Want to make your Oka go better?
01 Nov 2012 15:42 #1
by dandjcr
David and Janet Ribbans - Oka 148
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dandjcr created the topic: Want to make your Oka go better?
Forum Home > On the Road > Want to make your Oka go better?
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Peter & Sandra James Oka 374
Member
Posts: 412
This all started when I realised that 374 didn't have a rubber seal under the air cleaner lid.
Happened to be talking to Okapete about it and he had a quick look at three Oka's that were at his place at the time and none of them had a seal either. I looked in the parts book and yes there should be a rubber seal between the lid and aircleaner body, otherwise there is no point in the snorkle as air and anything else can easily be sucked into the air cleaner if there is no seal.
So I installed a seal and the next time I drove it it seemed even more gutless then usual, wouldn't rev easily and generally felt restricted.
So I took the lid off and went for a run, well the difference was noticeable, went quite a bit better, boost was a tad higher etc.
So I took the actual air cleaner element out , left the internal safety element in and went for run, bloody hell it goes now!
So then I tried a brand new element out surmising that while the one that was in there looked ok it must be blocked, no the brand new aircleaner element nobbled it as well.
Weird, so I pulled the air cleaner lid off the Humvee which also runs a huge Donaldson style cleaner to have a look inside it to see what was in there as it certainly doesn't have restricted airflow having 4 1/2 inch plumbing in and out.
I noticed that the shield inside the Humvee air cleaner housing is at least 25mm away from the actual element where the Oka one the shield sits pretty much hard against it, the Oka lid shroud also sits very close to the element.
Looking at the air cleaner element that was in the Oka I noticed that it was only dirty/dusted between the two shrouds, a ring around the element about 50mm wide where the airflow is unrestricted.
I had told Keith Harris about it and he had a look at his and found the same setup so decided to do something about it. He cut the inner shroud away just leaving a piece directly below the intake to deflect the air around the cleaner to keep the centrifugal affect and also cut the internal lid flange back to 25mm.
He reckoned the change in how it went was huge so I took the plunge.
I cut the inner shield away, leaving only about 25mm for most of the circumference and then left about 20% of it directly below the actual air intake to keep the centrifugal affect as Keith had done, then did the lid flange back to about 25mm with an additional bit just above the drain fluffer valve. Did it all in situ with a cutting disc on the dremel.
Well the change in engine performance was astounding, previously the boost gauge never went past 9psi and the engine was reluctant, just didn't go, the truck just chugged along and was flat out at 93kph.
After that test drive I was chuffed to say the least, big performance gains for no outlay with the only downside being an increase in induction noise through the snorkle.
While fitting an EGT gauge I also found that the accelerator whilst it was flat on the floor wasn't giving full throttle at the injection pump so after adjusting it correctly I went for another drive, now the old girl really got up and went!
Now boost has gone to around 16-17psi at 3500rpm and it pulls like a train from low down all the way up to max. As soon as we headed out yesterday Sandra said to me "what have you done, it is actually accelerating now!" It will now sit happily on 95-100kph at well under full throttle whereas before max was around 90kph with my foot flat on the floor.
I've yet to check fuel consumption but it seems to be better just watching the fuel gauge, will find out tomorrow as we are on the road again.
So I would bet that 374 isn't the only one with a poorly adjusted throttle cable and trimming the shields inside the aircleaner makes a huge difference to engine breathing and therefore performance.
The fact that just leaving the aircleaner lid off makes it go better is reason enough for a bit of surgery.
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Oka 374 LT Van
November 23, 2011 at 6:05 PM Flag Quote & Reply
Tony Lee
Member
Posts: 539 "the only downside being an increase in induction noise through the snorkle." Worth checking the seal between the snorkel and the side of the cab. I found even an unused screw hole lets a noticeable amount of noise into the cab. Originally the seal was completely displaced and the noise was terrible even with the window closed. Sealing it up with mastic made a huge difference.
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Tony
picasaweb.google.com/114611728110254134379
November 23, 2011 at 9:35 PM Flag Quote & Reply
Aussie Bight Expeditions
Member
Posts: 109
Question ?
I too once had an OKA that went to 3500 RPM but found the pulley on the alternator was the wrong size. Do you really think that it does 3500 rpm or is that just a typo as mine now at max RPM does 2400 to 2500 RPM. These motors were originally a 1750 RPM or so engine and with the pump redone taken to the say 2400 RPM, or is that just another OKA myth too.
Sounds interesting if you have more HP / Torque.
Regards ABE Tony
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November 23, 2011 at 11:14 PM Flag Quote & Reply
Cando
Member
Posts: 199
--
Happy trails
Cando and Bron XLT 112
November 25, 2011 at 9:53 PM Flag Quote & Reply
Tony Lee
Member
Posts: 539
Been waiting for the spirited discussion to start, but nary a peep so far.
