Prius engine conversion

[Daox]

If you're wanting a higher efficiency engine, go with diesel. They beat even the atkinson engines in efficiency, and you have low rpm torque.

[merccom]

Originally Posted by Daox

In order for it to make any sense you'd still have to put the drivetrain into a more efficient car (better aero and lighter weight). The only thing I can think of that would make sense is a first gen Insight, and I still doubt you'll see the king of hwy mileage the Insight does because of its lean burn (the Prius does not have lean burn). However, your city mileage would be amazingly high.

if the goal is mileage then of course you start with aeromods. but also if you're someone that lives out in the country and doesnt do a lot of city driving the low rpm problems of the prius engine become less of an issue

really what i'm looking for though is an A B compareison of this car gets this mileage with the stock drivetrain and it gets this mileage after the engine conversion.

ideally of course you would drop the prius engine into something like basjoos car and his commuteing situation. that is really the ideal. the first question to answer though what is involved in the conversion?

will the engine bolt to a standard transmission belhousing? can you get an ecu reprogrammed to run the engine or will you have to go with megasquirt? is there any point in the first place for example, if you get 60mpg with the stock engine and aeromods will the engine conversion get you 75mpg or will it get you 62mpg, 53mpg?

these are the things i'm wondering about

[merccom]

Originally Posted by Daox

If you're wanting a higher efficiency engine, go with diesel. They beat even the atkinson engines in efficiency, and you have low rpm torque.

however, legally running a kubota or even running an older rabbit or chevette diesel is going to be fairly difficult depending on what state you are in and TDIs = expensive.

[mort]

Originally Posted by merccom

really what i'm looking for though is an A B compareison of this car gets this mileage with the stock drivetrain and it gets this mileage after the engine conversion.

Hi merccom,
The Prius engine gets its high efficiency from operating as much as possible at WOT. You'll need the eCVT to use that, and probably the electric motor to help with acceleration.

-mort

[FXSTi]

I was wondering about the other side of this equation. Has anyone re-purposed the electric side of the Prius in an EV?

[Daox]

The whole setup just doesn't lend itself well to parting out and using things individually. If you guys look up how the Prius transmission is built and how it operates you'll understand much better.

[Ken Fry]

Originally Posted by FXSTi

I was wondering about the other side of this equation. Has anyone re-purposed the electric side of the Prius in an EV?

In one sense, there are loads of those. The plug-in hybrids that are based on the Prius are EV's when the gas engine is not running. They get about the same efficiency in terms of miles-per-kilowatt-hour (about 4) as a Leaf, or EV conversions of similar size.

I am not aware of anyone who is using just the motors from a Prius. That would seem to be difficult because the motors are so well-integrated into the transmission. There are other motors for EVs that are much easier to work with. Getting real efficiency data from a car manufacturer for something like the Prius motors is about impossible. However the actual efficiency of the plug-in hybrids when in electric mode suggests that they are no more efficient that many other electric motors.

[Ken Fry]

Originally Posted by merccom

is there any point in the first place for example, if you get 60mpg with the stock engine and aeromods will the engine conversion get you 75mpg or will it get you 62mpg, 53mpg?

these are the things i'm wondering about

A Prius engine would probably bolt up to an Echo transmission. However, the Prius (the car) gets its fuel efficiency from about 100 small optimizations, and several big obvious ones (engine efficiency, higher engine loading, energy storage to promote more time at high load, regen) But to make the comparison, you would have to look at the BSFC maps of the two engines in question. (The Prius map is probably on this site.) At peak, you can figure that the Prius engine is about 37% efficient, and that the engine in a modern fuel-efficient car is about 32%. Having looked at the Prius map for quite a while, I'd conjecture that the Prius maintains that roughly 16% advantage over much of its usable load/rpm profile.

I doubt that a Megasquirt would provide the required sophistication to maintain the full 16% advantage. Getting the Prius controller to work would be, potentially a chore. Just getting the plug-in conversions to work right was not simple.

It would be a fun project.

Another variable occurs to me: if you are getting 60 mpg, chances are that you are already doing a certain amount of hypermiling, which is, in a way, the poor man's approach to hybridizing. So if you were obsessive, you would have to look at the BSFC maps from the perspective of your actual drive cycles. Different engine respond differently to things like pulse and glide.

Yet another, possibly big one: This all assumes that the stock engine and the replacement are similar hp. If the stock engine is double the hp of the Prius engine, then the gains would be expected to be greater from going to the Prius engine. (In other words, going from a 37% peak-efficiency big engine to a 37% peak-efficiency small engine alone provides potentially large gains.)

[merccom]

Originally Posted by Ken Fry

A Prius engine would probably bolt up to an Echo transmission. However, the Prius (the car) gets its fuel efficiency from about 100 small optimizations, and several big obvious ones (engine efficiency, higher engine loading, energy storage to promote more time at high load, regen) But to make the comparison, you would have to look at the BSFC maps of the two engines in question. (The Prius map is probably on this site.) At peak, you can figure that the Prius engine is about 37% efficient, and that the engine in a modern fuel-efficient car is about 32%. Having looked at the Prius map for quite a while, I'd conjecture that the Prius maintains that roughly 16% advantage over much of its usable load/rpm profile.

I doubt that a Megasquirt would provide the required sophistication to maintain the full 16% advantage. Getting the Prius controller to work would be, potentially a chore. Just getting the plug-in conversions to work right was not simple.

It would be a fun project.

Another variable occurs to me: if you are getting 60 mpg, chances are that you are already doing a certain amount of hypermiling, which is, in a way, the poor man's approach to hybridizing. So if you were obsessive, you would have to look at the BSFC maps from the perspective of your actual drive cycles. Different engine respond differently to things like pulse and glide.

Yet another, possibly big one: This all assumes that the stock engine and the replacement are similar hp. If the stock engine is double the hp of the Prius engine, then the gains would be expected to be greater from going to the Prius engine. (In other words, going from a 37% peak-efficiency big engine to a 37% peak-efficiency small engine alone provides potentially large gains.)

no purchases have been made yet but i'm thinking along the lines of maybe converting an old tercel and aeromodding that.

the megasquirt 3 seems like a pretty significant step up so thats the one i would go for. as for a buch of extra controls on the prius engine honestly dont know anything about them i figure for the most part an engine is an engine, long as you can control the fuel map and timing i'm not sure what other concerns there are so any insights would be appreciated.

the example i used of a car getting 60mpg was just an example. i dont think inclueding hypermileing into an engine efficiency equation would provide an accurate answer. not that i'm not into hypermileing, i'm just sayin.

[kurzer]

as i sad, the simpel way is to keep trottle, injection and header etc. of the existing car and only go for the engine itself. what comes in and what comes out is pretty much the same in nowerdays. so if you can bolt this parts on, the engine will work.
2 points are to think of. how to drive the ignition (prius has coil on plug), and is the prius doing something with the camshaft.