Hi guys, I have been working far away from home for the last year and a half and am just getting back to my old truck to pick up where I left off.

Before I left I had just put on an adjustable boost elbow to try to raise my boost so I don't get too high of egt's towing up hills. ( I got to fairly severely limit my speed just to keep things under 1300F, even though I got plenty of power left) According to the guy who sold it to me, it should have been adjusted correctly, but it did nothing that I could see to my boost. I get about 25 lb max. So I have been turning it in a bit at a time and still nothing. It is currently about 1/4 turn from full closed and I still can't see an increase in boost.
Makes me think I don't know what I am doing . I thought you closed it to get more boost. Am I wrong? Should I be opening it to get more boost? (I lost the instructions). I have looked for leaks over the entire air intake system and cant find any.

 

With mine, the further I screwed the setscrew into the elbow, the more boost I got. I had to remove the brass elbow and put it in a vise to continue turning the setscrew. It felt like it was closed when on the truck because it didn't want to turn, but had a good ways to go. Right now I need to remove it and back it out a bit to limit myself to 30 PSI.

 

When I changed the exhaust turbo housing to a Bank's Quick Spool housing. I couldn't get over 26 lbs of boost.
Reinstalled the stock 12 cm housing- boost went to 32 psi.

 

i also have banks exhaust turbo and stock boost elbow. i did grind my fuel plate to a #10 (easy) and moved it all the way forward. i hit 32 psi boost and max out about 1275 pyro.... so my thought is why a new boost elbow? if i change mine will i get more boost? the banks exhaust turbo only lowered egt i was hitin 1350 put did nothing for boost. so my stock hx35 stock boost elbow is getting 32 psi.?

 

Getting more boost when you don't have the fuel to burn accomplishes nothing.
A bigger or more efficient turbo can pump more volume of air without increasing the boost pressure.

Seems like people get hung up on thinking high boost is going to create more power. You need more fuel first, which results in higher egts, then you need more boost.
If you aren't hitting critical egts more boost does nothing.

 

I assume, Bill, from your comments is the proper way to set your boost is to keep turning it up (or down) until you reach maximum egts (1250F or so) under full load?

 

I turn it up till it can hit about 1400 on heavy acceleration.
That way you leave room for a little foot control.

 

My 26,000 lb motorhome is set up to a max of 1200 degrees at 32 psi at WOT. It does run 26 to 32 psi at smaller throttle settings. My thinking is that the more air - the more chance of burning every molecule of fuel. Maybe I'm wrong, but 11 mpg at an average speed of 58 mph driving time per trip seems good to me.

 

I do believe in most stoichiometric processes, it is best to have the exact number of oxygen molecules to match up with the proper number of fuel molecules. However, in our imperfect world of imperfect mixing of air and fuel inside a combustion chamber, it is indeed preferable to have a few excess O2 molecules. However, too many O2's means you are wasting a lot of energy heating up air that you don't use.

 

By the way, Jstone was right. I pulled the elbow out, put it in a vice and worked the screw back & forth so it would go in further, re-installed, and I was able to set by boost to what Bill suggested. Works well now!