HDJ 100 4.2 TD upgrade ? (1 Viewer)

Joined
Jul 30, 2009
Messages
147
I am a ling term owner of my HDJ100 4.2 TD and have been toying with the idea of a mild improvement for a number of years. Lockdown fever has given me some time to consider options and look at the facts. I am not an automotive engineer and would like to get input from ‘those in the know’

1) How the factory set up works
The ECU is mapped from factory but has a number of adjustments built in such as short term fuel trim and long term fuel trim. These allow based on the operating conditions (say outside temperature which influences air density) to adjust fueling to maintain the target Air Fuel Ratio (AFR).
The factory map may be common to all countries and may be set conservatively (e.g. running rich especially at low rpms) to accomdate lower quality fuels (is that correct or a myth ?)
Engines produce peak power when the stochiometric ratio is optimun which for a diesel equals an air to fuel of 14.5:1
Adding fuel without adding air makes the mixture rich but doesn’t increase efficiency. You get marginally more power but produce more smoke and mpg goes down. Rich is safe for an engine perspective bit wasteful on fuel. Reducing richness to optimal afr increases power assuming the fuel is good enough to avoid potentially damaging lean situation.

2) what to do ?
Turbocharging is interesting in the sense that adding boost allows more air into the engine, enabling extra fuel and assuming you hit optimal afr then you create more power.

Staying within the limits of the stock set-up (injectors and turbo), it seems the most effective idea is a waste gate adjustment or a boost controller. Both would allow to increase the max boost provided by the turbo which in turn will provide more air to the engine when it is fully spooled up. There are limitations to the stock turbo (see graph)

But it seems that boosting rpm by 20% sort of still is within the reasonnable efficency point. That will however only work at top end boost. To affect the low end one may want to modify the turbo (different intake turbine to spool up faster etc).
However, on the exhaust side, running higher pressure will lead to increased temperatures. The stock turbo downpipe is an interesting point here because it acts as a bottle neck and also includes the catalyst which tend to suffer from heat which exceeds design paramters.

Replacing the downpipe for a wider diameter (from stock 2.5’ to 3’) and using sport cats which offer less flow resistance seems to be the correct way to avoid excessive exhaust gas temperatures.

So increasing boost by modifying the wategate (stiffer spring or boost controller) and avoiding excessive heat buildup through new downpipe looks like a cheap and effective way to probably pick up 10-20% extra power within the limits of the stock system.
Better intercooler can be added to add cooler / denser air and obviously bigger turbo but then you need to upgrade injectors and at that point the stock ECU is also running out of adjustment headroom. At that point, you probably need a full motec set up etc... not my objective

3) Piggy back units
For years I have been fascinated by these units like unichips. There are tons of dyno graphs and you tube videos.
Fundamentally I see how such unit can alter ecu signals to adjust fueling given various circumstances. But as long as no extra air is provided, i am not sure how much real effectiveness there is. What I can see is:
- they take out excess richness at low rpms which gives more power (and better mpg)
- they add more fuel which gives slightly more power but at less optimal AFR so efficiency goes down. Black smoke isn’t my cup of tea
- they can fuel to full throttle when you are only using part throttle giving the impression of more power
- they can be used to adapt the factory ecu to run a non stock set up (eg bigger turbo, intercooler etc).

While the piggy back will modify stock ecu instructions to the injectors, it will not affect the read the stock ecu makes from the lambda sond (I think, may be I am wrong). So the ECU may want to correct what it will perceive as overfuelling. So the piggy back unit will need to be set up so it can counteract that on a dynamic basis otherwise one gradually comes back to the previous situation.
Note: that may not necessarily be true in all cases as i understand that in wide open throttle position, the ecu may stop checking paramters. But we are not flat out all the time.

Where I stand ?
For a mild improvement, I think I will go for downpipe and wastegate mod. This is a low cost solution (less then 100gbp if diy and removing cats, more expensive if sport cats are used) I can understand how it works and stock ECU should be able to manage. Essentially that means that every day will be a nice cold day where the air is denser so more is available for combustion.

Adding a unichip is definitvely a different spend. The units can be bought for diy install but retail at 1000 gbp and you rely on the default map. Given the above, I see how this could correct some excess richness but then you will simply dumping more fuel. So you get into the diminishing returns and lower efficency / mpg
You need to find a unichip tuner to adapt the mapping to your own engine and with the car in france where I can’t find unichip dealers that is not practical.

Would like to hear the view from the TD experts on the forum.

77BECD62-8A71-4E2E-BAC7-A2CB83982D79.png
 
Joined
Mar 11, 2019
Messages
447
Location
80 Series 1HD-FT
Let me know how running at 14.5 AFR goes? May as well throw your rear vision mirror away ;)

No stock FTE would be anywhere close to that, most the ones I've seen have been well above 22:1. Also rich is actually unsafe and lean is safe, it's different to petrol which i think you may be getting mixed up with.
 

