Would a turbocharger help the performance of theV1?

[waboom]

Ok, ok, before you all grab your monitors and scream "It's a SERIAL HYBRID, you ninny! The engine doesn't drive the wheels!", bear with me a second...

I was over on the RotaMax (http://www.rotamax.net/) web site looking at power specifications for the 650cc engine, and noticed they list performance numbers for both a turbo and non-turbo version of the engine.

(Just for clarification for those who don't understand, the RotaMax engine is a rotary engine that Venture Vehicles is looking to use in the V1. You can see a picture of the engine in the Venture Vehicles "sand rail" test vehicle here (http://www.flytheroadclub.com/forums/showthread.php?t=274).)

From what I understand, adding a turbocharger improves your gas mileage by about 7%. The question is, would you get that improved gas mileage running the engine at a constant RPM and load (like the V1 engine would do), or does the turbo efficiency only happen during acceleration, when you feel the "kick" of the turbo's turbines spinning up?

If Ian was indeed using the non-turbo version of the engine, would switching to the turbo model get him a boost in the MPG of the V1?

[Baja_Traveler]

Seems to me that if you turbo or supercharged a small ICE to breath more air and boost it's horsepower, you could then reduce the size of the engine, and thus run more efficiently on less fuel (Since the only purpose of the ICE is to run a generator to charge the batteries, increasing horsepower over and above that necessary gains nothing) Combine that with direct injection (or ethanol injection), and then we're talking maximum use of the resource...

[TazmanianKoala]

I would certainly like the addition of the turbo, just to have extra power for the electric motors at hand when fully accelerating. And since the RotaMax engine will operate at its most efficient rpm, the increase of the MPG would also be nice.

[MikeB]

My Subaru WRX has a turbocharger, it gets 227hp out of a 2L engine, which is a pretty good power/weight ratio.

However, my Subie also requires Premium gasoline (to avoid predetonation at the higher pressures), which is about $0.30 more expensive than regular.

On the plus side, my Subie is also capable of running E85 without any real modifications, the ECU is just flexible enough to compensate, and having the turbo is part of the reason for that flexibility.

[nvrblu]

My Subaru WRX has a turbocharger, it gets 227hp out of a 2L engine, which is a pretty good power/weight ratio.

However, my Subie also requires Premium gasoline (to avoid predetonation at the higher pressures), which is about $0.30 more expensive than regular.

On the plus side, my Subie is also capable of running E85 without any real modifications, the ECU is just flexible enough to compensate, and having the turbo is part of the reason for that flexibility.

In Arizona, the price difference between regular and premium is $0.20. As prices continue to rise, the difference stays the same. At $4/gal, if you get 7% better mileage, you start getting positive returns when the difference is $0.28 between the grades.

[MVRacing]

I would certainly like the addition of the turbo, just to have extra power for the electric motors at hand when fully accelerating. And since the RotaMax engine will operate at its most efficient rpm, the increase of the MPG would also be nice.

Hi Taz,
Sorry, it won't work that way ... with the turbo,(more HP) you could turn a larger generator, but that only charges the batteries faster ... won't provide any more voltage to the electric motor(s).

In general, all turbo/superchargers only pack more air/fuel mixture into the combustion chamber ... the more air, the more fuel ... you still need to maintain the proper ratio.
In a normal car, you get better fuel milage as a result of the engine turning a lower RPM to maintain the same speed. Especially with a supercharger (& some turbos) that "cut out" when there is low load.

My experience with rotaries (have built over 900) ... the turbo & associated plumbing & bits would weigh nearly half of the rotary power source. Rotaries can be easily tunned (ported) for peak power at a specific RPM which will greatly reduce fuel consumption. Hopefully Rotomax has already done this as we are asking for a generator motor and I believe that is one of their major product lines.

[smoove7410]

Turbos only kick in in the upper rpm range. Since it is only charging the battery, all it would do is charge it faster, and perhaps, use less gas. The cost of using a turbo, and fixing them when they break, would outweigh the benefit, in my opinion.

[Baja_Traveler]

We have to remember that you can only charge a battery so fast - otherwise you risk having an anode meltdown, or at least a shortened lifecycle.

I also just read in an aviation forum that stations in Oregon are no longer going to carry premium fuels - (Not personally confirmed as I just read it)

[beeson]

Baja Trav. If that is true (oregon will no longer carry premium), it's news to me. Possible, but I have heard nothing about this. This would make my modified 280Z and BMW motorcycle very unhappy.

[Lumberjack]

No a turbo is not the way to go for a generator set. The engine will be tuned for a constant load and running it faster will only create problems. A diesel would actually be the the better choice as they excell at constant speed applications....

[WarpedOne]

From what I understand, adding a turbocharger improves your gas mileage by about 7%. The question is, would you get that improved gas mileage running the engine at a constant RPM and load (like the V1 engine would do), or does the turbo efficiency only happen during acceleration, when you feel the "kick" of the turbo's turbines spinning up?

Almost all literature and developement is on variable speed ICEs for obvious reasons. Apart from generator sets there really aren't many uses for constant rpm ICEs and so manufactures aren't interested in spending lots of resources on optimizing them.

IIRC turbochargers have troubles being effective over wide range of rpms. There are certain tricks (variable geometry, stacking etc) to widen that effective rainge but those also lower the maximum gain. It is possible to create a very efficient turbocharger for constant rpm ICE, trouble is in finding a manufacturer. Gains could be much higher than 7%. It all depends on RD.

[Baja_Traveler]

No a turbo is not the way to go for a generator set. The engine will be tuned for a constant load and running it faster will only create problems. A diesel would actually be the the better choice as they excell at constant speed applications....


Aptera's first prototype had a diesel genset for that very reason - awesome efficiency. They had to abandon the idea after they found that no small diesel genset engine could meet the tight emissions standards we have today.