MPG 24v vs 12v V6

[24V Renshaw 0]

Just wondering what MPG a 12v VR with just over 200BHP gets....

I have been driving the 24v for a few weeks now and over all sorts of journeys and driving I seem to get a fairly consistent 35MPG. Obviously that does not include really having some, but just general day to day enthusiatic driving.

 

Just curious really as to how that compares to a 12v VR6 with mods to get it to around the same power? (204BHP)

 

Ta for now.

 

Jay

[Kevin Bacon 5]

My 12V gave 36mpg on a constant 70mph run with the Schrick and Cams when I drove over to see VR6 on the Isle of Man. Power was in the 210 region with that lot.

 

With the charger it's gone weird on me....40mpg on a 70mph run apparently, but the chip is way off, so I'm discounting that. Having said that, the fuel in the tank isn't depleting any faster than it did when N/A but like you, I haven't given it the big un yet.

[24V Renshaw 0]

@ a constant 70MPH I am getting 38/40MPG so it sounds about right. I guess its a little more efficient as its 24v.

Its even better with the Cruise control on! :)

 

Just curious really.

 

Jay

[Kevin Bacon 5]

Yeah the 24V will be a little better on economy. It's OBD2 and has variable intake and cam timing, so should barely use anything on a steady part throttle cruise! It's smaller than the 2.9 aswell :wink:

[dr_mat 0]

How many lambdas on the 24v? Where are they? BMW get big economy (for it's size) out of their big sixes by using lambdas VERY close to the cylinders, therefore giving much quicker reacting fuelling adjustment feedback.

I'm sure my sticky brakes crippled my fuel economy, even on a run I rarely see an average greater than 32mpg...

[Kevin Bacon 5]

I think there's two on the 24Vs..... 1 per bank possibly for cylinder selective fuel trimming aswell as timing?

[24V Renshaw 0]

There are 4 Lambdas on the 24v but the second pair are for telling you if one of the CATs is knackered. The first two are on the down pipes so not that close to the cylinders.

Spent last weekend mounting all the Lambda connectors up in a little plastic box under the car that the MK4 uses. Initally I thought I would be OK just strapping them up under the car without it, untill they rubbed on the tarmac and I got a string of error lights!! :) It was the one thing I didn't do exactly as it is in the MK4 and I should have done it right in the first place! After lots of rewiring and making a proper factory like strap to hold the box thingy up its all good now and looks like it should be there.

 

Jay

[Kevin Bacon 5]

Tut tut Jay, that is inexcusable for a man of your talent :lol:

 

Cheers for answering the lambda question too.... didn't realise it had 4!!

[dr_mat 0]

The old 12v VR has to read it's fuelling data from right by the catalyst, so that's a lot of time away from the cylinder, by comparison. Every few milliseconds helps when they're doing closed loop part throttle economy in the ECU. I mean, those MPG figures you're talking about would not have embarrassed a 1.6 carb engine from 20 years ago, and now we can do that with a 2.8!

[24V Renshaw 0]

I know I know, it was one of those jobs where the car was basically ready to roll and I thought, sod it it will be OK! My mistake and thats exactly why I don't do that sort of thing normally!

 

Yep 4 of the bu99ers and all the connectors and wiring that go with them!, plus the 2 CATs themselves! Would be an expensive exercise if they all went, although if I de-cat it in the future I effectively have 2 spare Lambda probes! :)

 

Jay

[24V Renshaw 0]

dr-mat - very true I guess they are about 2 feet closer than in a normal VR, plus there are two.

I am well chuffed with the MPG of the 24v so far. I have gained 5BHP and a bucket of torque over my 200BHP G60 and I get 10MPG better ecomony!! Cool!

 

Jay

[CoxyLaad 0]

thats good news :-)

From what I have been led to believe the rear lambda probes are not the same as the fronts. the rears are basically a switch, that change state based on a threshold.

Basically they say either the cats are working, or they arent.

I dont think I am having a cat on my car, so I am either going to have the rear probes written out of the ecu or mount the back probes to open air so they read a very 'clean' mixture (unless I drive through Middlesbrough that is LOL )

[Kevin Bacon 5]

Dumping the cat on mine when it was N/A had quite a good effect actually, which I wasn't expecting. I dumped it in readiness for the charger (and saved about 20 kilos in the process, LOL!) and in N/A form, she definitely felt livlier....but the downside is the engine smells like an 80s escort 1st thing in the morning, which may or may not bother you. I hate the smell of fuel rich exhaust, gives me a headache! I quite like the smell of cat'd exhaust fumes 8)

 

So the 24V has pre and post cat oxygen detection? Cool....or maybe the second lot detect what ever it is the Cat gives off as a byproduct? Sulphur?

[CoxyLaad 0]

mmm I love that smell

My motobike smells like that that on startup - its class.

 

Smells like performance to me :D

[Kevin Bacon 5]

Most bikes that blast past me on the motorway stink of over-rich mixture, LOL! Guess that'll be the carbs/throttle bodies and no cat?

 

I dunno, there's just something wrong about a brand new bike smelling of a 2 stroke hedge strimmer engine!!

[dinkus 10]

Are you sure that you don't have a hydrocarbon sniffing problem Kev? :lol:

 

Edit: Oh and 2-stroke exhaust is by far the wost smelling :gag:

[CoxyLaad 0]

mmmmmmmm 2 stroke smell.........mmmmmmmm

[Kevin Bacon 5]

My model car has a 26cc 2 stroke engine and that stinks! Bloomin shifts though!

[Blair 0]

Mpg in the high 30s?!?!

 

I test drove the 24V version (still inside a GolfIV 4Motion) at the weekend and got 27mpg overall - wasn't even caning it.

 

I know, I know - it's heavier and it's got serious transmission loss for the AWD system - but still...10mpg down is a lot even taking that into account surely?

[dr_mat 0]

I suspect that if you hold it at a constant 56 mph and reset the mpg computer you'll see it settle to about 35 mpg ...

[Blair 0]

All I need is a large hill to roll it down to get to 56 before I hit the ignition and we're in business then...;)

[24V Renshaw 0]

Drove into work this morning, normal run through town, bit of open dual carrigeway, bit of twisty country road. Driving it all like normal. 25 mile drive. MPG 35.4

 

Jay

[Kevin Bacon 5]

That's good going.... although on Blair's theme, my MFA has dilusions of 39 to 44mpg at the moment, ever since I fitted the bigger injectors and last chip, LOL! Got another chip in the post this morning, which will hopefully correct it.

[dinkus 10]

Does that mean you'll be scaring the living bajeebus out of me on Saturday then Kev? :D

[24V Renshaw 0]

But mine is exactly as it came out of the 24v so its reading right. I am using wayyyy less petrol than I used to with the G60 lump in there.

 

Jay