David Jenkins
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| posted on 12/7/08 at 03:28 PM |
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Economical driving?
When I go out in my toy car I tend to drive either foot-to-the-floor or at high-ish revs in each gear. Why - 'cos it's fun and going like
the clappers is most amusing! The trouble is, I'm lucky to get 25mph at the end of it... 
...especially with the new bike carbs, which are VERY good at sucking fuel and air into the engine. 
Anyway the question is, sometimes I might want to go to a show (e.g. the East of England Show in August) and would rather not have to fill up once or
twice during the day. So what is the correct technique for keeping the mpg nice and high? So far I can think of:
1. Not revving too much in each gear as I accelerate.
2. Changing up early.
3. Keeping the revs down.
Any other bright ideas?
In the past I've driven cars that had 'economy meters' - if you were in the green bit of the dial then you were driving
economically. Anyone know what they were measuring?
[Edited on 12/7/08 by David Jenkins]
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eznfrank
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| posted on 12/7/08 at 03:30 PM |
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quote:
Originally posted by David Jenkins
I'm lucky to get 25mph at the end of it...
[Edited on 12/7/08 by David Jenkins]
Pinto huh????
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David Jenkins
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| posted on 12/7/08 at 03:32 PM |
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x-flow!
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blakep82
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| posted on 12/7/08 at 03:34 PM |
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drive in the highest gear the engine car work at,
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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NeilP
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| posted on 12/7/08 at 03:40 PM |
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And don't go faster than 60 mph or you are just working against too much air resistance (even in a little 7)...
If you pay peanuts...
Mentale, yar? Yar, mentale!
Drive it like you stole it!
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David Jenkins
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| posted on 12/7/08 at 03:45 PM |
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I detect a theme here... 
Ages ago I read a book about tuning Mini engines. Basically it said that if you do all the usual things to gain more power (gas flow, good exhaust
system, etc.) but then DON'T WELLY IT and drive moderately, you will gain a huge amount of extra mpg.
Now I have a good carb setup, an excellent exhaust system, and I'm prepared to drive in a relaxed and gentle manner. It would be interesting to
see what mpg I get...
...I detect an experiment coming on.
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Stuart_B
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| posted on 12/7/08 at 03:53 PM |
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quote:
Originally posted by David Jenkins
When I go out in my toy car I tend to drive either foot-to-the-floor or at high-ish revs in each gear. Why - 'cos it's fun and going like
the clappers is most amusing!
drive it like this still and just pay the money for the petrol and have fun.
stuart
black mk indy, 1.6pinto on cbr600 bike carb's.
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David Jenkins
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| posted on 12/7/08 at 03:56 PM |
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Going to a show usually means long journeys on boring roads like the A12 or A14. Finding ways of improving the mpg have value when you're
driving 100-150 miles each way!
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mr henderson
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| posted on 12/7/08 at 04:26 PM |
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Another way of saving fuel is to do less of whatever a powerful engne can do better than a weaker one. The main thing is acceleration. After each
unavoidable slowing down reason (traffic lights etc) just accelerate much more gently.
Top speed is more likely to be set by road conditions, traffic, camers etc, but obviously the slower you travel the less fuel you will use.
The other control that eats fuel is the brake pedal. Use it as little as you can, every mph lost is one that has to be regained
John
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rusty nuts
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| posted on 12/7/08 at 04:33 PM |
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Just stick a stink bomb on the throttle pedal , if it goes off your using too much right foot! Vacuum gauge may fit using all of the bike carb
vacuum take offs to give a steady reading
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smart51
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| posted on 12/7/08 at 04:51 PM |
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quote:
Originally posted by David Jenkins
So what is the correct technique for keeping the mpg nice and high? So far I can think of:
1. Not revving too much in each gear as I accelerate.
2. Changing up early.
These are probably the wrong thing to do. During acceleration, the engine is working at its most efficient at maybe 70% or 80% throttle at a speed
probably between a third and a half of max revs. Changing up too early and only using 10% of the throttle is just as wrong as revving it flat out to
the red line.
Once your acceleration is sorted, pick a gear that gives you about 2000 RPM or whatever the engine is comfortable at. Don't try to labour the
engine at 1000 RPM because it won't like it and efficiency is poor.
Look ahead. If you see an island or red traffic light, don't carry on until the last minute then brake to stop, lift off the throttle and allow
the car to slow on its own. With your foot off the throttle, you use less fuel.
Lastly, keep your speed down. The faster you go, above maybe 40 or 50, the more fuel you use per mile.
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ditchlewis
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| posted on 12/7/08 at 06:24 PM |
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just take it easy with the throttle.
the other way is to raise the gearing in top and fit a 5 speed.
ditch
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David Jenkins
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| posted on 12/7/08 at 07:28 PM |
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Got the 5-speed... 
