Time for new turbo?

[mudcat]

Well I got to do a little towing this weekend towing the camper about 4000lbs. It isn't too bad until you try to accelerate on a hill, or try to get out of the way. It runs about 850* on flat ground running 65 or so. But I can bury the pyro while trying to accelerate on a hill rather quickly. I know I can just let off but what fun is that when you are pulling away from a lesser truck. I don't tow that often but we make a couple trips to TN each year and local quite a bit.

How can I keep my temps down and maybe gain a little power too. I do allright on temps until I push the boost over 34 psi or so. I can take it up to 40 easy but the temps seem to climb just as fast. I take it that I am out of the map of the turbo. What would be a good charger to replace it with 40? What are the differences in the pdrhx35s and the hx35/16 I already have? How about a hybrid? I like the idea of twins but lack the cash.

 

[AlK]

If your truck were a standard then you could shift down to 4 gear. By the way are you running the standard air filter, if so, then a BHAF should help with the egt's.

 

[BushWakr - RIP]

If you are using a modified '35 then you are at the map limits of the turbo. Currently I am running a modified HX35/16 myself. (PDR HX35). The hybrid '35 will move more air and do it cooler. The map is extended to about 36psi as opposed to 26-28psi on a stock '35 which is a good improvement.

One of the big things I noticed was that the hybrid "held the temps in check" a bit longer and fought hard to reduce the "rate" of EGT increase when kept inside it's map.

If you have a stock '35 then you are well beyond the map... . try 26 - 28psi for a stocker.

BTW, the 16cm is THE housing to use here too... . it flows air like an 18. 5cm at the upper end but has the spoolup of a smaller housing.

I have done some porting to my setup and I, like you, run into the "map" at about 36psi. When pushed to or beyond that point it is simply generating overheated boost air. (BTW, 1*F increase in ambient intake air temp = 3*F EGT rise)



In addition, the modified afc pin/cone will be a big contributor to the EGT's.

Since you have POD's in the truck you are getting more than enough fuel at the low - mid range.

Now, what I'd try is increasing the AFC spring tension a bit more to hold off the boost triggered fueling (as controlled by the cone contour) AND, ease out the fuel screw a bit.

Believe it or not you can usually fine tune these things a fair bit and really only loose EGT's as opposed to HP or at worst, a couple HP right at the upper end WOT.



You should have zero (none) smoke screw protruding into the AFC housing. Again, the POD's send more than enough fuel to get things rocking. These injectors require a fair bit more tinkering/tuning to work well with towing applications.

I bet if you install your stock cone and set it at max fueling (just as a test) you'll find your EGT's are much more manageable and will leave you with more "usable" HP/throttle.

The trick is to have the boost fueling come on later (after more boost is built) which in turn will help the turbo control some of your EGT's a bit better.

At 36-40psi towing 4K (TOTAL weight =11,000 lbs !!!!) you are definitely needing to ease up on the fueling by tweaking each setting in concert with each other.....

Timing is another area that can help with EGT's at the upper end... if you haven't adjusted your pump timing then do so. You are aiming for about 15. 5 - 16. 5* advance. The 1/8" rule can be used here... .

Ok last item here... . if you haven't increased your governed speed then do so. You can safely run these old girls up to 3000 RPM without any real issues. You should of course have a good valve set. I recommend setting the intake (normally 10 thou. ) to about 8. 5 thou. and you can set the exhaust (normally 20thou to about 18thou. ) That is going to help your breathing a bit too.

When you get time, pull the exhaust manifold (maybe when you do the turbo) and port/polish all the intake runners 1 thru 6 as far in as you can, then do the same for the manifold outlet. This should help you with about 50-60*F improvement.



Did that make any sense ?????? HEY GUY'S... towing experience help here



pastor bob... .

 

[mudcat]

Wow thanks for the great info! I am running a stock 35/16 with a polished up ATS manifold. The smoke screw is not protuding into the housing at all. I will screw the afc spring tension down a little and back off the full fuel screw to try it out.

As far as timing is concerned I haven't done anything to it but, I do notice there is about an 18" difference in the marks already. Should I try to advance it a little more? I have not installed the gov springs yet and rarely run it up that high of an rpm. I can hit 3200rpm now. I do have the 60lb springs and a recent valve set too. By the way I am running a Mean Green open element air filter, that is fairly large sized.



I have some egt issues unloaded as well, so I am thinking about a new charger. Would the PDR hx35 be the way to go or something different? How much difference would I see over the stock hx35/16 I have now?

