1HD-T towing observations - high EGTs

[gbentink]

All my turbo testing is done towing.....wait for it..... up to 9000lbs but it weighs 6100lbs empty and can carry 1100lbs of water alone! I realise this exceeds the manufacturers vehicle ratings, but its my truck and risk and more than 30,000kms has been done on current engine in this config.

look at Offroad Caravan Hire in Perth | Bushtracker Hire to see the caravan - thats my website

Ive just returned testing the new Grunter 2 at up to 30psi for 7200kms. My goal is to stay in overdrive down to 80km/h (1600rpm) up most hills and never go lower than 20:1 AFR's.

I use the caravan because it is real world conditions and on a long hill gives a better idea on safety of tune, reaching design goals etc. The same on a typical dyno will overheat the dyno (that has ben my experience).

So, as far as engine performance and long heavy hauls, I believe that know what I am talking about. Now, I used a 100 series on this trip, but the same is true for the 1HDT in an 80 or 100 as I have used them all.

The owner of Bushtracker is an American fellow and drives F250/350 Dodge Rams etc etc and won't sell a caravan bigger than mine to a Landcruiser owner, but mine out pulls a 7.3 F250 easily! The last hirer of my van had a mildly chipped F250 7.3 to which he showed me a dyno printout (230whp if I recall correctly) and I took it for a drive with van in tow. I was really surprised how lacking it felt - I was expecting a while lot more for all the massive exhaust noise! I am glad I have a boosted 4.2 Toyota Diesel! Oh, the economy was at least 10% better as well. I tow at 100km/h up and down hills, mostly in overdrive but not possible up some. Never outside of 1:1 gearing above 1600rpm (4th on manual). With no wind, I use 18-18.7L/100km as measured by fuel bowser andy GPS.

Pre turbo EGT's that are safe vary a lot from say 1800rpm to 3000rpm in terms of what is safe. I have pre and post EGT probes. Factory from Toyota you will see 750C pre turbo on a long haul.

As far as damage to factory turbo, I would like to say that the damage is twofold:
*overspeed (the biggest problem) - comp wheels fly apart
*boost wearing thrust bearing and damaging the oil seals

So, adding an intercooler and 3" exhaust means that at the same boost setting the turbine rpm is higher at a given engine rpm. So, from an overspeed perspective, the stock comp wheel is in a more dangerous condition on an intercooled and big exhaust mods compared to same boost on stock exhaust/no intercooler.

The boost level aspect is thrust pressure and that is simply boost related.

FYI, Im trying high flowed injectors in the next few weeks - that will be a first for me.

Dougal,
you and i have been down this road in the past ...
we will agree to disagree.
until you are willing to replace peoples trans then those numbers are an unwise suggestion to agree with.
he will tow what he feels comfortable with.

 

[crushers]

(still won't recommend over 3500 lbs)

"I use the caravan because it is real world conditions and on a long hill gives a better idea on safety of tune, reaching design goals etc." now this statement i agree with, real world testing.

 

[blis]

(still won't recommend over 3500 lbs)

"I use the caravan because it is real world conditions and on a long hill gives a better idea on safety of tune, reaching design goals etc." now this statement i agree with, real world testing.

You do realize hj is rated for 3500kg tow-weight...

 

[crushers]

here is what i realize,
there have been a few in Canada that have bought the HDJ81 for towing their 5000 lb - 6000 lb trailers and selling them after a year and buying a real tow vehicle because of their findings at the wheel.

what something is rated for and what something is comfortable at accomplishing can be two different results.

i can tow 18,000 lbs with my 7.3 (did so for 5000 km ...)
the engine and the truck can accomplish the task, i am not comfortable doing it.

<i did not want to turn this thread into a towing debate like that last 3B rated debate>

 

[Tapage]

Those transmissions last fine in heavy towing. 80's and 100's are the most common tow rig here for caravans, boats and horses. .

you can see here too .. but I'm agree with Crushers .. that does not mean they ( 80 and 100 ) are happy doing .. just remember the environment conditions do huge effect in TDI engines .. while been here, with pretty hi humid and overall temp towing it's pretty tuff on engines and trannys ..

 

[Adam B]

Ive just returned testing the new Grunter 2 at up to 30psi for 7200kms. My goal is to stay in overdrive down to 80km/h (1600rpm) up most hills and never go lower than 20:1 AFR's.

Graeme, at what maximum elevation were you pushing 30psi?

 

[gbentink]

Hi Adam, sea level. Ambient temp up to 33C.

Also, hills here in flat Perth are not the same as overseas. We could both be talking "steep hills" and they could be significantly different.

Thus, towing experience, particularly in non modified auto 80 series, will vary.

I could well imagine unhappy owners with overheated auto boxes in the 80 and would recommend switchable TC lockup in 2nd and up.

*EDIT*

I would also reccomend a great intercooler, 20psi boost, by 1700rpm without going lower than 20:1 AFR's and the lockup. You will have a towing dream! Long windy steep hills, kept around the 1600-2000rpm range are so much fun and the mods mean your 80 or 100 just eats it up all the while delivering great economy for the service conditions

 

[mudgudgeon]

Graeme, at what maximum elevation were you pushing 30psi?