Can only conclude that it is for two possible reasons.
First is those who are experts and who know about such things are just to polite to break the bad news to the Dremel Duo that the only result of circumcising the inner shrouds of their previously perfectly good air-cleaner is that the engine will fall out on the road sometime pretty soon.
The other possibility is that those who thought they knew about such things and have spent thousands of dollars just so they can pass the odd heavy vehicle or break their drive train more often, have realised that they could have achieved the same result for no outlay other than a little bit of time and effort and they are too embarrassed to admit it on a public forum.
BTW My spares manual does not show any gasket under the lid. I imagine the wingnut done up tightly would result in a metal to metaal seal right around the perimeter.
--
Tony
picasaweb.google.com/114611728110254134379
December 2, 2011 at 9:52 PM Flag Quote & Reply
James & Usha (THEByleDuct)
Administrator
Posts: 161
Tony are you able to post a few pics of your handiwork?
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OKA #072
December 2, 2011 at 10:24 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
We're currently in the Vic high country and 3G signal is patchy especially when you are camped in deep valleys beside running rivers and creeks for days on end, hence the delay in replies.
I can check the RPM with aTiny Tach I have at home and the pics will also have to wait till we return in ten days or so. I suspect they are pretty accurate as it idles at the right RPM and watching boost, road speed and boost all seem to be in sync. Pics inside the aircleaner might be hard to work out as it is all black
)
Like Tony I was expecting a barrage of posts but it has been pretty quiet)
Now having driven it nearly 2k since the mods I can say that there is absolutely no comparison between how it was and how it is now.
The first part of the trip was about 600 odd k's down the NSW coast with a 7x4 trailer with cage on top and it easily went far better than without the trailer. We had never previously towed anything with the Oka. Dropping the trailer at the MIL's at Nowra we continued across the southern highlands and down into Vic via the Brindabella's, Kiandra, Cabramurra and then down to Omeo. We travel some of these roads at least once a year so know how they slow vehicles down. Plenty of long pulls and 374 pulled like a train usually climbing most hills on the highway in 4th or even 5th. Of necessity some were taken far slower because of bends and very steep bits but on the whole it went really well. Fuel consumption has increased as would be expected with more throttle and revs available never mind the long hillclimbs etc it still is averaging around 17l/100k.
Boost comes in really low down and by 1500rpm the gauge is showing about 9psi with full throttle and then it just climbs with the revs to 17lb at 3500rpm. As I'm waiting on the fitting for the EGT gauge probe I'm limiting rpm to 3k on the hills and long pulls, it doesn't seem to run any hotter than before on either of the temp gauges (standard one and an engine saver digital one)
Off road in low range it really goes well compared to before when it felt like it would run out of grunt on steep climbs, there are plenty of steep climbs down here,going down I really would like the exhaust brake to be working!
Tony I've been all over the snorkle and theinside cover and sealed all that previously, before the aircleaner surgery I couldn't hear it all in the cab with the window up, now it is just a hum in the background.
Re the gasket unde the aircleaner lid, one parts manual doesn't show it, one does and I asked Alan at Oka and there is supposed to be one there. Mine didn't seal very well at all metal to metal with a 6mm bead of packed dust in the gap on outback roads.
All I can say is if you are wondering about any effect on your Oka, take the aircleaner lid off and try it, some report big differences, some not, then remove the aircleaner and take it for a short run in a "clean" area and see what a difference it makes, the safety inner element will stop the big lumps but not dust.
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Oka 374 LT Van
December 3, 2011 at 8:28 AM Flag Quote & Reply
Tony Lee
Member
Posts: 539
One of the factors inhibiting lively discussion is the continuing claims of 3500RPM for hours on end let alone a second or two. If the tacho is so far out, it could be that the odometer is also way out and the personal sensation of increased speed and power could be just due to something you ate.
)))
Or you have a different engine in your OKA
--
Tony
picasaweb.google.com/114611728110254134379
December 3, 2011 at 9:00 AM Flag Quote & Reply
David Hallandal
Member
Posts: 133
I knew of this issue years ago, so I swapped the XT/LT air filter with an OptiAir 1100, the same unit as used in the current NT. I travel at 110km/h on most open roads with a trailer. See my webpage for photos of the old and new air filters.
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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
December 3, 2011 at 9:48 AM Flag Quote & Reply
Hal Harvey
Site Owner
Posts: 510
Re the spirited discussion, I too expected it although I did remember David's original modification to NT standard, just had never done anything about it. However I wasn't going to comment until I had a chance to have a play around with filter in vs filter out, as Peter suggests, and see what I could tell in a relatively controlled comparison. Has anybody ever run their OKA down a drag strip? Kind of embarrassing but all for a good cause. I'll be doing a long drive in clean air sometime in the next few weeks and will see what that can tell me too.
