Thread: D4 MY10 2.7L and 6 speed auto and some thoughts and data on driving and towing

D4 MY10 2.7L and 6 speed auto and some thoughts and data on driving and towing

Just back from a trip across the northern parts of this great country – some thoughts and data FYI.

My venerable MY04 D2a TD5 auto struggled to tow our caravan (the “Brick” behemoth almost 3.5T loaded van my dear wife had set her heart on). I would have preferred something smaller and lighter, but have to admit it is nice to be able to have just about everything needed for long term travel to hand with a payload approaching 1,000 kgm.

In considering an upgraded tow tug, I was very mindful of the (albeit small percentage) of D4 3L TD and SD vehicles that were having expensive engine issues, so elected to stick with the older, lower powered 2.7L (with then adding a light remap via DazzaTD5 on here).

For towing, just moving from the TD5 and Commodore style ZF 4HP22e and following the recommended towing in direct 3^rd and gear selection in S (for higher rev change points) to just being able to leave the D4 selector in drive (even though never getting higher than 5^th towing with the 6HP 26 speed box) makes for a more relaxing drive.

The TD5 auto is quoted maximum torque at 315 Nm and 101.5 kW @ 4,200 rpm (although mine had a mild Jose/TD5Inside remap for towing, plus a HD torque converter, larger intercooler with silicone hoses and a 2^nd ATF cooler, but was also fitted with oversize 265 75R 16 tyres).

The 2.7L TDV6 is quoted at 440 Nm torque and 140 KW. My remap is logged at 507 Nm torque at 2500 rpm and 164 kW at 3600 rpm from the graph. Both are obviously a significant enhancement over the TD5. Of course the 600 Nm SD 3L with the 8 speed gearbox would be another big leap.

However, I have noted that because I usually travel at about 85 kmph (just under 2,000 rpm in 5^th for the D4) and mostly on pretty flat roads, what I assume is an adaptive gearbox doesn’t always change down from to 4^th or even 3^rd on hills as quickly as I would expect, and a quick flick into S solves that concern. (I could only get into 6^th on a trailing throttle downhill well over 90 kmph)

I elect to follow the European style and keep the towball weight well under 10% - in the order of 180-200 kgm with van fully loaded a shade under the maximum of 3.499T, plus for this trip I removed the middle row of car seats to reduce weight and compensate for the full length roof rack, winch, extra body armour (underneath, front and rear) plus rear wheel carrier and long range tank that came with the car. All up, we then travel pretty close to maximum allowances for car axles, GVM and ATM.

Above 85 kmph poor road surfaces can significantly affect the handling, with the van trying to take control – not helped by having an extra-long “A” frame to cater for the 2m front opening/drop down veranda. The van has 4 wheel “offroad” independent coil with internal shock absorber suspension, and is nearly 3.2m tall, so not very aerodynamic.

The across AU trip has allowed for some indicative Gap Tool instrument mode information as detailed below.

In the ambient temp range up to 30-35 Celsius, and at 80-85 kmph towing the Brick, coolant sits at about 100 Celsius, with ATF temps slowly following behind to the same (and likewise more slowly dropping when slowing down). Engine oil temp then sits at about 125 Celsius and EGT is about 500 Celsius.

With a bit of headwind or increasing gradients, coolant and ATF temps have got up to 107 (max recorded) and oil temp to 135. If I’m to do more such towing, I feel additional engine oil and ATF cooling capacity coming on, which in turn should reduce coolant temps in heavier working scenarios.

Without getting into the argument about travelling at 85, my fuel economy data for the trip is as below. Less than 1,000 km was non towing, but even about half of that was 4WD/off road, so comparable economy to the towing on bitumen outcomes. The non towing trip from Denham to Cape Peron and back was about 100 km of sand bush track.

About 1,000 km was travelling east on the Great Central Road – in excellent condition formed gravel road part from lesser surfaces 30 km either side of Docker River on the WA/NT border.
We initially intended to follow the Savannah Way back From the Gulf towards Darwin from Doomadgee to Borroloola but after calling in on Paul (Jonesfamily on aulro), chickened out after hearing road reports and already having collected too much dust - and already replaced all 4 broken shock absorbers in Alice Springs (about to be unfinished business with the manufacturer).
At the time of replacing the dampers after the Great Central Road, the van had only done 10,000 km of which all except 1,200 km had been on good mainly WA bitumen and for the first 8,000 km was towed by the TD5).
The suspension is G&S chassis with Control Rider 4 wheel independent suspension and 4 x Gas-Magnum 4x4 TDT dampers if that means anything to anyone.

Total Mileage 21,019 km
Total Fuel Used 4,038.69L

Total Fuel Cost $6,122.11
Average Fuel Economy 19.21 L/100 km
Fuel Cost Max/L $2.045 @ Barkly Qld and $1.92 @ Doomadgee Qld

Originally Posted by jonesfam

I reckon you had 100kg of monitors & stuff on your dash not to mention the rest of your weight.
And your van is not a brick …………………………………. It is a Shipping Container!!

Yes Gavin has no lacking of equipment for providing useful information about his D4 and mobile house.
The mobile house is impressive, It's better equipped and setup than my house (and worth about 3 times as much).