Max Turbo Boost Pressure, Max Safe EGT?

[houdel]

Like many on this board, I'm thinking of turning up the fuel in my Deuce for a little more power, but I want to do it safely. I will install a boost gauge and pyrometer before I do anything else.

My first question is how much boost does a stock C or D turbo put out? Most people seem to run 30 psi boost gauges, but I believe I've seen postings that the stock turbos only put out 12-13 psi boost vs 25-30 psi that modern Cummins and Powerstrokes put out. I have found ISSPRO boost gauges in 20 psi and 30 psi max ratings. Since the stock Deuce boost is fairly low, should I get the 20 psi gauge for better scalability, or go for the 30 psi gauge in case I decide to get one of Dr. Foster's super turbos?

Second question is what is a safe max EGT? I've seen 1200 degrees F mentioned, is that as safe conservative limit? I'd like a little more power if possible, but not at the expense of potential damage to the engine or turbo.

 

[Djfreema]

In my experiences with the dueces I've had. A stock C turbo with no load puts out about 6 lbs, and a D is about 7 lbs. I think that is the max boost at that fuel setting where you dont have to ever worry about EGT's. I usually dont let mine get above 1200 degrees at 15 psi boost, (no load) although I think around 1300 degrees is the max I would ever go and only on a short burst. On loaded pulls (#13000) going up the grapevine I have to continually monitor my egts and back off the gas pedal then eventually end up downshifting into 3rd gear where the egt's are easier to keep in check. One day I cranked my fuel rate up all the way for fun and pegged my 20 PSI boost guage and the egts skyrocketed but boy was it fast!

 

[Deuceswild]

Hi Lee,

I think perhaps you may have seen my post where I did the turbo conversion?, I originally installed the "D" turbo and was very happy with the results, I also had my Pyro and Boost gauges installed, the readings were maybe 2 psi bosst city driving and about 7 psi going up a 5% grade about a 1/8 mile long and doing 45 mph, EGT varied from 600° city driving to 1,000° attacking the above mentioned grade.

Then I though about installing a "C" turbo, Really not much different as far as the readings go but the engine did suffer a little from the size difference, the C is smaller and a little more restrictive, but it does sound cool!

So now I get the idea to bypass the F.D.C. ( I posted this last saturday when the server crashed and the thread got lost ) and what a difference!! Hold On To Your Shorts!!
The boost and the EGTs rise VERY QUICKLY, Must Be Very Carefull as the engine responds to the throttle instantly.

Now I got more curious and installed the "D" turbo again, and again quite an increase compared to the "C", on the above mentioned grade I had to let off of the accelerator as the boost was approaching 14 PSI and still climbing, at the same time the EGTs were just start hit the 1,250° mark, again had to let off of the pedal, I also wonder how much boost these engines are capable of handling with out damage occuring, I have only driven it once the way it is currently.

PS, did you get my P.M?
Jeff

 

[ken]

Dwild, when you bypass the FDC your sopposed to bring the fuel rate down a bit. Bypassing it will let the IP have more fuel.

 

[Deuceswild]

Ken,

I know this is the case but I have not been able to locate the correct TM to do the calibration. The TM # is 2-2910-226-34, but I amcomming up with dead ends.
Jeff

 

[jasonjc]

Hey jeff trie TM 9-2910-226-34 it's on the LOGSA web site I'm downloading it now shuold have it in about 45 min (dia up Su**)

 

[Deuceswild]

Jason,

Thanks for the tip, but I couldn't access that TM through LOGSA, ( Its the 1st I've been to that site, perhaps I did something wrong .
However I did find it here http://www.tpub.com/content/fuelpumps/TM-9-2910-226-34/
Thanks for your suggestion though .
Jeff

 

[houdel]

OK, I think I'm getting the drift here. Stock engine with mild fuel delivery adjustment may top out at 6-7 psi boost. Up the fuel delivery, boost and EGT go up. Looks like maybe 15 psi max boost as long as EGT stays reasonable. So a 30 psi gauge would be sensible, if i can get to 15 psi boost with a safe EGT the boost gauge needle would be midrange, i.e. vertical, good for a quick visual check.

Jeff, I did read your post on bypassing the FDC before it disappeared. I'll leave the FDC as it is and just tweak the fuel adjustment as Bjorn described in http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=303. I've got some good long, steep hills around here, I'll just crank up the fuel 1/6 turn at a time until the EGT gets up to 1150-1200 and be happy with that. I'm not interested in drag racing or sled pulling, but if I can coax a few more ponies out of my engine I'll be happy with that.

I did not get your PM either. Not surprising, I've sent out a few PMs which were never recieved, and suspect a few sent to me never got here either. You can email me at houdel@carrinter.net. Thanks, Lee

 

[cranetruck]

Lee, my pump is not turned up and I usually see 6-7 psi accelerating down a level highway. Loaded down, 11-12 psi is not uncommon when hitting a hill and trying to maintain speed and I back off before the EGT shows 1,200.
Interestingly, with 100% biodiesel and veggie oil in the tank, the boost is reduced several psi and I have never been able to reach an EGT of 1,100°F even. Performance seems to be unaltered.
For reference, my deuce weighs 17,000 lb MT.

 

[jrobinson5093]

the boost in my deuce has never even seen 10 psi at full throttle in fifth gear at 2500 rpm it only reaches about 7 psi and i have the fuel turned up two flats and it smokes like crazy. it is a d turbo by the way, in the other gears i get very lil boost , does this seem normal?

 

[patracy]

Holy old thread revival.

Boost pressure, yes. What are you EGTs?

 

[tm america]

it depends on what turbo and air filter you are running..a whistler turbo with stock air filter will be 12-13 at 1200. i have a whistler on mine with a k&n filter and 1200 is 15-17 unloaded..I have mine cranked way up right now i can hit 26-27 psi right now .. and it never gets over 1200 till i hit 4th or 5th gear.Then the egt comes up fast.THe truck is super fast how it is now i am gonna put a cable to adjust the fuel on the fly cuz i love the extra power when i'm mudding.It never goes over 1200 when i'm offroad cuz it goes through the gears so fast.The other turbo i have you can safely get 20+psi out of it at 1200. it is a lds427 turbo. I am gonna throw that turbo back on the with the k&n filter to see what i can get out of it.. i'm guessing i will be around 23-24psi at 1200. but i will let you guys know in a week or two when i do the swap

 

[jrobinson5093]

I dont know I dont have a egt gauge. I just keep reading about people hitting 15 psi and above.

 

[Green Toys]

Well, if you crank your fuel, make sure your pyrometer is working corectely, mine started to seemed to be running cooler, well it wasent, it ended up blowing a head gasket, now I have 2 new pyrometers, there cheep compared to a motor, I run 1200 deg @ 20-30 lbs for hours and do fine, just don't push over that for too long. The cable operated fdc is the best

 

[Flyingvan911]

My LDS with c turbo will usually top out at 12 psi. Once in a while it will get up to 13. I haven't messed with the fuel and don't plan to. It has pleanty of power and speed for the kind of truck it is.