The D3 Bi Turbo engine

pete · Post by **pete** » Sun Aug 09, 2009 8:59 pm

Guys,when (apparently)every mapper can get this engine up to 240bhp have the more technical amongst us any idea why Alpina were more conservative in taking it up to just 211bhp(i think).

blacky · Post by **blacky** » Sun Aug 09, 2009 9:09 pm

I would have thought alpina have mapped it for a better spread of power rather than just chaseing a high peak

b10brian · Post by **b10brian** » Sun Aug 09, 2009 9:35 pm

coupled with engine longevitey, torque and consumption.

Bruce M · Post by **Bruce M** » Sun Aug 09, 2009 11:08 pm

With the d range mpg will be a big factor. More than that it will be a balance of torque verses fuel. At some point there will be a diminishing return where the line is drawn.

Beyond that, the torque limit of the clutch and gearbox could be a factor.

Also, with turbos there is a balancing act of air flow combined with air pressure against efficiency. Beyond a certain amount of boost the air gets hotter such that gains have limited value on the road.

Finally, the standard tuning has to cope with middle east temps as part of the BMW testing programme. This will give some head room that uk tuners can exploit.

GuyW · Post by **GuyW** » Mon Aug 10, 2009 12:54 pm

I checked out the Superchips web site and they offer a re-mapping giving 249 bhp, and 458Nm at 3132 rpm for the BMW 123d.

Since power = torque x revs, these re-maps are basically giving the same torque (450Nm on D3BT) but further up the rev band, and they seem to drop off the power faster than the D3 BT.

So the answer is that Alpina wanted a broader and flatter torque curve and to allow the engine to rev to the higher 5200 rpm. Having driven re-mapped diesels before buying the D3BT, I have to say I prefer the broader curve than the more peaky performance, even if absolute power is less.

Hector's Dad · Post by **Hector's Dad** » Mon Aug 10, 2009 2:44 pm

Talking to Kris from Alpina whilst at Sytner, Sunningdale just pre Rockingham, I inadvertently made his day by saying that on first acquaintance with mine (one week to be precise) I was amazed that there's no appreciable turbo lag and I'd yet to feel the second turbo come in. Apparently they worked long and hard to get a mapping to achieve just that.

As far as I'm concerned, it's the most petrol-like diesel I've ever driven.

pete · Post by **pete** » Mon Aug 10, 2009 3:13 pm

Thanks for your answers ,guys.So overall performance is better than a "standard " remap which may have more bhp.

So if you put a standard remap on the D3 would you have a "better"version of the alpina engine? i.e. would Alpinas power band etc still be there or would it clear alpinas mapping altogether?

Hector's Dad · Post by **Hector's Dad** » Mon Aug 10, 2009 3:30 pm

I'm getting out of my depth but Kris stressed that they start with a blank ECU and put their mapping on from scratch rather than adapt one of BMW's. As they choose not to adapt I suppose it means adjustment is possible, but as far as Alpina are concerned, not advisable. I expect it comes down to who you trust to give a better result - Alpina or the chipping company. And that's after you've defined what you think is better

pete · Post by **pete** » Mon Aug 10, 2009 5:28 pm

Thanks Hectorsdad,glad i asked ,because I allways wondered ,if I was lucky enough to get A D3 BiTurbo, would I feel "underchanged" against a remapped 240bhp version next to me at the lights.Now i 'm glad to say I don't believe I would

.

Hector's Dad · Post by **Hector's Dad** » Mon Aug 10, 2009 5:45 pm

It may possibly get off the line quicker I wouldn't know but subjectively, this car feels every bit as quick in real world driving at the 330Ci M Sport it replaced. This car is slightly lighter so the lower bhp is offset a little and the bhp/tonne is much closer.

Not sure I should admit this on here - in my defence I would not normally drive like this

- but on Saturday I made a 160 mile journey that was all dual carriageway or motorway. I wanted to see how good the consumption could be if driven deliberately carefully. I stuck to a steady 70-75 but allowed it to drop to 60 (no lower) on inclines in order to keep the consumption needle as high as possible. When I joined the car park called the M25 the on board computer was indicating a staggering 61.4mpg! 40 minutes of stop start inching along brought it down to 57 and I arrived home with it back to 58.8. When I fill up, from past experience I know the computer is optomistic but I think that would be a true 55mpg.

So, with Alpina's mapping, great performance when you want it and great economy for those rare times you don't! I'm a very happy bunny.

pete · Post by **pete** » Mon Aug 10, 2009 5:52 pm

That is truly amazing ,I have a year old 120d auto ,one night on the M4 a little experiment 10 miles at 80mph=47 mpg 10 miles at 70mph=56mpg and 15 miles at 55-60 mph (could not keep constant because of lorries) 72mpg

Can i ask you what group ins is it ? Is it still 20?
Thanks

Hector's Dad · Post by **Hector's Dad** » Mon Aug 10, 2009 5:53 pm

It's Group 14

pete · Post by **pete** » Mon Aug 10, 2009 7:24 pm

Thanks,That MPG is flippin marvelous

I regularly go from M4 up to Gloucester .Traffic apart i don't hang about ,normally ends up 45-47mpg never mid fifies.

Ikule · Post by **Ikule** » Mon Aug 10, 2009 7:46 pm

I would guess that warranty issues and a smooth power delivery were the deciding factors
coupled with emission regulations for certain markets.

Hector's Dad · Post by **Hector's Dad** » Mon Aug 10, 2009 7:58 pm

i don't hang about ,normally ends up 45-47mpg never mid fifies.

That's my normal too. I had to try hard to achieve that.