1hz turbo. DTS or Denco? oil or water cooled?

Submitted: Thursday, Mar 03, 2016 at 23:47
ThreadID: 131740 Views:10528 Replies:6 FollowUps:2
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hey i just got a turbo kit fitted to my hzj105 today. car was booked in for a DTS kit and exhaust and dyno tune. when i got the car home i found that a Denco turbo kit had been fitted. phoned the place it was done and they said DTS was bleep and had a lot of overheating issues and Denco was better.They all so said the that oil cooled turbo were better then watercooled one when i comment that the denco was only oil cooled. im not happy with the change in kits but unsure if its worth making a fuss over it.
dose anyone have any feedback on the 2 kits or on the turbo cooling type before i go see them tomorrow? thanks
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Reply By: racinrob - Friday, Mar 04, 2016 at 07:07

Friday, Mar 04, 2016 at 07:07
I can only reply on personal experience, I had a DTS water cooled turbo fitted to my HZJ75 at 100K and did another 300K without any problems. No rundown time at the end of a long haul.

AnswerID: 596942

Follow Up By: B1B2 - Friday, Mar 04, 2016 at 12:13

Friday, Mar 04, 2016 at 12:13
I also had a DTS fitted on the 1Hzzz at 85,000 and now at 280,000 without a problem including a lot of towing. After a long highway run I just don't shut down straight away. Boost is on the low side at 10psi.

FollowupID: 865941

Reply By: Malcom M - Friday, Mar 04, 2016 at 07:17

Friday, Mar 04, 2016 at 07:17
Perhaps ask the question at lcool.org
Lots of expertise there.
AnswerID: 596943

Reply By: Member - Rob 49 - Friday, Mar 04, 2016 at 08:06

Friday, Mar 04, 2016 at 08:06
Hi Tim
I would suggest that the reason for fitting the Denco unit instead of the DTS is called "MARGIN". The rest of the story sounds like fuzz. By the way, both are excellent units. Sorry to be so sarcastic.
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AnswerID: 596948

Reply By: Rob K (VIC) - Friday, Mar 04, 2016 at 09:14

Friday, Mar 04, 2016 at 09:14
Hi Tim,

If I was in your shoes I wouldn't be happy either! If you asked for a DTS kit and got something else the least I would expect is a heads up.

Now to give some feedback to your questions:

I have a 2003 HZJ105 with a AXT Turbo + 2.5 inch exhaust. It's done about 150,00 kms since it was installed. I have had no issues with the setup and she's just ticked over 230,000 kms. It's a Garrett, water cooled turbo and I fitted an air-over-water intercooler about 12 months after the turbo was fitted to help with exhaust gas temperatures (EGT). I've also fitted a boost and EGT gauge to monitor the turbo's behaviour while driving.

The 1HZ doesn't like running high exhaust temperatures (say 500+ degrees C) for extended periods without long term issues cropping up down the track. The air fuel ratio is the only variable that a workshop can play with on these motors and this is achieved by balancing fuel load and boost. I've got mine set at 12psi boost (max) with the intercooler and this keeps the EGT around 450 degrees under load. If it gets higher than this, I back off on the "go peddle" to keep EGT's below 500 degrees. Pre intercooler, the boost was set at about 8 psi to keep the EGT's under control. I'd recommend you install some gauges in your 4WD to monitor the turbo as well.

The DTS kit installed by MTQ in Melbourne is often tuned for maximum performance (read into this higher fuel load and higher boost) to get the biggest improvement in performance. If that is normal practice for a DTS kit I could well understand the comments about higher temperatures. I had MTQ in Melbourne do a dyno tune on my 4WD some time back and yes, got the power improvement but found the EGT's went up too high and the fuel consumption went up a fair bit as well. Ended up taking it back to AXT to "de tune" it so I had a better balance between fuel economy, power and EGTs. Ultimate power is not my priority, responsiveness when highway cruising and descent fuel economy are my main objectives. You might want to reflect on your reasons for the turbo with the above in mind.

Water cooled is considered better than oil cooled because the oil doesn't "cook" in the turbo galleries when the engine is turned off and the turbo is still very hot. Can lead to eventual blockage of galleries (I believe) and a blown turbo. This feedback is not based on personal experience, just research I did when first considering the turbo upgrade. If you have the oil cooled turbo, a turbo timer might be a good investment to cool things down before stopping the engine and oil flow, particularly after some hard work by the engine?

Fitting a turbo to the 1HZ, which is not designed for positive air induction, needs to be undertaken with an understanding of the impacts the turbo has upon the old motor. Keep the boost, fuel load and EGT's down and you'll have many years of improved performance without issues. Push the old girl to its limits and wait for the big bang. The 1HZ does need some TLC for longevity if a turbo is fitted.

Hope you sort out the situation with your workshop.


Rob K
AnswerID: 596949

Follow Up By: Member - WBS - Sunday, Mar 06, 2016 at 10:04

Sunday, Mar 06, 2016 at 10:04
With the exception of fitting an intercooler, your experience with the 1HZ engine matches mine. I had an AXT turbo fitted to my 80 Series. You have pretty much encapsulated my thoughts too.
FollowupID: 866037

Reply By: ExplorOz Team - Michelle - Friday, Mar 04, 2016 at 14:48

Friday, Mar 04, 2016 at 14:48
Here's an interesting article, plus video clip (your model) Turbo Charging the 1HZ engine.

We have the '97 GXL 80 - 4.2D manual and fitted a Denco turbo AND and EGT gauge in 2004. Best thing we ever did. Would highly recommend the Denco.
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AnswerID: 596970

Reply By: maurice b - Friday, Mar 04, 2016 at 21:08

Friday, Mar 04, 2016 at 21:08
I would be taking it back and ask for what you wanted .I have had a Switzer Denco kit on my 1hz for over 200k at 12psi, 3inch exhaust. I though it was way underpowered compare to my mates with a DTS kit .I then fitted there water to air intercooler kit including a boost compensator, had to change turbo housing for more flow. The barrel intercooler was useless due to the size of the heat exchange radiator.It was tuned properly and the fuel comp was set up to run air fuel ratio of 21 to 1 at 14 psi max at 500 egt under heavy load. Still would not match the power of the standard DTS kit .My fuel consumption was 17l/100 on trips with gear in my vehicle. I ended up upgrading motors .However there's 1000s of 1hz out there running 140+ kw at the rear wheels with long engine life expectancy. There's more to tuning a turbo diesel engine today than just adjusting the fuel screw. I personally think the best turbo kit on the market for the 1HZ for power and economy is the Gturbo kit made in WA and almost same price as DTS
AnswerID: 596991

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