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indykid
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| posted on 12/7/08 at 07:51 PM |
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quote:
Originally posted by smart51
These are probably the wrong thing to do. During acceleration, the engine is working at its most efficient at maybe 70% or 80% throttle at a speed
probably between a third and a half of max revs. Changing up too early and only using 10% of the throttle is just as wrong as revving it flat out to
the red line.
Once your acceleration is sorted, pick a gear that gives you about 2000 RPM or whatever the engine is comfortable at. Don't try to labour the
engine at 1000 RPM because it won't like it and efficiency is poor.
Look ahead. If you see an island or red traffic light, don't carry on until the last minute then brake to stop, lift off the throttle and allow
the car to slow on its own. With your foot off the throttle, you use less fuel.
Lastly, keep your speed down. The faster you go, above maybe 40 or 50, the more fuel you use per mile.
all the above sounds ideal for an injected engine where fuel metering is much more closely balanced to engine speed and acceleration.
from my experience of driving carbed cars though, david is onto the right idea. only rev to about 3000ish before changing up.
when approaching an obstacle, get off the gas asap and even get the clutch in and coast up to it. there's no lean burn program on a
carburettor.
the keeping speed down really is a massive benefit on long distances though. 60 on a motorway will use about 2/3rds the fuel as at 80.
tom
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David Jenkins
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| posted on 12/7/08 at 08:12 PM |
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quote:
Originally posted by indykid
when approaching an obstacle, get off the gas asap and even get the clutch in and coast up to it. there's no lean burn program on a
carburettor.
I've been very impressed when using my AFR meter after fitting the bike carbs - on over-run the AFR is 17:1 or 18:1, which I think is pretty
good.
I just have to stop getting 12.5:1 on wide-open throttle all the time...
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02GF74
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| posted on 12/7/08 at 08:27 PM |
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yep - what they say.
accelerate gently and do not exceed 2,000 rpm by changing gears.
keep speed to below 70
on hills, do not mainintain speed but keep to 2k rpm limit - you will drop down to 50 mph but so what?
keep long distance from car in front so you can avoid using brakes ; braking = petrol converted to waste heat.
rember top gear driving the diesel audi from london to scotland on one tank?
I tried the same tehnique in my volvo - usually get 25 mpg on this occasion got 36 mpg (100 mles) .... unfortunatley my boredom threshold is too low
for me to drive like that but was an interesting experiment. (should really measured how long the hjourney took)
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David Jenkins
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| posted on 12/7/08 at 08:35 PM |
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The boredom issue is a factor - especially on a 100 mile journey!
Also, due to the cam, my engine's not much use under 2000rpm - it pulls, but not happily.
Next time I fill the tank I might try being a nice civilised driver to see what mpg I can achieve... if I can keep the pedal off the floor!
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mr henderson
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| posted on 12/7/08 at 08:57 PM |
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quote:
Originally posted by David Jenkins
Also, due to the cam, my engine's not much use under 2000rpm - it pulls, but not happily.
Well there's some of the problem right there! I presume there's a lot of overlap on the cam? Might be worth reverting to the standard cam,
they are designed to balance power with economy
John
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David Jenkins
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| posted on 12/7/08 at 09:09 PM |
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I only want to be economical occasionally!
The rest of the time...
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ditchlewis
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| posted on 12/7/08 at 09:10 PM |
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i heard a radio show which claimed that accelerating to your chosen speed as fast a possible and then coasting and maintaining that speed was the most
efficent
i now accelerate as hard a poss till i hit three figures that's my excuse
ditch
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David Jenkins
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| posted on 13/7/08 at 10:31 AM |
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Went out for a nice drive to Shotley Point this morning - took it steady, changed up at 3000rpm, obeyed (most of) the speed limits and generally drove
it like a tin-top. I must admit that the petrol gauge didn't move down much...
Wife and I were without crash-helmets (just shades) so we kept the speed down and just looked at the scenery - there are a lot of lowish speed limits
on that route anyway, so it was easy.
Very pleasant morning out.
[Edited on 13/7/08 by David Jenkins]
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rusty nuts
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| posted on 13/7/08 at 12:15 PM |
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quote:
Originally posted by David Jenkins
Went out for a nice drive to Shotley Point this morning - took it steady, changed up at 3000rpm, obeyed (most of) the speed limits and generally drove
it like a tin-top. I must admit that the petrol gauge didn't move down much...
Wife and I were without crash-helmets (just shades) so we kept the speed down and just looked at the scenery - there are a lot of lowish speed limits
on that route anyway, so it was easy.
Very pleasant morning out.
[Edited on 13/7/08 by David Jenkins]
What about the fuel consumption???
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David Jenkins
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| posted on 13/7/08 at 12:58 PM |
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quote:
Originally posted by rusty nuts
What about the fuel consumption???
As I said - the petrol gauge didn't seem to go down much...
[Edited on 13/7/08 by David Jenkins]
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