Tow vehicle motors

[Guru036]

G'day all,

I was just ready the thread in in tech about tow vehicles and it got me thinking about mine.

I tow heavy car trailers with buggys (probably 2.5T - 3T) with my 3.5L EFI V8 Auto rangie. It tows well and gets about 300kms per tank (about 21-22Lper 100km) It holds road speed pretty well too.

But I have thought about putting a 300tdi in it with a 5 speed manual (as I already have the motor and box) but I'm worried that doing the conversion (which will cost me around $1000 to do myself) won't be worth it in the long run. How well do the 300tdi's tow? I would be keen to try one towing to see how they go if anyone is keen?

I'm keen for the economy, but worried about losing alot of road speed

[JohnE]

Here is food for thought, if diesels were no good they wouldn't be in trucks, then try and keep up with a truck at night.

But road speed and economy towing 2-3 tonne on a trailer, surely you can't be serious, I would err on the side of caution and forget the road speed, how quick will you be able to stop something like that.


john

[harlie]

Hi Guru

I owned a boat (sold late last year) that was 2.8t total road weight. Our previous 4*4 was a ’94 300tdi manual disco that happily towed it all over the place. I will add that my version of happy may not be the same as yours – highway I sat on 90 and it hung on well on the hills ie once rolling it was happy - but it was (worse than) dreadfully slow off the mark around town.
The injection pump had been “tuned” (Highway Diesel bne) - after that it was one gear better on hills, (highly recommend). Towing economy was around the 17 – 19L/100, essentially double what I got normally (low to mid 9s – the advantage to being slow).
Never had a cooling problem but I think the disco radiator would be larger than 3.5 rangie. And on the braking point my trailer was setup with one of the latest Electro Hydraulic marine systems through 12’ discs on all wheels and the total package pulled up nearly as well as the empty car – however it did take a while to get all the adjustments right in the beginning and I always used a HAYMAN REESE load distribution hitch to help with stability and put weight back on to the front axel of the car.

Its really going to be a personal choice V8 auto v tdi manual – its sure going to be different.
:)

[Taz]

The heaviest load I've towed with my manual 300Tdi was about 2.5t (a series 2a with spare motor on a car trailer) and it struggled to reach 80km/hr on long stretches with a slight uphill incline. And I remember using second gear on some hills. We also had a 15.5ft caravan (full height and full width) and we were down to 60km in some places when the incline and the wind was against you. We now have a camper trailer, which weighs as much as the caravan, however we can tow happily at 110 if there is no wind. So I think at lot of it comes down to the aerodymanics.
Now we are thinking about a bigger caravan again, and whilst the disco could tow it, we like touring holidays where we do 600-800km per day, and that just aint gunna happen with the 300Tdi/caravan combination (too slow), so we are also looking at more powerfull towing options. We have a 3.5 EFI Rangie also that we havent towed much with, but judging by it's normal road going acceleration (or lack of it) I suspect it wont be much better. And then there is the whole range thing (I like to have at least an 800km range when towing).

Cheers,
Taz.

[PAT303]

The heaviest thing I have ever towed was a broken down Prado and my truck towed it at 100k's no sweat but on hills and around corners it was slow.Saying that a 8o series towed it first before braking a cv joint and it was slower by a long way.Power is not a issue,stopping is. Pat

[Tote]

I've had a 300TDI Disco and my current TD5 and have towed car trailers with both of them. I always thought the 300TDI was the better tow package. Not as good at high speed cruising while not towing but definately a better vegicle to tow a heavy trailer with. It would hold 5th gear easily on hills where the TD5 needs top go back one or maybe even two gears.
Regards,
Tote

[redrover3]

I tow heavy car trailers with buggys (probably 2.5T - 3T) with my 3.5L EFI V8 Auto rangie. It tows well and gets about 300kms per tank (about 21-22Lper 100km) It holds road speed pretty well too.
That is pretty good economy for a heavy tow. I don't think that my 300tdi would do much better. Same issue with the power. You may be disappointed with the minimal gains for the conversion outlay. Unladen is another matter though.
Tony

[Redback]

With such a heavy load I'd put an auto in instead of a manual, taking off from a standing start will be a killer, especially if on a hill.

Baz.

[Lotz-A-Landies]

Here is food for thought, if diesels were no good they wouldn't be in trucks, then try and keep up with a truck at night.

john
Diesels are different, however the comparison of the 300TDi 4 cylinder and a modern diesel semi trailer is like comparing chalk and loungeroom furniture. It wasn't so long ago that diesel trucks always held up the traffic and crawled up mountains at walking pace. The modern semis have huge 500+ BHP turbo V8 engines and more importantly are designed to tow such loads. The 4 cylinder 300TDi needs to have additional cooling to safely tow the weights you are discussing.

Diana

[seriesly]

would that be the torqueflyte auto in the rangie???

wouldnt want to take that out of your tow car!

[Outback 1]

i have recently towed about 2.5 ton with my disco from dubbo to qld at times on steep climbs i was down to 60 kmh and yes it does affect the economy .If you are happy to just cruise along in no hurry the Tdi is the way to go as it is more economical than the v8 to start with:D

[Tank]

Diesels are different, however the comparison of the 300TDi 4 cylinder and a modern diesel semi trailer is like comparing chalk and loungeroom furniture. It wasn't so long ago that diesel trucks always held up the traffic and crawled up mountains at walking pace. The modern semis have huge 500+ BHP turbo V8 engines and more importantly are designed to tow such loads. The 4 cylinder 300TDi needs to have additional cooling to safely tow the weights you are discussing.

