Engine Conversions
- dandjcr
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30 Oct 2012 16:19 #1
by dandjcr
David and Janet Ribbans - Oka 148
Oka148 profile here.
Visit our technical and travel blogs: here.
dandjcr created the topic: Engine Conversions
Forum Home > OKA Maintenance > Engine Conversions
wessa #400
Member
Posts: 66
There has been a lot of talk in the past about engine conversions, Cummins, Perkins etc. Lately the information and feedback has dried up. I would be interested in how those currently doing conversions are going, successes if completed, hiccups and performances. If anyone out there is currently involved in the process any feedback including comments and costings would be appreciated.
I am sure there are lots of owners out there looking for up to date info.
Cheers
Wessa #400
--
June 21, 2012 at 1:48 PM Flag Quote & Reply
Pete Fox
Member
Posts: 140
Paul Nott is currently fitting a 6BT Cummins into his and is using the standard transmissions etc. You would get some good info there.
--
Peter Fox
OKA 266 Multi-cab.
Photobucket album
June 22, 2012 at 11:33 AM Flag Quote & Reply
wessa #400
Member
Posts: 66
Thanks Peter, I have been talking to Paul and he has his up and running, he is very happy with it. I was just wondering how everyone else that were working on it were travelling. Haven't heard anymore about the ones that were being done in Brisbane.
Cheers Wessa #400
June 22, 2012 at 4:29 PM Flag Quote & Reply
David Hallandal
Member
Posts: 133
I am in the process of getting my OKA done in Brisbane, We fitted a 6.5 Chevy V8 and an Allison 6 speed automatic and were told there was a standalone computer available but were miss-informed. We had a computer custom made to suit the Allison 6 speed but this did not work out. The 6 speed Allison relies on a cam bus system and is not compatible with a non-electronic motor.
We have a 5 speed Allison and wiring loom on the way and will be fitted very soon. The new computer will allow us to change the shift patterns to suit the vehicle as we get km on it. Initial testing was very positive.
--
David Hallandal
OKA-131 Home Page
OKA Camper Trailer
XT and LT Service Manuals on CD For Sale
20mm Spring Hanger Upgrade Kits For Sale
June 24, 2012 at 9:38 AM Flag Quote & Reply
Peter 334
Member
Posts: 118
Its funny how the engine debate pops its head up now and then , took a trip to melbourne on friday to pick up some things and while we were there called paul to have a look at his oka, while we were there,we had a look at how cummins engine fitted in his oka and i could not belive how much room there was, its as if there was something missing but no all was there, a few mods to the engine mounts, radiator shroud and other bits,and the engine looked it was ment to be there 200hp 6 cyclinder , i dont know why you would fit and 4cyl 110hp when they were made , the cummins engine was around the same time ? fuel usage is better i suppose price had a play in it ? if i was to change i would go to the cummins 6cyl.
June 24, 2012 at 4:25 PM Flag Quote & Reply
Moose2367
Member
Posts: 110
That's goods to know.
My conversion has hit a wall for a little while, waiting in a trans from the USA and a steering box modification. Been looking at the radiator and measuring etc, i was going to do a cartridge type setup, maybe on hinges, with the intercooler, rad and condesnsor all in one, just make the A/C pipes longer to accomodate.
My 6.7L has a fairly big air compressor on it too, might have to modify the rear section of the passenger seat area to make it fit.
June 24, 2012 at 5:18 PM Flag Quote & Reply
John and Lis
Member
Posts: 11
I have just returned from another trial run in 406 since I fitted a 6BT Cummins with the standard Oka bellhousing, 5 speed manual box and NP205 transfer case. I have now done over 6000km of 50/50 on road/ off road. This last trip was to Cape Melville N
--
June 30, 2012 at 5:27 PM Flag Quote & Reply
John and Lis
Member
Posts: 11
Opps, somthing went wrong with that last post of mine, most of it seems to have got lost in cyberspace.
--
June 30, 2012 at 5:57 PM Flag Quote & Reply
Tony
Member
Posts: 11
Can you give me an approximate all up cost of the Cummins conversion and what would it would have been if you threw in an Allison 5 speed auto?.
July 1, 2012 at 7:00 AM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
While I realise you are fitting 6 cylinder engines I've found with 374 the change to an auto behind these relatively small engines allows the engine to get on boost better off the mark and also allows the engine to stay in its powerband which in turn results in improved fuel economy and a much nicer drive.
