Turbo upgrade

More
22 Nov 2019 13:56 #521 by Daktari
Daktari replied the topic: Turbo upgrade
Awesome Alister, thanks so much for the info.

Please Log in or Create an account to join the conversation.

More
22 Nov 2019 17:28 #522 by Dean and Kaye Howells
Dean and Kaye Howells replied the topic: Turbo upgrade
The standard Oka Perkins is rated at 110 B(bullshit)HP :) at the flywheel on a good day when it was brand new. By the time it is nobbled with an 'ordinary' air intake and filter system and its output is delivered through an equally 'ordinary' power absorbing Rockwell transfer case the actual power delivered to the rear wheels is more like 70 (real)HP. Upgrading the turbo to Martyns externally waste gated one, opening the exhaust up and presumably doing something about the air delivery (if not this is a very good idea) you've achieved a 50% improvement in power with 105 HP at the rear wheels and have a similar improvement in torque.

Perhaps a relevant question here is not how much more power/torque could be achieved but should the engine be pushed further ? I'm not trying to be a kill joy but the output of a 25 year old Perkins engine has been increased by 50%, is it prudent to push it further. There's no such thing as a free lunch and the internal strain on/in the engine has already been increased significantly. The engine may be strong enough to handle this, I don't know but IMO worth considering.

I would advise extreme care if considering disconnecting the pressure hose from the waste gate actuator. The purpose of the waste gate in this type of turbo is to bleed off excessive air when the turbo pressure reaches a preset level. Disabling the waste gate means there's no regulation of turbo boost which can lead to over boosting and engine destruction. One way turbo boost can be adjusted is by changing the length of the waste gate actuator rod and they usually have a threaded section where this can be done. From memory when Martyn first supplied these turbos the pre set boost pressure was to be around 16 psi, perhaps Martyn can confirm this.

Regarding upgrading from the Rockwell to NP205 TC, this will give more useful power to the rear wheels as it noticeably less power draining than the Rockwell. A divorce mount NP205 suitable for the LT also needs different mounts and cable setup, upgraded speedo drive and rear axle wedges as the output shaft is higher than for the Rockwell. Paul Nott is a NP205 expert and has been re-building/re-furbishing these for years. For a complete rebuilt NP205 with upgraded input/output shafts, handbrake assembly and adapter kit I reckon you'd be looking at around $8K. I've got one in the shed to go in #413 but haven't got round to it yet :(, too many other projects. Another option may be to replace the Rockwell with a NT HD150 transfer case from Dean over there in WA but I've no idea as to the cost or availability.

Deano
The following user(s) said Thank You: Daktari

Please Log in or Create an account to join the conversation.

More
23 Nov 2019 07:41 #523 by Holmz
Holmz replied the topic: Turbo upgrade

Dean and Kaye Howells wrote: ...
I would advise extreme care if considering disconnecting the pressure hose from the waste gate actuator. The purpose of the waste gate in this type of turbo is to bleed off excessive air when the turbo pressure reaches a preset level. Disabling the waste gate means there's no regulation of turbo boost which can lead to over boosting and engine destruction...
...


Not much argument ^here^.

I am not sure that too boost will destroy the engine?
The cylinder pressure is a function of the boost pressure, compression ratio, volumetric efficiency, intake temp and combustion temp.
Just adding more air without adding more fuel results in a lower combustion temp, and the compression ratio is not changing, and also the volumetric efficiency goes down as pressure increases.

Certainly the power will not double with double the boost and a constant amount of fuel.
A few percent increase in efficiency, and reduction of nitrous oxides is most of what is happening with more air and the same fuel amount.

In my case the boost reported by others was 17psi.
So disconnecting the hose and getting 11psi is suggesting that wastegate actuator is not what is holding my boost back.
Therefore as a test it is one method to use.

Which still begs the question of whether I should be seeing 11 psi or 17 psi?
And the zorst pipe looks pretty blue.

Please Log in or Create an account to join the conversation.

