F1 6x6 Engine Conversion

[OVR1]

Howdy all,

My name is Van and i'm new to signing up, although I have read through posts on this forum in the past.

I am in the process of purchasing an F1 6x6 from interstate, as I am about to fly out for work I unfortunately won't be able to be in her presence until I return in 5-6 weeks time. In the meantime, I would like to collect as much information as possible in regards to what I will be facing during the first stage of the build.

For anyone interested, she is going to be the base for quite an extensive motorhome/housetruck build of a non conventional kind.

First thing I will be looking to do is change out the engine, it is currently running the stock petrol and the engine top of my list for replacement is a 6BT Cummins. Does anyone have any experience with this particular change over or is able to put me in contact with someone who does? I have read a couple times of others putting the 6BT into MK3/4/F's but have not read any information. I would like to turbo or compound turbo the motor, will a change of gearbox be required or advised? Will a turbo setup fit? What sort of bellhousing requirements are necessary for the swap?
The idea for a compound turbo setup is to produce smooth and efficient power/better economy across the band, not for high performance. I am however concerned whether the gearbox/transfer and diffs will be able to hand any sort of power increase. If so, are there any easily viable alternatives for the drivetrain?

Any help would be much appreciated and I look forward to finding out any new information to help on this quest.

All the best,

V.

[Bearman]

Welcome Van, I have very little personal experience with the F's but love them for what they are. I have seen them with a 6/354 Perkins conversion which was a good conversion. I would imagine a 6BT or even an Isuzu 6BD1T to be suitable donors for one. Hope you find out what you are after and hang around here, lots of knowledgable and friendly people who are quick to help.:)

[Lotz-A-Landies]

Hi Van

If you are doing a motorhome the F1 while extremely capable are probably not ideal.

1st. You do know that the gearbox in an F1 and its sisters are a crash box and the transfer box makes them very low geared for highway use. This is particularly important with a diesel that wont rev as high as a petrol engine. You may want to consider an overdrive six speed or double overdrive seven speed synchro box with cable or pneumatic shift. The original box runs a jack shaft to the transfer so conversion not so much of a problem doing the retrofit.

2nd. The rear axle group do not have a power divider so axle wind-up can be a problem. You way want to think about a dog clutch between the middle and rear axle to have it freewheel when not required.

3rd. You should seriously consider fitting power steering.

For info on Army Mk3, Mk4, F1, F2 and F5, you may want to visit the Army Inter Chapter on the REMLR forum International Truck Chat (http://remlr.com/forum/index.php?board=15.0)

[OVR1]

Cheers Bearman! :)
I have also considered the Isuzu and it is second on my list, I am not as familiar with the Isuzu's as the Cummins but I am open to the idea of them.
The main reason I have the Cummins on top is that there is a fairly large community running them on biodiesel/SVO, which is what the F1 will be fuelled by. As you can get IDI versions of the 6BT, this is favourable with SVO, and it is always nice to have a backing of community knowledge when going through the process and ironing out niggles. I won't be active on here too often with other commitments, but now that I have finally signed up I will definitely pop in once in a while, there is some great content here that's for sure!

Lotz-A-Landies - Vlad is a new one! But i'll take it ;)
Yes, I definitely understand the limitations of the drivetrain and it is something that was considered through a few times. I have been considering different trucks for close to 4 years now (everything from Bedford RL to Isuzu NPS, Canter's and between, even considered the going down the MAN KAT1/Tatra route!) and decided on the F1 for a few reasons.. I like the history and Australian heritage, I find the body aesthetics favourable and more to my style, considering the base cost of some other trucks I do not mind spending the extra on upgrading/changing parts on the F1 as the cost of the truck was minimal (next to nothing) compared to some of the other options.. I have thought about changing out the axle setup completely with something like portal axles from a 6x6 Volvo C303, as an idea. Above all else though, the right truck just happened to appear at the right time so I went for it :D
Great to know they use a jackshaft for the transfer, thank you for that, and a dog clutch is a great idea also, as is the power steering!
Thanks for the link to the remlr forums as well, I will make my way over there in time :)

[101 Ron]

The drive train is up to the job, but not the gearing to suit a diesel.
A one time there is was a Detroit GM conversion ,bolt in type thing developed by GM in Sydney when they were common after the army auctions years ago.
You would be living with a noisey diesel inches away from the driver.
It was noisey enough with a petrol.
Not the ideal truck to do what you want.
Great for off road hard work, but the best for on road distances with speed and comfort, especially with a diesel conversion.

