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Old 04-17-2012, 11:13 PM   #11 (permalink)
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Quote:
Originally Posted by chrisoverson View Post
I'm not using anything except the fuel usage monitor I've made with an arduino. I want to fit a vacuum gauge but haven't yet, is that what I need?
Your better way to gauge load will be with a vacuum gauge rather than throttle... use the search function of this site in the upper left hand corner and search for how to use a vacuum gauge for driving with load and P&G. There was a thread recently.

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Originally Posted by chrisoverson View Post
After reading about my engine management system it appears the injectors are always live and the ECU pulses the injectors to earth to trigger them. Could I therefore have them on a switch inside the car that I can activate to connect the injectors directly to battery live so as to effectively disable them?

Then on a glide I could flick the switch to effectively stop any fuel from being injected but keep all electronics going, then turn the injectors back on again for the next pulse.
This had been done. I have one too. Search for injector kill switch installs for your model here on ecomodder...

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Originally Posted by chrisoverson View Post
Eventually I would work to automate this somehow, but would this work for the moment? Also should I be aiming to do 50-60 rather than 50-70mph? Thanks!
Closer to 55 mph is better for cruise, as long as it is safe, You might pulse to 65 and glide to 55. That's what I do, seeking to average 60mph (a mile a minute).

Good luck... you'll get it... I did (mostly).

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See my car's mod & maintenance thread and my electric bicycle's thread for ongoing projects. I will rebuild Black and Green over decades as parts die, until it becomes a different car of roughly the same shape and color. My minimum fuel economy goal is 55 mpg while averaging posted speed limits. I generally top 60 mpg. See also my Honda manual transmission specs thread.




Last edited by California98Civic; 04-18-2012 at 02:40 PM..
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Old 04-18-2012, 04:02 AM   #12 (permalink)
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As Rovers were predominantely british cars I haven't found much on here about ecomods for it. One person came on last year with a ZR sporting a 1.4l K-Series that they said was "lean burn" but I have no experience with any lean burn set up on these cars. They are fairly efficienct though, and I want to boost it as much as possible.

So far what I'm wanting to try is:
-Dual hot/cold air intake, regulated electronically to control temperature
-Block one or both front grilles, possibly controllable at different speeds like the new ford focus
-Set up EGR to reduce manifold vacuum and allow the throttle to open further to get the same oxygen, reducing pumping losses, also hopefully cutting down on emissions from my next step
-Lean burn set up on low engine speeds only
-Fit the diesel model gearbox which gives me 14-17% lower RPM while cruising
-Injector disable/enable for pulse and glide
-Possibly a belly pan, not sure yet
-Implement cylinder deactivation under cruising
-Lower injector shut off point at zero throttle down to 1200RPM from 1600RPM

Cylinder deactivation I take it is tricky on a 4 cylinder engine because of how unbalanced it would make it. My plan is to use a microcontroller to disable one cylinder at a time but alternate between them. I.e. disable one for 0.2 seconds, then another, then another, moving in the firing order to minimize vibration. Don't know how well this would work but I'd have to see.

Ultimately I'd have to switch to my own form of engine management to make it run the way I want, but that would cost more than I'm prepared to spend at the current time. My main goal for the moment is to at least beat the Diesel model which gets 63mpg on the highway. I know if you drove it right you would get 70 out of the diesel, so that's the next target after that.

Am I heading down the right track guys? I'll be posting updates etc. to document the gains/losses and I'll try to make up some form of guide for the electronics if it pays off.
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Old 04-18-2012, 02:35 PM   #13 (permalink)
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Quote:
Originally Posted by chrisoverson View Post
Cylinder deactivation I take it is tricky on a 4 cylinder engine because of how unbalanced it would make it. My plan is to use a microcontroller to disable one cylinder at a time but alternate between them. I.e. disable one for 0.2 seconds, then another, then another, moving in the firing order to minimize vibration. Don't know how well this would work but I'd have to see.
Your O2 sensor is going to see extra oxygen in the exhaust and will richen the mixture to the other injectors. I don't think there's an elegant way to add aftermarket cylinder deactivation or lean burn, other than replacing/reprogramming the ECU.


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Originally Posted by chrisoverson View Post
Yes I meant a throttle position of 3/4, as in the pedal three quarters of the way to the floor. Is this not right?

I'm not using anything except the fuel usage monitor I've made with an arduino. I want to fit a vacuum gauge but haven't yet, is that what I need?
I was originally a little confused about this too. You reach full load when you have zero vacuum, but depending on how much air the engine is using that might be at different pedal positions. A decent way to gauge load is to find how far you need to press the pedal down before you stop seeing large gains in how quickly you accelerate, after this point you're already at full load and any gains are probably from the computer richening the mixture.

A vacuum gauge is probably your best bet, but you can get a good approximation of load without one.
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Old 04-18-2012, 03:23 PM   #14 (permalink)
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Ok so I can't do single cylinder deactivation very easily, fair enough.

Maybe something to look into when I do my own engine management... I guess this is the reason why VW's system closes off the intake and exhaust ports? Never really understood that before.