More
23 Nov 2019 10:10 - 23 Nov 2019 10:15 #524 by Dean and Kaye Howells
Dean and Kaye Howells replied the topic: Turbo upgrade
I am not sure that too (much) boost will destroy the engine?

Australias junk yards are littered with Nissan ZD30 engines (for example) that have blown up for this particular reason. As the engine ages the waste gate actuator/valve assembly wears. Sometimes the waste gate seizes. When it seizes open or partially open it results in lack of boost and poor performance and is relatively easy to diagnose and fix. If it seizes closed it's a different story as there is nothing to limit the engines boost. A typical owners response is .......... "The vehicles never gone so well, it was running like a dream and then bang !", This isn't me picking on Nissans ill fated ZD30 but a fact of life. Good CPU controlled diesel engines (such as the Landrover TD5) have an over boost sensor which is there to save the engine should over boost occur. Not so early ZD30's.
In general, when people play with the turbo they invariably play with the fuel as well so keeping the waste gate 'circuit breaker' connected is a very good idea. eg. A few years ago on a standard Landrover 300 TDi engine I disconnected the waste gate and connected the hose from the turbo directly to a pressure gauge. I didn't have a suitable T piece so I left the waste gate disconnected. The boost pressure readily ran up to 30 psi (gasp) before I noticed and backed off, 'normal' waste gated boost was 20 psi.

In the case you describe it may be that all is needed is to give the engine a bit more fuel (with the new turbo) to get it to spool up more effectively. The old Landrover 300 TDi (same injector pump as the Oka) 'rule of thumb' tuning was to find a hill and repeatedly drive up it each time increasing the fuel by 1/4 turn of the fuel screw until it started to smoke and then back off 1/4 turn. Then check the boost pressure and set it to the desired amount and go through the same process again. Crude but effective and I'm sure there's ways to to it better.

I can't really comment on the blueness of the exhaust, does this signify excessive heat ? In petrol engines running lean can cause an engine to run hot but I'm not sure if this is true for a diesel. If it is perhaps a 1/4 turn of the fuel screw may solve your problem :)

Deano
Last Edit: 23 Nov 2019 10:15 by Dean and Kaye Howells.

Please Log in or Create an account to join the conversation.

More
23 Nov 2019 10:50 - 23 Nov 2019 12:35 #525 by Holmz
Holmz replied the topic: Turbo upgrade

Dean and Kaye Howells wrote: I am not sure that too (much) boost will destroy the engine?

Australias junk yards are littered with Nissan ZD30 engines (for example) that have blown up for this particular reason. As the engine ages the waste gate actuator/valve assembly wears. Sometimes the waste gate seizes. When it seizes open or partially open it results in lack of boost and poor performance and is relatively easy to diagnose and fix. If it seizes closed it's a different story ...
...

I can't really comment on the blueness of the exhaust, does this signify excessive heat ? In petrol engines running lean can cause an engine to run hot but I'm not sure if this is true for a diesel. If it is perhaps a 1/4 turn of the fuel screw may solve your problem :)

Deano


Blue generally indicates too much heat, and as the F:A ratio increases, the combustion temp goes up.
A partially open waste gate would create too much fuel and higher combustion temps, and higher EGTs.
But colour does not replace an actual EGT number, so I have more work to do... to go from theory towards fact.

Too much boost in a Perkins results in too much air, which results in a lean mixture, which results in cooler combustions temps.
The only way to get more fuel in, is by attending to the fuel pump and fuel delivery system.
The OKA is an open loop system with no feedback of the air situation in relation to fuelling. It only changes at will of a person with a wrench and screwdriver "acting as a tuner".

A en.m.wikipedia.org/wiki/Nissan_ZD_engine is a different beast.
There is a MAF sensor, which lets "something" know what the mass of air is that in being ingested.
That "something" is an ECU, which then sees the air going in and adjusts the fuel going in... so that some target F:A ratio is achieved.
So overboost gives too much air and then the ECU puts in fuel to match the air... all in a closed loop fashion.
Now you have more power being generated.

The OKA has no such ECU, so it is a much different beast.