[OVR1]

The drive train is up to the job, but not the gearing to suit a diesel.
A one time there is was a Detroit GM conversion ,bolt in type thing developed by GM in Sydney when they were common after the army auctions years ago.
You would be living with a noisey diesel inches away from the driver.
It was noisey enough with a petrol.
Not the ideal truck to do what you want.
Great for off road hard work, but the best for on road distances with speed and comfort, especially with a diesel conversion.

Cheers Ron, see above (we must have clicked post about the same time!) in regards to some of the gearing. Do you know which engine was used in the Detroit conversion?
The noise (and heat) is another thing I will be doing my best to limit, I have a few ideas and will see how they could work once the truck is physically in front of me.

I also plan to spend minimal time on road, hence going with the 6x6 to begin with :)

[101 Ron]

I know these trucks very very well and spent much to me behind the wheel loaded, unloaded , overloaded and off road/ on road.
I have worked on them lots too.
They were a excellent truck for what the army used them for.
The standard 6x6 drive train was all Australian made and unbreakable.
If they were a good touring truck you would see alot more of them about on the highways.
You see them on farms and work sites etc for good reason.
They are not in the modern world of comfort or gearing for touring.

[101 Ron]

For on road work the 4x4 was better and it had the same size body on the back.
The best and easist conversion is a V8 petrol crate engine and no gearing corrections would be needed and performance would be brilliant, but that is not what you are looking for.
With diesel you would be looking for Three different ratio diff centres.
The diesel would really need to be a in line motor.
Extensive sound deading would be needed and difficult to install enough in a limited space.
Power steering with the extra weight of a diesel would be a must.
Standard gearbox is a very good one, but you need to learn the old ways of gear changing which many people are not prepared to do anymore.

[Lotz-A-Landies]

Hi Van

Don't know where Vlad came from. :o

My Mk3 has an Isuzu sixBB1 and it's matching 5 speed mechanical linkage box. The engine fits easily under the low Mk3 engine cowl although there is Donaldson cyclopac with raised intake behind the cab instead of under the cowl. The air intake tube to the engine has modified the base of the engine cowl.

The problem with lots of Isuzu 5 speed is that 5th is 1:1, there are some six and 7 speed Isuzu boxes on the sixBG1 engines that bolt to the sixBB1 and sixBD1 that have overdrive or double overdrive on sixth and 7th gears. These would counteract the low ratio on the transfer.

The mechanical linkage on mine is a problem as it sits between the engine cowl and the driver's seat. The standard cable linkage on the later box could easily be fitted back where the original gearstick was located and make a more natural driving position.

I'm considering swapping the sixBB1 for a sixBD1-Turbo. the turbo engine should fit easily under the F1 engine cowl. The turbo is on top left of the engine so the heat may be a problem for the passenger's seat. (not a problem for the driver). The turbo on the left would also solve the intake cutout on the cowl.

[OVR1]

Hi Van

Don't know where Vlad came from. :o

My Mk3 has an Isuzu sixBB1 and it's matching 5 speed mechanical linkage box. The engine fits easily under the low Mk3 engine cowl although there is Donaldson cyclopac with raised intake behind the cab instead of under the cowl. The air intake tube to the engine has modified the base of the engine cowl.

The problem with lots of Isuzu 5 speed is that 5th is 1:1, there are some six and 7 speed Isuzu boxes on the sixBG1 engines that bolt to the sixBB1 and sixBD1 that have overdrive or double overdrive on sixth and 7th gears. These would counteract the low ratio on the transfer.

The mechanical linkage on mine is a problem as it sits between the engine cowl and the driver's seat. The standard cable linkage on the later box could easily be fitted back where the original gearstick was located and make a more natural driving position.

