Turbo upgrade
- Peter and Sandra OKA 374
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Having also had a hose pop off between turbo and intake with a huge bang (normal worm drive clamps can't hack the pace), again you will initially think the engine has grenaded it makes such a loud boom.
On the intake side there is far less chance of noticing a leak, quite a few early 12HT powered Landcruisers ended up dusted when the turbo intake pip split just in from the RH front wheel, on dirt roads the engine was stuffed very quickly.
OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 680w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
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- Dean and Kaye Howells
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Deano

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- Tony Lee
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india.donaldson.com/en/engine/support/datalibrary/065850.pdf
Tony
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- Rick Whitworth
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Dean and Kaye Howells wrote: I totally disagree that water/air is more complex and difficult to install....Here's one I prepared earlier
Deano,
Thanks for the pics. Based on personal experience I found water/air unnecessarily complex....
At the time I researched water/air vs air/air I could not get reliable info to source parts and build a diy water/air solution that I could be sure would work. Apart from Tim Forsythes expensive non diy install I could not source any OKA related water/air info.
With Air to air there was no guessing, it was easy to install and it works extremely well esp in 40+ temps as predicted.
There are many more components and considerations in water/air, one critical one that is always discussed is the volume of water needed and the header tank size, an item that seems to be missing in your pics.
re my prev comments on turbo lag
I probably overstated it. All turbo charged diesels esp those with mechanical IPs have lag to some degree or other. Lets just say mine goes so well now

like Paul said we all want our bricks to run like Lamborghinis!
Rick Whitworth: OKA XT 149.
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- mort
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It is not my place to say mine is the superior because that is saying every one else has an inferior one.
Each system has its place and if designed correctly then it will work as expected.
There are differences though.
Why does a drag racer use water to air or why does a distance racer use air to air.
Water to air use water to take the heat out of the charge air and then use air to take the heat out of the water which is good for short runs but eventually the water reaches a point that the air cannot cool it any further so the radiator needs to be of a suitable size with good air flow and not that silly little one as above.
Yes water is a more efficient heat transfer medium but then you have to cool the water.
Air to air uses air to do the cooling but the efficiency is dependent on the air flow, air temp and wind chill factor.
Good for long runs and simple,if you will be idling or driving slow for long periods which means no air flow then not much cooling but remember that you also wont be on boost so not a lot of heat generated.
Remember that what you use is your choice you have done research and it is right for you and if some one knocks it is actually because they are just trying to convince themselves that they have made the right choice.
Martyn (its an OKA thing)
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- Rick Whitworth
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... I often noticed on the highway that the Perk would sing in the cool evening air with a noticeable increase in performance after struggling in the heat of the day.
Adding an intercooler without a bigger wastegated turbo to compensate for the loss in pressure and extra volume of air would have been a waste of time and Mort's turbo was the perfectly designed solution.
The IP, intake and exhaust mods were done to allow the turbo to run at its peak.
I had a number of classic motorbikes as a kid, mostly paddock bikes, a pastime that marriage cured for me but still pursued by friends today. In the early 70s a uni friend bought a Suzuki GT 750. Went like stink, but the water cooling gave him lots of grief with leaks and corrosion. It was chided with all sorts of knick names, the kettle, the steamer and why would ya water cool a bike?
At different times we have been proud owners of VW Beetle with a blueprinted 1600cc Formula V engine and an indestructible 2 litre Kombi. The simple full alloy Porsche and VW air cooled engines of the era were renowned for their robustness in all temperatures. Our Kombi was a serious off road camper.
These days, air cooled engines, even on motorcycles are becoming a thing of the past. All the same, bad memories of stuck thermostats, leaky radiator hoses, blown heater cores, stuck heater taps, corroded water pumps, seized bolts and rotten radiator cores and steam from under the bonnet always miles from anywhere have built strong suspicion toward any part of a donk that has water in it.
as Mort says if the wastegated Turbo is designed to compensate....?
Water to air?
...why would ya?
Answers: less joints, volume and pressure loss and better heat exchange (if properly designed)
It's horses for courses and if you have the wherewithal, go for it. As always, please contradict, the more ideas, opinions, info and varied successful solutions detailed on here the better.
Rick Whitworth: OKA XT 149.
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- Peter and Sandra OKA 374
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OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 680w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
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- Dean and Kaye Howells
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Aaahh .............. Formula Vee, if you had a 1600cc Formula Vee back in my old racing days you would have been strung up by the err ...... whatsits. 1200cc was the go and scrutineering was deadly. only a few engine builders were certified and NO reboreing was allowed. A great racing class, affordable, extremely competitive and great to watch.
Peter, thanks for the information


