Well after the mods I got a chance to head into New England and the mountains. I was suprised at the mountains in New Hampshire. They were pretty long steep climbs. I was really impressed with the additional power the mods made. One thing I was afraid of came true to a point. I had the throttle for more power but had to back out of it because of the egt's. This means I can't use the power I made with the mods under long pulls with the 12k fifth wheel. I sure was suprised how she would pull in fifth up grades. Like a new truck. I had to shift to fourth sometimes but nothing like stock. I ran between 1000 and 1200*f most of the time. Didn't allow it to pass 1200*. Problem is she got there pretty fast on a pull. Smoke was only bad if I shifted a bit early and poured on the coal. It cleared though at rpm.

I want to time the pump next. Mark at PDR said it will add a bit more power and lower my egt's. That would be exactly what I am lookin for. I see in some of the posts people saying timeing set at 16* and such. I really haven't looked at the pump yet for timeing but how much can I bump up the timeing and still be safe? How do I know when I have reached the best setting? I would like to get this done before I leave again in the middle of the month.

Thanks for the help

 

The quick and dirty method recommended by many (including Piers) is to advance the pump 1/8" according to the timing marks.

 

If you don't use the 1/8th inch relative to current timing method, you have to take the plug out of the center of the back of the pump, and measure the pump's plunger height at TDC with a dial indicator. Each mm of plunger lift semms to correspond to 1 degree of advance . . . the optimal seems to be 15 to 15.5 mm's at TDC for top-end power.

Did you happen to notice the relationship between rpm's and EGT's on your last run? I got sold hard on torque-rise as a youngster and while the common wisdom is that the 16 housing is better for towing, and I am pretty well convinced it is best for peak horsepower, if you are finding that you are getting excessive EGT's down at 17 or 1800 rpm, and having to let off and downshift (as opposed to running up at the governor and having to let off for EGT's) then it would seem to me that a smaller housing would help you out. If you have any info that would shed light on my theory, I'd appreciate it!

Thanks,

Alec

 

Alec

This is what was takeing place. First of all the terrain was pretty hilley in fact 9 to 11% grades at times. Not western hills but pretty steep. Now remember I am carryin 354's. At 1800 rpm I am runnin about 65 in fifth. Pullin the 12k fifth wheel I really don't want to do much more than that. 2000 rpm is about 70mph. Yes, as I would add power in this range my egt's would clime pretty fast. On a flat I maybe runnin 600*. When I get to a pretty long pull the egt's go up fast. I will have to back off the throttle while pullin to keep the egt's between 1100 and 1200*. Eventualy if the pull is long enough I will be almost out of the power down to 55 and shift into fourth. My egt's will drop and depending I maybe able to go to wot and my egt's will stay below 11 to 1200* without a problem. This of course is all relitive to the exact conditions. I have a lot of power left in the engine but in most cases I can't use it because of the egt rise. Don't get me wrong she pulls and drives like a new truck compaired with stock but when you have 3/4 throttle left under you foot and you have to back off is frustrateing. I am hopeing timeing the pump will help a lot in this problem. Maybe a couple extra horses too.

Is this the info you wanted? If not let me know and I will give ya more.

 

Gary -- that is pretty much what I was looking for, though I forgot to ask what boost you were running when you had to downshift.

Now here is my unsolicited hypothesis: You aren't shifting down until about 1500 rpms, where you are probably only making about 12 to 15 lbs of boost with the 16cm housing (?), because you are already running at too low an rpm to get maximum efficiency out of the turbo with that housing. If you could get more boost down at 1500 rpm, you could keep your foot on the accelerator and burn more fuel with safe EGT's A 12cm or 14cm housing should give you a higher manifold pressure in that critical 1500 to 2000 rpm range, enough to let you burn more fuel (and make more hp), though at higher speeds it might get restrictive enough to raise EGT's, and actually lower the max HP available at say 2500 rpm.

The only problem with this theory is the turbo flutter that I was talking about a while back (still haven't put the time and $$ into swapping to a larger compressor with map width enhancement to try to solve the problem) which you would get in spades trying to push 20psi at 1500 rpm, and the fact that EVERYONE says the 16 housing is the way to go for towing??

Since I have only ever had the 21 and 12 on my truck AND I don't ever really pull a real load, I am trying to test out my theory vicariously . . .

What do you all think?

Thanks,

Alec

 

This does sound interesting.

Ok I can pray to the boost gods and won't get over 15psi. In fifth with just a little incline I will average about 6psi. I don't know where these guy's are gettin the numbers I see like 22 and up but my best is about 15. Of course it drops faster than a ton of greased bricks when I lift at all off the accelerator. Even then I downshif for a hill and nail the trottle with egt's at 1100* or so I will start with 15 at the lower rpm range and decrease as the rpm goes up.

