1HD-T towing observations - high EGTs

[finderscuba]

I was towing my 2000lb tent trailer this past week and wanted to share some observations.

Ambient temperatures were around 30°C. There was about a 40km/h headwind most of the way and the roads are fairly flat.

Cruising at 100 km/h I saw 2500rpm, 10psi boost and 1100°F EGTs. The EGTs would climb to 1250 on inclines. It would have gone higher if I didn't lift off. The floor and center console were hot during this drive. There were a couple of times when I couldn't accelerate past 100 due to too high EGTs.

Without the headwind, at 100 km/h, I would see 2500rpm, 8psi boost and 1000°F EGTs. This is more in line with what I recall seeing last summer while towing.

We're planning on trading in the tent trailer for something bigger and heavier (~4200lbs). With my current setup, I'm not confident I could pull much more weight, especially not double.

So, time for an intercooler? Air to air would bring my EGTs down by 100-200°F right? My boost is set to max 12psi. Very little smoke - some black when rowing through the gears accelerating.

 

[blis]

First thing that comes to mind is that you're towing on fifth gear and that is pushing up the egts?

If that is not the case then perhaps bump up the boost to around 1,5bar or something like that and throw in the IC, Also changing the exhaust to a more freeflowing one is a good way to lower the egts a bit...

 

[finderscuba]

Yeah I'm in 5th most of the time. 1.5bar = 22psi. That's much higher than I would go. I'm set at 13psi max.

 

[SHREDwagon]

My EGT's dropped 100C with an ATEB 3" exhaust and a tune. That's after John increased both fuel (power rod mod) and boost (15 psi). Completely different truck after. I'd highly recommend a 3" exhaust first.

The Safari IC dropped my EGT's another 150 to 200C on top of that. But I haven't upped anything as I've all the power I need. Just enjoying low EGT's, for now......

Problem now is where to fit a tranny cooler! Do you have a Tranny Temp gauge?

Edit: Assuming your EGT's are pre-turbo, 1250f (700C) is what I was running on steep hills, with no trailer, before a 3". My gauge alarms at 750C and I'd see that many times driving in the rockies.....

 

[IanB]

My EGT's dropped 100C with an ATEB 3" exhaust and a tune. That's after John increased both fuel (power rod mod) and boost. Completely different truck after. I'd highly recommend a new 3" exhaust first.

The Safari IC dropped my EGT's another 150 to 200C on top of that. But I haven't upped anything as I've all the power I need. So just enjoying low EGT's for now......

Problem now is where to fit a tranny cooler! Do you have a Tranny Temp gauge?

Edit: Assuming your EGT's are pre-turbo, 1250f (700C) is what I was running on steep hills with no trailer before a 3". My gauge alarms at 750C and I would see that many times driving in the rockies.....

He has a manual transmission, and I think he already has the exhaust done on his truck as well.

 

[blis]

Yeah I'm in 5th most of the time. 1.5bar = 22psi. That's much higher than I would go. I'm set at 13psi max.

Well, for starters stop towing in fifth gear, atleast h55f doesnt last long if you tow heavy loads in fifth... Most likely you'll also get lower egt's by sticking to fourth gear...

 

[SHREDwagon]

He has a manual transmission, and I think he already has the exhaust done on his truck as well.

Didn't see the 5 speed

Intercooler time......

Edit: Check out the Safari group buy on LCOOL. Full kit and 1.5 day install.

 

[lumpy70]

I put a G-turbo on mine (automatic) with 3" exhaust. Slightly increased fuel, and 20 lbs of boost (stock turbo can't imo efficiently handle that boost). It dropped my EGT's 400 degrees and I hold 110-120 kph up hills all day long without dropping down a gear. EGT's don't go above 825 degrees up a long full speed highway hill, used to be at 1200 degrees till I let off throttle and dropped to 90 kph in 3rd gear.

I wanted this setup to tow my trailer, and while I haven't towed yet with this new setup, I'm confident I'll be in good shape now. I was in the same boat as you towing before.

 

[Radd Cruisers]

Depending on where you're pyro probe is located, you are okay with those temps - but 1250F is getting up there.

I would be far more worried about the transmission over-heating and the trailer having brakes, than what the EGTs alone are doing.



The problem with over-boosting the 1HD-T is that you'll push the boost compensator diaphragm (and "power rod") into the "massive de-fuel" zone... if you're going to run higher boost pressures than about 12 PSI, you're going to have to play close attention to the amount the boost compensator is moving and you may have to set the guide bushing (the spring tension on the boost compensator) to prevent it from massively de-fueling the engine...

Some guys who are seeing large EGT drops at higher boost pressures are seeing it because the engine is being de-fueled at these pressures, and not because you're just running a lot of boost.

I would also recommend an inter-cooler when running boost pressures up much higher than about 12-14 PSI.