Deano

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- Outback Jack
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Bit like Holden or Ford argument.
My set up is Factory 6BTA and will some day give its own cooling system. Some have said to go Air To Air etc.
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- Rick Whitworth
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there you go, there's an answer to everything
...even my whatsits!?
Rick Whitworth: OKA XT 149.
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- Dean and Kaye Howells
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Outback Jack wrote:
My set up is Factory 6BTA and will some day give its own cooling system. Some have said to go Air To Air etc.
Interesting OBJ, what have you done to enhance the standard LT cooling system to cope with the increased demands from the 6BT and the additional water/air intercooling load ?
Deano

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- Outback Jack
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Has about 26 liters plus of coolant.
In 34 degrees plus heat with 60 percent humidity doesn't get above 85 degrees C. Fan switches on at 85 and it hasnt switched on yet.
Still playing around a little and may have to change cooling fan, but time will tell.
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- Peter and Sandra OKA 374
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OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 680w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
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- Dean and Kaye Howells
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Deano

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- mort
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Your last part 20 HP I think you would mean 20 PSI but what do you mean can it only handle 20 PSI or was it only used in engines producing 20 PSI.
Martyn (its an OKA thing)
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- mort
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when used in marine application the cooling of its water is via a heat exchanger which is cooled via sea water.
Most boats dont have room so the engine is cooled via the same heat exchanger which means your using engine coolant for the inter-cooler this can mean that the charge air will be at a constant temp and so you can rely on a constant power output.
The same setup can be used on the OKA using the engine coolant to cool you wouldn't have fluctuations like driving through snowy mountains in winter or the desert in summer, or can have its own dedicated system.As it was used in marine application I dont know how efficient it is or whether there is better after market models
Martyn (its an OKA thing)
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- Peter and Sandra OKA 374
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OKA 374 LT Van, converted to camper/motorhome,
400ah Lithiums, 680w solar, diesel cooking heating and HWS,
Cummins 6BT, Allison 6 speed auto, Nissan transfer.
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- Ralley
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In the case of the first gen cummins in the Ram the intercooler gave no increase it was all about pollution.
I think with all the helpful things that have been shared it highlights the need to research to figure out what will suit your application. There can be a huge difference in what you can achieve and it's not always about HP. To me the things that need to be considered are.
* When researching remember that diesels spend more time on boost than a petrol. Don't get caught when they start talking about HP ratings for cooler it's usually petrol ratings.
* The efficiency of the charged airflow, to much restriction could cause to much pressure drop. (effect turbo efficiency and possible power gains)
* The efficiency of the cooler to remove the hot air. Things could go south pretty quick if things get heat soaked, especially if it's tuned when thing are all good.(The cooler may work ok on a cool day but how will it work when it's 45c and you have altitude)
* How does your speed affect the ability to cool. (We may think that we don't push them at slow speed but we have sand driving and some steep climbs even bulldust when towing)
* Complexity is also another consideration and to be honest I think they on pare.
* Availability of parts. To do an air to air for the cummins there is really nothing that I could find that was big enough. There isn't enough room to fit the ones from the US. The only local option was from a truck, size becomes a problem as well.
* The importance of running both a boost and EGT gauges.
* Can the cooler you choose handle the Boost you intend to run (I have read of coolers cracking with high boost)
* Obviously cost is important to all of us.
* For me enduring a Kangaroo strike was also a big consideration on what I did (I know most of you don't drive at night but for some of us it's part of the deal, 18 and counting)
Feel free to add to the list
Rob
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- Dave and Pauline Gray
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On balance my preference would be air to air as its more controllable on a wider range of ambient temperatures and I don't drive that much at night any more.
Cheers Dave
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- mort
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Martyn (it a a not fully informed thing)
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