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...)
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
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.