I'm considering swapping the sixBB1 for a sixBD1-Turbo. the turbo engine should fit easily under the F1 engine cowl. The turbo is on top left of the engine so the heat may be a problem for the passenger's seat. (not a problem for the driver). The turbo on the left would also solve the intake cutout on the cowl.

Haha, no problem :p

Lots of good info there, thanks. I am not familiar with the 6BB1, is this is earlier variant of 6BD1's?

I have a few considerations with heat, there is a company out of the UK that makes a flexible ceramic heatshield which has been picked up by Formula One and other racing circles the last couple years. They make various thickness aluminium backed pads and one gold. The thick aluminium sheet reflects/stops heat absorption by 85% and the gold works to 98%. Quite expensive for the thicker aluminium sheet ($300 for a 500x900 sheet), but in relativity to what it is doing I think entirely worth it.

[OVR1]

For on road work the 4x4 was better and it had the same size body on the back.
The best and easist conversion is a V8 petrol crate engine and no gearing corrections would be needed and performance would be brilliant, but that is not what you are looking for.
With diesel you would be looking for Three different ratio diff centres.
The diesel would really need to be a in line motor.
Extensive sound deading would be needed and difficult to install enough in a limited space.
Power steering with the extra weight of a diesel would be a must.
Standard gearbox is a very good one, but you need to learn the old ways of gear changing which many people are not prepared to do anymore.

I definitely considered a Mk3/4 as well, however the chassis didn't quite have the length. If I am not mistaken, the trays are different size and are 4x4/6x6 specific.
I'm not following on the three different ratio diff centres, do you mean each diff centre will need a different ratio? What is the reason for that?

Sound deadening will be done through CLD tiles, CCF and MLV. I have a fair bit of experience with these on past projects so while I'm not expecting a quiet ride, I think with ceramic shielding under the cowl/body and the above on the inside it will be quite bearable.

I was lucky to be taught double clutching and speed matching as a kid, though I must admit it's been a long time since driving anything of the sort so it will take a little to get used to :)

[101 Ron]

bodies on a 4x4 and a 6x6 interchange.
The 6x6 has jerrycan/tool box behind cabin ?
To change overall gear ratios , the easy way would be to change out all three diff centres for ones of higher ratio, assuming you can find higher ratio items from another model truck which used the same type of diff.

[OVR1]

bodies on a 4x4 and a 6x6 interchange.
The 6x6 has jerrycan/tool box behind cabin ?
To change overall gear ratios , the easy way would be to change out all three diff centres for ones of higher ratio, assuming you can find higher ratio items from another model truck which used the same type of diff.

Ahah! That makes sense, I got a bit confused between the cab body and tray. Yes, the 6x6's did have jerry can/tool box's behind the cabin, well at least some from what I have seen. There are differences between the tray's on the back, but yes, cabs are the same.

And yes, all three centres will be changed out if gearing needs to be sorted, that won't be a problem. For a moment I thought you meant all three would need to be different ratio's (as in separately/independant ratios) and that had me scratching my head.

[101 Ron]

...

[101 Ron]

What I meant was the rear tray/body is the same on both the 6x6 and 4x4.
The Australian army International series was extremely inter changeable.
There was slight differences with the driver cabins between earlier and later versions.
The 4x4 had a syncro clark? 5 speed gearbox while the 6x6 had a much bigger Australian made one off 5 speed constant mesh gearbox.
transfercases were the same.
6x6 have stepdown boxes on the rear diffs, not for gearing purposes, but for tailshaft and ground clearance purposes.

[Lotz-A-Landies]

Haha, no problem :p

Lots of good info there, thanks. I am not familiar with the 6BB1, is this is earlier variant of 6BD1's?

