Engine/Transmission (1994 - 1998) Problems with boost on HX40

[JBlackwell]

Hey guys, need some help.

When I had the stock turbo on it, it the wastegate would open at 37#. Now with the PDRHX40 it only builds to 30-32# boost. Now this is when the fuel shutoff solenoid is working good and I have the TST fuel plate kit, so I still have the Wastegate control fitting. But I believe Piers gates their 40's at 39# I think. I know when it stops building boost at 30-32# the pyrometer starts climbing faster... I let off at 1500+* pre-turbo... . so I know it is getting plenty of fuel for the turbo to make more boost then it does now. All of the lines seem to be tight can't find anything loose. How can I check for boost leaks?



Oh, check my gallery for pics of how I have my boost lines ran. I just took them specifically for this thread. Maybe I routed something wrong??



Justin

 

[JGheen]

Well, from looking at the pics, I am curious to know where the "T" in your line off of the wastegate actuator is going?? Also, it looks like there are a few extra lines going somewhere off of the AFC housing. Should be one line coming off the manifold to the AFC and from the AFC across the engine to the wastegate.

 

[JGK]

I presume you're using an exhaust housing that came with the 40. If that is true, I'm not so sure they are set to dump at ~40 lbs like before. They may have backed it off some since 40's are known to not like 40 lbs of boost. (I recently went through 2 "new" PDR 40s that seemed to be OK until I pushed them over 35 lbs, then the bearings went. I'd call and check with PDR to see what the waste gate is set at, and/or test it yourself with a compressor and an accurate pressure gauge. )



Also, a larger, well designed turbo will flow more air at a lower boost pressure, which is a good thing. But if you're seeing higher EGTs at roughly similar loads and rpms with the only difference being the turbo, then it would imply the 40 is not providing the air you need, or even had with your stock turbo.



As to how to check for leaks, you need to construct a boot of some kind you can fit over your turbo inlet and clamp it on and connect it to a compressor. With about 30lbs going in, spray all the joints with soapy water. Check with a plumbing supply store for a rubber boot that will fit over the turbo inlet, then reduce it down until you can put a schrader valve (tire valve) in for connecting to a compressor. I did this some years ago, but don't remember just what parts I used. But I found them at the plumbing store. Also, if you can include a pressure gauge, you can charge up the system and see if the pressure drops, like a cylinder leak-down test.



Oh, the fun of new turbos...

-Jay



Edit: Just looked at pics. What Joe asked/said. What's the story with the T at the waste gate actuator?

 

[nascar mark]

We do not waste gate our 40's at 39psi. They are set to open at 32psi, so you are just opening the wastegate but don't have anough fuel to push more boost. We set the 40's at 32psi as a precaution as many heavily fueled trucks would shoot right past the 38psi max psi that we want any of our hx40's to run or you overspeed the turbo and will cause a shortened life of the turbo.



With your amount of fuel, you can adjust the waste gate accuater arm shorter to allow more boost up to 38psi max. This will help lower your egt's some.

 

[JGheen]

There ya go, straight from the experts!



I am still curious to know what the wastegate line "T" is going to as well as your plumbing around the AFC.

 

[JBlackwell]

Man, you guys respond quick. I appreciate that.



JGheen: I have it "T" in like that is because when I got it, it already had the line running from the wastegate to the housing and I didn't know anything else to do but "T" it in with the boost line. And I bought this turbo 2nd hand, but the guy had it for 7,000 miles and it was on a 24V. Not sure if that had anything to do with it. I didn't even have to reclock it, just bolted right up.





Nascar Mark: Thanks for the info. You answered exactly what I needed to hear. I don't have the fuel to push any higher. Still running stock DV's on the 175 pump and #10 plate slid up about . 030 So I am not heavily fueled enough to push it on up there. I will adjust the arm like you said.



Appreciate everyones replies,

Justin

 

[JBlackwell]

As to how to check for leaks, you need to construct a boot of some kind you can fit over your turbo inlet and clamp it on and connect it to a compressor. With about 30lbs going in, spray all the joints with soapy water. Check with a plumbing supply store for a rubber boot that will fit over the turbo inlet, then reduce it down until you can put a schrader valve (tire valve) in for connecting to a compressor. I did this some years ago, but don't remember just what parts I used. But I found them at the plumbing store. Also, if you can include a pressure gauge, you can charge up the system and see if the pressure drops, like a cylinder leak-down test.

I appreciate the help there, I will do that because I will need to use to check boost leaks from now on.



Justin

 

[JGK]

You can run a line from the compressor housing to the waste gate actuator or from the hose on the AFC housing. Either/or, but not both (not that it would hurt anything). Both the compressor housing and the AFC provide boost to run the actuator. So take out the T and use either source you prefer.



JGheen, I assume you're refering to the small, milky white tubes in Justin's picture of the boost line at the AFC. I, too, thought those were part of the boost plumbing, but I think they are unrelated and just look like part of the plan due to the angle of the picture. Justin... ?



-Jay

 

[JBlackwell]

JGheen, I assume you're refering to the small, milky white tubes in Justin's picture of the boost line at the AFC. I, too, thought those were part of the boost plumbing, but I think they are unrelated and just look like part of the plan due to the angle of the picture. Justin... ?



-Jay

That tube is to the boost guage. My buddy did that when we were putting the head back on. I was on one side hooking everything up and he was on the other side.



Justin