Nodge68
Well-Known Member
Just mapping, the engines are the same.
It's possible to remap the TD4 to the same power as the SD4, although if the TD4 has a manual box, then it won't last long, has the box torque limit is 400Nm, which is why the SD4 is only available with the auto gearbox.
It's possible to remap the TD4 to the same power as the SD4, although if the TD4 has a manual box, then it won't last long, has the box torque limit is 400Nm, which is why the SD4 is only available with the auto gearbox.
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SWalker
Active Member
when i rang up to insure my mini they went through a long list of mods - the only one i said no to was disability.... all in all STD mini these days
Nodge68
Well-Known Member
It shouldn't make much difference to turbo life, if the TD4 is mapped to the same output as the SD4. A tiny turbo can make huge amounts of power, and on the whole, manufacturers prefer smaller turbos, as it reduces turbo lag.
Running a smaller then ideal turbo won't in itself reduce turbo life, but the turbo housings and compressor ratios will be optimised for the higher power being generated.
Hippo
Lord Hippo
It was a question I asked the tech's at lr. It's the answer the gave. They say it won't last long term. There must be a reason as they changed the turbo on the SD4.
There are some after market chippers who get more power from the TD4. Up to the owner if they want to do it. In years to come we will see if turbo's become a problem for them.
Nodge68
Well-Known Member
For my driving style, the TD4 is more than powerful enough, and having a manual means I can work the box to keep the torque on tap.
Even though mine still has this annoying misfire, it's no slouch.
GrumpyGel
Well-Known Member
Does the SD4 rev to a higher limit than the TD4?
If it does not, which I think is likely, then as the engines are the same size there will be no more air flowing through the turbo on an SD than a TD - so how would the extra power harm the turbo?
To create the extra power, and burn the fuel as efficiently and environmentally clean you would need extra oxygen in the cylinders. To achieve that, you would need a "bigger" turbo - or a turbo that will output higher compression anyway.
If it does not, which I think is likely, then as the engines are the same size there will be no more air flowing through the turbo on an SD than a TD - so how would the extra power harm the turbo?
To create the extra power, and burn the fuel as efficiently and environmentally clean you would need extra oxygen in the cylinders. To achieve that, you would need a "bigger" turbo - or a turbo that will output higher compression anyway.
Adele Sleep
New Member
Adele Sleep
New Member
Well I was going to remap my td4 but not risking it lol
Nodge68
Well-Known Member
If it does what you need, then there's no point in reducing the life of the expensive components.
The TD4 is mapped to reduce torque output to under 350Nm when 1st gear is selected. This can be felt when driving the vehicle, as it's quite noticeably power limited in 1st.
The reason for torque limiting in 1st is to reduce the chances of damage to the gear cluster. The gearbox manufacturer's data shows the maximum permissible torque is 400Nm, but also suggests some form of torque limiting be applied in the lower gears.
When the TD4 gets remapped, often the 1st gear torque limit is removed, which while making the vehicle feel much more responsive, will have a detrimental effect on gearbox life.
I must just mention, there are actually 2 TD4 engine outputs. The TD4 without a DPF has 160 BHP, and 420 Nm of torque. This is what mine is.
There's also a DPF equipped TD4, which has a lower output of 148 BHP, with 400 Nm of torque.
The SD4 also has a DPF, but has been modified and mapped to make 187 BHP, and 440 Nm of torque.
On the non DPF TD4, the engine is already making more than the 400 Nm limit of the box, so a remap on this engine is unwise IMO.
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Nodge68
Well-Known Member
In answer the question, although nearly 3 years late.
From the data I've seen, the SD4 has a very similar torque curve to the TD4, and no it doesn't rev much higher. The additional power is generated by additional fuel, along with a 5 PSI boost pressure increase.
The TD4 has a boost pressure of 17 PSI, with a short term over boost of up to 22 PSI under certain conditions.
The SD4 has a boost pressure of 22 PSI, with an over boost of 28 PSI under certain conditions.
The ECM decides when to apply over boost, but I've never seen it on mine.