Or
The other way to think about it is that the Nissan with 5psi is 20psi absolute. If the waste gate gets stuck shut And the boost goes to 25psi, then that is 40psi absolute.
So the power doubles in a 40psi/20psi sense.

The Perkins might get a couple % more power doubling the boost with no extra fuel... assuming that the mixture is not too lean to get a good combustion happening. In apetrol engine it would be so lean to likely misfire and balk.
Last Edit: 23 Nov 2019 12:35 by Holmz.

Please Log in or Create an account to join the conversation.

More
24 Nov 2019 05:50 #526 by Rick Whitworth
Rick Whitworth replied the topic: Turbo upgrade

Holmz wrote: I have more work to do... to go from theory towards fact.

.....never a truer word

Rick Whitworth: OKA XT 149.
The following user(s) said Thank You: Holmz

Please Log in or Create an account to join the conversation.

More
24 Nov 2019 08:02 - 24 Nov 2019 08:05 #527 by Rick Whitworth
Rick Whitworth replied the topic: Turbo upgrade
The Perkins Phaser engine is simple, resilient and refurbishable.

Dean and Kaye Howells wrote: Perhaps a relevant question here is not how much more power/torque could be achieved but should the engine be pushed further ? I'm not trying to be a kill joy but the output of a 25 year old Perkins engine has been increased by 50%, is it prudent to push it further. There's no such thing as a free lunch and the internal strain on/in the engine has already been increased significantly. The engine may be strong enough to handle this, I don't know but IMO worth considering.


I agree Deano but this topic, the Swift turbo and assoc mods have allowed discerning Perkins owners to get the best out of their orininal Phaser 110 engines. There was some wisdom in the OKA designer's original choice of the 110 over the 138. (clearly flywheel ratings that, like any manufacturer, apply to a brand new engine straight off the production line). They were hoping to secure fleet markets. The power output is way under stressed and well below the capacity of the crank, camshaft and other engine ancillaries not to mention the OKA's transmission and running gear. This lead to the longevity of so many of the originals. Sure they under performed on the highway but their capability off road (in their element for which they were designed) performance was undeniable.
As dry sleeve engines the Phasers were designed to be 100% continuously refurbishable if properly operated and maintaned. Many mechanics across a huge range of uses of the powerplant will attest to this.
I was lucky to have my engine fully reconditioned by the old gard at Trickies in Bendigo before they retired. At that stage it had done 1.5 million kilometers was blowing so much smoke the RTA had put it off the road, alloy casings and parts had almost disintergrated and yet despite the smoke the engine started and ran like a bird. The OKA was still good for over 100k/hr. Tests showed that the crank mains and big ends were perfect. They tested and strongly recommended that the block and head should last forever.
Following the refurb I have done 100000 kms and the Perk has not missed a beat and that includes the Swift upgrade with other respiration mods that almost doubled the horsepower and torque. (My original IP settings were significantly detuned)
I note that resleeve, bearing kits are still readily available for competant home mechanics to DIY

Now I have gobs of power that gives me the choice to wear the engine out quicker or conserve rather than that being limited and governed by the manufacturer which was OKAs choice.

The Swift upgrade has freed us from that limitation but having since done a rear diff, a front and a rear axle I agree there are no free lunches. Operator's choice.

Rick Whitworth: OKA XT 149.
Last Edit: 24 Nov 2019 08:05 by Rick Whitworth.
The following user(s) said Thank You: Dean and Kaye Howells, 210greg

Please Log in or Create an account to join the conversation.

More
24 Nov 2019 10:06 #528 by Holmz
Holmz replied the topic: Turbo upgrade

Rick Whitworth wrote:

Holmz wrote: I have more work to do... to go from theory towards fact.

.....never a truer word


I admit the coffee shot out the nostrils.
Well done sir!

Please Log in or Create an account to join the conversation.