What else do ya need

 

Alec-
In my experience with a high torque rise engine with gauges (the Cat 3126 in the work truck in my sig), I have found the highest EGT's at and below peak torque. The engine is rated for 300 hp @ 2200 RPM and 860 ft# @ 1400 RPM. At full load at peak torque, boost is 18 psi, EGT will climb past 1150 post turbo if I keep my foot in it and the truck is unable to gain RPM. At full load at or near peak HP (say from 2000 to 2300 RPM), boost is 23 psi (max wastegated, hits that at 1900 RPM under full load) and EGT is 950. Basically, the lower the RPM goes, the hotter the EGT gets, and this thing will make 15 psi of boost at 1200 RPM. It will pull hard down there, but it gets hot fast. I try to keep the RPM above 1800 if I'm working it, but on a flat road cruising I'll take advantage of the torque and cruise as low as 1200 RPM. I think high torque rise is fine when you don't have a big load, but when you're working a diesel hard, you have to let it rev.
Dave

 

Gary

Your manifold pressure seems a little low to me overall. On a hill in 4th with a trailer and the pedal to the floor, you should be able to run up to 2400rpm and build up at least 20psi of manifold pressure. As long as the engine is getting full fuel (e.g. running at full load at that particular speed) boost should go up with rpm on our trucks.

I could get 15psi with my 21cm housing and the AFC eccentric set to max, no adjustment to the power screw. That was at 2300 rpm WOT and normally about 80mph on a hill passing. With my 12 now I get about 23 PSI max, but I have never really kept my foot in it for more than a couple seconds at over 2000 rpm since I put the housing on -- keep running out of road.

I would check that your AFC eccentric is working properly: Did you set it for max fuel, and does it have an appropriate stop washer under it? If the washer were too thin, it might explain what you are seeing with the boost actually dropping off at higher speeds. I would also say check out your intake and exhaust restriction, but it looks as though you shouldn't have trouble there according to your signature.

How does this gybe with your actual experience?

Additionally, you might want to down-shift earlier. You can downshift out of overdrive at anything below 1900 rpm. (1900/.78=2436 the Getrag has a .78 OD)

Dave

As for high torque rise engines, we used to run 237 Maxidynes which have a 50% torque rise, and pulled down to 1100 rpm. I think peak torque was around 1000 lb/ft below 1200 rpm. They cut the fuel enough at higher rpms so that max boost is around 1700rpm and then drops off. Egt's do get high at lower speeds, but you could run those engines at WOT from 1200 to 2100 rpm all day -- lots of fellas down in WV had them in logging trucks with a straight 5 speed or a 5 speed with a lo-hole, and they could out run a Jimmy 318 with a roadranger in the hills cause you only had to downshift once on the grades instead of three times . . . A high torque rise engine won't accelerate the same way a no torque rise engine will, though, because if it takes a certain hp to maintain a specific speed, then it takes more hp to go faster, everthing else staying the same. With a high torque rise engine, as the engine speed increases, the hp remains the same, so you reach an equilibrium, or max speed, "faster", or lower in the rpm range. Conversly, when you start to lose speed, instead of hp falling off as the truck slows, it stays steady, allowing you to stay in a higher gear, and you can normally maintain a higher speed on hills because you don't have to downshift.

Torque rise is not a total substitute for peak hp, though it adds to drivability and fuel economy. It also requires a sacrifice in peak hp as far as I can tell -- and that is really where I was curious about the 16 vs. smaller housings. Everybody says the 16 is best for towing, but it seems to me that in the hills you would be able to downshift later and less with a smaller housing, and run lower rpms overall, equalling better drivability and better fuel milage, but not winning any DynoDaze . . . So I was trying to see if I am right or wrong .

Alec

 

Alec

You said a lot here but let me answer what I can. I have the diaphrame turned 120*. I think that is full fuel or close to it. Now on a pull with the fifth wheel if I shift into fourth at 55 to 60mph which is about 1700rpm I will get 15psi of boost until I have to start backin off the throttle because of the egt's. I have never run over 15 psi. Stock I only got 10 psi. The star wheel is turned in 1/2 turn and power screw one turn in. The washer is the stock nylon one. I haven't touched it. When I downshift and if I can maintain speed the boost will hold at 15psi until I lift the throttle.

