Maximum pre-turbo EGT's?

[lindstromjd]

Ok, well, I learned some stuff today about my engine.

1. It runs a lot better now with the pressure line going to the IP (and starts better)
2. Fuel leak = bad
3. No airflow through intercooler = bad

I re-routed my intercooler to go in front of my radiator. So now my EGT's don't climb anywhere near as quickly on the road, but they do still get up there. At least it's a start.

Second, I hooked up the IP line, and hooked my boost gauge into it with a brass T fitting. All hard lines with compression fittings (except the boost gauge, but nothing is leaking). But, my boost gauge doesn't read anything. And I know I'm getting pressure from the turbo, because I took the intercooler lines off right before they go into the intake, and ran it to see if the turbo was working. It does, and I get plenty of extra air flow through it. Why doesn't the boost gauge work? I have no idea.

Turns out I also had a pin-hole in the banjo bolt that my fuel feed line goes into. I didn't notice it before because it would only spray a fine mist of fuel. With some things cleaned up, it sprayed a constant small stream of fuel. So I had to JB weld it because I don't know where to find another one that fits. Here's to hoping that these things combined will help me out a little on the road.

[bluescout]

Glad you're making progress. Try tapping your boost gauge in to the wastegate line that goes right from the compressor housing. Maybe there's a restriction somewhere. Also, test the boost gauge. That banjo bolt is available somewhere I'm sure.

[lindstromjd]

Well, I figured out the boost gauge problem. I stomped on the gas today and brought the rpm's up quite a bit on the road in 2nd gear (watching EGT's of course) and guess what? I got a whopping 4 lbs of boost showing on the gauge. So that solves that much. The HX just can't spool up fast enough for the SD33. Seems that the SD33 just isn't big enough to push enough air for the Holset HX-35. Lesson learned.

Started putting my stock turbo back on tonight; at least I kept everything from when I replaced it. I'm still running the intercooler, but now I have to build all new exhaust, AGAIN, and I'm back with a tiny turbo. But I know it works, and I know I can't hurt the engine with stock parts.

I also fixed the fuel leak. The engine was much happier on the road when it wasn't almost starving for fuel at 55-60. That's when I figured out the boost problem with the HX. Seems I can't fix all my problems at once. Sigh.

[gregor]

holset.co.uk says;

"Designed primarily for 6 cylinder engines of 5.0 to 6.5 litre capacity, the Holset HX35 turbocharger has higher flow aerodynamics capable of providing up to 0.46 kg/s at 3.0:1 pressure ratio."

So that doesn't sound promising for the little Nissan, but then it says;

"A number of compressor and turbine options are available all featuring excellent map width, pressure ratio and efficiency"

So, could you adjust yours with more appropriate 'options'

[lindstromjd]

I didn't know they had different options for the HX-35. I do now. I wonder if the 12cm housing would work? Too bad I need to take the truck on a 10 hour road trip this weekend, and I don't have $450 to buy it.

[gregor]

That's OK, we can wait until you're back from your road trip and have saved up for the experiment

[xyz12383318]

A 12mm hx35 maybe the ticket. I am more inclined toward an hx30 from a 4bt. Or because those are hard to find, an hy35 off of an early common rail Dodge may be just the ticket. It has 9mm intake and is made to spool early to keep those new dodges clean. Of course every thing I have read suggests the Mercedes compressor wheel is a great turbo mod.

[lindstromjd]

I looked into the Mercedes turbo mod, but wanted something a little more unique. Guess I got what I deserved by spending probably 3x the amount on this Holset (with the new housing) as you guys with the Mercedes mod would. I had also thought about getting an HX1c, because they're supposed to spool up faster as well, but got a good deal on the HX35. Not a good enough deal to have to do all this extra crap to it though.

At least with the stock turbo on, I'm getting a little lower EGT's on the road, and I'm seeing boost a little earlier now without having to wrap out the engine rpm's. It's not getting much more than 4-5 lbs though. I wish I could get 8. Sigh.

It'll be a bit before I can do the 12cm mod to the HX35. I'm going to look at and hopefully buy a 76 Terra this weekend, so I can do my 6.2 conversion in it. Why can't I ever start one project, and see it done before I start another!?!?

[2nd Scout]

Sorry for your troubles. It can be frustrating, I know. In stock form, I don't recall having any trouble hitting 7 psi, which is when the wastegate opened. Maybe you should plug your WG tube and see if you can get a little more boost. If not, something else might be wrong, like a leak or something. I'm no turbo expert though, so take this for what it's worth.

[lindstromjd]

Ok, so a little more progress today. I figured out that I can, indeed, get 8 lbs of boost out of the stock turbo, but it's at such high RPM's that it scares me. Normally I would never take any engine that high, much less a diesel, but I had to see what the problem was. So, is it normal to not push more than 3-4 lbs of boost when you're at lower RPM's on the road? When I'm in 4th gear, I don't even see any boost at all until I get over 60 mph. Oh, and my EGT's are now running right around 1100 max when I really get into it.