 

[BushWakr - RIP]

Just to clarify for you... you want to raise the Starwheel UP... that will increase the tension on the afc diaphram and hold off boost fueling a bit longer. That in turn will help a bit with low end smoke as well as allow the turbo to, at the very least, keep up by getting more boost on line.

As I said, these injectors will need to be tuned/tweaked a fair bit until just the right combo/settings are found for your application.



Yes, the modified '35 is going to make a noticable difference in your temps, your "map", and your usable HP. It's a bit hard to "nail down" the improvement value but I'd expect to see 100*F or maybe a tad more improvement in EGT's. I'd also expect to see the hybrid hold the temp increase RATE back as well... basically it should take longer to hit your peak EGT's. Like any modification, the benefits will be impacted by your pump settings/injectors/timing/air intake/exhaust etc.

If you already have a 1/8" gap between your pump index marks then you should leave that alone. If you want to go to the work of finding TRUE TDC and then determining your actual timing you may find that there is a bit more available or perhaps, you already have the optimum value which is usually around 16-17*advance.

Remember, the higher the advance the higher the cylinder pressures... if more is good too much is NOT better... . (like I should talk )



pb.

You'll have an enhanced usable HP range.

The governor spring is not really needed in your case. This is particularly true if you can already pull 3K or more RPM.

 

[mudcat]

Thanks Pastor Bob. I'm going to do a little tuning and tinkering while I am saving my lunch money. It is livable now but ya know how it is... . we always think we need more.

 

["Mad Max"]

while we're on the subject - my 93, similar setup, has been making a light fog/haze at idle, not bad but easily noticable, and my off the line response is lackluster. I had to turn the diaphram all the way lean and the starwheel all the way up to get it to pass CO smog laws, and now I'm wondering if the difference between where I used to live (CA) and here made a difference in where I should set my timing? I also noticed my boost has gone down as a result of the detuning. I want to tweak the rig as best as possible before tearing it apart, but the setup going in nesxt will be a lot differrent than now, so maybe just wait for the head/cam/twins?

The idle haze is my primary curiosity - want to figure out why it's fogging out. No issues with being followed by a hungry pak of mosquitos tho :-laf .....

ALso, I'd really like to increase the rpms - PB, how does that spring work/what does it do, and how far apart does the pump have to come to get it in? I know there's a lot more hp in my pump... I just haven't gone looking for it.

- Sam

 

[mudcat]

Samsrams I've noticed quite a bit more haze lately myself. I guess because of the cooler weather maybe.

 

[BushWakr - RIP]

Hi Sam,



I'll post a quick link to the governor spring install here... I'm assuming that is the "spring" you're referring to.



http://turbodieselregister.com/forums/showthread.php?t=73761



Bascially you can raise your governed speed using the high idle screw. Now when you use that your governed speed is raised but the normal defuel point still happens about 300 RPM before the actual governed limit.

So, for example if you have a gov speed set to, say, 3000 RPM then as you approach 3K the governor function begins to take hold roughly 300 RPM prior to that... .

Then as the gov. reduces the fueling (defuel) the rate of RPM increase begins to slow until eventually you reach your 3000 RPM limit.

You recognize this event by the "falling on it's face" feeling as you hold WOT. .

Now the replacement spring, which is designed to be used in another application with different counterweights/cam/roller ring etc just ignore's the normal governor effort to defuel. This happens because of the springs' tension. (tougher)

So in essence what happens is the heavy rate of fueling which would normally begin to be decreased more and more as you approach your 3K limit, is pretty much disregarded due to the heavier spring.



That causes the pump to push max fueling pretty well right up to the physical gov limit setting.

Since the spring is so stiff it is also pretty touchy... .

I did a runaway test on my brothers truck that demonstates this. .

His truck has a gov spring as well as some other neat little tricks done to it...

When I went to do my "runaway test" the following happened. .

As I slowly depressed the throttle toward my normal test RPM (about 2000 RPM) we reached roughly 1500 RPM and the pump started to 'give off that hint' it was gonna act funny... .

I stopped all further pedal pressure and waited... after about 5 or 6 seconds the RPM began to climb on it's own, slowly at first then quicker and quicker.

We reacted right away thinking it would just continue to run wild.

After 3 or 4 runs at this, I held the pedal a bit longer while the RPM climbed...

when it reached about 2600 RPM the governor suddenly kicked in and just grabbed the pump, stopped the upward climb and hauled it back down to about 2350-2400 RPM. At that point the governor released and the climb began again until we hit roughly 2600'ish again... and it repeated the process of catch/defuel/resume. .