More
25 Nov 2019 07:04 #529 by Daktari
Daktari replied the topic: Turbo upgrade
Well some nice healthy discussion going on here ... it's great to get perspectives and pool the collective knowledge. In relation to my little project I have no intention of disconnecting anything, merely adjusting the rod (which, yes, is a threaded one) to alter when the wastegate opens. It clearly opens at 11psi currently as evidenced by a change in tone. I will adjust for wastegate opening at 16-18psi. I love the simplicity and strength of the Perkins and have no intention of over-stressing it. I am very fortunate that my truck has not done many k's (<250k) and I believe as long as I keep an eye on my boost guage and EGT (plus engine temp etc) I can comfortably optimise available power and efficiency, ... and longevity :-)
Thanks all for your ongoing comments and discussion, and debate ... that's what a forum should be about IMHO.

Please Log in or Create an account to join the conversation.

More
25 Nov 2019 08:40 #530 by Holmz
Holmz replied the topic: Turbo upgrade
I am pretty sure that you will want to get the boost pressure adjusted first, and then attend to the fuelling(?).
And the EGT gauge will be helpful to know you don't have too much fuel going in.

With forum opinions, one sort of gets what they pay for... so there is no dishonour in using a knowledgable diesel fitter/tuner.
The following user(s) said Thank You: Daktari

Please Log in or Create an account to join the conversation.

More
26 Nov 2019 01:34 #531 by Rick Whitworth
Rick Whitworth replied the topic: Turbo upgrade
The Bosch Injector Pump upgrade kit and final dyno tune done by Turbo Engineering Corporation in Thomastown gave a big increase in my Perkins power. The objectve was to optimise IP fuel delivery to balance the new turbo pressure, Optiair intake, reduced intake temps from the intercooler, improved exhaust flow and removal of other intake restrictions.
The manager, Ray believes all of the old manually injected diesels with no ECU and equivalent capacity and no of cylinders have the same potential power, it is just a matter of fuel/air respiration and tuning.
He asked if I wanted to have the wastegate adjusted.
He was not too keen without info from the supplier showing the reationship between rod adjustment and output pressure. Given the effort and testing done by Mort and the supplier we thought it better not to lose the stock setting on the first tuning round.
When he was done Ray thought he could get still more out of the engine by adjusting the wastegate and retuning the IP.
I have not gone down this path as I have all the power I need. In fact I have considered having it detuned slightly for the reasons Deano mentioned above but then that would be taking away half the fun
One area where wastegate adjustment may be an advantage would be not so much the amount of boost but modifying when it comes on. I have all the boost I need but find in some situations eg in heavy high dunes in the middle of the day I am conscious of keeping the revs high enough to keep the boost up ready when you need it.

Rick Whitworth: OKA XT 149.

Please Log in or Create an account to join the conversation.

More
26 Nov 2019 10:04 - 26 Nov 2019 10:04 #532 by Holmz
Holmz replied the topic: Turbo upgrade

Rick Whitworth wrote: ...
When he was done Ray thought he could get still more out of the engine by adjusting the wastegate and retuning the IP.
I have not gone down this path as I have all the power I need. In fact I have considered having it detuned slightly for the reasons Deano mentioned above but then that would be taking away half the fun
One area where wastegate adjustment may be an advantage would be not so much the amount of boost but modifying when it comes on. I have all the boost I need but find in some situations eg in heavy high dunes in the middle of the day I am conscious of keeping the revs high enough to keep the boost up ready when you need it.


Can you ask Ray if the boost can be safely raised without adjusting the IP?

I was under the impression that the wastegate does not affects when the power comes on, and that it was more dependent on turbine and compressor housing ratios. But the 3-D topo map plot always do my head in, so I am not sure.
Last Edit: 26 Nov 2019 10:04 by Holmz.

Please Log in or Create an account to join the conversation.