Yes it does still slow down on hills but the whole process is much more relaxed as the engine is nearly always at its sweet spot which seems to be around 2200 rpm.
I suspect this is the point where the power and torque curves cross.
The auto also made a big difference on the recent Simpson desert trip as we drove all the dunes without needing a tow and never needed to resort to low range when taking off on the dunes.
--
Oka 374 LT Van
July 1, 2012 at 8:28 AM Flag Quote & Reply
John and Lis
Member
Posts: 11
It looks like cyberspace has kept that lot, so I will retype it.
Basically I was singing the praises of the 6BT and its simplicity and suitability for the Oka. Around the 200hp seems a good fit as on road performance is similar to a family car where you cruise at 90 to 110 kph easily and accelerate with safety to overtake semis or road trains without needing that 3km straight stretch you do with the Perkins. I havent had my truck on the dyno yet as the engine is too new but will do so later this year. The off road, both gravel roads and slow bush work are equally impressive with all the torque you would ever need down low. I accelerate up hills now at 100km/h rather than change down to 3rd at 60km/h. You do have to watch your boost and EGT gauges as these 6BT engines will just keep putting out the power and it is possible to drive them too hard, particularly with the P7100 Bosch pump. The rotary pump on earlier models is more conservative. This web site is a very good source of info on the Cummins. www.turbodieselregister.com
I am now running the 325/85r16 xml michelins and with the 4.88 ratio diffs I am doing 100km/h at 2000rpm, which I find is acceptable noise levels.At higher engine rpm the Cummins sounds busy, even though it is possible to work this engine up over 3500rpm, I would not want to be driving it at that level. The torque curve seems to peak around 1500rpm, although I havent checked that with Cummins literature.
An auto would be nice when in the heavy going as changing gears every minute or less for 4 hours as in driving the last 47km into Cape Melville can get the shoulders aching, but I have no plans to swap gearboxes yet. There may be some truth in the auto letting the engine build up to boost quicker as that is the one area where this engine is a bit slow. I'm not convinced my engine has been setup correctly by the guy I got to rebuild it, and I will be playing with the fuel pump and turbo a bit more in the future. At the minute though I just want it "on the road" so I can do a few more miles before it gets to hot and wet at the end of the year. I'm not complaining though as it is still far ahead of the Perkins at the traffic lights. At least I can beat the push bikes now.
I can't give a cost estimate as I did a total rebuild of the whole vehicle including reskinned both cabs, blast and paint everythind, fitted the Spicer 80 series L/S diffs and new housings front and rear, 1480 drive lines, spring and shakle pin upgrades, dual air intakes, 3.5" exhaust system, etc, etc. All up I spent over $100,000-00, but the vehicle is now new. The rebuilt engine cost me $10,000-00, 5 core radiator $1600-00, plus the custom adaptor plate to reuse the old bellhousing, custom flywheel to use the larger organic clutch Paul sells, upgrade to the old pressure plate as it cannot take the torque of the Cummins. ( I tried it, went around the block once and pulled the gearbox back out. Slipped the clutch in 4 out of the 5 gears.) My wild guess would be you would need something like $30,000-00 to $50,000-00, but it would depend on many variables. I found that labour cost represented more than half total cost for my rebuild.
The engine fits in easily in the Oka. There is plenty of room in every direction, and it is actually na lot easier to work on now than the Perkins was. It is all the small fitoffs that take the time. Radiator hoses, engine mounts, throttle relocation, fan position and fan shroud mods, etc, etc.
My fuel consumption is looking very similar to the Perkins, but I havent checked it accurately yet as I am still running the engine in and taking it a bit easy with it. I am getting over 5km /l at least, where the Perkins was averaging 5.5 to 5.7km/l. Over the next 12 months I will measure it accurately in highway use and heavy bush use as I need to know my range obviously under each condition.
I now have a vehicle that is a pleasure to drive and look forward to pushing it all over this great country till I am too old to climb up into the drivers seat.
--
July 1, 2012 at 9:56 AM Flag Quote & Reply
Tony
Member
Posts: 11
Thanks very much for a very comprehensive report. Way to go!!!!
July 2, 2012 at 5:19 AM Flag Quote & Reply
Outback Jack
Member
Posts: 381
What Auto did you fit behind the perkins??? How hard was it and what was the cost?
