Video: how to Pulse & Glide in a Prius - 85 mpg!

[Christ]

Originally Posted by RobertSmalls

The answer is the same as the answer to the question "Is it safe to tow the CVT Insight with four wheels on the ground?". So, I dunno.

And yes, P&G will save gas in any car that can coast with the engine off. The key will be to glide as long as possible (down gentle hills is the only place I bother), and accelerate as efficiently as possible. I think the right way to do that in the CVT is with gentle action on the skinny pedal, so as to keep RPM's down.

Off topic: the 2010 Insight's "EV mode" still has the gas engine rotating, but with all 8 valves closed to reduce, but not eliminate, frictional losses in the engine.

I really don't think the two are the same.

When you tow, you tow for miles and miles... how often do you coast even one mile? There's a huge difference there. The fluid in the bearings isn't going to dissipate that fast, I hope.

Just my opinion, though. I think people look too far into it when they're asking if a vehicle is safe to flat-tow when they're considering EOC.

[RH77]

Originally Posted by RobertSmalls

I think the right way to do that in the CVT is with gentle action on the skinny pedal, so as to keep RPM's down.

Off topic: the 2010 Insight's "EV mode" still has the gas engine rotating, but with all 8 valves closed to reduce, but not eliminate, frictional losses in the engine.

To continue off-topic (briefly) I have been searching for more details (without success) on how this engine works. Is there a good source you recommend? Thx...

RH77

[user removed]

First you have to understand the average speed is the critical component. You can get 80 MPG in a lot of cars if your average speed is 22 MPH.

Second in regards to a CVT Insight. All last summer I managed close to 80 MPG in my daily 38 mile round trip drive after warming the engine up. My best was 83 MPG one way, while averaging 40 MPH through over 40 traffic lights.

The CVT will climb very shallow grades at over 55 MPG, with acceleration that is very very gradual, measured in several seconds per MPH increase in speed, while climbing a very very slight grade, measured in a few feet per 10th mile.

Then on the very slight downgrades the instantaneous mileage will jump to 125-150 if you allow the car to very very slowly decelerate. The other traffic on the road will hardly notice the changes in speed because they are microscopic.

The best summertime mileage I got in the CVT averaging 55 MPH was 70.2 MPG for 577 miles in one day. Mostly daylight, with absolutely no accessory loads whatsoever.

I don't do engine off coasting in the Insight, not interested in wrecking a 5k transmission.

regards
Mech

[RobertSmalls]

Originally Posted by RH77

To continue off-topic (briefly) I have been searching for more details (without success) on how this engine works. Is there a good source you recommend? Thx...

RH77

I got that tidbit from some car magazine, but there's always Honda's website.

You can try cruising the forums at InsightCentral, but the modifications made by current 2nd gen owners tend to be window tint, stereos, interior lighting, blah blah blah.

[RH77]

I found the same on specialty sites: a whole lot of nothing. I did find a helpful video on the Honda site that describes the LDA-Series 3-Stage VTEC and IMA system (for what I assume is for both the HCH-II and 2010+ Insight). It didn't discuss the dual ignition per cylinder, but there is lots of documentation elsewhere. The search terms of "Insight" and "L13A" or other engine terms yielded a bunch of fluff. I only assumed the Civic setup was similar, which apparently it is.

Unfortunately, most of the Insight's details are marketing ploys, blogs, and games. It was refreshing to finally figure out how the "EV" mode worked! (thanks for the re-direct).

Apologies for the "off-topic" folks -- the thread is now resuming regularly scheduled programming, already in progress...

RH77

Originally Posted by RobertSmalls

I got that tidbit from some car magazine, but there's always Honda's website.

You can try cruising the forums at InsightCentral, but the modifications made by current 2nd gen owners tend to be window tint, stereos, interior lighting, blah blah blah.

[fatman57]

coasting is fine in most modern vehicles as when you take your foot off the pedal as long as the revs are above idle no fuel will be injected into the cylinders...................just leave the car in gear and take your foot off the pedal.

I have a CVT and it has a wet clutch. Coasting should be fine in it as long as it is in 'drive' - it depends on the gearbox but in my case this allows both cones to rotate. This will turn the engine over but also pump oil onto my primary cone (which is connected to the engine side) - and you really do want a lubricated cone! If the cone were to remain static with no oil that could easily mean damage being done............

[PaleMelanesian]

If it's in Drive, that's not coasting. You're describing fuel-cut engine braking. That's useful in it's place, like coming up to a red light or down a mountain. It's not useful for Pulse & Glide.

[fatman57]

Originally Posted by PaleMelanesian

If it's in Drive, that's not coasting. You're describing fuel-cut engine braking. That's useful in it's place, like coming up to a red light or down a mountain. It's not useful for Pulse & Glide.

my apologies - I stand corrected!

I think in terms of a CVT the engine will need to turn over to drive the hydraulics, so it is necessary to keep it in drive. This again depends on the design of CVT.

unless of course you install a manual clutch inbetween the gearbox and the engine but that is a different story all together!

[fatman57]

leaving CVT aside - on a manual you could mod it for pulse and glide.........

simply install a switch that turns the injectors on and off - so then you accelerate, turn the injectors off and open the throttle body to full to reduce pumping losses............................then turn on when needed.

I think this would be easier and safer, even if less efficent then a full pulse and glide.

[daring4]

Originally Posted by fatman57

leaving CVT aside - on a manual you could mod it for pulse and glide.........

simply install a switch that turns the injectors on and off - so then you accelerate, turn the injectors off and open the throttle body to full to reduce pumping losses............................then turn on when needed.

I think this would be easier and safer, even if less efficent then a full pulse and glide.

Wow, I never thought of turning off the injectors and flooring it! I have just been mostly just pushing it into nuetral to coast in traffic and using the kill switch when I know I'm gonna sit at a light when I stop.