14/15 of your fuel as you drive along. http://fsae.com/groupee_common/emoticons/icon_smile.gif

I note that Electric "Fuel Cell" vehicles are supposed to be the White Knights about to ride in and save us all (because they breathe air). These work by taking chemical energy in a hydrocarbon (or H2), combining with O2, creating electric energy, then converting this into the mechanical energy that makes the wheels go round.

Conventional "heat" engines (steam, petrol, diesel, jet...) take chemical energy, convert to heat energy, then convert to the mechanical energy that makes the wheels go round.

But there is a better way! Go direct from chemical energy to mechanical energy.

How??? Well, Nature has been doing it for at least half a billion years. And it is very sustainable! The answer, of course, is muscle. Eat some hydrocarbons, breathe a lot of air, then something to do with the chemical ATP (my chemistry is not good), apply a low energy electrical trigger, and then swim, crawl, walk, run, and fly! http://fsae.com/groupee_common/emoticons/icon_smile.gif

You heard it here first boys and girls. The person who productionizes "artificial muscle" will be a household name in a thousand years time. (Mind you, given the attitude of the SAE, motorsport rule makers, etc., we might have to go through another dark ages before it happens. Remember Hero of Alexandria built a working steam turbine almost two thousand years ago. It was probably banned... Would've put the slaves out of work...)

But now I'm rambling again...

Z

[Mbirt]

Originally posted by Z:
But there is a better way! Go direct from chemical energy to mechanical energy.

How??? Well, Nature has been doing it for at least half a billion years. And it is very sustainable! The answer, of course, is muscle. Eat some hydrocarbons, breathe a lot of air, then something to do with the chemical ATP (my chemistry is not good), apply a low energy electrical trigger, and then swim, crawl, walk, run, and fly! http://fsae.com/groupee_common/emoticons/icon_smile.gif I think my recharge times (during off-peak hours, of course) are only slightly better than the commercially available EV's.