I can tell ya it made a huge difference with the 16cm housing. The power this thing has now over stock with the housing and the mods is wonderful. You always want more power but she runs fine. I would like to get more boost though. I figure more boost equals more power and less fuel comsumption. I will be timeing the pump in a day or so.

 

For the sake of this discussion, there are three major things that affect manifold pressure (excluding leaks, and intake and exhaust restrictions which we will assuem are not an issu in this case): Exhaust housing size, engine speed, EGT's.

Which is really: exhaust housing size, engine speed, fuel delivery/timing.

Advancing the timing will reduce BOTH Egt's AND manifold pressure at a given speed. It will let you turn up the fuel more, however, until you increase the EGT's back up to unsafe levels.

My seat of the pants analysis of the 12cm housing is that it doesn't really make the turbo and engine work efficiently together until about 1500 rpm. I would gues that the 16cm housing doesn't start getting optimal until about 1700 rpm.

I think you will see a marked difference in your truck's performance if you wind it out more (down-shift between 60 & 65) and will also see higher manifold pressure under load at those engine speeds, with lower, "safe", EGT's.

I also think it is worth taking the AFC apart again, double checking that the deepest part is facing forward (grease it up and rotate it with the accelerator held down, you should be able to feel when the pin is extended furthest), and putting in a thinner washer (I would measure the specific pump as I outlined in the other thread). Have you checked to make sure that your accelerator linkage is pulling through the break-over spring/ does your truck pull up to 2600 rpm?

If after going through all of that, you would like to run the truck down in the 15 to 1700 rpm range, then i would suggest buying an hx35 with a 12cm housing (you could just buy the 12cm housing, but then you will have the "flutter" problem we talked about a while back). It will give you more boost and lower Egt's in that rpm range.

And you thought my last post was long enough -- I hope this is somewhat helpful. I figure it is about time to put the podium away ;D

Alec

 

Alec

I didn't mean to give the impression that your post was to long. I just ment there was a lot to think about in the post. I wasn't a simple yes or no answer.

Since I just bought the 16 cm housing I will have to stay with it for a while for sure. What my goal here is to make the most useable safe power I can with what I have. To tell the truth she runs fine right now except of the egt's. If I can get a little more out of the boost that would be great. I will check the AFC tomorrow and make sure it's set to the max.

Anything you can tell me to tweak this thing would be great.

 

Thumbs, your problem eludes me. Check my profile. I've never had a egt problem. I've ran flat out with up to 5K behind me and never seen the temps you've seen! 15lbs of boost sounds pretty stock to me to the temps have me baffled. 24lbs 1.7mm timing and 2900 rpms and I'm no where near the danger zone! You have to be blowing boost out somewhere to hit those temps. Leaking intercooler?

 

Blowndodge

I am runnin my rpm much lower than you. I think that has something to do with it. I am probably not runnin er up enough and shifting later than I should. When I shift and get the r's up the temps go down to 1000 to 1100 deg. It very well maybe operator error.

 

[quote author=Blowndodge link=board=9;threadid=20263;start=0#msg191256 date=1064981684]
Thumbs, your problem eludes me. Check my profile. I've never had a egt problem. I've ran flat out with up to 5K behind me and never seen the temps you've seen! 15lbs of boost sounds pretty stock to me to the temps have me baffled. 24lbs 1.7mm timing and 2900 rpms and I'm no where near the danger zone! You have to be blowing boost out somewhere to hit those temps. Leaking intercooler?
[/quote]

I'm with BD.. I have stock pump timing and stock exh housing, but I still don't have any problems with EGT. I hauled a 27' loaded trailer when I moved and never shifted out of 5th, it was over 80° ambient and never got over 1150°F EGT. The steepest grade was about 6% for 3 miles. ???

If you pull down below 1800, you are out of the effective torque range and not getting enough boost. IMHO.

J-eh

 

I went to a 16 CM housing. then later went to a 14 nonwastegated. The 14 is very good at lower RPMs and from a stop light it wont smoke as long cause the boost comes up quicker. My EGTs run high under a load however Im running POD nozzles which really put the fuel to it. The 14 housing seems to be a little restrictive at higher RPMS. You said your going to stay with the 16 for a while put with your set up I would consider the 14 housing. I have never tryed the 12 but think it could be a little too restrictive.
Im probably going to go back to the 16 with a hybrid HX 35 turbo. Im currently pulling 37 PSI boost with the stock WH1C with the 14 housing. without the PODs and with the 16 housing I believe I was around 23 or 24 PSI boost
I believe there is something wrong if your only getting 15 PSI boost. I would check your fresh air boost hoses and the air to air aftercooler. Then I would be checking the pump out some more.
Frosty