HDT paired with a442f dogs in 4th

[SKULLGRINDER]

1990 HDJ81 1HD-T with full hydro 442f. 315/75r16 C27 turbo. Pump turned down a good bit. Truck rocks 1-3rd gear as soon as it locks up in 4th up any sort of hill EGTs rocket to 1200+ MPHs drop and slowly climb along with boost. Forcing me to stay in 3rd up hills creating tons of heat. Even with my oversized trans cooler I don’t see longevity in it. Possibly taller narrower tires and a g turbo to help keep things cool and more drivable? Or is this just the program with this set up? Any info or hate please send it my way
Note: I understand this is not a race truck but damn it’s worse than my 1FZ LOL!

 

[TheBussman]

1990 HDJ81 1HD-T with full hydro 442f. 315/75r16 C27 turbo. Pump turned down a good bit. Truck rocks 1-3rd gear as soon as it locks up in 4th up any sort of hill EGTs rocket to 1200+ MPHs drop and slowly climb along with boost. Forcing me to stay in 3rd up hills creating tons of heat. Even with my oversized trans cooler I don’t see longevity in it. Possibly taller narrower tires and a g turbo to help keep things cool and more drivable? Or is this just the program with this set up? Any info or hate please send it my way
Note: I understand this is not a race truck but damn it’s worse than my 1FZ LOL!

4.10 gears? it drives fine before the converter locks up in 4th? do you have a boost gauge? you shouldn't drop much boost shifting from 3rd to 4th.

 

[bug616]

1200 EGT isn’t hot. My stock 1HDT hits 1450 on hills in 4th - also A442.

Also, how big is your transmission cooler. I use a 34 row rated to 59,000 BTU per hour. Could easily go bigger. A442 notorious for generating heat.

 

[duece71]

At 900’ above sea level where I am, if I put foot to floor I am at 1200 degrees plus quickly. Stock turbo, stock gears on 33” tires. I have concluded that I will need an intercooler in the future……being that Tucson is 2600’ above sea level, not surprised you are seeing high egts quickly. If I press the pedal through TC lock up…..no loss of power at all, just high egts. Intercooler and gears would be my choice for research.

 

[AirheadNut]

At 3500-5000' it is pretty normal to see 1200ºF and higher on hills and during moderate to heavy acceleration. That's with 33" tires, intercooler, performance aneroid pin and a mildly tweaked IP. Still running a bit rich so the temps could be lower, but it makes pretty good power if you keep your foot in it.

 

[IanB]

Full hydro A442F locks up only in OD/4th, which really serves to "load" the engine, so it's going to feel a lot different than 1-3, and it makes sense that EGT's would rise. At what speed and RPM are you seeing the 3-4 shift, and TC lockup when accelerating, and what's the timing of that transition? It can almost feel like another gearshift if that makes sense. 3>OD>Lockup

It's possible you need to adjust your shift cable so you hold 3rd longer, and aren't falling out of the powerband/bogging, I'm not sure what RPM you're seeing that shift at. Full hydro's don't have the ECT button, so when it shifts is entirely a mechanical adjustment via the shift cable. If it shifts at 2800rpm when held to the floor, maybe try manually holding 3rd via the shifter to a higher RPM and see if that alleviates the issue some.

1200 is the highest I like to see my EGT's, maybe if I lived in the mountains my tolerance/comfort level would be different? I assume your turbo is a CT26 - stock unit, and C27 was a typo? You could try turning that up via a boost controller to ~14psi, makes a huge difference at highway speeds in getting up to speed and keeping EGT's lower. Pay attention to your boost gauge and when you're hitting max boost, and consider that to make more power from that point you're dumping fuel in to do it. Adding air = cooler.

 

[SKULLGRINDER]

Full hydro A442F locks up only in OD/4th, which really serves to "load" the engine, so it's going to feel a lot different than 1-3, and it makes sense that EGT's would rise. At what speed and RPM are you seeing the 3-4 shift, and TC lockup when accelerating, and what's the timing of that transition? It can almost feel like another gearshift if that makes sense. 3>OD>Lockup

It's possible you need to adjust your shift cable so you hold 3rd longer, and aren't falling out of the powerband/bogging, I'm not sure what RPM you're seeing that shift at. Full hydro's don't have the ECT button, so when it shifts is entirely a mechanical adjustment via the shift cable. If it shifts at 2800rpm when held to the floor, maybe try manually holding 3rd via the shifter to a higher RPM and see if that alleviates the issue some.

