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Tahrey1043 wrote:LOL @ gareth..... ok to be as short as i possibly can

i was mostly thinking in terms of the 8p i tried to have put on.... the maths of the different situations are there ready-typed two of my posts previous the AHZ (?*) is same as a GT box insofar as i can remember. as for there being much "go" in 5th from 8p, frantic acceleration and high maximum speed is not really what the mod is about the engine has it's best go-ness - what there is of it with a 1043 - on the motorway in 4th, which is properly set for maximum speed at max power (or 3rd for good acceleration ie a brief stint in the middle lane getting past a truck in traffic) but is crap in general for cruising. And they're much the same box after all, 8p vs 4-speed.
(* im too lazy to check )

At truck-drafting speeds on 8P i'd be round max torque revs, supposedly good for economical cruising, and definately good for getting up the majority of hills without having to change down (I don't think i changed out of 4th for reasons other than stop/start for the entire journey, and that included getting round a drafting partner that hit a 1 in 10 (8? there was a sign...) hill and dropped thru 45mph before a biiiiig gap appeared..still on the same hill), and at 70 there'd still be a fair bit of reserve for easy cruising - sod what it says on PoloG40 site, there's no way this car's at 90% throttle at a steady 70... a steady *80* perhaps!
Most cars are geared lower than you think

The one with the slightly lower final drive would be an even better match for the 1L (~2800 @ 56, ~3000 @ 62) but like i'm ever going to track one of THOSE down

(whats that.... 20 lines?)
(opens bird cage to clear up worms )

Argh. I doubt very much you would be able to climb hills with an 8p. After all max torque is only achieved at max throttle, and max throttle up a hill = bad for economy. It would be great on level ground with nowt in the car (or behind a lorry like you say) but considering youve lost about 20% of the power and torque when compared to a 1.3, and also a 1.3 mk3 doesnt pull very well in this gear (its alot better in a mk2) then im afraid the gear will be almost unusable. Still you will have the other gears for all the other eventualities, just dont expect better economy. I still say the AHZ (which is indeed the same as a GT but a different final drive so u do more revs than a GT in the same gear) would be best.

Well its all conceptual / theoretical anyway seeing as i dont have access to
* one (or more) of those cars / engines / gearboxes
* the full technical theory behind it all .... probably requires an automotive engineering degree!
* some kind of testing centre, with an all-extremes track and full dyno/windtunnel setup


well, if even the 1.3 is pretty b@ll@cksed by that gear, maybe for the best that i didn't get it when i tried......... still intrigued by the possibility of the variant on that which is like the AHZ to the GT...
(and i dont think itd be worth getting an AHZ given the microscopic change between that and my current one - may as well just fit tyres with a larger rolling circumference!)

still taking the "full throttle uphill at max torque = BAD" thing with a pinch of salt though. i'd rather run it full throttle uphill at 45 in top (around the same..) than at part throttle in 3rd (~3750 rpm) if it's able to handle it without dropping speed - ditto 5th vs 4th at 55 or 60.
if you're thinking in terms of a full-throttle switch which drastically increases fuelling etc, then only the G40 has that... maybe the GT, not sure. Certainly not any SPi car from what i've seen of the wiring layouts. Running rich (without the benefit of the charger) reputedly decreases your power output after all... just makes the engine a bit smoother! (ah, reminds me - need to jam the throttle pedal against the stops, take the air filter box off, and see whether the valve can actually be opened any further past that.. feeling a little down-powered at full throttle of late, and even if thats not the cause, a bit extra airflow & run of the potentiometer cant hurt!).

anyway. balls to that discussion, unless you fancy continuing it. who wants to tell me where a good place to attach a pair of electric "hub motors" to the rear wheels would be? Just a couple of 1-hp jobs robbed off some leccy-assist bikes my dad still has knocking about. Assuming they have the requisite oomph to shift the car at a reasonable jogging pace that is - havent done that test yet! It'd really help in stop-start traffic and down hills that aren't *quite* steep enough to allow coasting (particularly if i figure out how to make 'em regenerate)
(heheh)

Power is regenerated by attaching a dyno of some sort to the axle that engages only when the electric motor isn't running.. I have to say, adding a system like this onto your car bodged up from bits of an old bike sounds like something of a nightmare.. but I'd be very impressed to see it done