Just a few thoughts for y'all.

~John

 

[lumpy70]

Some guys who are seeing large EGT drops at higher boost pressures are seeing it because the engine is being de-fueled at these pressures, and not because you're just running a lot of boost.

~John

Agreed. I slowly upped and upped my fuel until I started seeing diminishing returns, then backed it off till the smoke came back, just a poof of it. In the end it was about two full turns done 1/2 turn at a time for me.

My performance tells me that it worked, better speed, no gearing down, and lower EGT's.

Craig.

 

[finderscuba]

My pyro probe is pre-turbo. I also have a power rod.

I spent some time getting the setup where I want it. Lots of low down grunt and very little to no smoke.

I will spend less time in 5th when towing and more time in 4th. I'm also going to start sourcing an intercooler. I'm not keen on the price of the Safari kits or similar.

 

[SHREDwagon]

I'm not keen on the price of the Safari kits or similar.

Agreed. At the time I paid around $500 more for the Safari kit with the group buy, than the cheapest homebrew set-up.

After installing it - I thought "who the F#!k am I kidding - design my own....". It's a tight fit and IMHO takes ALOT of time to design, aquire the RIGHT parts and install. But that's me.

The kit is quality and you get what you pay for. Depends how much your going to abuse it I guess.

I was originally eyeing a Frozen Boost Air/Air.....

Good luck man

 

[Dougal]

If your measurements are accurate (probe long enough etc), then those temps aren't a problem.

But to reduce them, more boost, intercool and better turbo (in that order).

 

[roscoFJ73]

Well, for starters stop towing in fifth gear, atleast h55f doesnt last long if you tow heavy loads in fifth... Most likely you'll also get lower egt's by sticking to fourth gear...

No 80 series ever had the H55F fitted,but I still wouldnt be towing in 5th into a 40klm headwind.Thats just killing it

 

[ElectricDyck]

I have 489 gears, 35" tires, 4" lift, 3" exhaust and when I pull my 2000lb trillium with my canoe on the roof I'm at 2500 rpm at 95/100km/h and max boost, 11psi and about 1050 degrees, if I have a headwind, that goes up 1150-1200 degrees. On steep hill I'm in 2nd or 3rd gear at 2800/3000 rpm to keep the egts and tranny happy.

I've recently turned up the boost to 16 psi with amazing results, more power and egts lowered by 100 to 150 degrees at highway speeds. I'm around 14 psi at approx 100km/h. I still need to experiment more, I've only done one trip with the trailer since upping the boost.

I'm very curious about this comment:

The problem with over-boosting the 1HD-T is that you'll push the boost compensator diaphragm (and "power rod") into the "massive de-fuel" zone... if you're going to run higher boost pressures than about 12 PSI, you're going to have to play close attention to the amount the boost compensator is moving and you may have to set the guide bushing (the spring tension on the boost compensator) to prevent it from massively de-fueling the engine...

Some guys who are seeing large EGT drops at higher boost pressures are seeing it because the engine is being de-fueled at these pressures, and not because you're just running a lot of boost.

So are you saying the tapered rod that the fuel pin rides on pushes past the curve and then back on to the raw profile of the rod? Doesn't make sense to me, please explain.
Here's a pic stolen for here on mud.

 

[ElectricDyck]

Here' a pic of my set up

 

[finderscuba]

That's my fuel rod. The profile was actually ground into a stock fuel pin. The profile is such that the fuel pin does not reach any "de-fuel" zone.

I'm tempted to do some experimenting with fuel and boost settings again. But it took me a lontime to get it to where I liked it. If I recall correctly, my boost spring preload was screwed almost all the way down (minimal preload). Fuel turned up to the point of smoking, then back a quarter turn. Manual boost controller set to max out at 13 psi. I figured 13 was about max for the stock CT26
This tuning gave me egts below 1200 while towing up slight inclines in 5th maintaining 100. That was setup 2 years ago. Time to retune?

 

[ElectricDyck]

Your boost seems low for that rpm level? Fuel, air, exhaust?

So explain the "de fuel" zone.

 

[finderscuba]

Your boost seems low for that rpm level? Fuel, air, exhaust?

So explain the "de fuel" zone.

There is a pin that pushes against the profile on the fuel rod. When there is no boost, the pin pushes against the thickest part of the rod near the end. As boost pressure increases, it pushes on the rubber diaphragm at the top of the boost compensator. This pushes the rod down. As it moves down, the pin follows the profile. As the profile narrows, the pin moves forward causing an increase in fuel delivery. Eventually, the profile starts coming back out, which reduces fuel delivery. Then the rod hits bottom. This would be the "de-fuel" zone. Mine does not push the pin back out.

 

[ElectricDyck]

Thanks, good explanation.