AussieHJCruza

SILVER Star
Joined
Jul 8, 2013
Messages
1,918
Location
New South Wales, Australia
Yeah, stoich on a diesel won't go so well for you. On a factory petrol engine, yes the tune is generally on the rich side. Rich is safe in a petrol, but a diesel is the polar opposite.

From what you've said I suspect you're not familiar with diesel tuning, would recommend getting familiar with diesel specific details rather than generic petrol stuff.

What are you looking to gain? Are you after as much power as possible or a bit more poke and better economy, or just for the sake of modding something?
 

Nz Nath

SILVER Star
Joined
Dec 16, 2017
Messages
135
Location
Northshore, Auckland NZ
Besides looking up general diesel tuning info, I'm pretty sure there's also very easy to find info specifically on getting more performance from the 1hdfte motor. There's plenty of aussies getting stupid high torque and power figures out of stock motors and injection pumps.
 
Joined
Jul 30, 2009
Messages
147
My objectives are:
- 20-30% increase in torque esp low rpm
- best reliability bearing in mind the car is a 98 and has 165k miles on it. While I maintain it seriously, it’s not brand new
- budget is gbp 1.5-2k

For that budget I guess I could do the downpipe and unichip. But I can’t find and clear source of information about how unichip works on these and there arent unichip tuners in france so would rely on their stock map for the car.

I have also looked at Gturbo grunter I could get from Australia. Even with import duties it is cheaper than what I can source in france (hybrid ct26 turbos from reputable firms are 3k). They do a package with an ecu but again not tuned specifically. I have no confidence in the mambatek / kinugawa turbos but perhaps this is unwarranted. They are very competitively priced for sure.

In france there is a tuner called Adonis technologies who sells an ecu. Doesn’t seem to include boost control and claims 250 for the street version. There are some negative reviews in some french websites

So the three options are:
- forget about it as my objectives can’t be met
- do something as above
- do something else

Really I am looking for guidance
 
Last edited:

AussieHJCruza

SILVER Star
Joined
Jul 8, 2013
Messages
1,918
Location
New South Wales, Australia
My objectives are:
- 20-30% increase in torque esp low rpm
- best reliability bearing in mind the car is a 98 and has 165k miles on it. While I maintain it seriously, it’s not brand new
- budget is gbp 1.5-2k

For that budget I guess I could do the downpipe and unichip. But I can’t find and clear source of information about how unichip works on these and there arent unichip tuners in france so would rely on their stock map for the car.

I have also looked at Gturbo grunter I could get from Australia. Even with import duties it is cheaper than what I can source in france (hybrid ct26 turbos from reputable firms are 3k). They do a package with an ecu but again not tuned specifically. I have no confidence in the mambatek / kinugawa turbos but perhaps this is unwarranted. They are very competitively priced for sure.

In france there is a tuner called Adonis technologies who sells an ecu. Doesn’t seem to include boost control and claims 250 for the street version. There are some negative reviews in some french websites

So the three options are:
- forget about it as my objectives can’t be met
- do something as above
- do something else

Really I am looking for guidance
165k is a non-issue. I'd suggest starting with a full 3" exhaust. See what you think after that
 
Joined
Jul 30, 2009
Messages
147
Thank you. I recently changed the back end the exhaust which was corroded around muffler. New part is oem.
Would focusing on the downpipe and center part be an option ?
I also really want to retain catalysts to ensure I remain compliant (egr was binned a few years ago)
 
Joined
Mar 11, 2007
Messages
2,352
For those sort of gains you need a uni chip. I have a 3'' exhaust, Safari intercooler, Armax snorkel and raised boost, at best it builds torque slighlty earlier and is more responsive. For anything meaningful, you need to tune it.
 
Joined
Feb 26, 2007
Messages
522
Location
CO USA
It isn't my truck or my money but if it was I would add:

Gturbo Grunter Extreme with the Gturbo piggyback computer tuned to accommodate for about 22-24PSI of boost
3" exhaust from dump pipe all the way back to the tailpipe to maximize air flow outbound
Upgrade to a larger intake airbox (similar to Moonlight Fab box) to maximize air flow inbound

Drive it and enjoy the increase in zip and economy.
 
Last edited:
Joined
Sep 30, 2014
Messages
492
Not sure if the FTE is better than the FT in regards to dump pipe, but I’d be upgrading the dump when you do the exhaust. Very little point having a 3” system with a 2.5” dump pipe...
 
Joined
Jul 30, 2009
Messages
147
Thank you for the feedback
The downpipe is definitvely on the list
Any thought about the standard program for the unichip ?
Does unichip control the boost of the turbo or not ?
 

