Engine/Transmission (1994 - 1998) Keeping an HX-35 alive

[DESL PWR]

My HX-35 has served me well for 233k with minor fueling increases(3k GSK, 100 plate, stock injectors). I did add a 14cm wg turbine housing since the stock wg failed. During wot runs and sledpulling, my EGT's will climb and max the 1600deg pyro. Wastegate is set at 35psi but as the rpm and EGT climb, the boost will start to creep past that.

My question is, with the soon to be added DDP3 injectors, what steps can I take to keep this turbo from parting itself out? Also, what is the real enemy here? Is it EGT? Drive Pressure? Boost Pressure?

 

[Vaughn MacKenzie]

Yikes, at 1600F you need to worry more about the motor than the turbo
I think you need to part ways with the turbo and get something more appropriate, but 1600F seems on the hot side for just a fueling plate. I'm thinking you got a healthy boost leak somewhere, might explain the high EGTs & only 35psi boost. As far as boost levels, by the time you get to the upper 30s though you're out of your turbo's efficiency map.

 

[DESL PWR]

Yikes is what I say too when the EGT's climb like that. I do not let it stay there for very long when I see that. While I would love to part ways with this turbo, it just isnt in the wallet right now. Thats why the DDP3's are still on the workbench.

I'll check for boost leaks, but I was thinking the high EGT's were a result of turbine housing restriction. Hopefully more folks will chime in on this.

 

[Fordiesel69]

All I can say is all the diesels I have been around, they say no more than 1250 and that is the max, I would allow your EGT's to cool to 300 before shutting down, you will be fine with your turbo.



Some diesels can make a lot of power before getting to 1250 deg EGT, and our cummins is one of them. My old 6. 9L fords used to get to 1250 real quick.

 

[MMcCallie]

Mine also sees well over 1,600 EGTs. Turbo has a lot of lag unless its very cold outside. It also barks very loudly between gear shifts or when letting off the fuel pedal. It is time for a turbo upgrade. I think you'll want one as well. It seems normal to have such EGTs for short runs like on a dyno, a race, or a pull. I see these temps with injectors. You may indeed have another issue to track down.

 

[DESL PWR]

While crusing down the road empty I see...

60mph 6-7psi 625-650deg

65mph 9psi 650-675deg

70mph 12psi 690-700deg.



Also, I do religiously wait till below 300 before I shut the truck down.



So, do these numbers seem reasonable? Reminder this is with 3. 54 gears and 35" tires. I havent found any boost leaks, so other than that, what?... . timing a bit retarded? :-laf(pun intended) I am going to have that addressed here soon anyway. I want to bump up to 16. 5deg. Hopefully that will bring EGT down a bit, while not raising cylinder pressures too much and compromising the headgasket.

 

[Vaughn MacKenzie]

Spiking past 1600F on dyno runs & pulls aren't going to kill a Cummins, but I think if done fairly often it'll have a cumulative effect and take a toll on the motor after awhile (cause premature wear).