Basically this shows the "touchy" nature of the other gov spring. Unlike the proper one which responds early and smoothly this new one is a bit more touchy.

I'd describe it as showing "poorer driveability" ... .

Ok, pretty long winded... . sorry. .



As for your emissions testing I had a thought this year... when I went in last time I backed out the fuel screw so far the darn thing would barely run. . literally.

I rotated the AFC to lean and made sure the starwheel was right at the top.

We are allowed a reading of 30ppm. On that previous test I turned in a reading of 26. 9 I believe.

This year I tried something different. .

I disconnected the boost tube to the AFC and plugged it off... then I dropped the timing back to just barely over "factory" index marks and turned the full fuel out 1/2 - 3/4 turn.

Off I went... I was seeing a healthy 32psi boost, little to no smoke as boost built up to 6-8psi.

The test results... ... . 14. ?ppm EASY PASS !!!!!



The surprise was that with THAT much fueling removed I only lost about 10'ish psi boost and dropped from an easy high of 1500*F on a pull to a hard to do 950*F ... ... . go figure. .

I am still running around with the truck set as above and it seems to really be "happy" with itself... course I really would like to have the "jump up a tree" response when I touch the throttle, but, for winter it works for me.



I also have a valet switch behind the seat that is going in as soon as I get ambitious... and maybe a little something that will allow me to control the full fuel setting remotely as well.....



Ok that's enough I'm tired of typing. .

Ok one last thing... it's been my experience that the POD's like to have a cleaning and reset about once every year or so. The tip design is prone to needing a bit of tweaking and reset. You might want to try having them reset to about 260-265 bar to...

pb...

 

[dpuckett]

Having never run PODs myself, I cant tell you about them. But I will say, that when I was hauling hay out west a few years ago, I'd have a GCVW of 22-25K, and run 65-70 in 5th gear all day long from central KS to ColoSpgs. Never had any EGT issues, except up one hill, I'd downshift to 4th and run 60 to the top.



What washers are you running with the PODs? How old are the PODs? If you dont do a whole lot of towing, they can coke up faster than if you run it hard all day long. Not sure why, but the injectors out of the fleet truck I bought with almost 200K had LOT better tips- as far as pop pressure and spray pattern than the 93 farm truck I'd had earlier with only 135K. How fast are you building your boost? Mine is a little slow on the bottom end, but really goes once it hits 24psi or so. High 30s for boost numbers are impressive, but if you can build up to say, 25psi fairly quick, and peak at "only" 32-34, you will have more useable boost on the bottom end, and consequently less heat due to slightly lower RPMs and fuelling. ANyone else confused? Think I need to come back later and clarify this one



Daniel

 

[KeithTaylor]

Any thoughts on putting a larger intercooler (2nd gen) on to help hold the EGT's down? If 1* ambient = 3* EGT, I would think that more intercooler would be good . . .

 

["Mad Max"]

Bob - you are a friggin witch - ya know that right?? Dude, I think you've probably forgotten more about our trucks that all of us will ever know! Thanks for the intel - I'm going to be doing some serious digging on my pump in search for the magic tweak, and I want to know what I'm doing before I tear the whole schmeal apart... .

Thanks Bob - much appreciated.

- S

 

[BushWakr - RIP]

"..... Bob - you are a friggin witch - ya know that right?? ... . "



Naaaaa... . I'm just anal... or so I'm told occasionally



Daniel is correct... these nozzle's will foul up if you don't take 'em out and "hog on 'em" with some good hard run's/EGT's once in a while not to mention, a good dose of detergent/cleaner additive as a "chaser".

Also, as I mentioned they really do like to have a reset and tweak about once a year.



Yes, you'll see more smoke this time of year when it's cold... again because of the tip design and the tendency to want to have some coarse spray. That is why I have some POD's that have been tweaked up to 270'ish bar. I'm going to do some testing to see

A)If there is any difference in the performance/smoke/egt's etc. and;

B)If the pump will put up with that setting for pressures.

The "manual" says that the VE is good to 350 bar but you know what the manual is good for right... .



Keith you are on the right track too... . the larger more efficient IC would help a fair bit in our application but mostly at the upper end of the "insanity scale"

Most guys can reach 300 - 350 RWHP without "TOO" much $$$ and trouble. It is a bit of strain on them but it is do-able as alot of signatures indicate... . It's the next 100-200 and maybe 300 RWHP that is the real $$$/wear and tear/rip into the guts/hold your breath and hope for the best situation.



Still, I think we will see another new milestone for VE performance in the coming months... . and no, I don't mean 500 RWHP from a VE I mean..... ??? you guess



pastor bob...