Remapping a 730d to be a 740d

[Honeywell]

B57B30O0 is a 730d and a B57B30T0 is a 740d - 620Nm of torque becomes 680Nm.

If this solely the engine map or are there any components that change? I’m thinking of buying a G11 730d out of warranty and remapping to 740d power if it’s simply a software issue.

Any BMW Diesel engine beards care to comment?

[Wills2]

740d is twin turbo 730d single, I've got a 740d and the 320hp is about right but not huge amounts in a car of its weight.

[Monkeylegend]

Why not buy a 740d?

[KPB1973]

If the same nomenclature applies from the 6 and X5/X6 series cars, x30d is a twin scroll, single turbo. The x40d is a twin turbo.

The 30d engine could have an optional 'PPK' kit to boost it to around 300bhp, so you should be safe remapping up to the levels you mention.

Approx 700Nm > 730Nm is usually seen as an approx safe limit for the ZF8 gearbox.

[naturalaspiration]

Both share the same ZF 8HP75 (xdrive guise for 740xd) gearbox - the 75 in the gearbox code refers to 750Nm it can handle.

[Honeywell]

They now use variable geometry turbos this I’m not convinced the 740d has two turbos anymore,

I have an F10 535d and understand the old tech. My suspicion is that with a variable geometry turbo the only difference between 730d and 740d is software mapping.

There is lots more choice of 730d XDrive and they are cheaper and I want a 7 with a very rare spec and out of warranty so may as well remap it to 740d power if I find a correct spec 730d and if it’s just a software difference not a mechanical one.

[Wills2]

Honeywell said:

They now use variable geometry turbos this I’m not convinced the 740d has two turbos anymore,

I have an F10 535d and understand the old tech. My suspicion is that with a variable geometry turbo the only difference between 730d and 740d is software mapping.

There is lots more choice of 730d XDrive and they are cheaper and I want a 7 with a very rare spec and out of warranty so may as well remap it to 740d power if I find a correct spec 730d and if it’s just a software difference not a mechanical one.

What do you mean you're not convinced? Strange.

Here are the part numbers for the two turbos you don't think exist:

11658570241/11658570243.

Edited by Wills2 on Thursday 14th February 21:51

[Honeywell]

But why would you have two turbos when a variable geometry turbo is a better solution to the sane problem and you already have engineered in a variable geometry turbo to the engine?

A variable geometry turbo is a solution why you needed two turbos in the first place,

I’m specifically talking about the G11 7 series not the previous model or other models which are clearly reviewed as having two turbos.

[Wills2]

Honeywell said:

But why would you have two turbos when a variable geometry turbo is a better solution to the sane problem and you already have engineered in a variable geometry turbo to the engine?

A variable geometry turbo is a solution why you needed two turbos in the first place,

I’m specifically talking about the G11 7 series not the previous model or other models which are clearly reviewed as having two turbos.

I have a 740d xdrive G11 those are the part numbers for the turbos on the engine sat on my drive, it's not a conspiracy, you seem to be trying to make stuff up to convince yourself.

Carry on by all means, but it's a bit strange.

[Wills2]

Wills2 said:

I have a 740d xdrive G11 those are the part numbers for the turbos on the engine sat on my drive, it's not a conspiracy, you seem to be trying to make stuff up to convince yourself.

Carry on by all means, but it's a bit strange, the current 740d is clearly reviewed as having two turbos.

[Honeywell]

Oh, OK then. It’s not strange it’s just a rational scepticism about using multiple turbos when variable geo ones are already available and engineered. If you have this exact model then it’s very useful for you to clarify the situation for me - no review I could find was specific.

I’ll drop ithe idea then. How do you find the 740d? Have you got the drive assist tech by any chance?

[cerb4.5lee]

Honeywell said:

But why would you have two turbos when a variable geometry turbo is a better solution to the sane problem and you already have engineered in a variable geometry turbo to the engine?