Altitude in Aus would be (at a guess) mostly insignificant for tuning.
Our tallest "hill" is 2229m total elevation, with most significantly less than that. 1000-1500m is considered a mountain over here

 

[Adam B]

Dave - that's exactly why I ask. Our big "hill" in BC (for most of us) is the Coquihalla Highway, which takes you from close to sea level up to 1442m or so. That's about 4000'. On some of my driving I get up to about 5000' but that's the limit.

I'm wondering about pressure ratio, not AFRs. Elevation can be relevant to tuning, depending on how deep you want to get into it, but it's turbo destruction I'm considering....

For every 1000' of elevation gain the atmospheric pressure drops .5psi. If you calculate pressure ratios, 30psi @ sea level is about a 3:1 pressure ratio, equivilent to 24psi at 5000'. If I take a turbo that he's tested at 30psi at sea level and try running it at 30psi at 5000' I just might be approaching a limit. That's like him boosting 36psi at sea level with that same turbo.

 

[gbentink]

Adam, as you suggest there is an issue with compressor overspeed potentially on the basis of pressure ratio. In fact, I'm not too close at sea level and 30psi at 2500rpm however at 3500rpm would be getting close. However, the turbine side won't flow it for that spec. At 3500 I could get 1.8 Bar max. It is a nice safety management method. Additionally, the reason I test at such high boost is to account for customers at higher altitudes and to check turbine drive and turbine shaft strength at high torque. I would test to 2.2 Bar however my boost controller doesn't support it. In fact I usually don't go right up to 2 Bar because the boost controller alarm goes off and boost goes back to wastegate setting. This is most annoying when Travelling up a hill, towing 4t (8800lbs) while passing a truck with 4 trailers - sudden loss of torque equals shock for driver.

So, in essence, I usually ask the customer what altitude they usually drive to and what is the maximum. Based on that information and others, I select housing mods, turbine and compressor spec. Back calculate shaft speed and flow etc.

I have towed with the first spec Bad Boy at 1.7 Bar up to a town called Threadbo. I can't remember the elevation but if I recall correctly it is around 1500m asl.

 

[mudgudgeon]

Thredbo is lower than that ~1350m from memory, but you cross passes a little higher than that to get there.


Greame, are you saying turbine flow capability is limiting compressor speed, giving a safety margin?

 

[gbentink]

In the case of the G2, yes, the wastegate flap blows open by itself with backpressure. I shouldn't call it a failsafe, but it helps.

It happens around the 1.7-1.8 Bar and 3000-3300rpm range, where as the comp wheel efficiency falls away and turbine flow is exceeded. It's a nice balance.

It's kind of academic, I mean I dynoed the G2 the other day on 1HDFT and made 139rwkw at 2000rpm (750nm at crank) 172 at 3000 and 169 at 3500. So, for exceedingly spirited driving (for a heavy, old 4.2 diesel) I seldom had the need to push high in revs.

New injectors are being fitted in 1-2 weeks - 100% more flow than stock. I'm building a 300whp at 3000rpm, 35psi turbo for myself for testing - the "Head Kicker". My goal is 310hp, just "because". I'm capping torque at 850nm to hopefully not break the trans. Based on that, 150-160kW will be the 2000rpm limit. If I can tune more than 550nm into it at 1600rpm I will be most pleased. I had the custom parts made ages ago, so will be nice to finally test it.

This is of course relevant to the thread because more torque/power = better towing

 

[Tapage]

Graeme .. you still have factory IC on your 100 with FTE .?

 

[gbentink]

Graeme .. you still have factory IC on your 100 with FTE .?

No, did away with that a long time ago. It didnt make a huge increase in power (at that point, 16psi), however the power was more consistent when vehicle was hot compared to cold or outside air temp was hot or cold (morning/evening etc).

In addition, the stock intercooler pipes are no good for much more than the stock 14psi. I retained one of the rubber hoses at one point (a long hose ~ 300mm long) thinking OEM would be really great; but it burst spectacularly at a time when I really needed it.... towing the caravan up to Australias highest town (Threadbo) on one of the steepest sections.

 

[gerg]

Hehe I know how you feel. I had a hose burst in the interior towing my trailer and when you hear the nasty pop-whoosh and your egts go through the roof and you cant exactly pull over on the side of the road climbing a huge hill. Make me shiver just thinking about it.

 

[Adam B]

Been there.....pyrometer and boost gauge needles suddenly moving very quickly in opposite directions, and more black smoke than you'd see at a tractor pull.....and of course it happens part way up a very steep hill with nowhere to pull off the road.

Perhaps the worst part is the smiles from all the people you just passed as they get their revenge.

For those who know the Coquihalla, it happened to me in the snowshed tunnel. The exact same spot where 3 teeth decided to free themselves from the rear pinion gear in my mini truck a few years prior. That time I just turned around at the Falls Lake exit and drove all the way home (~2hrs) with earplugs in - it was unbearably loud.