1200 is the highest I like to see my EGT's, maybe if I lived in the mountains my tolerance/comfort level would be different? I assume your turbo is a CT26 - stock unit, and C27 was a typo? You could try turning that up via a boost controller to ~14psi, makes a huge difference at highway speeds in getting up to speed and keeping EGT's lower. Pay attention to your boost gauge and when you're hitting max boost, and consider that to make more power from that point you're dumping fuel in to do it. Adding air = cooler.

My bad not sure why I said c27 possibly thinking of some equipment at work…. Turbo is a BLITZ ct26s which the only info on it I can find lies in old fourm posts talking about putting them on mk2s and supras. It’ll make mid 20s with ease however I have turned down to max around 20. Shift from 3rd to OD or bog is around 2700ishhh rpm and like you said it almost feels like a whole new gear set. If I stay in the pedal eventually the turbo lights up and it’ll cause I just tend to instantly back out as soon as I see my EGTs spike beyond 1200. With a turbo no one seems to have ever ran on these things im thinking maybe a green wheel may be worth trying….

 

[IanB]

Driving style makes a difference, high RPM + low load = lower EGT's, while low RPM + high load = higher EGT's.

Keeping EGT's under control in the mountains is really where an intercooler would shine IMO, driving by EGT gauge is stressful. Here on the prairies I find at highway speeds, even a medium wind can make a big difference in boost level required, and EGT's to maintain speed on cruise control.

Wholesale automatics sells a valve body upgrade for your transmission that allows for TC lockup in 3rd and OD, among other benefits.

I just saw your post about having a Blitz turbo, intended for a gas engine...and I think that might explain a lot. I would expect that turbo to be set up expecting a high RPM engine feeding it, it's probably way outside it's efficiency zone on a diesel engine. Right frame size, bolt on, yet all wrong for this application. You have a boost gauge, at what RPM are you seeing boost start, hit 10psi, etc?

 

[SKULLGRINDER]

Driving style makes a difference, high RPM + low load = lower EGT's, while low RPM + high load = higher EGT's.

Keeping EGT's under control in the mountains is really where an intercooler would shine IMO, driving by EGT gauge is stressful. Here on the prairies I find at highway speeds, even a medium wind can make a big difference in boost level required, and EGT's to maintain speed on cruise control.

Wholesale automatics sells a valve body upgrade for your transmission that allows for TC lockup in 3rd and OD, among other benefits.

I just saw your post about having a Blitz turbo, intended for a gas engine...and I think that might explain a lot. I would expect that turbo to be set up expecting a high RPM engine feeding it, it's probably way outside it's efficiency zone on a diesel engine. Right frame size, bolt on, yet all wrong for this application. You have a boost gauge, at what RPM are you seeing boost start, hit 10psi, etc?

Great point on it being a turbo set up for small gas engine with attitude. Don’t really see double digits on my gauge until 1800-2k? Don’t quote me. Really think I’ve squashed this whole chasing my tail trying to adjust the waste gate and pump and need to start off with the correct turbo.

 

[IanB]

Great point on it being a turbo set up for small gas engine with attitude. Don’t really see double digits on my gauge until 1800-2k? Don’t quote me. Really think I’ve squashed this whole chasing my tail trying to adjust the waste gate and pump and need to start off with the correct turbo.

I tried googling for some more info on that turbo, from what I can gather it's an upgraded compressor housing and turbine on an otherwise stock, gas engine spec CT26. The gas engine versions of these turbos have larger exhaust housings, so they spool up slower on a low revving diesel, I think you're on the money with a properly spec'd turbo being your shortcut to driveability.

 

[TheBussman]

I think you got it figured out, somebody with a 7MGTE would like that blitz turbo I'm sure it was super pricey back in its day.