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Hal
December 3, 2011 at 3:55 PM Flag Quote & Reply
Ewart & Vivian Halford
Member
Posts: 117
Hi all I have just gone for a run up the Collie hill, with air cleaner side cover off, then air cleaner out and it made little differance to 365.
Ewart
December 3, 2011 at 4:51 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
I would strongly suggest that as I did you also check that the accelerator is giving you full throttle at the pump.
Not hard to do, open the engine hatch, place right foot on the accelerator, hold it hard on the floor and then check the throttle on the pump has gone fully anticlockwise and is resting against the stop on the passengers side. There is adjustment on the actual accelerator cable connection to the pump linkage but if it is adjusted fully as mine was then you may have to bend the actual pedal upwards a little bit as I did. All doable in the truck, one person with a big shifter holding the pedal near the pivot point and the other on the end bending it very slightly.
Re the engine RPM there is webpage where you can put gear specs in and get rpm per distance.
I have an electronic speedo with tripmeter which has been calibrated over a set kilometre so I know it is accurate, also checked on the road with the GPS, which just leaves the tacho accuracy which i will check in a fortnights time with the Tiny Tach.
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Oka 374 LT Van
December 3, 2011 at 5:27 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
I've had a squiz in the owners manual and on the net and while I've found nothing definative max power is at 2800rpm so i would imagine that max rpm is not much higher which means the tacho is telling big porkies.
Will find out when I connect an external tacho.
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Oka 374 LT Van
December 3, 2011 at 7:17 PM Flag Quote & Reply
Hal Harvey
Site Owner
Posts: 510
Peter, any chance of some pics of this surgery?
I haven't had the chance to make a long drive in clean air for comparison, but I did get to confirm that #260 has no rubber seal, and it does have an inconsistent pattern of red dust on the big filter.
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Hal
January 30, 2012 at 7:25 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
I'll try and remember to take some.
I have tried an external tacho and the tach is way out, is ok at idle but the error climbs as the tacho climbs to be indicating 3500rpm when in fact the max revs are in the order of 2800rpm.
I did jot down engine revs at different road speeds, it is in the truck and will post them later.
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Oka 374 LT Van
January 30, 2012 at 10:07 PM Flag Quote & Reply
Tony Lee
Member
Posts: 539
Bought an Aldi el-cheapo version of a dremel the other day so ready to perform surgery on the aircleaner - just as soon as I get some time to spare
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Tony
picasaweb.google.com/114611728110254134379
April 2, 2012 at 10:21 PM Flag Quote & Reply
OKA in Africa
Member
Posts: 34
I would like to buy and install a VDO boost gauge for the turbo pressure. Do you have any recommendations which pressure range gauge I should buy? Some gauges have a range of negative and positive pressure, others only positive pressure.
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OKA 327 in Africa
photo album
April 3, 2012 at 9:58 AM Flag Quote & Reply
Tony Lee
Member
Posts: 539
Cut 60mm off the inner sleeve and 30mm off the lid sleeve so will see if it makes any major difference. No fancy angled cuts - just straight around so the inner sleeve still covers the part under the inlet so the centrifugal effect shouldn't have changed too much.
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Tony
picasaweb.google.com/114611728110254134379
April 3, 2012 at 8:46 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
Oka in Africa, I just fitted one I had which goes from 0-15psi and it wasn't enough at the higher end, it goes around to about where 17 psi would be)
I'd go for just a positive 20psi which should be enough, possibly more important though is an EGT gauge especially if you intend to adjust the fuel delivery. From what I've been told and seeing what I get on 374 normal running temps at 100kph are anywhere from 400 to 550 deg C, making it lug a bit in the gear with high throttle inputs see it climb up to 630 deg C. changing down a gear and raising the revs brings it back down rapidly. I've been told that up to 650 is ok for short stints - less than a minute but you shouldn't keep it above that and 750 is terminal.
I bought the EGT gauge from www.auberins.com , model SYL-1813. you can actually use the same gauge for either boost or EGT but not both at once. They will fit in the standard round dash blanks with a bit of careful cutting and then clip the round blank back in the hole in the dash. You also need to buy the necessary probe and wiring for whatever you are using it for. They come in different display colours, dim when the dash lights come on and have an adjustable alarm point. Auberins also ship promptly.
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Oka 374 LT Van
April 4, 2012 at 7:26 AM Flag Quote & Reply
Dandj
Member
Posts: 367
Peter, very useful EGT info.
Which probe did you get and how did you connect it in?
Like many US companies, the Auberins website provides a myriad of options.