More
26 Nov 2019 18:38 - 26 Nov 2019 18:41 #533 by Dean and Kaye Howells
Dean and Kaye Howells replied the topic: Turbo upgrade
I don't think you've quite got the operational concept of the externally waste gated turbo :)

The turbo is essentially an exhaust gas driven turbine connected to an air pump (compressor) to provide air at higher than atmospheric pressure to the engine. For the engine to work efficiently the amount of fuel must also be increased to maintain optimum fuel/air ratio for best engine performance. The end result is a more powerful engine for its capacity than a comparative 'naturally aspirated' engine :)

Martyn's 'Swift' turbo as supplied to replace the original Oka turbo is an externally waste gated turbo as opposed to the factory Oka turbo which is a non waste gated (sometimes referred to as an internally waste gated ) turbo.

For a vehicle engine it's desirable to have constant power across it's rev range (or as near as possible) to give consistent and predictable performance. To achieve this the turbo needs to deliver a consistent maximum boost as early (revs wise) as possible. All well and good but unfortunately if left to its own devices such a turbo spins faster as more fuel/air is burnt and more exhaust gasses are generated. This causes an exponential rise in turbo 'boost' as even more 'high pressure air' is delivered to the engine. If this is not addressed the engine can be 'over boosted' to destruction. This is where the waste gate comes in.
The waste gate is basically a 'feedback mechanism' when at a pre-set (compressor) pressure a diaphragm connected to a rod moves and opens a valve on the exhaust (turbine) side of the turbo 'dumping' exhaust gas straight into the exhaust thus bypassing the turbine and reducing its 'pumping power'. Equilibrium is reached and the exponential rise in turbo boost flattens off to basically a straight line.

In a non waste gated turbo this happens a bit differently. The turbo is designed so that the compressor pressure increases at a linear rate and doesn't exceed a safe level even at maximum revs. These turbos are simpler and cheaper to build and are most useful in an engine used at constant revs such as a water pump, generator or marine engine. They can also be used in vehicles with an automatic transmission where the torque converter is used to keep the revs up. Early Dodge Ram's are a good example of this application. Such a turbo is a poor choice for a manual transmission vehicle as with the turbo boost being a function of engine rpm boost (and engine performance) drops as you change (up) gears. Unfortunately Oka chose this type of turbo for the Oka. IMO a very poor choice.

Deano :)
Last Edit: 26 Nov 2019 18:41 by Dean and Kaye Howells.
The following user(s) said Thank You: OKAPETE

Please Log in or Create an account to join the conversation.

More
26 Nov 2019 18:57 #534 by Peter and Sandra OKA 374
Peter and Sandra OKA 374 replied the topic: Turbo upgrade
But it did mean that when silly buggers like me bolted an auto behind the Perky it got up and boogied really well.
I never touched the Perky in 374 and when I fitted the auto it actually went pretty well for a bog standard setup, boost maxxed out at about 17lb.

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.
The following user(s) said Thank You: OKAPETE

Please Log in or Create an account to join the conversation.

More
26 Nov 2019 19:17 #535 by Dean and Kaye Howells
Dean and Kaye Howells replied the topic: Turbo upgrade
Yep, you'd certainly get better performance. A pity Oka couldn't figure that one out :(

BTW, you've got a HX35 non waste gated on the Cummins right ? Can you give me the number and how many vanes on the compressor and turbine if you know. I've got a HX35 non waste gated, made in Huddersfield of all places), 3536473, to swap over for my H1C. It has a 12 bladed turbine in a 18.6mm housing with a std. 8 blade compressor.

Deano :)

Please Log in or Create an account to join the conversation.

More
26 Nov 2019 19:31 - 26 Nov 2019 19:33 #536 by Peter_n_Margaret
Peter_n_Margaret replied the topic: Turbo upgrade
A few years ago I fitted a Garret T2554 turbo to the Perkins. It is waste gated but never needs to "waste". Its main feature is that it starts boost much earlier than the original. It will boost to 17psi at my current fuel settings. Fuel makes boost.
My need for power is when we are halfway up a dune at 1,000rpm and it is a significant improvement compared to the original in that regard. What the boost is at 90kph is of no consequence to me.
Cheers,
Peter

Cheers, Peter.
OKA196 tinyurl.com/OKA196xtMotorhome
Mob.0428171214
Last Edit: 26 Nov 2019 19:33 by Peter_n_Margaret.

