Fuel consumption
Turbo Mini Forums

I have a 1275 Midget engine with the standard Metro turbo set up,but using the Midget 8.9 compression pistons and a bleed valve.I have a small intercooler.It has an RC40 exhaust and is running a 3.9 axle ratio.I get 21/22mpg, even when I am not towsing it !!It weighs about 750kg,but this is too much liquid gold for my taste.What do you think is reasonable,please?n

Hi,
Unfortunately with the low diff ratio and the low CR you're always going to suffer on the economy front.
Have you had it setup properly?
Have you got the part throttle lean off pipe connected?
I don't know what you should get, others will be along to get a concensus
Cheers,
Gavin :)

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mid twenties i think is the normal.

i'm single figures with mine... but then it only gets driven with an on/off switch!!!

Acting on advice,I have blocked off the part throttle leanoff,and burned my boats in this respect because Ihave run a drill through the small tube into the inlet manifold and used it for the boost guage takeoff.The fuel consumption plummeted after I fitted the intercooler and upped the boost, previously I was getting 32-36mpg.Guess you cant have your cake and eat it too.

Hi,
Did you block the lean off pipe the same time you upped the boost?
Cheers,
Gavin :)

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Do you have mapped ignition?

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

The lean off pipe has always been blocked off -the received advice is that it reduces the risk of high speed lean out and detonation i realise that this will hurt the part throttle economy.
Im afraid Im still running a distributor -this is a budget effort and the fuel costs are killing the budget !

Totally random idea but what about connecting the bleed solenoid to a switch on the throttle so you only get full boost at 80% throttle & there on up and less boost at part throttle? I'm sure one of the others will be able to shed a bit more light on this or shot me down if I'm talking out of my backside.

Hi,
Someone posted up on here about a solenoid it the lean off pipe, that could be worth a look. You'd need something to switch it though, like a switch on the throttle pedal or a pressure switch in the inlet. You'll need to repair/remake what you drilled out though...
It's not going to be easy, but worth it in fuel savings, maybe enough to by an MJ!
You can have you cake and eat it, with a well setup system or efi
You've lost 10 MPG, I'd be looking to get that back, even if it's just to pay less to the govmnt!!!!
Cheers,
Gavin :)

Edited by Bat on 3rd Aug, 2008.

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i used to get mid 40's out of mine on a motorway run and around 30 driving to work and back. if i was hooning around though it's drop to 15/20 mpg.

I'd say either take it to a rolling road and get it checked out, or invest in a wideband and mappable ignition and play with it yourself.

the advice above is hard to beat

Good advice,well received - except perhaps for the bit about playing with it !.

now where Nic

tadge if it helps , i run around on 9 psi ,150 bhp ,8.5 :1 cr ,and get 41 to the gallon , i have the lean off pipe working ,and it made a huge diff to economy .
my wide band guage runs at 16 to 17 to 1 at cruise ,then 13 to 12 to 1 on power over 3k rpm .
my car weighs 660 kg empty ,or 750kg driving weight .
3.1 diff . straight cut box .

regards robert

Edited by robert on 6th Aug, 2008.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

This forum is great ! I used to get good economy until I fitted the intercooler and I have not changed anything else other than the mixture.I run 3.7 axle with 165/70x13 and the car weighs about 750kg empty -its not a Mini.Your figures are outstanding -i hope I can get 150 bhp on 9psi, I am running 9psi at the moment and although its fast,its not 150bhp fast.I am building a 1360,with 1.5 rockers, a decent cam and hope to afford a Benross head,but it does seem that Megajolt is a very important part of the job I have no clue how to go about it and I HAVE read through the forum.Peter Baldwin has said he can produce reliable results with my distributor setup,but prefers megajolt for accuracy and performance.Is there any kind of local meet where you swap ideas ?I dont live a million miles from you ,Robert,in neighbouring Bucks.

Tadge,
Try here for the basics.
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=5741
I'm going down the Megasquirt route (ignition and fuel) so I don't need the EDIS module but the key to it all in either case is getting a good trigger wheel and sensor setup.
So then do a search on "trigger wheel" and you should find loads of different ways of doing it although the most common is Tom's bracket and machined pulley (search in the "For Sale" section).

Rod.

Schrödinger's cat - so which one am I ???

if fuel consumption is a real problem, sell the car and get an oil burner

Thanks,retired.
Turbo shed, I alrwady have a "chipped" oil burner which does 125mph and 50mpg.I have four vehicles on the road at the moment so fuel consumption is an issue generally.The real issue with the turbo A35 is that it only has a 5 gallon tank and 100 miles is a piss poor range.I guess lots of minis are in the same position.

yep, i have a minivan ( i think thats 6 gallons? i could be wrong and often am!) and i drove it to LeMans, took me 3 tanks of fuel to get there and only ran out once!

I,d hazard a guess that you are not on a fixed income(swing the lamp)