Pulse & glide in a non-hybrid?

I couldn't really figure out a more appropriate place to ask this question, so here it is.

Is there any benefit of doing some form of pulse & glide in a non-hybrid car? I kind of doubt it, since, from my understanding, the benefit comes from the glide part, where the ICE is not running, so you are running completely on inertia. With a non-hybrid, this is not the case, since the ICE runs anyway. The only way to get a similar effect would be to turn off the ignition during a glide, and then restart for a pulse.

So, is it better to just maintain a constant speed in a non-hybrid car?

Yes it is possible and very dangerous but people do it. It involves turning off the engine with the key during the glide portion. I have seen video of it and I guess the MPG results can be pretty good.

G

It would not be wise to turn off your engine because you will lose your power steering and brakes. I coast down 6% grades with the engine at idle and then bring the rpm up to 1/3 of my speed before putting it back in gear. It does help your mpg greatly to do that but you have to be good a sinking your transmission rpm’s with the engines rpm’s. You get a mismatch and you will feel it jerk. I have it down to a science but it is not recommended for everyone. Also, it is not recommended for automatic transmissions to glide with your engine off. That's why you see all the motor homes pulling their stick shif cars behind them.

With stick shift, put in neutral if you try to maintain current speed for as long as possible, especially on a gentle down slope. Leave in gear when approaching red light or trying to slow down significantly. My 12 year old car MPG just jumped from 35 to 40+

Hi RS,

Go over the CleanMPG.com , they have all sorts of comments and advice for non hybrid cars fuel economy. Pulse and Glide does work for non-hybrid cars. It was a technique common in the Mobil Fuel Marathons in the 60's. I read about that in the 70's. Argonne and Virginia Tech just published an SAE paper about the technique using a Prius and a non-hybrid cars. In both cases dramatically increased fuel economy was obtained. I do not think the non-hybrid car had the engine shut down, just idled.

The issue with non-hybrid cars is that Automatic Transmissions are typically not designed to be rolled down the road with the engine off. There are a few exceptions - primarily those that are towable. Damage to the transmission can result. Some people will neutral shift, but this is very very dangerous in regards to going past neutral. The shifters with the button on the side are better for this. And some automatic tranmissions are designed to permit this, and others not. CleanMPG will be the best source of info on this.

I've read that a transmission in neutral will not circulate transmission fluid properly, or something like that, and can cause damage. So I stopped doing that with my wife's Echo.

P&G on non-hybrids works either way, engine idling or engine off. I keep engine on, and coordinate with rolling hills, but don't do it on flats. Engine off is an advanced technique that gives higher numbers, but would cause too much wear and tear on my pre-hybrid manual transmission cars. I just bought a hybrid instead.

Loss of power steering and brakes is a canard. Having learned to drive in old cars that frequently stalled at inconvenient times, I learned that power boost is a convenience, not a necessity. Non-power steering is hard only at parking lots speeds, not highway speeds. Brake accumulators store vacuum for several applications, after that you just have to stomp harder. If you don't get several applications, GET YOUR BRAKE BOOSTER FIXED!!. If a car is so big or clumsy that it cannot be controlled without power boost, I won't own it, and strongly suggest that you don't either.

I second the comments that CleanMPG is a better reference for this.

Taxi drivers in Beijing drive this way. Either they don't know how to drive, or they are trying to eak out slightly better gas mileage. I think they are going for the gas mileage. While I can appreciate the desire to save gas and $, it makes me uke:

Using a pretty radical pulse and glide I was able to improve my mileage in my Camry from 9 litres per 100 kilometres to 7 litres per 100 kilometres but a less radical version of pulse and glide achieved 8 litres per 100 kilometres.

Radical = engine off glide, so no power steering, restart engine by selecting 5th gear and engaging the clutch at about 50km/h then accelerate to 68km/h then engine off glide again. Engine off at traffic lights, start the engine in 1st gear to get moving.
Less radical as above but allow engine to idle rather than turn it off. Engine off at prolonged stops at traffic lights, restart before green light and move off normally.

Oh I also accelerated pretty hard in first and second gear up to 60km/h then select 5th gear in both methods, this seemed to work for the 2 litre Camry.

Your results may vary.

FAS = Forced Auto Stop which is keying the engine off but leaving it back in the run position so you still have steering and your accessories. You can pulse and glide in any car without shutting the engine off. With a Scangauge, pulse up to you max speed, feather the throttle back while watching your tps, lod, ign, and MPG. When you see your MPG hit max MPG (ultimately 9999mpg), you are in fuel cut. Set your foot into rigor mortis (you will have to feather off the throttle) and glide down to your minimum mph and start the process over.

What is FAS?

Hmm, something changed?

Making the engine spin for no gain is wasteful. Disengage transmission and turn the engine off saves fuel.

Shutting off the engine in most cars will kill the power steering. If you have electric power steering it doesn't. You can still steer but it is heavier, in a straight line you hardly notice but if you have to turn it's hard. Brakes still have boost for one or 2 applications, then the brakes will become very heavy.

When I kill the engine I always turn the ignition on ready to restart. Although I have the transmission in neutral I keep the clutch depressed ready to restart quickly if needed. If I need to restart I just throw it into 5th or 4th and lift my left foot, back to normal driving.

P&G, neutral while stopped, etc. etc. -NOTHING- improved the mileage of the anti-Prius (2001 Nissan Pathfinder). It burned fuel just to keep the cat warm, it injected extra fuel just to keep the cat cool. Apparently fuel was an ejectable resource.

That's in some auto transmission, manual cars are built to coast. I haven't gone to the extreme of shutting of engine, but if you leave key in ignition II, depress clutch and leave in the proper gear, restart is instant and does not cost anything.

I can't pretend to understand the technicalities of implementing P&G in
a non-hybrid. That said, it looks like the most complete discussions of it
are here:

Fuel Economy, Hypermiling - Ecomodder.com Fuel Economy Forum :cheer2:

CleanMPG Forums - Powered by vBulletin :cheer2:

I lurk there because I've come to respect the ingenuity and pioneering
spirit that is so often demonstrated in the funds/resources limited real
world search for high FE/MPGs that faces the majority of drivers on the
road. :rockon:

Many of the technical gurus and ++MPG seekers/achievers who are
members here also post on these boards. It is always a pleasure to
see them carrying the flag for the Prius/HSD in the non-marque
specific discussions that characterize these boards. Well done.

Returning to the OP, I have another comment ...

P&G should work better in a non-hybrid than in a hybrid, on a proportionate basis. Traditional American non-hybrids cruising at highway speed are operating far out of their engine's most efficient energy conversion range, so there is a lot of improvement available. Hybrids should be operating much closer to their maximum efficiency, so P&G in them has less potential for improvement.

The right place is CleanMPG.com. Alternatively, since this is not a 2010 Prius specific question, "Fred's" might be a better place.

Yes, because in an Otto powered vehicle, the engine thermodynamic efficiency increases with a more open throttle. In contrast, our hybrid Atkinson based engines appear to have better thermodynamic efficiency at partial power. I have brake specific fuel consumption data that shows this is the case, if you are interested.

It is easy to rig a 'kill switch' and stop the engine.

Yes, piece of cake on an isolated road with no traffic in sight. The practicality is a separate question but you are asking the right question even if in the wrong forum.

Bob Wilson