Indestructible 47

SILVER Star
Joined
Jun 23, 2014
Messages
1,229
Location
Straya
Thank you for the feedback
The downpipe is definitvely on the list
Any thought about the standard program for the unichip ?
Does unichip control the boost of the turbo or not ?
Not on a wastegated turbo. The ECU takes a boost reading that the chip will use, to control the fuel delivery. To adjust the boost, you need an adjustable boost controller.
 
Joined
Jul 30, 2009
Messages
147
Not on a wastegated turbo. The ECU takes a boost reading that the chip will use, to control the fuel delivery. To adjust the boost, you need an adjustable boost controller.

Ok understood. So I could just change the spring of the wategate to move the turbo boost a bit and unichip will reduce fueling if the temps get out of hand.
What is the safe boost level for a stock CT 26B ? I think I read the stock is 11-12 psi. So stiffer spring to boost to 15-16 psi should be safe enough ?

Any thought about standard unichip map vs custom tune ?
 

Indestructible 47

SILVER Star
Joined
Jun 23, 2014
Messages
1,229
Location
Straya
Ok understood. So I could just change the spring of the wategate to move the turbo boost a bit and unichip will reduce fueling if the temps get out of hand.
What is the safe boost level for a stock CT 26B ? I think I read the stock is 11-12 psi. So stiffer spring to boost to 15-16 psi should be safe enough ?

Any thought about standard unichip map vs custom tune ?
I've been there and done that with my fte. Stock the turbo is good for 14psi Max imho. I would forget changing the wastegate spring, just install a boost controller. I would be custom tuning the unichip, every vehicle is different. Make sure the afrs are good, and install a quality egt probe.

In my experience, the performance available through the stock turbo isn't much better than stock at a safe AFR. Unfortunately, there is no good and cheap way to get power out of cruisers. If you want to spend money, they are a great platform.

As soon as you do turbo, with an auto you should be doing a bigger trans cooler and a valve body, clutch on a manual.

Keep in mind, fuel is power. So reducing fuel to keep the egts safe is going to be disappointing for you.
 
Joined
Jul 30, 2009
Messages
147
Ok thank you
I think for now I will focus on the downpipe and center exhaust. At least one can’t go wrong with that.
 
Joined
Mar 26, 2012
Messages
281
Location
Australia, NSW
I’ll play devils advocate here - I don’t think there’s much to be gained changing the dump pipe. It’s actually 2.75”, and most tuners here (Australia - the land of the landcruiser) say the dump pipe is not restrictive and doesn’t make a measurable difference swapping out to a bigger one.

Upping the boost to 16psi, especially along with a 3” exhaust, high flow snorkel, egr delete and intake clean and maybe IC upgrade will give you some performance increase. Also you’d pick up a little fuel usage improvement and the engine will thank you.

Next up is a good chip and upping the boost to 18psi. The turbo will still be ok and and quite a respectable power increase can be had from just this and a uni chip/DTE.

Lastly if you want big power you need a Gturbo/equivalent UFI, upgraded injectors, better FMIC and upgraded air box
 
Joined
Jul 30, 2009
Messages
147
Really the dump pipe isn’t restrictive ?
It’s oem with the catalyst in it.
I was thinking bigger and switching to hi flow catalyst. That alone should make an difference.

My current view is that dump pipe plus unichip plug and play. If someone feels I am making a mistake, please let me know !
 
Joined
Mar 26, 2012
Messages
281
Location
Australia, NSW
Really the dump pipe isn’t restrictive ?
It’s oem with the catalyst in it.
I was thinking bigger and switching to hi flow catalyst. That alone should make an difference.

My current view is that dump pipe plus unichip plug and play. If someone feels I am making a mistake, please let me know !
We might have a mix up of nomenclature. The dump pipe is the short elbow that adapts the back of the turbo to the exhaust. A catalytic converter has its own chamber in a separate part of the exhaust. One of the reasons the dump alone doesn’t make any measurable difference (unless you’re chasing massive massive power) on its own is its so short.

If you’re talking about replacing the whole exhaust including a cat then yes gains are certainly there to be had and I’d almost say it’s pointless chasing any power upgrade without starting with the exhaust
 
Joined
Jul 30, 2009
Messages
147
Perhaps there is a different spec in australia bit in europe, the catalyst is in the downpipe. One of the popular mod is to replace with a downpipe that doest (so called african spec in france)

F41D541F-3314-41A3-8067-26F09CF1A48E.png
 
Joined
Feb 26, 2007
Messages
522
Location
CO USA
Throw the existing Factory exhaust in the garbage and go 3" diameter from the dump pipe to the tailpipe and be done with it. Add a high flow muffler if you'd like while you're at it.

Replacing sections here and there won't do much aside from cost you time and money for little to no improvement in performance.
 

Users who are viewing this thread

Top Bottom