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David and Janet Ribbans, Oka 148
April 4, 2012 at 7:56 AM
Peter & Sandra James Oka 374
Member
Posts: 412
David I just bought one of their complete kits, gauge (red display) and probe, used the 1/8 NPT (TC-KEGT-NPT ) probe and drilled and tapped the manifold about 130mm in front of where it comes out of the turbo,right on the bend. I'll stick a pic up in my album. I had a NPT tap but they also sell a probe with a 1/4 BSP fitting as well. Very easy to drill and tap the manifold it's about 3/16" thick.
I drilled and tapped the inlet manifold to fit the boost gauge as well, just did it right on top towards the front.
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Oka 374 LT Van
April 4, 2012 at 2:01 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
David pics are up, think it might be less than 130mm from turbo looking at the pic, was just above the number cast onto the manifold anyway.
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Oka 374 LT Van
April 4, 2012 at 2:15 PM Flag Quote & Reply
Dave and Pauline Gray
Member
Posts: 84
Peter interesting topic but could you tell me if the fitting instructions for the probe stated the exhaust manifold is a prefered point and I ask this because with all the trucks I have had any thing to do with the probe has been fitted on the outlet side of the turbo in the exhaust to muffler section within 6inches of the turbo. I have refrained from fitting a pyerometer to mine because I could see I would probably have to fit a new exhaust line and this one will probanbly last a fair while but might not take to kindly to drilling and then welding the probe holder in place .
Cheers Dave
April 4, 2012 at 2:35 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
Dave I was told to mount the probe within six inches of the turbo outlet which in the Oka's case is a cast manifold which is then connected to the exhaust.
Any further away from the turbo and there is too much temperature drop to make the readings meaningfull. As it is the combustion temps seen post turbo would still be far less then the cylinder temps.
.JPG)
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Oka 374 LT Van
April 4, 2012 at 7:19 PM Flag Quote & Reply
Dave and Pauline Gray
Member
Posts: 84
Peter you have got it spot on I misinterpreted your explanation and to be honest I forgot about the cast manifold on the outlet side, your fit should be fine .
Cheers Dave
April 4, 2012 at 7:27 PM Flag Quote & Reply
Hal Harvey
Site Owner
Posts: 510
>> All I can say is if you are wondering about any effect on your Oka, take the aircleaner lid off and try it, some report big differences, some not, then remove the aircleaner and take it for a short run in a "clean" area and see what a difference it makes <<
I finally got to do that yesterday. A friend has a PerformanceBox, which we attached to the windscreen and in our limited time available, did four runs along a flat stretch of freeway. The standing start was achieved from the emergency lane, and despite light rain, two of OKA's more questionable joys were employed: we didn't suffer any wheelspin, and we didn't break the speed limit.
The first two runs, one north and one south but in virtually no wind, were in standard trim. Times from zero to 400m were 30.44 seconds at 74.3km/h, and 33.22 seconds at 66.5km/h.
For the second two runs the air cleaner lid was removed and the large air cleaner taken out. There was immediately heaps of induction noise that I don't normally have, so evidently the sealing that I do have is good (although I don't have a rubber seal on the outer lid). Times were 30.68 seconds at 71.7km/h, and 30.00 seconds at 74.86km/h.
Make of that what you will!
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Hal
May 6, 2012 at 11:52 AM Flag Quote & Reply
Pete Fox
Member
Posts: 140
Hal
I would really like to see someone try the same thing with the outer in place and the inner filter removed. I have been thinking that the inner filter was the Achilles heel as it has a much smaller surface area for the air to move through.
The Oka is the only 4wd that I am aware of that uses a safety filter, it is normally limited to earthmoving machinery and large trucks but in these vehicles the filter assy is sized appropriately but on the Oka it seems to be a bit marginal.
Pete
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Peter Fox
OKA 266 Multi-cab.
Photobucket album
May 6, 2012 at 3:11 PM Flag Quote & Reply
Tony Lee
Member
Posts: 539
Hal reported --
"The first two runs, one north and one south but in virtually no wind, were in standard trim. Times from zero to 400m were 30.44 seconds at 74.3km/h, and 33.22 seconds at 66.5km/h.
For the second two runs the air cleaner lid was removed and the large air cleaner taken out. ...Times were 30.68 seconds at 71.7km/h, and 30.00 seconds at 74.86km/h."
Second run may have been little wind, but either a fair breeze or different driving techniques in the first test. Wind direction must have swapped between the tests as well.
Maybe inconsistent driving technique might explain all of it)))
Still, if you do a straight average of each set of two runs, for the 400m, time was 1.5 seconds less and final speed was 2kmph faster without the filter - not earth shattering but hardly trivial either.