I have a few considerations with heat, there is a company out of the UK that makes a flexible ceramic heatshield which has been picked up by Formula One and other racing circles the last couple years. They make various thickness aluminium backed pads and one gold. The thick aluminium sheet reflects/stops heat absorption by 85% and the gold works to 98%. Quite expensive for the thicker aluminium sheet ($300 for a 500x900 sheet), but in relativity to what it is doing I think entirely worth it.The 6BB1 is an earlier or at least smaller capacity 327CID (5393cc) Isuzu engine used in the early SBR trucks the 6BD1 was 5785cc and came in both NA and Turbo variants. The Isuzu turbo variants have oil squirters under the pistons to keep them cool and therefore are more reliable. I like the B series Isuzu engines because they are still mechanical. No electronics or common rail problems or radio interference.

You can get ceramic done in Oz, a Land Rover mechanic friend recently designed a set of extractors for a Land Rover straight six, in production (Moorebank Sydney) the sets are ceramic coated. The heat output of the extractors is noticeably less than the standard manifold. There is no reason why you couldn't have the standard manifold and the engine/turbo pipe ceramic coated before fitting. Not sure if you could also have the turbo coated too.

They could probably ceramic coat heat shields once you had designed then for the truck.

[OVR1]

What I meant was the rear tray/body is the same on both the 6x6 and 4x4.
The Australian army International series was extremely inter changeable.
There was slight differences with the driver cabins between earlier and later versions.
The 4x4 had a syncro clark? 5 speed gearbox while the 6x6 had a much bigger Australian made one off 5 speed constant mesh gearbox.
transfercases were the same.
6x6 have stepdown boxes on the rear diffs, not for gearing purposes, but for tailshaft and ground clearance purposes.

Ah, ok. I had been told contrary and that there were differences in the tray's between 4x4 and 6x6. Thanks for clearing that up and the extra info, much appreciated.

[OVR1]

The 6BB1 is an earlier or at least smaller capacity 327CID (5393cc) Isuzu engine used in the early SBR trucks the 6BD1 was 5785cc and came in both NA and Turbo variants. The Isuzu turbo variants have oil squirters under the pistons to keep them cool and therefore are more reliable. I like the B series Isuzu engines because they are still mechanical. No electronics or common rail problems or radio interference.

You can get ceramic done in Oz, a Land Rover mechanic friend recently designed a set of extractors for a Land Rover straight six, in production (Moorebank Sydney) the sets are ceramic coated. The heat output of the extractors is noticeably less than the standard manifold. There is no reason why you couldn't have the standard manifold and the engine/turbo pipe ceramic coated before fitting. Not sure if you could also have the turbo coated too.

They could probably ceramic coat heat shields once you had designed then for the truck.

Cheers Lotz-A-Landies. The 6BD1T is still looking like a great engine. My main draw back is lack of experience with WVO/Biodiesel. I might start searching more though over the next month and see what I can find.

Yes, will definitely get the manifolds ceramic coated and wrap them with an exhaust wrap. The tiles I mentioned are called Zircoflex by a company named Zircotec (bit of an odd name really), check them out if you like. They are quite unique in the automotive application in that they are a self adhesive type roll and can easily be stuck on the underside of cabs/firewalls etc. They run just under a mm thick with the reflective coating.

I have been concerned that trapping too much heat under the cab and not allowing it to escape through conducting into the cab may actually make the engine work too hard. Any thoughts?

[Lotz-A-Landies]

One good thing about Isuzu diesels is that the cabs of the trucks rust away so the engines become available. I think you have to go to the 6BG1-T engines to get the double overdrive boxes, but worth the trouble.

The engine cowl does drop down behind the engine so there is a little obstruction, but there is lots of space between the chassis rails either side of the engine and box.

[Dieselman]

Hi Everyone,
I have just started looking for information on the ACCO 6x6 ex army trucks as I have purchased one now. My idea is to put the 6bt Cummins diesel engine in with a 4 speed 48re + gear vender over drive or a 68fe 6 speed + overdrive unit, this covers the drive line problem. With heat I will use ceramic coating through out the engine and if there is limited room in the engine bay the turbo can be place to the rear of the engine.
Water injection also helps with keeping the combustion tempeture down.


Does anyone know what other diff ratios will fit into the diff centres?
If anyone else has done a simular conversion or is thing about it please contact me at vanderhee@hotmail.com or 0418193479