--
July 6, 2012 at 7:17 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
I wrote an article which is in the documents section of the forum in pdf form to download.
Cost will depend on how much you do yourself and how much you spend on the required bits. It totally transforms the Oka, much more pleasant to travel in, seems to go better and uses less fuel, the last we were not expecting but presume it is because the auto keeps the Perkins in its sweet spot most of the time.
--
Oka 374 LT Van
July 7, 2012 at 8:30 AM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
Here is the page www.oka4wd.com/apps/documents/?&page=6
--
Oka 374 LT Van
July 7, 2012 at 8:34 AM Flag Quote & Reply
Outback Jack
Member
Posts: 381
Thanks for the link.
Looks good, I wish I had the machining equipment to do it. If it was a off the shelf conversion as such, I would jump at it.
--
July 7, 2012 at 8:16 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
Apart from making/adapting the rear bellhousing mounts and making a few simple brackets for the linkage cables, handbrake cables etc it is basically a bolt in job, no machining required.
--
Oka 374 LT Van
July 8, 2012 at 8:41 AM Flag Quote & Reply
OKAPETE .......... Peter and Sharon Furlong.
Member
Posts: 33
For anyone interested I have a spare conversion adapter setup as I supplied to Peter James to bolt a TH400 or 4L80e Auto to the Perkins. It comes with HD Flywheel, SAE 3 bellhousing, Auto to b/housing adapter and torque converter to flywheel adapter that mimics Chev crank. I also have a TH400 or 4L80e if interested. If you read Pete's link to his conversion writeup (above) you will see what's involved.
I also have a 6.5 litre Chev diesel mated to Allison AT542 transmission which will be available for sale soon.
PM me or ph 0412376556. okapete.
July 9, 2012 at 9:50 AM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
Another engine that could be used is the Steyr monoblock design in either 4 cylinder of 6 cylinder, AM General (Humvee manufacturer) is producing the 6 cyl version under licence to be used in the Humvee and is about to start retailing them. The cost would seem to be around $US6-10k for turn key versions and they bolt direct to a 4L80E. While electronically controlled they have full mechanical limp home version apparently but seem to be very reliable in existing Steyr form.
Link to pdf of Steyr versions steyr-motors.com.au/images/stories/brochures/Vehicle.pdf
--
Oka 374 LT Van
July 15, 2012 at 9:02 AM
wessa #400
Member
Posts: 66
There has been a lot of talk in the past about engine conversions, Cummins, Perkins etc. Lately the information and feedback has dried up. I would be interested in how those currently doing conversions are going, successes if completed, hiccups and performances. If anyone out there is currently involved in the process any feedback including comments and costings would be appreciated.
I am sure there are lots of owners out there looking for up to date info.
Cheers
Wessa #400
--
June 21, 2012 at 1:48 PM Flag Quote & Reply
Pete Fox
Member
Posts: 140
Paul Nott is currently fitting a 6BT Cummins into his and is using the standard transmissions etc. You would get some good info there.
--
Peter Fox
OKA 266 Multi-cab.
Photobucket album
June 22, 2012 at 11:33 AM Flag Quote & Reply
wessa #400
Member
Posts: 66
Thanks Peter, I have been talking to Paul and he has his up and running, he is very happy with it. I was just wondering how everyone else that were working on it were travelling. Haven't heard anymore about the ones that were being done in Brisbane.
Cheers Wessa #400
June 22, 2012 at 4:29 PM Flag Quote & Reply
David Hallandal
Member
Posts: 133
I am in the process of getting my OKA done in Brisbane, We fitted a 6.5 Chevy V8 and an Allison 6 speed automatic and were told there was a standalone computer available but were miss-informed. We had a computer custom made to suit the Allison 6 speed but this did not work out. The 6 speed Allison relies on a cam bus system and is not compatible with a non-electronic motor.
We have a 5 speed Allison and wiring loom on the way and will be fitted very soon. The new computer will allow us to change the shift patterns to suit the vehicle as we get km on it. Initial testing was very positive.
