Thread: 300tdi vs a td5?

Originally Posted by shedlock2000

Hey Slunnie,

I don’t think cruise was an option on any Defender, was it? I had a pretty tricked out Defender back in the Uk (it was a 2002 and brand new with all options, and it didn’t have cruise).

Did they uptune the TD5 for the D2, then? I had a D2 with a TD5 in it — it was a great vehicle, but presumably it had different transfer box and diff ratios.

There are not many places in Canada that can tweak a TD5 (or a Tdi, for that matter!). One benefit from the TD5 is the bigger heater matrix (any help I can get will count!). The prices here are scary (buddy wants $40k for this!!), though, and the most disadvantageous aspect of the TD5 is that it’s RHD — not great for resale in LHD country!

Id didn't think the tdi had CC, but if the TD5 didn't either I guess it's not a factor between the engines. I'm a compulsive CC user which is why I brought it up.

I dont think it was so much they uptuned the TD5 from the Defender to the Disco, as I understand it, it had more to do with the induction side of the engine being different due to packaging constraints. The transfers are different as you've rightly said. The differences are the high range ratio (110/130 are 1.4, Disco is 1.2) and the tyre diameter (90/110/130 31", Disco 29").

I had my TD5 tweaked, but to be honest, my thoughts are that if you're sitting on those speeds which will create higher EGTs than normal driving, that personally..... now that I've had experience with a hot engine tune...... I would still uprate the intercooler but I would be reluctant to have the ECU modified or use a very light upgrade WITH an uprated intercooler because I think that too many are running too high EGT's which ruins the TD5 motors in a number of areas. I remember years ago thinking the uprated intercooler and the uprated ECU give about the same performance increases.

Both engines are good for long hauls and high mileage. A TDI will likely be cheaper to maintain. Both can do 70mph all day long on the flat. If you are going to tow a large van and hope to hold some speed, go with the TD5

Gearing on the defender TDI/TD5 means both will sound like they are reving their nuts off at 80mph. A loaded 110 on a 1.2 ratio xfer box would not go well up hill so I would keep the 1.4 ratio and look to reduce cruising revs with taller tyres or an overdrive unit.

With the cooler climate you probably dont need AC, so you will have plenty of space for a full width IC in front of your rad. A healthy TDI would comfortably hold 70-80mph with all that cold air. The fuel pump tweak to match a bigger IC is well documented and easy to DIY.

For comfort a webasto coolant heater would be high on my list. We had one in the UK. It can heat up the engine, interior and defrost the windows before you get in and turn the key! Any uprated heater box/matrix available for the td5 will fit the tdi.

Originally Posted by Slunnie

Id didn't think the tdi had CC, but if the TD5 didn't either I guess it's not a factor between the engines. I'm a compulsive CC user which is why I brought it up.

Yeah -- me too. I am glad this was brought up! I didn't think about CC; you don't really need it in the UK -- but over here is a different story. I shall look into the CC, but from what has been said above, it doesn't sound like too much of an issue.

Originally Posted by Slunnie

I had my TD5 tweaked, but to be honest, my thoughts are that if you're sitting on those speeds which will create higher EGTs than normal driving, that personally..... now that I've had experience with a hot engine tune...... I would still uprate the intercooler but I would be reluctant to have the ECU modified or use a very light upgrade WITH an uprated intercooler because I think that too many are running too high EGT's which ruins the TD5 motors in a number of areas. I remember years ago thinking the uprated intercooler and the uprated ECU give about the same performance increases.

This is good info -- I was going to re-map the TD5 if I got it, but it's nice to know that the Tdi can keep those speeds too. Do you think that a larger IC can make that much of a difference? It does get balmy hot over here as well -- the summers are often +40c or more (not quite what you guys experience, but its tricky here planning for a 90 degree change in temperatures between summer and winter!!) Frankly, if it can keep up at 70/80 mph and doesn't loose too much on the hills, I won't mind. My primary concern is the heat and the starting in the winter.

Originally Posted by manic

Both engines are good for long hauls and high mileage. A TDI will likely be cheaper to maintain. Both can do 70mph all day long on the flat. If you are going to tow a large van and hope to hold some speed, go with the TD5

Good to know! Thanks. I won't be towing with it, but I will have a bunch of stuff on the rack (usually 4 kayaks, 2 jerry cans, water storage options, and two 2'x4' storage bins).

Originally Posted by manic

Gearing on the defender TDI/TD5 means both will sound like they are reving their nuts off at 80mph. A loaded 110 on a 1.2 ratio xfer box would not go well up hill so I would keep the 1.4 ratio and look to reduce cruising revs with taller tyres or an overdrive unit.

Boo.... I might go for slightly oversized tyres, but narrowness is a thing for me. I was hoping to keep somewhere near stock but maybe use the Boost Alloys for a slightly wider track... I am not certain how that will pan out. Apparently, there is some dude over here making Defender overdrives of some repute! I have not looked into them yet. I had a Fairey overdrive on my '81 RRC a long time ago, I noted that the carb V8 wasn't really able to keep up with the ratios in the wind and the top speed would drop to well below 70. Have you noticed this sort of an issue with the Defenders?

Originally Posted by manic

With the cooler climate you probably don't need AC, so you will have plenty of space for a full width IC in front of your rad. A healthy TDI would comfortably hold 70-80mph with all that cold air. The fuel pump tweak to match a bigger IC is well documented and easy to DIY.

