19 replies to this topic

[Neg]

After prevaricating for 18 months, I am on the verge of getting a stage 1 remap for my VXT (I'd go for a stage 2, but I'm too tight to junk a perfectly good exhaust - might remove the pre-cat tho !). The one thing still holding me back is fuel consumption. At the moment my VX consistently does ~ 200 miles on 28 - 30 litres of fuel (30-32 mpg). This figure is reasonably constant, regardless of how much 'fun' I'm having. I'm worried that the extra fuel for power and 'cooling' will see a huge reduction in range, and refuelling is a pain in the @rse at the best of times ! If anyone can offer any advice I would be eternally greatful, particularly mpg on standard / stage 1 / stage 2 VXTs for stop-start / normal / 'racing' driving conditions Neg

Edited by Neg, 31 December 2004 - 11:30 AM.

[nakajima]

more power always (normally) use's more fuel. cant expect it any other way if you ask me

[clipping_point]

On the N/A the remap prolly means that more fuel is supplied to the engine, the engine feels better after the remap, prolly runs "rich". On a turbo I do not think it is necessary to throw in more fuel, instead the pressure is increased. That means that the engine back-pressure increases somewhat and the efficiency drops marginally AFAIK. However the engine is more powerful and can be used in higher gears so many people experience a lower fuel conumption, at least on "personal sedans" (Audi A4 1.8T etc).

[Bengie]

From talking to ShinyAndy it seems that the Stage 3 NA doesn't use any more fuel than a standard NA when driven the same way. I'd also imagine this to be true for the modded Turbo lumps - higher up the rev range they dump extra fuel into the engine to keep things cool - if it's modded it'll just burn this extra fuel rather than wasting it. You may find consumption goes down, cause you'll be able to stay in a higher gear for longer. TBH I had a VXT for 12 weeks, and I never got anywhere near 200 miles out of a tank! In fact most tanks were around the 120-140 mile mark...

[Whiteboy]

After a remap my car would do 1/2 mpg better.

[damontite]

i first had a supercharger and my mpg went down to 8 miles per gallon, i could travel about 50 miles before i had to refuel...crap! ive now got a turbo conversion and i get about 20mpg at most with 270bhp. so i about make it to asda and back before i have to flintstone the vx home! thanks damon

[da_murphster]

[/QUOTE]8 miles per gallon,[QUOTE]



[QUOTE]50 miles before i had to refuel[/QUOTE]



Takes the edge off being able to drive fast when every metro driving granny can get from A to B faster than you coz you have to stop every few hundred metres for fuel!!

[SPLAM]

i first had a supercharger and my mpg went down to 8 miles per gallon

I do hope you mean on the track. even so that is still sh*t.


Do SC's drink lots more for some reason.


Ricky does yours drink LOTS more since the conversion.


I know that more fuel will be supplied due to more power, but 8mpg.

[earlystock]

Stage 1 remap, made no real difference to Fuel consumption....still get 30-35 mpg in normal driving 239 bhp

[speedyK]

i first had a supercharger and my mpg went down to 8 miles per gallon

I do hope you mean on the track. even so that is still sh*t.


Do SC's drink lots more for some reason.


Ricky does yours drink LOTS more since the conversion.


I know that more fuel will be supplied due to more power, but 8mpg.

Doesn't Thorney also get about 8mpg on track?

I don't think the SC causes significantly higher consumption in everyday use from the tests I've seen – more torque means less down changes and lower revs. Only if you constantly call up the the extra horses by revving it will it get to be a big factor (more power requires more energy or simply put, you don't get owt for nowt!).

High revs nearly all the time takes its toll on consumption in any car. I was just checking my Durango 4.7litre V8's thirst on the german autobahn yesterday:

steady 120km/h = 16.5 litres/100km = 17mpg

steady 180km/h = 32 litres/100km = 8.8mpg

So 50% increase in speed approximately doubles the consumption. Over a long journey it is still quicker to travel faster and refill more often (though the Durango does have a 100litre tank). Thorney's X5 is probably not better either...

[SPLAM]

I don't think the SC causes significantly higher consumption in everyday use from the tests I've seen – more torque means less down changes and lower revs. Only if you constantly call up the the extra horses by revving it will it get to be a big factor (more power requires more energy or simply put, you don't get owt for nowt!).

That is what i was thinking.


It's just 8mpg seems an awfull lot of fuel on track as the delta charger only puts out 200 BHP.


Edit;

Just remembered it also had a stage 3, damon do you know what power your VXS was?


Obviously not enough for you.

Edited by SamH, 01 January 2005 - 04:04 PM.

[damontite]

hi mine was running really rich cus i had a problem with it at the time. thats why i got the 8mpg. i think it was about 15mpg just before i got rid of it. cheers damon

[Thorney]

Some of these numbers sound like further investigation would be needed tbh. I get about 28mpg on normal road driving (ie 'spirited' ) which is about 2mpg worse than most. On a track I get as low as 8mpg if I drive like a twat (which is freqhent and often). Normally you'll get a minor (less than 1%) worsening in fuel consumption but this actually reverses to 1-5% better when cruising as the car is fucntion more for performance and less for 'base covering'

[cyberman]

With the Stage 3 AmD conversion to the VXT I get about 13 -15 mpg on the road. Like most I don't hang about but this is largely motorway work at 100 mph cruise. It also seems a bit variable. But thats what its doing at the moment. It has always felt rich to me. I slipped in 4 pints of IMS on one occasion (err basically making 10% gasohol) which improves the burning range for the air / fuel mix. This smoothed it out a bit probably confirming the diagnosis. It doesn't seem as good as my old Double Six Daimler some days: at least you could squeeze a fair bit of fuel into that... Regards - Ian

[stomper]

Neq " I am on the verge of getting a stage 1 remap for my VXT (I'd go for a stage 2, but I'm too tight to junk a perfectly good exhaust - might remove the pre-cat tho !). " Reference your opening comments - Pre-Cat removal on a Turbo is apparently not acheiveable. I wanted to do this too but it transpires that the only route is a replacement down pipe on the VXT. Thorney was going to edit the Car Care section to make this clear but it probably slipped his mind after he went off at Brands Hatch (Druids) the day after we discussed this issue at Plans Motorsport. If you mail him - he will give you the low down on this whilst no doubt still bemoaning the fact that he completed 54 track days without incident and then trashed the Lotus only session - see the Track day forum for full gorey detail..... (Sorry Thorney - it may be that some people still don't know about your "off"!)

[SPLAM]

Quite a few different numbers coming out here.

[Turbo Head]

Stage 1 remap, made no real difference to Fuel consumption....still get 30-35 mpg in normal driving

239 bhp

Same here haven't noticed much change in fuel consumption since my stage one.

[Joss]

my (still standard) vxr gives better mpg at 3500 miles than my (standard) vxt did at 11000. Inculding on the track. So more power doesn't necessarily mean worse mpg. I think the cars vary so much you can't predict it.

[Neg]

Thanks for all of your replies. Whilst the consensus seems to be that the difference is negligable for normal driving, Mrs. Neg would like you all to say that you get less than 50 miles per tank If it is true that extra fuel for cooling is only really used higher up the rev range, it sounds like a no lose situation. What with AMD's extremely tempting Christmas offer (Stage 1 £350 + vat), it seems like a no-brainer (which is handy !) Neg