--
Tony
picasaweb.google.com/114611728110254134379
May 6, 2012 at 10:17 PM
1 2 Next »
Peter & Sandra James Oka 374
Member
Posts: 412
This all started when I realised that 374 didn't have a rubber seal under the air cleaner lid.
Happened to be talking to Okapete about it and he had a quick look at three Oka's that were at his place at the time and none of them had a seal either. I looked in the parts book and yes there should be a rubber seal between the lid and aircleaner body, otherwise there is no point in the snorkle as air and anything else can easily be sucked into the air cleaner if there is no seal.
So I installed a seal and the next time I drove it it seemed even more gutless then usual, wouldn't rev easily and generally felt restricted.
So I took the lid off and went for a run, well the difference was noticeable, went quite a bit better, boost was a tad higher etc.
So I took the actual air cleaner element out , left the internal safety element in and went for run, bloody hell it goes now!
So then I tried a brand new element out surmising that while the one that was in there looked ok it must be blocked, no the brand new aircleaner element nobbled it as well.
Weird, so I pulled the air cleaner lid off the Humvee which also runs a huge Donaldson style cleaner to have a look inside it to see what was in there as it certainly doesn't have restricted airflow having 4 1/2 inch plumbing in and out.
I noticed that the shield inside the Humvee air cleaner housing is at least 25mm away from the actual element where the Oka one the shield sits pretty much hard against it, the Oka lid shroud also sits very close to the element.
Looking at the air cleaner element that was in the Oka I noticed that it was only dirty/dusted between the two shrouds, a ring around the element about 50mm wide where the airflow is unrestricted.
I had told Keith Harris about it and he had a look at his and found the same setup so decided to do something about it. He cut the inner shroud away just leaving a piece directly below the intake to deflect the air around the cleaner to keep the centrifugal affect and also cut the internal lid flange back to 25mm.
He reckoned the change in how it went was huge so I took the plunge.
I cut the inner shield away, leaving only about 25mm for most of the circumference and then left about 20% of it directly below the actual air intake to keep the centrifugal affect as Keith had done, then did the lid flange back to about 25mm with an additional bit just above the drain fluffer valve. Did it all in situ with a cutting disc on the dremel.
Well the change in engine performance was astounding, previously the boost gauge never went past 9psi and the engine was reluctant, just didn't go, the truck just chugged along and was flat out at 93kph.
After that test drive I was chuffed to say the least, big performance gains for no outlay with the only downside being an increase in induction noise through the snorkle.
While fitting an EGT gauge I also found that the accelerator whilst it was flat on the floor wasn't giving full throttle at the injection pump so after adjusting it correctly I went for another drive, now the old girl really got up and went!
Now boost has gone to around 16-17psi at 3500rpm and it pulls like a train from low down all the way up to max. As soon as we headed out yesterday Sandra said to me "what have you done, it is actually accelerating now!" It will now sit happily on 95-100kph at well under full throttle whereas before max was around 90kph with my foot flat on the floor.
I've yet to check fuel consumption but it seems to be better just watching the fuel gauge, will find out tomorrow as we are on the road again.
So I would bet that 374 isn't the only one with a poorly adjusted throttle cable and trimming the shields inside the aircleaner makes a huge difference to engine breathing and therefore performance.
The fact that just leaving the aircleaner lid off makes it go better is reason enough for a bit of surgery.
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Oka 374 LT Van
November 23, 2011 at 6:05 PM Flag Quote & Reply
Tony Lee
Member
Posts: 539 "the only downside being an increase in induction noise through the snorkle." Worth checking the seal between the snorkel and the side of the cab. I found even an unused screw hole lets a noticeable amount of noise into the cab. Originally the seal was completely displaced and the noise was terrible even with the window closed. Sealing it up with mastic made a huge difference.
--
Tony
picasaweb.google.com/114611728110254134379
November 23, 2011 at 9:35 PM Flag Quote & Reply
Aussie Bight Expeditions
Member
Posts: 109
Question ?
I too once had an OKA that went to 3500 RPM but found the pulley on the alternator was the wrong size. Do you really think that it does 3500 rpm or is that just a typo as mine now at max RPM does 2400 to 2500 RPM. These motors were originally a 1750 RPM or so engine and with the pump redone taken to the say 2400 RPM, or is that just another OKA myth too.
Sounds interesting if you have more HP / Torque.
Regards ABE Tony
--
November 23, 2011 at 11:14 PM Flag Quote & Reply
Cando
Member
Posts: 199
--
Happy trails
Cando and Bron XLT 112
November 25, 2011 at 9:53 PM Flag Quote & Reply
Tony Lee
Member
Posts: 539
Been waiting for the spirited discussion to start, but nary a peep so far.
Can only conclude that it is for two possible reasons.