Please Log in or Create an account to join the conversation.

More
26 Nov 2019 21:47 - 26 Nov 2019 21:51 #537 by Holmz
Holmz replied the topic: Turbo upgrade

Dean and Kaye Howells wrote: I don't think you've quite got the operational concept of the externally waste gated turbo :)

The turbo is essentially an exhaust gas driven turbine connected to an air pump (compressor) to provide air at higher than atmospheric pressure to the engine. For the engine to work efficiently the amount of fuel must also be increased to maintain optimum fuel/air ratio for best engine performance. The end result is a more powerful engine for its capacity than a comparative 'naturally aspirated' engine :)

Martyn's 'Swift' turbo as supplied to replace the original Oka turbo is an externally waste gated turbo as opposed to the factory Oka turbo which is a non waste gated (sometimes referred to as an internally waste gated ) turbo.

For a vehicle engine it's desirable to have constant power across it's rev range (or as near as possible) to give consistent and predictable performance. To achieve this the turbo needs to deliver a consistent maximum boost as early (revs wise) as possible. All well and good but unfortunately if left to its own devices such a turbo spins faster as more fuel/air is burnt and more exhaust gasses are generated. This causes an exponential rise in turbo 'boost' as even more 'high pressure air' is delivered to the engine. If this is not addressed the engine can be 'over boosted' to destruction. This is where the waste gate comes in.
The waste gate is basically a 'feedback mechanism' when at a pre-set (compressor) pressure a diaphragm connected to a rod moves and opens a valve on the exhaust (turbine) side of the turbo 'dumping' exhaust gas straight into the exhaust thus bypassing the turbine and reducing its 'pumping power'. Equilibrium is reached and the exponential rise in turbo boost flattens off to basically a straight line.

In a non waste gated turbo this happens a bit differently. The turbo is designed so that the compressor pressure increases at a linear rate and doesn't exceed a safe level even at maximum revs. These turbos are simpler and cheaper to build and are most useful in an engine used at constant revs such as a water pump, generator or marine engine. They can also be used in vehicles with an automatic transmission where the torque converter is used to keep the revs up. Early Dodge Ram's are a good example of this application. Such a turbo is a poor choice for a manual transmission vehicle as with the turbo boost being a function of engine rpm boost (and engine performance) drops as you change (up) gears. Unfortunately Oka chose this type of turbo for the Oka. IMO a very poor choice.

Deano :)


Dean and Kaye Howells wrote: I don't think you've quite got the operational concept of the externally waste gated turbo :)
...


There is no time like present for me to learn then.

Dean and Kaye Howells wrote: ...
The turbo is essentially an exhaust gas driven turbine connected to an air pump (compressor) to provide air at higher than atmospheric pressure to the engine. For the engine to work efficiently the amount of fuel must also be increased to maintain optimum fuel/air ratio for best engine performance. The end result is a more powerful engine for its capacity than a comparative 'naturally aspirated' engine :)
...


However... I seem to believe that optimal in terms of max power requires more fuel, but optimal in terms of BSFC does not require more fuel. And that a diesel can run lean just fine.
So "efficiently" means it is actually better to be lean?

Dean and Kaye Howells wrote: ...
Martyn's 'Swift' turbo as supplied to replace the original Oka turbo is an externally waste gated turbo as opposed to the factory Oka turbo which is a non waste gated (sometimes referred to as an internally waste gated ) turbo.

For a vehicle engine it's desirable to have constant power across it's rev range (or as near as possible) to give consistent and predictable performance. To achieve this the turbo needs to deliver a consistent maximum boost as early (revs wise) as possible. All well and good but unfortunately if left to its own devices such a turbo spins faster as more fuel/air is burnt and more exhaust gasses are generated. This causes an exponential rise in turbo 'boost' as even more 'high pressure air' is delivered to the engine. If this is not addressed the engine can be 'over boosted' to destruction. This is where the waste gate comes in.
The waste gate is basically a 'feedback mechanism' when at a pre-set (compressor) pressure a diaphragm connected to a rod moves and opens a valve on the exhaust (turbine) side of the turbo 'dumping' exhaust gas straight into the exhaust thus bypassing the turbine and reducing its 'pumping power'. Equilibrium is reached and the exponential rise in turbo boost flattens off to basically a straight line.

