optimium boost level while towing and engine longivity

[pwr2tow]

I know boost, fuel, and EGT's are all relavent to each other, and one controls the other.



I know some guys are running 50+ lbs of boost at the track but that is for 12-13 seconds.



My question is for heavy towing and extended periods of time what would be the optimium boost level without hurting the engine ie, stretched head bolts, damaged bearings, or the turbo.



I bought this truck for towing, and for what they cost and what I have into it, I need to make it last as long as possible without problems.



Ron

 

[pwknapp]

I run 20-24 lbs of boost and 950-1100 when loaded heavy and with wind or aerodynamics an issue all day long. Hit 30 or so on the hills and don't go over 1250 or 1300 egt when running long runs. If it seems to be stressing harder than normal I just back out of it. It has worked for the last 400k.

 

[D. Showan]

How about 18-20psi. Thats what mine is stock. I'm sure you could run 24hr/day at that low boost level. my . 02

 

[LSMITH]

Your engine is designed to run at max rated power for it's entire life, so holding 20 PSI or so is a cakewalk for it. The only thing I would worry about at high boost levels for long periods is the lower end. I have heard the ISB275 is factory set at 30PSI, and the bottom end is identical to ours. So to hold it at 30PSI for days would not bother me at all. I would also not be worried in the least about holding a 24V at 1300 EGT for days on end either.



I have also heard that the crank, rods, block and bearings of the marine 375HP 12v are the same as the 12v in the dodges, that thing has got to be running way over 30 PSI.

 

[Joe G.]

I agree with LSMITH. Don't worry about the boost so much. Keep the EGT reasonable and it will run until pigs can fly.

 

[pwr2tow]

Thanks for the imput guys,

I have a full set of gauges, comp box, and stage 1 injectors.

The reason I was questioning the boost is last weekend when I was towing approx. 21,000 lbs combined weight and towing into a 35 MPH wind the boost was 22 psi and temps were 1000 degrees with comp shut off running boost only, normal towing the same weight is 12-14 lbs boost and 850-900 degrees.



The part that scared me the most was gaining speed from a dead stop or turning and gaining speed. The temps were 1200 degrees and boost was 28-30 psi.



I figured I was o. k. but it never hurts to find out from some real life examples from the great group of guys on the TDR.



I have two boost elbows and I plan on opening the orifice a little on one of them and experiment a little on keeping boost down to around 24 psi and see what that does to EGT's, I like to error on the side of caution, not that I don't take anyones advice as good information, I just have this nagging gut in me to experiment and prove to myself how things work.



Thanks to everyone for the guidence to my experiments.



Ron

 

[Big John]

Not sure where my '99 will run because I have not towed much with it yet. My '96 and '94 both towed best at 12 to 14 boost while running level. I got my best performance and milage there. That usually ment I was running about 62 to 67 mph. I still had plenty of reserve, max boost on both was around 32 psig. When I would go to higher boost, say 20 to 22, my milage went south and I did not gain that much speed. Head winds caused me more trouble than the hills.



I tow a lot in Texas with ambient temps from 95 to 100 degrees. The truck seemed to love the hot weather and I never have had an engine temp problem. I read somewhere, I think it was on the Pittsburg Diesel website, that boost times 10 equalled horsepower used. Both of the 12 valve trucks were set up at @ 285 to 300hp. My '99 is running more HP, so I may find that boost numbers differ with this truck. I plan a trip to Colorado at the end of May and will know more after that.



Big John

 

[LSMITH]

Ron, if you open the orifice up you will gain boost, not drop it down. What you can do to play with the boost levels is take the hose from the turbo to the wastegate off and replace it with a longer hose. Put a Tee fitting in the longer line and a needle valve in the single side of the tee. Use the needle valve to reduce the pressure on the wastegate actuator. You can drive for a few days at each boost level you have "dialed in" with the needle valve. Couple bucks for hardware and it is a TON easier than adjusting the wastegate every couple of days. Oh, the elbows with the screws in them are useless too, the screw adjusts nothing that I can tell. I think you will be surprised to find that your performance is better at lower boost levels than you are curently running. With just the stage ones and the comp on level one about 24-26 is just right. Set your needle valve for EGT, not boost. I like to be able to get 1250*- 1350* or so when run hard, that is where mine feels the strongest. Hope this helps.

 

[pwr2tow]

LSMITH,

Thanks for the how to on the wastegate.

The elbows with the orifice inside the elbow is what I have and I thinking I could just drill it out a little to increase the size which should give me more air through it which in turn should give less boost. If increaseing the hole size doesn't work I will use your setup, maybe i should just use yours anyhow since it seems that with your setup I could adjust it any time I want to any setting.



Thanks for the info.

Ron