Diana
And they average 4 mpg, my Mack was a 285 Coolpower and it averaged 7mpg, always a downside for Power, Regards Frank.

[redrover3]

And they average 4 mpg, my Mack was a 285 Coolpower and it averaged 7mpg, always a downside for Power, Regards Frank.
Considering the huge weight, that's pretty amazing really. I've had cars that only get twice that economy.
Tony

[Lotz-A-Landies]

i have recently towed about 2.5 ton with my disco from dubbo to qld at times on steep climbs i was down to 60 kmh and yes it does affect the economy .If you are happy to just cruise along in no hurry the Tdi is the way to go as it is more economical than the v8 to start with:D
https://www.aulro.com/afvb/images/imported/2012/11/727.jpg

This was last Sunday. We calculated the gross trailer mass at something between 3 and 4 tonne and would have loved to have done 60 KPH up Mount Victoria but it wasn't the case. The auto transmission temp just would not cope with the load so we took it very easy.

Whatever you power the tow vehicle with the ideal transmission is a manual.

The Rangie is a 4.6 efi on LPG so the fuel costs at 60c/litre would have been comparable or better than a diesel 300TDi at $1.30+/litre.

Diana

[Outback 1]

The Rangie is a 4.6 efi on LPG so the fuel costs at 60c/litre would have been comparable or better than a diesel 300TDi at $1.30+/litre.

and how many km per litre do you get on gas?

[LRHybrid100]

G'day all,

I was just ready the thread in in tech about tow vehicles and it got me thinking about mine.

I tow heavy car trailers with buggys (probably 2.5T - 3T) with my 3.5L EFI V8 Auto rangie. It tows well and gets about 300kms per tank (about 21-22Lper 100km) It holds road speed pretty well too.

But I have thought about putting a 300tdi in it with a 5 speed manual (as I already have the motor and box) but I'm worried that doing the conversion (which will cost me around $1000 to do myself) won't be worth it in the long run. How well do the 300tdi's tow? I would be keen to try one towing to see how they go if anyone is keen?

I'm keen for the economy, but worried about losing alot of road speed

Dave, if you want you can see how mines goes - but would recommend the Auto with the Tdi for towing, mines been used as a tow mule many a time :

https://www.aulro.com/afvb/images/imported/2007/10/239.jpg

I did have the standard tyres on this time though.

LRH

[p38arover]

I think the 4BD1-T would be the best LR engine for a tow vehicle.

[BigJon]

And they average 4 mpg, my Mack was a 285 Coolpower and it averaged 7mpg, always a downside for Power, Regards Frank.

From memory, the roadtrains around here use about 1 litre per kilometre fully loaded on the highway. Sometimes a little less.

[mcrover]

I would keep the V8 and spend the money on gas injection and set up your gearing for towing.

I wouldnt go manual with the TDI for towing really heavy loads as with the auto you get better torque multiplacation from the torque converter and it also alows slippage to get the turbo spooled up where the manual you either have to take off really slowly or rev crap out of it and burn out the clutch.

The 4bd1-t would ba a much better conversion with a manual or auto conversion for towing but the 300TDI auto will tow significant loads all day everyday with out too much dramas but as said before, auto cooling and engine cooling is very important.

Make sure what ever engine you have if your using an auto you fit an external trans oil cooler and towing large loads you take off in lock low (manually selected 1st) to limit load on the sprag (one way clutch).

[JohnE]

Diesels are different, however the comparison of the 300TDi 4 cylinder and a modern diesel semi trailer is like comparing chalk and loungeroom furniture. It wasn't so long ago that diesel trucks always held up the traffic and crawled up mountains at walking pace. The modern semis have huge 500+ BHP turbo V8 engines and more importantly are designed to tow such loads. The 4 cylinder 300TDi needs to have additional cooling to safely tow the weights you are discussing.

Diana


Sorry Diana, i only used it as an example of the diesel vs petrol. perhaps in hindsight a poor example.

glad you explained it.


john

[Lotz-A-Landies]

..... and towing large loads you take off in lock low (manually selected 1st) to limit load on the sprag (one way clutch).
McRover

That's some information that I didn't have - my ZF and I thank you.

Diana :):):)

[p38arover]

McRover

That's some information that I didn't have - my ZF and I thank you.

Ditto from me, too. Not something I knew.

Some more interesting info here: http://member.rivernet.com.au/btaylor/BMWText/technical/AutoGearboxZF-HP22.html

The HP22 is the box used in many Discos/RRs

[Pierre]

Perhaps consider LP gas fumigation on the 300TDi for the extra power and torque. As a qualifying conversion, you get $2K government subsidy.

We found 300TDi auto towed 2 tonne well, but the auto needs to be well cooled and in good shape to start with.
Monitoring the trans temperature is an important factor.

I agree with the other comments, too. Off the line, it was slower than any pushbike!

Pete

[Guru036]

okay,

thanks heaps for the response

I have a ZF behind the Auto. I was only going the manual cause I'm old fashion and auto's to suit 300tdi's are $$$$.

But if the 300tdi gets around 19L per 100kms towing then there isn't much point in spending the money to do the conversion......

I currently run 235/85 R16 tyres which allow the car to sit on 2000rpm at 110kph with no trailer. but when the trailer is on it struggles to stay in 4th very often. maybe going back to a 31" tyre would do the trick??

[Phred]

Considering the huge weight, that's pretty amazing really. I've had cars that only get twice that economy.
Tony

To get that sort of fuel consumption (1.6-1.8 km/l) in a b-double on the hume is about par, whats amazing is to get that sort of consumption while averaging 89 km/h in truck that is speed limited to 100km/h.One of the major factors in getting good consumption will always be the drivers right foot.