Tahrey1043 wrote:
still taking the "full throttle uphill at max torque = BAD" thing with a pinch of salt though. i'd rather run it full throttle uphill at 45 in top (around the same..) than at part throttle in 3rd (~3750 rpm) if it's able to handle it without dropping speed - ditto 5th vs 4th at 55 or 60.
if you're thinking in terms of a full-throttle switch which drastically increases fuelling etc, then only the G40 has that... maybe the GT, not sure. Certainly not any SPi car from what i've seen of the wiring layouts. Running rich (without the benefit of the charger) reputedly decreases your power output after all... just makes the engine a bit smoother! (ah, reminds me - need to jam the throttle pedal against the stops, take the air filter box off, and see whether the valve can actually be opened any further past that.. feeling a little down-powered at full throttle of late, and even if thats not the cause, a bit extra airflow & run of the potentiometer cant hurt!).

Its not just bad for economy its bad for the engine as well, Its the same as labouring the engine if u need full throttle for a long time when not accerlerating. This puts tremendous strain on the crankshaft bearings and the like. (probably not too much strain for a 1 litre tho) But its what happened to my black GT's engine - full throttle for ages following a G40 (hayseys) and a couple of other cars alot faster than a GT. I melted a conrod bearing shell. But anyway. You obviously dont drive like you describe "full throttle up hill at 45 in top" because you get such good economy! Im not quite sure how the fuelling is calculated by the ECU on an SPi, I had always assumed it was mostly down to the lambda probe, but this is only part of the story. I would need to look at my haynes manual to find out exactly how it deals with full throttle but u are correct its not a switch, but nor is it on a GT is a full blown whole range of throttle sensor! Besides, havent we been here before eith the more throttle more fuel argument?

GroovyCarrot wrote:Power is regenerated by attaching a dyno of some sort to the axle that engages only when the electric motor isn't running..

so how's them regenerative-braking hybrids work then? apparently the motor itself is responsible for it somehow....
(like, you throw it into reverse? but instead of using electricity, it recharges the battery??? um!)

i'd need to do a fair few mods to the motors to make them workable if they fit anyway, such as removing the minimum and maximum speed lockouts, adding a reverse "gear" switch and circuit, etc... may as well investigate the possibility of regenerative braking if they don't already offer that possibility. (which they likely don't, coming from chinese-made chinese-aimed bikes with only one gear, granny saddles, and weighing probably the same as a smart roadster each... which at least bodes well for them being torquey enough!)

Gareth_GT_Hatch wrote: Its not just bad for economy its bad for the engine as well, Its the same as labouring the engine if u need full throttle for a long time when not accerlerating. This puts tremendous strain on the crankshaft bearings and the like. (probably not too much strain for a 1 litre tho)

You mean at low speed, or at any point?

But its what happened to my black GT's engine - full throttle for ages following a G40 (hayseys) and a couple of other cars alot faster than a GT. I melted a conrod bearing shell.

Yikes! What kinds of revs were you pulling? (on the standard box chasing G40s/etc i'm thinking.... 6000+ for an overly extended time). Pain!
Then again that's not what i'd call labouring - more like thrashing. Kind of like when i try to make the 150 miles to/from bangor in less than 2 hours, including all hills and traffic. Labouring conjours up more like 1500rpm or less with the throttle nailed, car gradually losing speed, with it painfully obvious to everyone but the driver that you really should change down as the engine is about to shake to pieces
(I still do like to have the odd thrash from time to time, this economy experiment is more so i can find out what *is* possible, rather than a 24/7 for the rest of time thing..... so i can feel less guilty about the odd blast because it can be "made up for" later on! for example, getting home last night, i was working far later than i was told i was going to and couldnt be arsed with it any more as i had to be up today. just blasted it all the way. 6 miles in 8 minutes cross-country and city? you betcha....)

But anyway. You obviously dont drive like you describe "full throttle up hill at 45 in top" because you get such good economy!

Well, that *was* an isolated case, getting past a truck i was streaming that was clearly going to force me into lower gear and a dangerously low speed for starting an overtaking maneuver, if i didn't get past it right away. And it was only a quarter mile... if i was to face that grade of hill along the entire route, i'd end up higher than everest before i was a third of the way back! Birmingham's only at about a 200m elevation compared to sea level after all (with various parts of the south coast themselves being atop 20m+ cliffs)....
Most of the ride I was just at a fairly light touch on the throttle, on the flat and fairly shallow hills, doing that old 55-60mph in the stream of the trucks with the engine reaching 90 celcius for want of the usual cooling (and drag-tastic) airflow.

