Turbo Overheating

[ISX]

I found this pdf by garrett and although our turbos aren't water cooled, it does teach you a lot. http://www.turbobygarrett.com/turbobygarrett/sites/default/files/Garrett_White_Paper_01_Water_Cooling.pdf

On the 5th to last page they show an oil slinger groove, one that was fine and one that was overheated. Mine looked just like the overheated one yet this was before I had ever ran over 35psi. Before I had it, it was a completely stock hotshotter truck. I always let it idle a long time if I had ran it hard and turned it off at 300F.

Soo...what gives! What do you guys think caused it? Is 35psi actually too much for an HX35? We know they are all wastegated to 20ish so 35 is pretty far past that..

Also found this, kinda interesting. http://www.dieselpowermag.com/tech/dodge/1209dp_the_worlds_biggest_turbo_test/viewall.html

Here's pics of the original shaft I took out (before the mill had its way with it lol)

[98whitelightnin]

You dont think the previus hotshotter ran the poop out of it? Most of my buddies dont let the turbo cool down and never look at the egt gauge at all.

[ISX]

No clue. Still makes one wonder. I'm reading about turbos and it seems when they go out of their range they have to spin very fast to get any more boost. We like to say this point is 35psi, but I'm not so sure. Still reading, still looking, still learning. Need to find an official HX35 map, rather than these home drawn ones.

[98whitelightnin]

I recently ordered an adjustable boost elbow because I'm make 45 psi with my edge non adjustable elbow and my setup. I'm gonna see if I can get it around 35-38 or so.

[ISX]

According to this 35psi is indeed past the right side of the map, but only above about 2500RPM. At 30psi you can get away with about 3000RPM. This is using 100F ambient temps, colder temps actually put it even farther to the right of the choke line. When you go past the map to the right (last line being the choke line), it is defined as efficiency going under 58% and the turbo having to spin a lot faster for little gain and it basically is overspeeding. If I put in a stock value of 22psi per say, it is actually well suited at 3000RPM. The sweet spot seems to be around 17psi and 2200RPM. Now there is a range of values so I just picked a spot and aimed for it. Basically the thing is set up stock, for towing. It has lag down low but towing it is perfect. Running 35psi is not good on it and to keep it within its design limits it needs to well, basically stay wastegated. Since we can outfuel the wastegate up to 30psi+, the wastegate needs modifications so it will keep it around <25psi. Thing is, more boost is how we cool these things off at higher power levels. I am not about to backtrack to make the turbo happy.. But, there are turbos with broader power curves that would be much better suited for the task that would also be happy with the high power runs (towing up steep hills or something, with a turned up truck). The stock one is perfectly matched to the engine at stock power levels.

[AH64ID]

We use airflow, not boost, to keep the motor cool. Boost is the measurable byproduct. But it is possible to increase boost and increase EGT's based on an inefficient compressor. According to the map you posted the HX35 is capable of 47 psi at sea level and ~30lb/min. It peaks at 29 psi and ~55-60 lb/min. Going above that means hot air. The other thing people don't look at is the turbine flow ratings. The compressor on the HE351 is good for about 4:1 and 61-63 lb/min but the turbine maxes out around 45-50 lb/min (of intake air, and guessing based on experience). Exceeding the turbine flow specs also increases turbo speed, even if the compressor flow is on the map.

[cajflynn]

I switched from an hy 35 to a hx 35 to a super b in my 01. The super b is 1,000,000,000 times better at everything. The difference is so complete it is hard to overstate. Egt's are 200 degress lower. Power is up everywhere. One of my favorite upgrades.I always thought the sweet spot for my stock turbos was around 10 to 12 pounds of boost when towing. Any higher and I was getting 8 mpg. Any lower and I was going 55 mph.

[AH64ID]

My turbo upgrade to the Garrett has been a great update as well. I didn't spend much time at the same power setting, but I am up about 75 rwhp at about 50° lower EGT's, lower IAT's, lower boost, etc. My cruise EGT's are a little higher, but the stock HE351 made 8-10 psi at 75 and the new turbo makes 4, so at low load the HE351 would move a little more air, but once any load is applied the Garrett outperforms the HE351.

[cajflynn]

I have always heard good things those Garretts. Sounds awesome.

[ISX]

If you use flow then how do you get the pressure ratio for the map... I didn't mention flow because we can't measure it so I guess I didn't mention it but I did calculate for it which is where I came up with the points I did. You need flow AND boost to mark a point on that map.