First is those who are experts and who know about such things are just to polite to break the bad news to the Dremel Duo that the only result of circumcising the inner shrouds of their previously perfectly good air-cleaner is that the engine will fall out on the road sometime pretty soon.
The other possibility is that those who thought they knew about such things and have spent thousands of dollars just so they can pass the odd heavy vehicle or break their drive train more often, have realised that they could have achieved the same result for no outlay other than a little bit of time and effort and they are too embarrassed to admit it on a public forum.
BTW My spares manual does not show any gasket under the lid. I imagine the wingnut done up tightly would result in a metal to metaal seal right around the perimeter.
--
Tony
picasaweb.google.com/114611728110254134379
December 2, 2011 at 9:52 PM Flag Quote & Reply
James & Usha (THEByleDuct)
Administrator
Posts: 161
Tony are you able to post a few pics of your handiwork?
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OKA #072
December 2, 2011 at 10:24 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
We're currently in the Vic high country and 3G signal is patchy especially when you are camped in deep valleys beside running rivers and creeks for days on end, hence the delay in replies.
I can check the RPM with aTiny Tach I have at home and the pics will also have to wait till we return in ten days or so. I suspect they are pretty accurate as it idles at the right RPM and watching boost, road speed and boost all seem to be in sync. Pics inside the aircleaner might be hard to work out as it is all black
)Like Tony I was expecting a barrage of posts but it has been pretty quiet
)Now having driven it nearly 2k since the mods I can say that there is absolutely no comparison between how it was and how it is now.
The first part of the trip was about 600 odd k's down the NSW coast with a 7x4 trailer with cage on top and it easily went far better than without the trailer. We had never previously towed anything with the Oka. Dropping the trailer at the MIL's at Nowra we continued across the southern highlands and down into Vic via the Brindabella's, Kiandra, Cabramurra and then down to Omeo. We travel some of these roads at least once a year so know how they slow vehicles down. Plenty of long pulls and 374 pulled like a train usually climbing most hills on the highway in 4th or even 5th. Of necessity some were taken far slower because of bends and very steep bits but on the whole it went really well. Fuel consumption has increased as would be expected with more throttle and revs available never mind the long hillclimbs etc it still is averaging around 17l/100k.
Boost comes in really low down and by 1500rpm the gauge is showing about 9psi with full throttle and then it just climbs with the revs to 17lb at 3500rpm. As I'm waiting on the fitting for the EGT gauge probe I'm limiting rpm to 3k on the hills and long pulls, it doesn't seem to run any hotter than before on either of the temp gauges (standard one and an engine saver digital one)
Off road in low range it really goes well compared to before when it felt like it would run out of grunt on steep climbs, there are plenty of steep climbs down here,going down I really would like the exhaust brake to be working!
Tony I've been all over the snorkle and theinside cover and sealed all that previously, before the aircleaner surgery I couldn't hear it all in the cab with the window up, now it is just a hum in the background.
Re the gasket unde the aircleaner lid, one parts manual doesn't show it, one does and I asked Alan at Oka and there is supposed to be one there. Mine didn't seal very well at all metal to metal with a 6mm bead of packed dust in the gap on outback roads.
All I can say is if you are wondering about any effect on your Oka, take the aircleaner lid off and try it, some report big differences, some not, then remove the aircleaner and take it for a short run in a "clean" area and see what a difference it makes, the safety inner element will stop the big lumps but not dust.
--
Oka 374 LT Van
December 3, 2011 at 8:28 AM Flag Quote & Reply
Tony Lee
Member
Posts: 539
One of the factors inhibiting lively discussion is the continuing claims of 3500RPM for hours on end let alone a second or two. If the tacho is so far out, it could be that the odometer is also way out and the personal sensation of increased speed and power could be just due to something you ate.
)))Or you have a different engine in your OKA
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Tony
picasaweb.google.com/114611728110254134379
December 3, 2011 at 9:00 AM Flag Quote & Reply
David Hallandal
Member
Posts: 133
I knew of this issue years ago, so I swapped the XT/LT air filter with an OptiAir 1100, the same unit as used in the current NT. I travel at 110km/h on most open roads with a trailer. See my webpage for photos of the old and new air filters.
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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
December 3, 2011 at 9:48 AM Flag Quote & Reply
Hal Harvey
Site Owner
Posts: 510
Re the spirited discussion, I too expected it although I did remember David's original modification to NT standard, just had never done anything about it. However I wasn't going to comment until I had a chance to have a play around with filter in vs filter out, as Peter suggests, and see what I could tell in a relatively controlled comparison. Has anybody ever run their OKA down a drag strip? Kind of embarrassing but all for a good cause. I'll be doing a long drive in clean air sometime in the next few weeks and will see what that can tell me too.