Im not quite sure how the fuelling is calculated by the ECU on an SPi, I had always assumed it was mostly down to the lambda probe, but this is only part of the story.

I don't know man. It hasn't a full throttle switch, it hasn't an air-flow meter (um? maybe it does. dunno for certain), far as i can tell it's got the throttle potentiometer, the lambda probe, the temp sender, and a rev count from the hall sender... and thats about it. Very simple design. It beats the carbuerettor technology-wise.... but only just!

Besides, havent we been here before eith the more throttle more fuel argument?

Yeah and I'm about as sick of it as you are I'd prefer if we could find some propeller head who actually knows the facts of the situation to settle the argument (unless you are one yourself and are just stealth at the moment ).... with textbook or journal references as proof....

Til that point i'll still put forward my argument against your standpoint that, if t'were true, i'd get better economy in 3rd gear than 4th at both 55 and 70mph (more revs = more power AND easier gearing = much smaller throttle setting needed).... but i'll wait til the next time i fill it and have a trip coming up to test that - and will be watching the temp guage intently! Have a feeling it'll drop me below 30mpg for the first time ever, at 70...

(56mph in 3rd = about 4500rpm, 70 = about 5600 --- at 56, having the potential to generate considerably more power than the equivalent revs in top, and at 70 still about 10% more...)

Tahrey1043 wrote:Til that point i'll still put forward my argument against your standpoint that, if t'were true, i'd get better economy in 3rd gear than 4th at both 55 and 70mph (more revs = more power AND easier gearing = much smaller throttle setting needed).... but i'll wait til the next time i fill it and have a trip coming up to test that - and will be watching the temp guage intently! Have a feeling it'll drop me below 30mpg for the first time ever, at 70...

I dont quite know what to say. How do you figure you would be using less throttle? The equation in the brackets is a contradiction. How can you produce more power and not use more fuel?

My theory was and still is this

Each gear has a maximum efficiency at a certain speed. (remember that diagram I showed you?) The higher the gear you are in the higher speed this maximun efficiency is at.

This is affected by the load the engine is under, and sometimes (like when climbing hills) Its more efficient to be in a lower gear. i.e when you get to the point that the engine starts to labour.

What more can I say? Its down to interpreting driving conditions. There are no hard and fast rules, just a few basic priciples you need to follow.

Please tell me you understand because Im about ready to give up on you.

Point is that I *wouldnt* be producing more power. For the same forward speed the car would require the same power output from the engine - right? What I'm doing is being open enough to test your theory. At those higher engine speeds in 3rd gear, the engine has the potential to produce more power (say, at about 65mph - 45hp in 3rd vs maybe 37hp in 4th).... therefore to get that same power the car needs to keep moving forwards vs wind drag, rolling resistance off the tyres, gradient etc, it uses a smaller percentage of the maximum available power, hence a smaller throttle setting and thereby using your theory, better economy. Same as the comparison between my current 4th and a theoretical added 5th of any flavour.

Who knows, it might work. Not having a brilliant grasp of the physics behind the whole situation, and having a wierd selective memory that keeps making me forget to google for the answers (or do my learndirect course), i'm willing to try it and see what happens. Don't suppose it'll cause any engine damage anyway - those are the sort of speeds seen at maximum velocity after all, but with a smaller throttle opening (so less air = less compression = less stress ??)

But it'll take a couple weeks before i'm ready to try it. Need to take enough out of the tank to justify a fill up, and save some money in case of mega-consumption or engine damage.

there's something that may be highly revealing, or maybe just hogwash, on this page which mainly deals with CVT issues....
http://cvt.com.sapo.pt/control/control.htm

it's got what could be a highly informative diagram on power vs engine speed and stuff, but trying to figure out what all the pretty colours and the somewhat confus-ed/ing text actually means is making my head hurt. not least because its 6.10am and i just got in from work

(no i didnt go searching for it at that time - it was still open on my pc screen from before i went out)

I Give up. Im tired and hungover and Im off to a polo meet. Feel free try try out my theory whatever it is you think my theory is.

:p

truce, its not worth a fight