TDi engines, difference between Discovery and Defender

Graham Hi,

AFAIK it was not the 300Tdi but the 200Tdi that was tuned slightly lower on Defenders (107 bhp instead of 111 bhp on Discos) but that was on the first years of production of this engine.

Then it was tuned for the same power output and when the 300Tdi was introduced in 1995 it was tuned for the same power and torque output on both Discos and Defenders.

The introduction of an automatic gearbox on Discovery vehicles also saw the application of a slightly more powerful engine variant of the 300Tdi (122 or

124 bhp if I remember well) which was also fitted with the electronicaly regulated fuel pump and this additional power (and torque) came from different tuning of the module so as to compensate for the power that an automatic gearbox robs from the engine unless the torque converter is fully locked up.

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The problem with your fuel pump may be due to different (not so succesful) setting of the timing of the pump relative to the engine. Or maybe your pump needs to be "tweaked" either by turning the diaphragm, or the torx bolt on its head or the rear screw.

Hope this helps.

Take care Pantelis

Hi Graham, I'm going through the same process of comparing the 300 Tdi in Disco and Defender.

The Defender is much slower mid to top rpm, which leads me to suspect the difference is in the inlet side. If you look at the metal pipe that connects the air intake to the intercooler you will see that the pipe has been indented near the passenger wheel guard. This reduction in the ID of the pipe will impact the performance.

I plan therefore to replace this pipe with a pipe of the same OD but without the indented section. I will also port match the inlet manifold to the head. Have seen a lot of 300 (Disco and Defender) where the inlet manifold has oval shaped ports which don't match the round ones on the head-in some cases as bad as 2.1mm of excess metal. Removing this and make the inlet manifold ports the same as the head makes a surprising difference.

Cheers

Phillip Simpson

Apart from the position of the turbo I doubt there is much difference. In fact I would hazard a guess that any paper difference in power output is purely a marketing strategy.

As far as reconditioning the pump goes, I have found a less than 50:50 chance of the repair shop getting it right first time. I have often had to return pumps at worse and alter the fuelling myself at best when a repaired pump is reinstalled. The last one I did was a Delphi four cylinder rotary pump where the maximum no-load speed was set 25% short of what it should be. Easily sorted but it should have been right first time. That one was also due to water damage.

Huw

There's no excuse for pumps coming back wrongly calibrated - it takes less than half an hour to run one up on the test bech and calibrate it properly. In the overall cost of rebuilding a pump with a new cam, rollers and elements the cost of calibrating it is insignificant.

If you're getting pumps back that haven't been calibrated correctly then start looking for another firm to rebuild them for you in future.

Easy enough to say but the local LSUK was so bad they had to give it up. There are three or four other companies in S. Wales approved to do warranty repairs on Lucas/Delphi and Bosch equipment and I use two on occasion. It is my experience that Delphi pump equipped engines such as Perkins vary in power up or down by 15% from spec from the factory and in most cases require dyno testing and tuning at pdi. This has always been the case from the days of the old DPA pump as fitted to series Land Rovers. Thank goodness for the mechanically simple computer controlled injection equipment which are nothing if not consistent in their calibration and performance.

Huw

Now I've left the automotive trade I generally rebuild my own pumps and calibrate them myself on the test bench at the local diesel injection specialists. They rebuild a lot of CAV/Lucas/Delphi pumps and have no trouble at all getting them calibrated correctly before they leave the premises - they have done all my pump rebuild work for the last 20 years and I've never had a problem with a lack of power on a rebuilt pump.

Probably what helps is that they are a smallish independant outfit who carry the can themselves for any mistakes they make. They can however do warranty work as they do all the overflow stuff the local Bosch and Delphi agents can't fit in their schedule. And they are reasonably priced - I pay under 20 quid each for rebuilt injectors and the last pump they did for me came to well under 300 quid.

Since the Defender and Discovery have different overall gear ratio's (The Discovery is raised to give better "top end") and radically differing aerodynamics, then without using the same engine and box in both vehicles a comparison is relatively meaningless. Try a Discovery transfer box in a Defender 110 - goes like stink - eventually, but tows bugger all!

The figures quoted in "the literature" will be very carefully selected (i.e. at a particular rpm/road speed) to get the best marketing figures, and insurance group.

Richard

What I mean is that engines for both vehicles probably come with the same horsepower but LR choose to market the defender with a very slightly lower power on paper only. Maybe the manifold arrangement is responsible for some slight difference mind you.

Huw

I agree - LR don't even (or perhaps didn't) give a 0-60 figure for

110's (though they did for 90's) - "Interesting, that" observed the previous NFU rep in this area.......

Richard

Thanks for all your comments, I'll let you know how I get on.

Cheers Graham