Having the two turbos also gives you more flexibility for power. I used to have a 640d(3 litre 6 cylinder twin turbo) and it had 313bhp/464 torque. I now have a Merc GLC350d(3 litre 6 cylinder single turbo) and it only musters 250bhp/457 torque.

The single turbo engine feels flat to me in comparison to the twin turbo engine I had, and there is only 90kg difference in kerbweight between the two cars. I personally much prefer a twin turbo set up that's for sure.

Funny enough Merc have now decided to scrap their single turbo 3 litre 6 cylinder diesel engine(I'm not surprised in fairness), and their new 6 cylinder 3 litre diesel engine now has two turbos bolted to it.

[Honeywell]

Variable geometry turbos are usually the better solution though rather than one big one small one. Certainly in aircraft they are preferred but then there’s more concern with single point of failure issues.

I was interested to see the current 530d has the same torque as my F10 535d despite not having twin turbos and the reason is variable geometry.

To be fair the 730d will probably respond well to a remap anyway if I find it lacking. Which I probably won’t. I never exceed 100mph so the horsepower again is irrelevant. Having x drive traction and the same torque as the 535d probably means the 730d is going to get off the line and thrust down the road just as well through traction advantage.

[cerb4.5lee]

Honeywell said:

I was interested to see the current 530d has the same torque as my F10 535d despite not having twin turbos and the reason is variable geometry.

Bmw do seem to have really moved things on with their single turbo diesel 3 litre engine for sure(especially the current stuff). I remember my old 2006 330d making 369 torque(I thought it was good at the time), now its up to 413 torque(last gen 330d).

I've been recently thinking about a 430d(I like the extra performance of the 435d but not interested in the xdrive side of it). 0 to 60 in 5.5 for the 430d versus 6.7 when I had my old 330d!

I can't believe I'm going on about diesel engines so much...I think I deserve a slap or a ban!!

Edited by cerb4.5lee on Thursday 14th February 23:15

[bigdom]

Honeywell said:

Variable geometry turbos are usually the better solution though rather than one big one small one. Certainly in aircraft they are preferred but then there’s more concern with single point of failure issues

Variable vane turbos are a compromise, and just a cheaper option to doing the job properly.

There’s quite a difference in operation between cars and aircraft, the latter are not sitting around idling for long periods of time.

Cars are subject to a far greater range of general operating conditions, heatsoak being one. VVT’s are subject to corrosion, sooting up, and premature failure over a fixed setup, mainly by not driving them hard enough and lack of WOT usage.

If they are the preferred option, do you think it’s strange BMW have 4 turbo’s bolted on the new X5 50d?

Edited by bigdom on Friday 15th February 12:42

[Honeywell]

Twice the bearings, twice the plumbing, twice the chance of a failure and two turbos need more space than one variable geometry one.

I’ve no particular expertise in car applications but variable vane turbos were seen as a great advance over multiple fixed turbos when they were invented.

[bigdom]

Honeywell said:

Twice the bearings, twice the plumbing, twice the chance of a failure and two turbos need more space than one variable geometry one.

I’ve no particular expertise in car applications but variable vane turbos were seen as a great advance over multiple fixed turbos when they were invented.

Less chance of a fixed vane turbo failing, there’s less to go wrong, each do a single job, rather than multitasking, you know, two things not done so well. The ancillaries can cause issues on the multiple turbo setups, solenoids, air hoses etc. Dirty oil/oil supply is the biggest killer of turbos, pre intercoolers, heat in general.

VVT serve a purpose, they get to 80% of the flexibility/power of a twin (which is more than sufficient for most of the driving public), with cheaper manufacturing, although they are not the forced induction panacea. Where cost is not an option, multiple setups always win.

[Honeywell]

Ok, it’s nkt what I would have thought but then that’s why I asked the question. Thanks for the info.

Not sure if the extra £5k for the second turbo is really something I can justify. It’s hardly going to be night and day better.