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Hal
December 3, 2011 at 3:55 PM Flag Quote & Reply
Ewart & Vivian Halford
Member
Posts: 117
Hi all I have just gone for a run up the Collie hill, with air cleaner side cover off, then air cleaner out and it made little differance to 365.
Ewart
December 3, 2011 at 4:51 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
I would strongly suggest that as I did you also check that the accelerator is giving you full throttle at the pump.
Not hard to do, open the engine hatch, place right foot on the accelerator, hold it hard on the floor and then check the throttle on the pump has gone fully anticlockwise and is resting against the stop on the passengers side. There is adjustment on the actual accelerator cable connection to the pump linkage but if it is adjusted fully as mine was then you may have to bend the actual pedal upwards a little bit as I did. All doable in the truck, one person with a big shifter holding the pedal near the pivot point and the other on the end bending it very slightly.
Re the engine RPM there is webpage where you can put gear specs in and get rpm per distance.
I have an electronic speedo with tripmeter which has been calibrated over a set kilometre so I know it is accurate, also checked on the road with the GPS, which just leaves the tacho accuracy which i will check in a fortnights time with the Tiny Tach.
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Oka 374 LT Van
December 3, 2011 at 5:27 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
I've had a squiz in the owners manual and on the net and while I've found nothing definative max power is at 2800rpm so i would imagine that max rpm is not much higher which means the tacho is telling big porkies.
Will find out when I connect an external tacho.
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Oka 374 LT Van
December 3, 2011 at 7:17 PM Flag Quote & Reply
Hal Harvey
Site Owner
Posts: 510
Peter, any chance of some pics of this surgery?
I haven't had the chance to make a long drive in clean air for comparison, but I did get to confirm that #260 has no rubber seal, and it does have an inconsistent pattern of red dust on the big filter.
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Hal
January 30, 2012 at 7:25 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
I'll try and remember to take some.
I have tried an external tacho and the tach is way out, is ok at idle but the error climbs as the tacho climbs to be indicating 3500rpm when in fact the max revs are in the order of 2800rpm.
I did jot down engine revs at different road speeds, it is in the truck and will post them later.
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Oka 374 LT Van
January 30, 2012 at 10:07 PM Flag Quote & Reply
Tony Lee
Member
Posts: 539
Bought an Aldi el-cheapo version of a dremel the other day so ready to perform surgery on the aircleaner - just as soon as I get some time to spare
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Tony
picasaweb.google.com/114611728110254134379
April 2, 2012 at 10:21 PM Flag Quote & Reply
OKA in Africa
Member
Posts: 34
I would like to buy and install a VDO boost gauge for the turbo pressure. Do you have any recommendations which pressure range gauge I should buy? Some gauges have a range of negative and positive pressure, others only positive pressure.
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OKA 327 in Africa
photo album
April 3, 2012 at 9:58 AM Flag Quote & Reply
Tony Lee
Member
Posts: 539
Cut 60mm off the inner sleeve and 30mm off the lid sleeve so will see if it makes any major difference. No fancy angled cuts - just straight around so the inner sleeve still covers the part under the inlet so the centrifugal effect shouldn't have changed too much.
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Tony
picasaweb.google.com/114611728110254134379
April 3, 2012 at 8:46 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
Oka in Africa, I just fitted one I had which goes from 0-15psi and it wasn't enough at the higher end, it goes around to about where 17 psi would be
)I'd go for just a positive 20psi which should be enough, possibly more important though is an EGT gauge especially if you intend to adjust the fuel delivery. From what I've been told and seeing what I get on 374 normal running temps at 100kph are anywhere from 400 to 550 deg C, making it lug a bit in the gear with high throttle inputs see it climb up to 630 deg C. changing down a gear and raising the revs brings it back down rapidly. I've been told that up to 650 is ok for short stints - less than a minute but you shouldn't keep it above that and 750 is terminal.
I bought the EGT gauge from www.auberins.com , model SYL-1813. you can actually use the same gauge for either boost or EGT but not both at once. They will fit in the standard round dash blanks with a bit of careful cutting and then clip the round blank back in the hole in the dash. You also need to buy the necessary probe and wiring for whatever you are using it for. They come in different display colours, dim when the dash lights come on and have an adjustable alarm point. Auberins also ship promptly.
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Oka 374 LT Van
April 4, 2012 at 7:26 AM Flag Quote & Reply
Dandj
Member
Posts: 367
Peter, very useful EGT info.
Which probe did you get and how did you connect it in?
Like many US companies, the Auberins website provides a myriad of options.
