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Old 09-22-2010, 04:34 PM   #6 (permalink)
EcoModding Apprentice
Join Date: Aug 2009
Location: London, UK
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Originally Posted by Air-Hybrid View Post
I await the ridicule!
.... and ..... ha ha, the ridicule didn't arrive *gets out of the foetal position!*

Sorry if the explanation was a bit confusing in places, I went off on a tangent about the car and then ran short of time!

Thanks again all 3 for the confidence boost!
Thanks to Daox additional for finding a nice clear pic of the Imp and its engine layout.

So I'm going to have a go at expanding this a bit more:

Originally Posted by gasstingy View Post does it help? Is it a way to restart the engine after you've shut it off for stopping?, or some way to reduce the strain on the engine while going down the road?
In answer, my ideal is -the best (most efficient) I can manage- on pretty meagre finances! I currently drive (in what I consider to be) a reasonably efficient manner (by normal standards but not on the eco-modder scale I'm sure). I will turn the engine off at (or sometimes approaching) long traffic lights and drift up to junctions or stationary traffic. So for me a auto-start-stop system is handy, but I doubt would make much difference. >As an aside, can you guys put me straight on the switching-off policy? Other people have said that more fuel can get used in restarting (but I don't know the principles & whether old or new cars differ).<
Anyway, going back to the analogy of the engine assist being like going downhill (on a flat road) I would have thought a system that delivered an almost constant torque would be some bit easier to 'wire' than a more advanced hybrid (as a newbie I expect I am underestimating it though).
That said, if I had a system that for negligible weight would 'puff' my little engine over whilst stationary (idle jet 'off') that would be pretty cool. However for the money and time that building such a system would entail it would certainly be a bonus if it can give an assist here and there! A good analogy would be my flat spot pump - when I (occasionally) push down hard on the 'gas' it sends a squirt of neat petrol down the venturi and the vacuum pulls the dissy round a tiny bit. I was thinking that for starters this would be a perfect job for our electric assist. No crudely chucking a chunk of unmixed fuel at the cylinders or buggering with the timing (so much), just a firm push from the e-motor. Of course, at this stage you may all be saying 'you need to go injection anyway', but it's easier (for me at least) to picture in mechanical terms.

I also expect you are beginning to wonder how I hope keep my mild hybrid topped with electricity. It was the mild hybrid route that most attracted me after I found an article on GM's BAS (belt alternator starter) system. I was already fairly certain that some flavours of motor could operate almost as efficiently as generators and finding the BAS system appears to prove it. It also seems perfect for a light small engined car as the power cost of adding weight is that much worse by have two separate units.
So the (as of today, only academic) question is what cycle of operation would I need to keep an averaging load on my little 875? I understand that as with any hybrid I'm only going to be carrying 'dead' weight on a ideal straight motorway with no braking or accelerating, but I know that (at least with the sports head & a progressive-choke Webber at least) my MPG falls quite considerably in town driving (careful as I am). Here I could get some real savings.

I have just thought of the (lets call it) over-aggressive engine braking being a real nice way to help keep that battery pack full. The only real downside is ideally it would be better to have the 'regen' on the front wheels and adding another generator would be especially complex on an imp.

Phew (again)... tired fingers, stopping now.

ps. They did make a van-shape imp, but alas it's not as nice a shape...

Last edited by Air-Hybrid; 09-22-2010 at 04:42 PM..
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