I'll see about fitting a vacuum guage then I don't mind doing that as the rest of the stuff I'm doing is enough work anyway.

Has anybody attempted to make an automatic pulse and glide system yet? Like a very advanced cruise control aimed specifically at fuel efficiency.
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Old 04-18-2012, 03:43 PM   #15 (permalink)
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It's not quite what you're asking about, but...

Hyundai did on the Sonata hybrid. It runs the engine at high load, diverting the excess output to the battery pack. Then it runs in EV mode until the charge is low. Then it fires up the engine for another pulse. It keeps constant speed, pulsing and gliding the engine and electric mode instead.
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Old 04-18-2012, 04:45 PM   #16 (permalink)
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Quote:
Originally Posted by PaleMelanesian View Post
It's not quite what you're asking about, but...

Hyundai did on the Sonata hybrid. It runs the engine at high load, diverting the excess output to the battery pack. Then it runs in EV mode until the charge is low. Then it fires up the engine for another pulse. It keeps constant speed, pulsing and gliding the engine and electric mode instead.
Eh, this isn't that good imo since you have several conversion losses. The differential being driven backwards will be somewhat more inefficient (okay but it's like 90% instead of like 96% or something), motor losses, power electronics, and finally the battery. Then square all of those efficiencies because you are trying to put the energy back. It's likely not favorable.

Shorter pulses reduce power lost to rolling/air resistance per distance travelled since the higher speed part of the pulse is using much more power than the lower speed part of the pulse, and your average speed is a harmonic rather than arithmetic mean.
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Old 04-18-2012, 06:35 PM   #17 (permalink)
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^ All 100% true, but even with the efficiency losses I'm pretty sure the Hyundai still gains efficiency over a conventional combustion engine system of similar output, with the advantage over our pulse and glide that you're not constantly accelerated and decelerated while driving.

I think someone on this forum was working on, or at least talking about, setting up a cruise control system to do P&G automatically.
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Old 04-19-2012, 03:54 AM   #18 (permalink)
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interesting...

There must be a fair amount to pulsing and gliding perfectly. I found on a site somewhere (wikipedia maybe) that pulse and glide can return upto triple the standard highway MPG when done right according to computer simulations.

I assume to do this you'd need a car with very low drag and low rolling resistance, and switch everything off when the car is in glide mode.

So if I start simple with an injector kill switch for glides, should I always shift to neutral and have to bump start the engine every time? I suspect that on a long journey that wouldn't do the clutch/gearbox etc much good if you have to do it hundreds of times.
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Old 04-19-2012, 04:42 AM   #19 (permalink)
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You raise some very valid questions. The factor of increased wear to the vehicle should indeed be considered. Less so if you are able to maintain the car yourself.

In my limited experience, I've found that bump starting in 5th gear is a lot smoother than trying in a lower gear and seemed to minimise the 'shock'!

De-clutching or coasting in neutral with the engine idling could be safer and a bit less wearing to the clutch, but with a lesser return.

Circumstances vary - so 'you pays your money, you makes your choice'...
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Old 04-19-2012, 06:20 AM   #20 (permalink)
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I suppose anything you can do to encourage the engine to use less fuel on idle would give you an advantage in that case, because you can then keep everything working perfectly and not have the risks of no power assisted brakes or steering.

Or if the 5th gear RPM is low enough to not add significant load onto the engine during gliding, the safest thing would be to leave it in gear. It does slow you down but you'd use zero fuel. I suppose all that depends on the car in question though...

Perhaps in an ideal world you could keep the driveshaft spinning and turning the pulleys but not pump the pistons up and down, minimising the parasitic load as well as engine wear.

I did have an idea for a hydraulic system of pistons rather than using a solid piston rod, which could allow easy cylinder deactivation and also (my favorite bit) change how far the pistons moved up and down on the fly, allowing you to effectively change engine displacement and compression ratio whenever you wanted. I don't know how you could design such a system, but if possible it would be very interesting. I very much doubt anybody could make that at home though, would have to have a lot of time and money invested by a car manufacturer.

I, Christopher J Overson hereby claim this idea as mine, on 19/04/2012. Just incase nobody's already thought of it

Anywho, for the mean time we need to determine which is best for pulse + glide:

1. Engine in neutral, still running as normal for safety (shift to pulse)
2. Engine in neutral, fully turned off to save fuel (bump start to pulse)
3. Engine in gear, injectors off and throttle closed for least effort (apply throttle to pulse)
4. Engine in gear, injectors off and throttle wide open for lower pumping loss (activate injectors to pulse)
5. Engine in gear, fully turned off (turn key to restart + pulse)

I'd guess that how much the engine slows the car down on zero throttle depends on the engine size. Mine is a 1.8 inline 4 cylinder engine, but I expect someone here with a big 5l v8 would see much bigger losses from leaving in gear...

Ultimately I want to add such things as regenerative braking and a mini motor to assist the engine, but I don't know what kind of motor to use or where to aquire batteries.

The other question is, which is more important? Reduced fuel during pulses, or increased glide duration... I suppose if either is significantly improved then its a win win, but which is likely to acheive more with least effort?

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