Regear to help with EGTs (1HDT) (1 Viewer)

[mxtaco48]

I added an intercooler to my 1HDT swapped HZJ73 last month and while it helped with my EGTs, it still isn’t great. I did a recent trip from Texas to NM and CO. I was Fully loaded with an RTT mounted on top. Highway speed was somewhat limited to around 65 mph which was not fun for 10-15 hour days.

Im still running the stock 4.10 gears. I run 35x12.5” tires. I think the next move might be to regear up to 4.88s. My question is if anyone has done this to a 1hdt, how much has it helped with EGTs? It seems that it was put less stress on the engine which is part of when the EGTs spike. I dont Have any issues for around town driving.

another option is to regear my t case. Any suggestions on gearing in this situation? I appreciate the help in advance.

 

[ZCissner]

What are the temps you are seeing?
Do you have the h55 or h150/151?

 

[mxtaco48]

What are the temps you are seeing?
Do you have the h55 or h150/151?

H55f, I should’ve mentioned that.

1200-1250 at 65mph on flat ground. The slightest uphill or overpass and that’s easily hitting 1300+ which is when i have to back off the throttle thus decreasing my speeds further.

 

[SNLC]

Is it tuned correctly? What is the timing set at?

Those are to hot of numbers, I would explore other things before doing diff gears.

What are EGTs at idle?

Cheers

 

[mxtaco48]

With AC running, they are 360 degrees at idle.

the IP was set to factory specs. I had it rebuilt a couple months ago. I’m not sure about timing and tuning correctly.

im completely open to other options rather than gearing too.

 

[brownbear]

That's also pretty warm at idle. Even with an AC. I don't know for sure, but I watch my EGTS on my diesel, not the same as yours and I don't really make much heat. Barely can warm it's self up.

I would like to know your boost numbers at 65, when you are not making boost they can get hotter. As they instantly are over fuelling. Any smoke?

Now all that aside, gauges can be wrong too. thermocouples can be bad. See if the brand of gauge you have say how you test them? Must be a cold spec on resistance for the thermocouple.

 

[ZCissner]

Did you do a top mount or front mount?
2.5 or 3 inch piping if front mount?
Anything done to the exhaust?(3 inch?)
Are you blowing black smoke everywhere?
What rpm are you seeing these temperatures at?
Just as a comparison,I’m in a 80 series, 7000lbs with a tent on 37s and it is almost impossible to get it over 1000 degrees,
But it is 4 inch intake, 3 inch inter cooler piping and 3 inch exhaust.

run that thing in 4th gear and check the temps

 

[mxtaco48]

That's also pretty warm at idle. Even with an AC. I don't know for sure, but I watch my EGTS on my diesel, not the same as yours and I don't really make much heat. Barely can warm it's self up.

I would like to know your boost numbers at 65, when you are not making boost they can get hotter. As they instantly are over fuelling. Any smoke?

Now all that aside, gauges can be wrong too. thermocouples can be bad. See if the brand of gauge you have say how you test them? Must be a cold spec on resistance for the thermocouple.

I dont have a boost gauge on it yet so I dont Have the psi at hand.

And you’re right. The temps may not be right.

Im using Aubers water temp and egt gauges. My EGT probe is mounted pre turbo.

 

[mxtaco48]

Did you do a top mount or front mount?
2.5 or 3 inch piping if front mount?
Anything done to the exhaust?(3 inch?)
Are you blowing black smoke everywhere?
What rpm are you seeing these temperatures at?
Just as a comparison,I’m in a 80 series, 7000lbs with a tent on 37s and it is almost impossible to get it over 1000 degrees,
But it is 4 inch intake, 3 inch inter cooler piping and 3 inch exhaust.

run that thing in 4th gear and check the temps

Top mount IC
3” exhaust. No muffler.
the RPMs aren’t even that high. There’s still a lot of power to go faster. I’ll have to go and take better notes tomorrow or RPM and temps

 

[AussieHJCruza]

That's hot at idle - how long has the engine been idling for when that temp is reached?

 

[mudgudgeon]

I’m not sure about timing and tuning correctly.

This is the first thing you need to figure out.

Anything else is kind of pointless until you know what you're starting from.

Set the timing correctly, not just lining up match marks.
Do some reading so you understand how to tune it.
Get some gauges so you can answer what boost and peak EGTs you have at full load, WOT

Gearing is not going to fix any underlying issues with timing and tune etc.

FWIW, I'd happily run a HD-FT at 1300f without a blink of an eye. Provided the tune is good, and cooling system is up to scratch, 1300f is no problem.

 

[mxtaco48]

That's hot at idle - how long has the engine been idling for when that temp is reached?

When I typed that #, I was Sitting in it. I think I had Just started it a few minutes before.

 

[mxtaco48]

This is the first thing you need to figure out.

Anything else is kind of pointless until you know what you're starting from.

Set the timing correctly, not just lining up match marks.
Do some reading so you understand how to tune it.
Get some gauges so you can answer what boost and peak EGTs you have at full load, WOT

Gearing is not going to fix any underlying issues with timing and tune etc.

FWIW, I'd happily run a HD-FT at 1300f without a blink of an eye. Provided the tune is good, and cooling system is up to scratch, 1300f is no problem.

Yeah, that’s what I’m thinking right now too. Get a solid baseline and move forward from there. I guess I’ve had blinders on and have forgotten about checking those two things since I did The swap. I’m reading the IP tuning/mod thread for how to advice.

I’m not too worried about 1250-1300 either.

 

[mxtaco48]

To answer a previous question, there’s no noticeable smoke when driving.

 

[AussieHJCruza]

When I typed that #, I was Sitting in it. I think I had Just started it a few minutes before.

Oh hang on, I was reading that as Celsius. Still warmish if it's only been running a couple of minutes with no load. I would start by checking timing

 

[mxtaco48]

Yes. All in Fahrenheit.

 

[brownbear]

Boost is very important to know too. I would get a boost gauge for it also. Lower boost results in higher temps. I've lowered my EGTs increasing my boost. More air... to a point though as you need an intercooler to also keep it down.

 

[mxtaco48]

Boost is very important to know too. I would get a boost gauge for it also. Lower boost results in higher temps. I've lowered my EGTs increasing my boost. More air... to a point though as you need an intercooler to also keep it down.

luckily I’ve got the intercooler installed already.

 

[IanB]

I assume you're running the stock turbo still? Add a boost gauge and manual boost controller, bring the boost up to 14-15psi from the stock 10-11, and you should see EGT's go down and useable power at highway speeds go way up.

You say you have 3" exhaust, does that include the downpipe, or is it still stock? If stock, it's a major bottleneck in the exhaust, FYI.

Start with setting the timing on the IP and increase your boost level, then tune and reevaluate. With an IC and exhaust you should have no issues keeping it safe and cool while still making good power.

 

[mxtaco48]

I assume you're running the stock turbo still? Add a boost gauge and manual boost controller, bring the boost up to 14-15psi from the stock 10-11, and you should see EGT's go down and useable power at highway speeds go way up.

You say you have 3" exhaust, does that include the downpipe, or is it still stock? If stock, it's a major bottleneck in the exhaust, FYI.

Start with setting the timing on the IP and increase your boost level, then tune and reevaluate. With an IC and exhaust you should have no issues keeping it safe and cool while still making good power.

I built a new 3" exhaust including the downpipe. A relative pain in the ass because you're going inside the engine bay, over and outside of the frame, then back over the frame and across the drivetrain.

I honestly would like a .5-1" body lift for clearance.