An Engine's Power Output

Actually that's very close to BL's late 1960 "smog" technology, where they used an engine driven air pump to provide fresh air to the combustion chambers on the overrun to reduce emissions. Who would have thought that such technology would be continued after all those years!
 
I wonder how much benefit you'd get from a KERS system on an economically driven road car. To drive most economically, the ideal would be to use the throttle to a minimum and coast to a halt, timing lifting off the throttle so you came to a stop without having to use the brakes. If you need to use the brakes, you've effectively used the throttle for more than you need to and have wasted fuel. I know that this isn't always practical, but the basic principals still apply. A KERS system is a regenerative system, designed for recapturing energy you've already spent. Because you can't achieve 100% efficiency, you're not going to be able to regenerate all the energy you've spent. You'd need to be braking hard and very late to generate the most electricity, meaning more time on the throttle. Add in all the extra weight of the kit, and this further hampers economy. Obviously, if the car is driven hard all the time (like an F1 car), using a KERS system will see an increase in economy over a car using solely conventional brakes. I still remain a little unconvinced for a road car though.
 
webmaster said:
I think the big trick we're missing for economy is recovering heat energy into something usefull.
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Now that is genius!!, the simplest of ideas are usually the most fruitful.
The standard internal combustion engine uses heat to advantage with regard to piston - bore tolerances but other than that....I am sure you could make huge advantages of all that waste heat. Instantly to mind is the Sterling engine principle to help recover that heat energy to make motion

Graeme
 
IAmTheResurrection said:
Someone, I think, mentioned the subject of engines with both super- and turbochargers, like VAG's 1.4TFSI lump - am I the only one who thinks the idea completely batty? Hideously complex (especially what with the supercharger disconnecting as the turbo boost reaches acceptable levels), reportedly not a paragon of reliability and, by all accounts, ruinously expensive to make.
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Richard here is the Daihatsu I refered to earlier. OOps appears to be a deisel not petrol as I had stated, but then it was many years ago

http://www.carenthusiast.co.uk/news2509/daihatsu.htm

http://www.daihatsu.com/brand/motorshow ... index.html

Graeme
 
Doesn't the Adiabatic engine do something like that? I remember reading something about it in PPC magazine a few years back. Developed by race driver Smokey Yunick, apparently it promised massive gains in performance and economy. If I remember the story correctly, it used the coolant heat and exhaust heat to superheat the intake charge. The secret to how to stop the engine melting or detonating was lost when Smokey died, before the rights to manufacture the design were resolved with any manufacturers. If the story and figures are true, then it's amazing, but I remain a little sceptical as it seems that no one else has ever been able to figure it out 20+ years later. Makes interesting reading though.
 
If I read that correectly, all he's really done is make sure he gets complete combustion of the petrol. You don't need to heat it up to do that! I'm also none too comfortable with the thermodynamic rigour of the analysis - I don't see where he's really winning energy. Looks more like a perpetual motion type fraud.

Rather than raising the inlet temperature, raising the final temperature is worthwhile. This can best be done by changing the cooling system medium, oil is easy instead of water; if you're feeling really gung ho you could even use sodium as in a nuclear power station!

Chris
 
I don't know if it worked or not, further reading on the web shows the jury's still out. If I understand it, I think the intake charge was heated so the petrol vaporised. Then it was thoroughly mixed, so the intake charge became one evenly combustible gas. This gives the more complete combustion, and the heat used to do that was energy that would otherwise have been wasted. Current systems burn the petrol in a liquid form, all be it as finely atomised particles. As the petrol is in the charge as discrete drops, it can only burn from the outside surface of the droplet. Maybe it's less applicable now as injector technology has moved on, giving more finely atomised petrol spray.
 
Smokey was a gifted off the wall race engineer, showman, bender of rules and the cause of a lot of extra scrutineering. 7/8 scale model Nascar race car? Oh yes he built them, causing profile gauges. B17's he flew them, the Ozzie Osborne of race engineers, his side pod car, Insane

550-yunick-johns-299.jpg


His autobiography is a fantastic read. Including his part in the Flying Tigers.
 
Hi, I thought the idea was to keep the air intake temp down so the air is denser
(more Oxygen) which is why intercoolers are fitted? We go to lengths to stop fuel
vapourisation now it is being advocated. Does this mean we can do away with the
carbs and have the pump going straight into the manifold? Atomised fuel that is
going into the heated inlet manifold is going to vapourise job done, I don't think
any more heating is required. Could we just heat the fuel tank so fuel vapour is
piped along to the manifold, thus doing away with the pump as well?

I am not convinced by any of this. This has a distinct smell to it!!

Colin
 
You're absolutely right, the reason for intercoolers on forced induction engines is that cooler air is more dense and contains more oxygen. This allows the engine to burn more fuel for a given volume of intake charge, so making more power, but it doesn't necessarily mean that the fuel is burned more economically.

Fuel vaporisation in our cars is bad because it occurs in the fuel lines before the carburettors, and the carburettors are designed to work with the fuel in it's liquid state. In Smokey's engine, the vaporisation occurred after the fuel was mixed with the air. You'd still need the carburettor, or injection system to meter the correct fuel to air ratio.

I've no idea if it actually worked as claimed, or if it's just a wonderfully fanciful story. Being a designer, I would like to think it did, simply because I like the idea that things can still be improved by throwing away the rule book and looking at things with a fresh approach. However, I don't know enough about thermodynamics to understand if it did or not, and the fact that it hasn't appeared anywhere else does make me wonder.

Petrol vapour is potent stuff though, it's what catches people out when they try lighting fires with petrol. I remember watching a friend trying to light a BBQ with RC car nitro fuel, despite everyone else's best advice. He got within 6 inches of the BBQ with his match before the vapour caught light and went up in a big fireball. Luckily, he got away injury free except for the removal of all the hair on his right arm!!

Anyway, back on topic what seems to be a little vague is how the system prevented the charge from detonating. Preventing this is part of the reason we strive to control intake temperatures in conventional engines.

Tom
 
On the single point injection 800, there is a big heater element under the injector, and the fuel is sprayed onto it, I guess this helps the vapourisation, and won't really affect the intake air temp.
 
Hi, Tom w You do know I was being ironic/sarcastic? I agree with you about the rule book
and the fresh approach but I am not sure this has got legs.

Colin
 
webmaster said:
On the single point injection 800, there is a big heater element under the injector, and the fuel is sprayed onto it, I guess this helps the vapourisation, and won't really affect the intake air temp.
Click to expand...

carb'd K series had this as well, a big monster heater.
 
colnerov said:
Hi, Tom w You do know I was being ironic/sarcastic? I agree with you about the rule book
and the fresh approach but I am not sure this has got legs.

Colin
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:LOL: yep, got the irony Colin :LOL:
 
Smokey's Boss 302 Mustang is also a beautiful example of how to use lateral thinking. Haven't seen it in the flesh (its on my bucket list), but some of the modifications leave you thinking "I wish I'd thought of that".
 
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