--
David Hallandal
OKA-131 Home Page
OKA Camper Trailer
XT and LT Service Manuals on CD For Sale
20mm Spring Hanger Upgrade Kits For Sale
June 24, 2012 at 9:38 AM Flag Quote & Reply
Peter 334
Member
Posts: 118
Its funny how the engine debate pops its head up now and then , took a trip to melbourne on friday to pick up some things and while we were there called paul to have a look at his oka, while we were there,we had a look at how cummins engine fitted in his oka and i could not belive how much room there was, its as if there was something missing but no all was there, a few mods to the engine mounts, radiator shroud and other bits,and the engine looked it was ment to be there 200hp 6 cyclinder , i dont know why you would fit and 4cyl 110hp when they were made , the cummins engine was around the same time ? fuel usage is better i suppose price had a play in it ? if i was to change i would go to the cummins 6cyl.
June 24, 2012 at 4:25 PM Flag Quote & Reply
Moose2367
Member
Posts: 110
That's goods to know.
My conversion has hit a wall for a little while, waiting in a trans from the USA and a steering box modification. Been looking at the radiator and measuring etc, i was going to do a cartridge type setup, maybe on hinges, with the intercooler, rad and condesnsor all in one, just make the A/C pipes longer to accomodate.
My 6.7L has a fairly big air compressor on it too, might have to modify the rear section of the passenger seat area to make it fit.
June 24, 2012 at 5:18 PM Flag Quote & Reply
John and Lis
Member
Posts: 11
I have just returned from another trial run in 406 since I fitted a 6BT Cummins with the standard Oka bellhousing, 5 speed manual box and NP205 transfer case. I have now done over 6000km of 50/50 on road/ off road. This last trip was to Cape Melville N
--
June 30, 2012 at 5:27 PM Flag Quote & Reply
John and Lis
Member
Posts: 11
Opps, somthing went wrong with that last post of mine, most of it seems to have got lost in cyberspace.
--
June 30, 2012 at 5:57 PM Flag Quote & Reply
Tony
Member
Posts: 11
Can you give me an approximate all up cost of the Cummins conversion and what would it would have been if you threw in an Allison 5 speed auto?.
July 1, 2012 at 7:00 AM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
While I realise you are fitting 6 cylinder engines I've found with 374 the change to an auto behind these relatively small engines allows the engine to get on boost better off the mark and also allows the engine to stay in its powerband which in turn results in improved fuel economy and a much nicer drive.
Yes it does still slow down on hills but the whole process is much more relaxed as the engine is nearly always at its sweet spot which seems to be around 2200 rpm.
I suspect this is the point where the power and torque curves cross.
The auto also made a big difference on the recent Simpson desert trip as we drove all the dunes without needing a tow and never needed to resort to low range when taking off on the dunes.
--
Oka 374 LT Van
July 1, 2012 at 8:28 AM Flag Quote & Reply
John and Lis
Member
Posts: 11
It looks like cyberspace has kept that lot, so I will retype it.
Basically I was singing the praises of the 6BT and its simplicity and suitability for the Oka. Around the 200hp seems a good fit as on road performance is similar to a family car where you cruise at 90 to 110 kph easily and accelerate with safety to overtake semis or road trains without needing that 3km straight stretch you do with the Perkins. I havent had my truck on the dyno yet as the engine is too new but will do so later this year. The off road, both gravel roads and slow bush work are equally impressive with all the torque you would ever need down low. I accelerate up hills now at 100km/h rather than change down to 3rd at 60km/h. You do have to watch your boost and EGT gauges as these 6BT engines will just keep putting out the power and it is possible to drive them too hard, particularly with the P7100 Bosch pump. The rotary pump on earlier models is more conservative. This web site is a very good source of info on the Cummins. www.turbodieselregister.com
I am now running the 325/85r16 xml michelins and with the 4.88 ratio diffs I am doing 100km/h at 2000rpm, which I find is acceptable noise levels.At higher engine rpm the Cummins sounds busy, even though it is possible to work this engine up over 3500rpm, I would not want to be driving it at that level. The torque curve seems to peak around 1500rpm, although I havent checked that with Cummins literature.
An auto would be nice when in the heavy going as changing gears every minute or less for 4 hours as in driving the last 47km into Cape Melville can get the shoulders aching, but I have no plans to swap gearboxes yet. There may be some truth in the auto letting the engine build up to boost quicker as that is the one area where this engine is a bit slow. I'm not convinced my engine has been setup correctly by the guy I got to rebuild it, and I will be playing with the fuel pump and turbo a bit more in the future. At the minute though I just want it "on the road" so I can do a few more miles before it gets to hot and wet at the end of the year. I'm not complaining though as it is still far ahead of the Perkins at the traffic lights. At least I can beat the push bikes now.