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David and Janet Ribbans, Oka 148
April 4, 2012 at 7:56 AM
Peter & Sandra James Oka 374
Member
Posts: 412
David I just bought one of their complete kits, gauge (red display) and probe, used the 1/8 NPT (TC-KEGT-NPT ) probe and drilled and tapped the manifold about 130mm in front of where it comes out of the turbo,right on the bend. I'll stick a pic up in my album. I had a NPT tap but they also sell a probe with a 1/4 BSP fitting as well. Very easy to drill and tap the manifold it's about 3/16" thick.
I drilled and tapped the inlet manifold to fit the boost gauge as well, just did it right on top towards the front.
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Oka 374 LT Van
April 4, 2012 at 2:01 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
David pics are up, think it might be less than 130mm from turbo looking at the pic, was just above the number cast onto the manifold anyway.
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Oka 374 LT Van
April 4, 2012 at 2:15 PM Flag Quote & Reply
Dave and Pauline Gray
Member
Posts: 84
Peter interesting topic but could you tell me if the fitting instructions for the probe stated the exhaust manifold is a prefered point and I ask this because with all the trucks I have had any thing to do with the probe has been fitted on the outlet side of the turbo in the exhaust to muffler section within 6inches of the turbo. I have refrained from fitting a pyerometer to mine because I could see I would probably have to fit a new exhaust line and this one will probanbly last a fair while but might not take to kindly to drilling and then welding the probe holder in place .
Cheers Dave
April 4, 2012 at 2:35 PM Flag Quote & Reply
Peter & Sandra James Oka 374
Member
Posts: 412
Dave I was told to mount the probe within six inches of the turbo outlet which in the Oka's case is a cast manifold which is then connected to the exhaust.
Any further away from the turbo and there is too much temperature drop to make the readings meaningfull. As it is the combustion temps seen post turbo would still be far less then the cylinder temps.
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Oka 374 LT Van
April 4, 2012 at 7:19 PM Flag Quote & Reply
Dave and Pauline Gray
Member
Posts: 84
Peter you have got it spot on I misinterpreted your explanation and to be honest I forgot about the cast manifold on the outlet side, your fit should be fine .
Cheers Dave
April 4, 2012 at 7:27 PM Flag Quote & Reply
Hal Harvey
Site Owner
Posts: 510
>> All I can say is if you are wondering about any effect on your Oka, take the aircleaner lid off and try it, some report big differences, some not, then remove the aircleaner and take it for a short run in a "clean" area and see what a difference it makes <<
I finally got to do that yesterday. A friend has a PerformanceBox, which we attached to the windscreen and in our limited time available, did four runs along a flat stretch of freeway. The standing start was achieved from the emergency lane, and despite light rain, two of OKA's more questionable joys were employed: we didn't suffer any wheelspin, and we didn't break the speed limit.
The first two runs, one north and one south but in virtually no wind, were in standard trim. Times from zero to 400m were 30.44 seconds at 74.3km/h, and 33.22 seconds at 66.5km/h.
For the second two runs the air cleaner lid was removed and the large air cleaner taken out. There was immediately heaps of induction noise that I don't normally have, so evidently the sealing that I do have is good (although I don't have a rubber seal on the outer lid). Times were 30.68 seconds at 71.7km/h, and 30.00 seconds at 74.86km/h.
Make of that what you will!
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Hal
May 6, 2012 at 11:52 AM Flag Quote & Reply
Pete Fox
Member
Posts: 140
Hal
I would really like to see someone try the same thing with the outer in place and the inner filter removed. I have been thinking that the inner filter was the Achilles heel as it has a much smaller surface area for the air to move through.
The Oka is the only 4wd that I am aware of that uses a safety filter, it is normally limited to earthmoving machinery and large trucks but in these vehicles the filter assy is sized appropriately but on the Oka it seems to be a bit marginal.
Pete
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Peter Fox
OKA 266 Multi-cab.
Photobucket album
May 6, 2012 at 3:11 PM Flag Quote & Reply
Tony Lee
Member
Posts: 539
Hal reported --
"The first two runs, one north and one south but in virtually no wind, were in standard trim. Times from zero to 400m were 30.44 seconds at 74.3km/h, and 33.22 seconds at 66.5km/h.
For the second two runs the air cleaner lid was removed and the large air cleaner taken out. ...Times were 30.68 seconds at 71.7km/h, and 30.00 seconds at 74.86km/h."
Second run may have been little wind, but either a fair breeze or different driving techniques in the first test. Wind direction must have swapped between the tests as well.
Maybe inconsistent driving technique might explain all of it
)))Still, if you do a straight average of each set of two runs, for the 400m, time was 1.5 seconds less and final speed was 2kmph faster without the filter - not earth shattering but hardly trivial either.
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Tony
picasaweb.google.com/114611728110254134379
May 6, 2012 at 10:17 PM
David and Janet Ribbans - Oka 148
Oka148 profile here.
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