Performance chip

Thinking about putting a performance chip on my 98 range rover P38 2.5 diesel automatic whats the best one and what will the mpg be like

Mike at dyno chips

+1

Tread carefully, the auto box may not cope with the extra power

Is there a huge difference between chipping/psi powerbox, pros/cons?

If you are thinking of towing with the car don't even think about fitting a chip. Most of the damage done to the gearbox will come towing over 50 MPH in torque lock. Little damage can occur at normal town speeds because of torque slip. But if you use the extra power and torque around town stop/start you WILL use more fuel. Because of the more linear map you may see a couple of MPG improvement on a long steady run on the motorway. Other than that no matter what the adds say you CANNOT increase power and torque without injecting and therefore using more fuel. It is not possible.

RangeRoller dt said:

Is there a huge difference between chipping/psi powerbox, pros/cons?

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Chipping in theory should be better if done properly because the torque reduction on shift needed to protect the gearbox should be taken into account, sadly most don't bother, so, like a power box it will eat your gearbox.
Fuel consumption will look a lot better on the dash computer, but in reality will either be worse if you use the power, or very slightly better on long runs as it will hold top gear for longer on inclines. I sold the power box mine came with after it screwed the gearbox.

If you have a manual gearbox no probs at all even towing.

brianp38dse said:

If you have a manual gearbox no probs at all even towing.

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We know this, but the OP owns an automatic.

brianp38dse said:

If you have a manual gearbox no probs at all even towing.

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It's good to know the manual box will take it. I'm thinking of psi powerbox DA4419 if I can source one reasonably priced. Atleast then it's no biggy to take back out if need be. Will the xtra fuelling from chip/box likely help a little on hot starts? My '95 has no trip thankfully. Don't trust that sort and One less thing drawing off my battery

RangeRoller dt said:

It's good to know the manual box will take it. I'm thinking of psi powerbox DA4419 if I can source one reasonably priced. Atleast then it's no biggy to take back out if need be. Will the xtra fuelling from chip/box likely help a little on hot starts? My '95 has no trip thankfully. Don't trust that sort and One less thing drawing off my battery

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The clue is in the name to how much torque the manual can take R380

A stock M51 produces a modest 134hp and 271nm of torque..

Chip her up too much and you'll be eating the manual aswell.

Not to mention the clutch

A chipped 2.5 diesel produces a little less BHP than the 4.0 litre petrol and about the same torque. The petrol uses the same gearboxes auto and manual. The only difference being the different torque curves. Problems come with the diesel when a chip is fitted to what maybe a neglected auto box. And the sprag clutches fail due to torque or primary plate clutch fails because of a sticky valve block. Not using it for towing reduces these eventualities considerably.

RangeRoller dt said:

It's good to know the manual box will take it. I'm thinking of psi powerbox DA4419 if I can source one reasonably priced. Atleast then it's no biggy to take back out if need be. Will the xtra fuelling from chip/box likely help a little on hot starts? My '95 has no trip thankfully. Don't trust that sort and One less thing drawing off my battery

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No help for the hot start problem, need to adjust the FIP timing to account for worn chains or fit new chains & sprockets.

RangeRoller dt said:

Is there a huge difference between chipping/psi powerbox, pros/cons?

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Powerbox just tricks the ECU into throwing in more fuel. That can cause uneven heating on the head and cause it to crack. For that reason I would only go for a chip.

Gearbox: the HP24 gearbox from the 4.6 can be fitted to the oil burner, @ovalandrover did it to one / both of his.

Grrrrrr said:

Powerbox just tricks the ECU into throwing in more fuel. That can cause uneven heating on the head and cause it to crack. For that reason I would only go for a chip.
What do you think a chip does if not "throw more fuel in" Heads generally crack because of repeated overheating.

Gearbox: the HP24 gearbox from the 4.6 can be fitted to the oil burner, @ovalandrover did it to one / both of his.

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I will be fitting an HP24 next year to replace my dodgy HP22 that suffered with the power box as I have had one offered by a friend here in France.

If you are going to chip it do it in the ECU. And do NOT chip it to improve a sad engine, get that running perfectly first. Masking poor performance is not what chips are for.

@Data: chip changes curve but shouldn't exceed current maximums. The powerbox chucks more fuel in all across the range including the current maximums. That's where the damage can occur, or so my reading led me to believe. Not seen a side by side trial with any decent number of engines but why risk it if it sounds plausible? Chip for me every time.

Grrrrrr said:

@Data: chip changes curve but shouldn't exceed current maximums. The powerbox chucks more fuel in all across the range including the current maximums. That's where the damage can occur, or so my reading led me to believe. Not seen a side by side trial with any decent number of engines but why risk it if it sounds plausible? Chip for me every time.

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With the correct map and up rated turbo charger the M51 can output well over 200 BHP and does so in some BMW saloons. However that power and torque curve would not suit a 2.25 ton four by four.

Grrrrrr said:

@Data: chip changes curve but shouldn't exceed current maximums. The powerbox chucks more fuel in all across the range including the current maximums. That's where the damage can occur, or so my reading led me to believe. Not seen a side by side trial with any decent number of engines but why risk it if it sounds plausible? Chip for me every time.

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Of course chipping it increases the maximums as you put it, how else would you get more power? What it does not do is drop the torque on shifts to a level that will save the HP22 from damage.