I think the 12cm housing is killing my top end. I can actually run up through the gears cooler if I mash it, but shift at 22-2300, vs running it to the gov but only using 2/3-3/4 throttle. I know I'm behind the 8 ball with no i/c and 3'' pipe, but I can't afford to change that right now, as I just filled my tank Sooo, my free option would be to go back to the 18 untill I decide what's next---think the 18 will let me use the rpm...I know I can spool it

g

 

Won't hurt anything to try it, you certainly have the low RPM fuel to get it spooled.

Where's the TurboMaster set? If you're going much over 30 psi you're just heating the air and choking the engine on the exhaust side.

 

Dave,
The TM is set at roughly 30psi. Truthfully, I rarely go WOT cause broken parts scare me. Today, however, I leaned into 5th down low and I could actually watch the wastegate open on the boost gauge---went to 32psi, then dropped to 30. At that point, I laid into it from about 2/3 throttle and boost would directly follow my foot...I let out at 38psi@75mph.

 

edit---would letting it waste waaay early be of any benefit by backing the TM off real far?

 

Since it sounds like your pushing more fuel than the wastegate can flow, why don't you modify the wastegate by drilling out the divider in the exhaust housing, that will keep your boost in check.

 

I was unable to keep the boost under control with the TurboMaster and POD's, but I never had problems with the stock injectors. I just backed it off further for less boost. I'm not so sure you saw the wastegate open on the boost gauge. If you hold the accelerator in one position, as soon as the governor "catches up", the pump will defuel a little and boost will drop. I think you have it set at 38 PSI.

 

Rockjeep73:the divider is drilled
Wanna:I see your point. Now, let me ask you this--how much bigger are my non i/c nozzles vs stock i/c nozzles? Is the difference negligable (sp) in this case? All in all, I love the way the truck runs and behaves, it just seems that I'm building boost when I don't need it. Even with the starwheel all the way up, afc fueling has to come in at, what, 20psi anyway, right? Jeezz, I can hit 20psi with less than half throttle. I guess there's a burn efficiancy/fuel delivery threshold that probably lands right about where the 14cm w/g is, naturally...thanks for the replies so far!

g

 

Stock non intercooled injectors are about the same as 185's.

With the star wheel all the way up you ought to have all the AFC fuel around 15 - 18 psi.

Remember that "half throttle" doesn't really mean anything on a diesel, especially one with a stiff governor spring. At 1500 RPM, halfway to the floor or on the floor is pretty much the same thing with a 3200 RPM spring. Actual fueling rate depends on RPM, the higher the RPM the more pedal travel is required to get the same fueling rate.

You will know that you've backed off the TurboMaster too far when the truck is slow to build boost.

Since you are non-intercooled, 38 psi is probably about the same turbo speed as 32-35 psi on an intercooled truck. If EGT is better at 38 psi peak boost than 30 or 35 psi peak boost don't be afraid to run that high, just try to keep it under 40 psi. On my WH1C with POD's it was just plain hot, didn't matter if it made 30 or 35 psi, so I tried to run it at the lower pressure to reduce drive pressure.

 

Ok, I see what you mean about throttle position. Guess I need one of them thar valet switches, hehe. On a somewhat related note, would one or two (or three or four!) injectors popping off early act like advanced timing? Now that my fuel pressure is under control and I've pulled the pump back to compensate, I'm actually hearing more 'ping' rather than less, but it's not even, as though only some cylinders do it some of the time. Tired injectors? I've been doing about a 40 gallon tratment amount of power service for every 25 gallons of diesel, so they're as clean as they're gonna get while in the head. I'm mostly just nit-picking and fine tuning now---the truck runs grand and gets great mileage too. Just, like I said, pick pick picking

g

 

Ok, to the top with this old relic! Swapped the 18 back on this afternoon. It was a lot easier to get everything off the second time, even without neversneeze First off, the important stuff---I still have the whistle at idle! Must be something to do with the pipe coming out in front of the rear tire, cause that's the only difference from before, and I don't remember a whistle pre-12cm. Oh yeah, and it's LOUD!!!! The 12cm really muffled the roar. Anyway, after playing with the Turbo Master to no end, I still couldn't use any loud pedal over 2200 without my pyro doing a mad dash toward cheek pucker zone, hehe. Once it hit 700, if I was still into it, I had about 4 seconds before it swept past 900. With the 18 back on, I've only been on two test drives, but I can already tell the top end is opened up considerably, and the pyro does more of a steady march toward 900 rather than a frantic sprint. Some of that could be due to the size difference, but heat is heat. I'll have a better idea after I drive it for a couple days. Cruise temps and boost are down. Feels like a dog even with the AFC grind, but it's nice to not hit 25psi in every gear no matter how light my foot is--the poor h1c has 400k on it; less spinning has to be easier on it. I hit a solid 32psi rolling on in 5th, about 3/4 throttle, so I've definitely got fuel to spool! Though the bigger housing is not for everyone, I love it. I would tentatively say the 12cm is a bit small for a non ic truck that sees speeds over 65-70 regularly or has the 3200 spring installed. The 12 made it seem more like a gasser, which is good for around town, but I don't do enough stop and go to justify the flat top-end. That's my story, for the moment...

greg

 

That is only partly true. But if you floor it sitting still, you won't build boost. Little to no load on the engine. Put more load on the engine, it will require more fuel and make boost.

 

Ok, I guess I gotta eat my words. At least I'm among friends, right? RIGHT?!! hehe, j/k. One day with the old 18cm and I'm over it...any fuel I saved on the highway was used twice over in town in the form of closing down lane after lane of traffic with soot...guess the AFC grind really needs the insta-spool 12cm more than I thought. I guess hot boost is better than no boost with the little H1C and no intercooler. It's now my mission to find the biggest i/c I can and hack the core support apart! Sometimes ya just gotta learn the hard way...good news is I pulled the 18cm back off and had her fired up with the 12cm in 26 minutes!

humbledgregout

 

Sometimes I miss the "insta-spool" housing too...

 

But there are a few sizes in between 18 and 12, looks like a comprimise would be better for you.

 

I think I'm gonna hold out for a 14cm w/g as that seems to be the best compromise before twins. I backed my fuel screw out 1/2 turn with the 18cm and still hit almost 40 psi, so I'm guessing the 16 would hit the wall sooner yet. With my fuel backed off even more, the 12cm will hold now at 36psi and a light haze. Not as fast, but a bit more self limiting which makes it easier to drive. I'm gonna stay away from pods this year, but there will be an HTT stage III coming soon, as well as an intercooler. Hopefully that will allow me to burn what fuel I have and then I can throw some more kerosene on the fire, haha.

greg