In a non waste gated turbo this happens a bit differently. The turbo is designed so that the compressor pressure increases at a linear rate and doesn't exceed a safe level even at maximum revs. These turbos are simpler and cheaper to build and are most useful in an engine used at constant revs such as a water pump, generator or marine engine. They can also be used in vehicles with an automatic transmission where the torque converter is used to keep the revs up. Early Dodge Ram's are a good example of this application. Such a turbo is a poor choice for a manual transmission vehicle as with the turbo boost being a function of engine rpm boost (and engine performance) drops as you change (up) gears. Unfortunately Oka chose this type of turbo for the Oka. IMO a very poor choice.

Deano :)


And changing the waste gate to dump at a different pressure does not change the spooling rate.
That is solely determined by the turbine and compressor ratios.
So below the waste gate opening the waste gate has no effect.
?

Or the other way to think of it, is that it is intentionally produces too much boost and too soon, And to keep from over revving the turbo and over boosting the waste gate is put into the turbo that is a touch too small.
Last Edit: 26 Nov 2019 21:51 by Holmz.
The following user(s) said Thank You: Dean and Kaye Howells

Please Log in or Create an account to join the conversation.

More
26 Nov 2019 21:49 #538 by Rick Whitworth
Rick Whitworth replied the topic: Turbo upgrade

Dean and Kaye Howells wrote: I don't think you've quite got the operational concept of the externally waste gated turbo :)
....
Martyn's 'Swift' turbo as supplied to replace the original Oka turbo is an externally waste gated turbo as opposed to the factory Oka turbo which is a non waste gated (sometimes referred to as an internally waste gated ) turbo.


???

The turbo I purchased from Mort has an internal wastegate.
The standard XT turbo I removed has no wastegate.

There is plenty of expert material on the web and youtube that distinguish non wastegated, and internal vs external wastegated turbos.
Also much on tuning fuel and boost.

Rick Whitworth: OKA XT 149.
The following user(s) said Thank You: Dean and Kaye Howells

Please Log in or Create an account to join the conversation.

More
26 Nov 2019 22:11 - 26 Nov 2019 22:34 #539 by Rick Whitworth
Rick Whitworth replied the topic: Turbo upgrade

Peter_n_Margaret wrote: What the boost is at 90kph is of no consequence to me.

Agree on the dunes but having enough to give it a squirt and overtake in a gap on highway at 90+ kph now makes huge difference compared to how it was. No longer relegated stuck behind a truck or caravan for endless upcoming hills.

I find on the real steep mountain heart on the mouth stuff, I dont mean dunes but the rough vertical stuff with reasonable traction, in first low, the OKA behaves the same as it always did with the old turbo and still crawls up with little or no boost at all.

Rick Whitworth: OKA XT 149.
Last Edit: 26 Nov 2019 22:34 by Rick Whitworth.

Please Log in or Create an account to join the conversation.

More
27 Nov 2019 03:40 #540 by Peter and Sandra OKA 374
Peter and Sandra OKA 374 replied the topic: Turbo upgrade
Deano I've got no idea of numbers, measurements etc of the turbo, it does have 8 vanes from memory and it is the one that came with the engine. The auto allows it to get on boost pretty early and at my present state of tune it runs up to 28lb boost at 2300 rpm. I have seen a lot more, well over 30lb before I backed the fuel off to drop EGT's back to safe levels.
With the current setup with the W2A intercooler it could handle a bit more fuel and that would get the max boost up to just over 30lb but I would have to drive it on the EGT's once away from sea level which becomes a pain.
A 4" exhaust would drop the EGT's a little bit I suspect.

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.
The following user(s) said Thank You: Dean and Kaye Howells

Please Log in or Create an account to join the conversation.

Powered by Kunena Forum