Puzzling acceleration comparo of Prius and Insight

[GasSavers_maximilian]

Here's the HowStuffWorks article on it.

[GasSavers_bobski]

That's... strange.
So it does have a CVT, just not the kind that often comes to mind when someone says "CVT". The output from the engine and generator is a sum of the two devices' RPMs, allowing one or the other to maintain a constant speed (optimum power output) while accelerating or decelerating.
I'm not sure what the value of the second motor/generator is, and why bother with a chain?

[kamesama980]

in short: instead of a fluid turbine torque converter it uses magnetic fields.

torque curve is going to have a LOT to do with the acceleration. if one makes good down low torque but crappy up high it can end up with the same ratings as the other that makes good torque throughout the rev range. that's the joy of piston engines is that there are a thousand variables that will drastically change how an engine runs.

[GasSavers_bobski]

Originally Posted by kamesama980

in short: instead of a fluid turbine torque converter it uses magnetic fields.

That's not what I got out of the description in the above links. As I understand it, the Prius gear box just combines the power output from the engine and from an electric motor using an interesting planetary gearbox configuration. It appears the gear box provides independent, fixed gear ratios for each device and the output of the gear box is a sum of the torque/RPM supplied by each device. You could replace the electric motor with a second engine and get the same effect.

[dkjones96]

I think you guys are talking about two different parts of the driveline. Russell is talking about MG1 while bob is talking about the power split device.

[R.I.D.E.]

The Insight uses the 1.3 liter ISDI engine. That engine uses two plugs per cylinder and two valves per cylinder. The plugs firing sequence varies with speed and load. The plugs are located where the extra valves would be in a typical 4 valve engine. That engine is designed for high efficiency, not performance. Obviously no VTEC, but it may have some valve control otherwise.

I believe that engine is unique to the Insight in the US. Other ISDI engines in even smaller displacements are used in non Hybrid applications in other countries.

I think I read about a Fit that used that engine that got 25 KM per liter with a manual transmission. Might have been in Hong Kong or near there.

The configuration creates a lot of turbulence in the combustion chamber, and supposedly gets mileage comparable to the original VX engine under identical controlled testing, without the lean burn and the NOX spike from operating in lean burn conditions.

It would be really neat if they would put that same engine in a Fit with a manual tranny, but the mileage would probably not be that great in US spec configuration. Even then it would probably be as good as the US Insight.

We can dream. Something like the Yaris hatchback with that ISDI engine with start-stop, alternator and starter combination, pushing 50+ MPG, without any hybrid components. Now that would be a nice RIDE .

regards
gary

[R.I.D.E.]

Or a body like the Insight, with a 6 speed and a CD of .22, taching 2k at 70 MPH and 60 MPG, non hybrid with start stop.

regards
gary

[GasSavers_bobski]

Originally Posted by R.I.D.E.

The Insight uses the 1.3 liter ISDI engine. [...] I believe that engine is unique to the Insight in the US.

The new Insight uses an LDA3 (L engine family, "D" for the displacement... I assume that's something Honda uses for hybrid engines as it's typically the displacement x100 CCs, and A3 for the revision) engine, the '03-05 Civic Hybrid used an LDA1, and the '06+ Civic Hybrid uses an LDA2. So while strictly true, the Civic engines should be nearly identical in design and function. I've looked at both of the Civic engines and seen the eight ignition coils on the valve cover.

[JanGeo]

You guys think too much - get a Yaris and put Synlube in it and you should get 50mpg easy - my last tank in the xB was 45mpg 8.5 gallons. $10-15k extra will buy a lot of gas!!!

[dkjones96]

I know the spark plugs are different between the LDA1 and LDA2. The 1 takes a 3/4 reach plug and the 2 takes a 1" reach.