With gasoline prices once again rising, attention is turning to engine variations to increase mileage and efficiency. The ethanol boosted, turbocharged gasoline engine combines a number of well known, current technologies for substantial improvement in mileage at lower cost and complexity than with a hybrid.
Two fellows at MIT came up with the idea of using both turbocharging and high compression on a small engine, which would give you a lot of power but would quickly lead to detonation. Their answer is to add direct ethanol injection whenever knock would otherwise occur. The ethanol injection would, in effect, raise the octane rating of the fuel to 130, eliminating knock allowing the high compression plus turbo to work. The turbo only kicks in when extra power is called for. Because of the power gained from both turbo and high compression, the engine size could be halved and still get equivalent performance.
They calculate 30 percent higher efficiency than a standard engine, just slightly less than a Prius, without the added complexity of the hybrid drivetrain or the need to replace any batteries. The added cost of this system would be $500- $1000 per vehicle, far less than the $5000+ cost differential for a hybrid.
This system does require a separate ethanol tank but the amount used is very small and would only require refilling every 2 or 3 months, similar to an oil change interval. The size of the ethanol tank in a car would be only 2 to 6 gallons.
Everything in this system is already standard technology found on many modified motorcycles, the amount of ethanol necessary for this setup on a motorcycle would be very small. If manufacturers like Yamaha are tinkering with hybrid motorcycles like the Gen-Ryu, they could do something like this quite easily. Whether this system would make sense on a motorcycle is open to debate, but then, so are hybrid motorcycles.
Links: Ethanol Boosting Systems via Technology Review
The Kneeslider: Yamaha Gen-Ryu in Tokyo
The Kneeslider: Yamaha Gen-Ryu
Chris says
Isn’t this similar, at least in concept, to the water injection used by the monster radial engines on WWII-era aircraft as well as early jet engines? The water in those cases was used for additional cooling, rather than being combustible, but it seems like this is just an evolution of a very old concept.
It also seems like their estimate of $500-1000 per vehicle is awfully high if that’s the case.
cl
C.J. Luke says
Actually, the water was used for two things…to eliminate detonation caused by hot spots in the combustion chamber, and for the additional power created by the expansion from liquid to steam.
The Ethanol will actually raise the octane rating…high octane means the fuel is stable at higher temperatures. That will allow the engine to have a higher compression ratio (for 130 octane maybe as high as 16:1 with modern electonic fuel injection) and that means that you could take a 12:1 600 cc engine, boost it with a turbo by say 30% increase, and effectively get the performance of a 780 cc engine running about 12:1. Those numbers aren’t absolute…but they are a close approximation of the increase.
C.J. Luke says
An addendum….I don’t see how it will make the engine more fuel effecient. There will be a small increase due to the increase in power created by the higher compression, but in the above scenario, the original 600 running gas and the boosted 600 running gas and ethanol will get very similar milage, with maybe a slight advantage going to the boosted engine.
Dodgy says
Increasing the compression ratio makes your engine more efficient by firstly making more power, for the same amount of fuel (as does turbocharging). So the same displacement engine with these ‘improvements’ can pull much higher gearing, or be operating at a much smaller throttle opening.
A rough calculator http://www.bgsoflex.com/roughhp.html ,given a 100 CID engine gives 91 Hp at 5000 RPM at 10:1, 137 at 15:1, and if we get it to rev to 8000 RPM it gives 218 HP!
Just keep in mind that ethanol is just an octane improver (anti-knock additive the same as tetra-ethyl lead was… But clean.
C.J. Luke says
hmmm….not to be argumentative, but I was under then impression that turbo charging would also use more fuel. I agree that the higher compression will generate more power using the same fuel and am suprised at the power increase numbers that you listed. But keep in mind that more rpm always = more hp…but it takes more fuel to run the higher rpm.
Anyhow…if those numbers are close for an increase in hp due to higher compression ratio…then consider that in my example, we boosted it by 30% with the turbo making it ‘look like’ an almost 800 cc engine so add those two together and you are gonna make some impressive power while it last 🙂
Hangtight says
It should last fine. I’ve been working with highly tuned drag racing two strokes for a while, and given that the mechanical limits of a component are not exceeded, what kills engines is detonation. Boost the effective octane, raise cylinder pressures and control the inevitable detonation and power densities really start to climb. Combine these characteristics with the apparently superior combustion surface temperature control of the Pivotal engine and things start to get interesting!
Mind you, it’s going to make life interesting for bike designers. There’s going to be plenty of plumbing!
Al Fairbanks says
Question which I need an answer to ASAP
I am about to change the was I am building my3.3 subie motor that is going in my sand buggy. Can we run 10.2 compression ratio on Ethanol and still pull 25 pounds of boost with the proper turbos.
Or, would you suggest I go a different way. I am into the motor over $20,000 at this point and am not sure I am going the right way.
If you could let me know on my email address. alf@paragonpress.com It would be much appreciated.
Al