Hmmm, I am not desperate for the AC, but it has it and it might be nice. As I mentioned to Slunnie, it does get monty hot here too. I don't mind travelling with the windows and vents open, but it does get noisy!

Originally Posted by manic

For comfort a webasto coolant heater would be high on my list. We had one in the UK. It can heat up the engine, interior and defrost the windows before you get in and turn the key! Any uprated heater box/matrix available for the td5 will fit the tdi.

This is also good to know. I think the Webasto/Eberspacher units are a must up here -- I am really worried that the thin panels and lack of insulation in the Defender will just let the little bit of heat be sucked right out of the vehicle in the cold. One year I drove my RRC to Calgary in an emergency and it hi -58c. We had to stop and partition the the rear off from the front with blankets to try and keep the heat in. The windows kept freezing up on the inside and, in the end, we had to stop and purchase cold weather coveralls because the cold was so bad -- and the early RRC heaters were pretty good! I don't know whether even an Eberspacher cab heater would be sufficient to keep out that cold -- but I suppose we have the fatty for such trips.

Originally Posted by shedlock2000

This is good info -- I was going to re-map the TD5 if I got it, but it's nice to know that the Tdi can keep those speeds too. Do you think that a larger IC can make that much of a difference? It does get balmy hot over here as well -- the summers are often +40c or more (not quite what you guys experience, but its tricky here planning for a 90 degree change in temperatures between summer and winter!!) Frankly, if it can keep up at 70/80 mph and doesn't loose too much on the hills, I won't mind. My primary concern is the heat and the starting in the winter.

I've never driven with a tdi that is remotely similar to the Td5 on the highway personally, especially when its not flat. The normal is to slow down and wait but others may disagree. The hotter it gets the more you will draw on the larger intercooler to keep the temps down, its a safer way to gain more power. At 40+ I'd really question upgrading the ECU personally, but the intercooler will benefit and as per normal you will feel a big differnce between hot and cold days. In my seat of the pants opinion the larger intercooler did make that much difference. The ECU and Intercooler were done on successive days. I'm not sure about the tdi, but the Td5 isn't particularly affected by the cold, they usually start straight away, when below zero just give it a short pause for the glow plugs and they start straight after that.

Originally Posted by shedlock2000

One year I drove my RRC to Calgary in an emergency and it hi -58c.

Oh! Thats a whole different ball game to cold here!!! Where I live only gets down to -5!

Originally Posted by Slunnie

Oh! Thats a whole different ball game to cold here!!! Where I live only gets down to -5!

Hahah! Yeah, when it gets really cold it’s a big issue. Below -20 the carb V8 RRC wouldn’t start: the fuel condensed too much in the inlet manifold. When it’s really cold, even new petrol engines can be mighty sluggish.

I’m assuming that it’d be difficult to squeeze a bigger IC in with the Ac condenser at the front? Can additional units be installed anywhere?

A taller skinny tyre option is the 255/85

Lets not compare the experience driving TD5/TDI discoveries to TD5/TDI defenders. In the defender 80+ mph feels like you are trying to break the sound barrier, the aerodynamics and gearing with a TDI or TD5 makes them both feel like they are being overworked at those speeds. Out of the factory there was around 11BHP difference between these motors. So if you find a good LHD TDI dont rule it out as not being powerful enough to cruise highways at the speed limit - it can. A slight fuel pump tweak on the TDI will see it cruise alongside a factory tuned TD5. Both these motors will fall off 80mph on a steep incline. If you want to storm up steep hills in a Defender a tuned up TD5 can leave the TDI for dust, but it will still sound like it is being absolutly thrashed!

A large IC certainly does make a difference, it allows you to up the fuel delivery without increasing EGT. If you do end up with a TDI, a full IC and fuel tweak can get you 35% more power ( up to 160BHP according to allisport). I doubt you would push it up to those figures in the real world, but a modest fuel adjustment to suit the IC could reliably produce more than a 122bhp TD5. The 300tdi behind the autobox was dialled up to 122BHP at the factory with a stock IC.
Defender 300 Tdi Full Size Intercooler - AlliSport

One option for getting a full width IC on a TDI with AC might be to fit a larger grill/nose panel found on the later defenders. You can also replace the belt driven fan and shroud with an electric fan, which would free up a bunch of space allowing you to move the rad further back towards the motor. An electric fan mod might be a good idea for the cold!

I have a TDI in a 90, lighter vehicle than the 110 but I have a lot of kit on it and its pulling through a r380 + 1.2 ratio xfer box, and 255/85 tyres. Electric rad fan conversion has always been enough to keep it cool even here in Australia. Runs a double core IC (not full width: Defender 300 Tdi uprated double core intercooler - AlliSport ). Fuel pump tweaked to maintain safe EGT levels. I have no idea what the BHP/power figures would be but it can roar up most highway inclines at 70mph (in 4th) and on normal undulating road it can pur along at 75mph in 5th. Because my 5th gear is now way too tall I cant hold 80mph+ unless the road is flat. So effectivly I have four gears that pull and 5th as the overdrive. Its not the perfect set up but a huge improvement over the LT77+1.4box I had before, which howled along at 70mph in 5th on the flat!

110kph being the highway speed limit in Canada, and with no mention of towing, I would say soundproofing, gearing and cruise control would do more to improve your highway driving pleasure in a Defender than TD5 over TDI.