I can't give a cost estimate as I did a total rebuild of the whole vehicle including reskinned both cabs, blast and paint everythind, fitted the Spicer 80 series L/S diffs and new housings front and rear, 1480 drive lines, spring and shakle pin upgrades, dual air intakes, 3.5" exhaust system, etc, etc. All up I spent over $100,000-00, but the vehicle is now new. The rebuilt engine cost me $10,000-00, 5 core radiator $1600-00, plus the custom adaptor plate to reuse the old bellhousing, custom flywheel to use the larger organic clutch Paul sells, upgrade to the old pressure plate as it cannot take the torque of the Cummins. ( I tried it, went around the block once and pulled the gearbox back out. Slipped the clutch in 4 out of the 5 gears.) My wild guess would be you would need something like $30,000-00 to $50,000-00, but it would depend on many variables. I found that labour cost represented more than half total cost for my rebuild.
The engine fits in easily in the Oka. There is plenty of room in every direction, and it is actually na lot easier to work on now than the Perkins was. It is all the small fitoffs that take the time. Radiator hoses, engine mounts, throttle relocation, fan position and fan shroud mods, etc, etc.
My fuel consumption is looking very similar to the Perkins, but I havent checked it accurately yet as I am still running the engine in and taking it a bit easy with it. I am getting over 5km /l at least, where the Perkins was averaging 5.5 to 5.7km/l. Over the next 12 months I will measure it accurately in highway use and heavy bush use as I need to know my range obviously under each condition.
I now have a vehicle that is a pleasure to drive and look forward to pushing it all over this great country till I am too old to climb up into the drivers seat.
--
July 1, 2012 at 9:56 AM Flag Quote & Reply
Tony
Member
Posts: 11
Thanks very much for a very comprehensive report. Way to go!!!!
July 2, 2012 at 5:19 AM Flag Quote & Reply
Outback Jack
Member
Posts: 381
What Auto did you fit behind the perkins??? How hard was it and what was the cost?
--
July 6, 2012 at 7:17 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
I wrote an article which is in the documents section of the forum in pdf form to download.
Cost will depend on how much you do yourself and how much you spend on the required bits. It totally transforms the Oka, much more pleasant to travel in, seems to go better and uses less fuel, the last we were not expecting but presume it is because the auto keeps the Perkins in its sweet spot most of the time.
--
Oka 374 LT Van
July 7, 2012 at 8:30 AM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
Here is the page www.oka4wd.com/apps/documents/?&page=6
--
Oka 374 LT Van
July 7, 2012 at 8:34 AM Flag Quote & Reply
Outback Jack
Member
Posts: 381
Thanks for the link.
Looks good, I wish I had the machining equipment to do it. If it was a off the shelf conversion as such, I would jump at it.
--
July 7, 2012 at 8:16 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
Apart from making/adapting the rear bellhousing mounts and making a few simple brackets for the linkage cables, handbrake cables etc it is basically a bolt in job, no machining required.
--
Oka 374 LT Van
July 8, 2012 at 8:41 AM Flag Quote & Reply
OKAPETE .......... Peter and Sharon Furlong.
Member
Posts: 33
For anyone interested I have a spare conversion adapter setup as I supplied to Peter James to bolt a TH400 or 4L80e Auto to the Perkins. It comes with HD Flywheel, SAE 3 bellhousing, Auto to b/housing adapter and torque converter to flywheel adapter that mimics Chev crank. I also have a TH400 or 4L80e if interested. If you read Pete's link to his conversion writeup (above) you will see what's involved.
I also have a 6.5 litre Chev diesel mated to Allison AT542 transmission which will be available for sale soon.
PM me or ph 0412376556. okapete.
July 9, 2012 at 9:50 AM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
Another engine that could be used is the Steyr monoblock design in either 4 cylinder of 6 cylinder, AM General (Humvee manufacturer) is producing the 6 cyl version under licence to be used in the Humvee and is about to start retailing them. The cost would seem to be around $US6-10k for turn key versions and they bolt direct to a 4L80E. While electronically controlled they have full mechanical limp home version apparently but seem to be very reliable in existing Steyr form.
Link to pdf of Steyr versions steyr-motors.com.au/images/stories/brochures/Vehicle.pdf
--
Oka 374 LT Van
July 15, 2012 at 9:02 AM
David and Janet Ribbans - Oka 148
Oka148 profile here.
Visit our technical and travel blogs: here.
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