M35A2 pegging 30lb boost meter WOT

[Badlatitude]

I have been inquiring about a few deuces for sale and have come across a great looking truck with options I like. My worry is 30lbs of boost sounds like ALOT to me. Should a Deuce and a half be capable of pegging a 30Lb boost gauge?

The truck has no EGT on it so I have no idea what the EGT is.

 

[Westech]

no.. that is too much. I would think that the boost gauge is messed.

 

[tm america]

MIne will hit 30psi. but if you do it in third,fourth, or fifth you are way above 1200 on the egt. .. either turn the fuel down or get a pyro so you can keep an eye on the egt . Also what turbo are you running?

 

[Flyingvan911]

My stock LDS will put out 13 at the very most. 30 is sky high. I wonder how the pistons are surviving.

 

[Badlatitude]

I really dont know. I just know that the previous owner ran waste oil cut with diesel and the current owner says the boost gauge pegs at 30PSI. That sounded off the rictor scale for a big diesel. The truck is about 900 miles away from here and its a proposed trade for a chopper. I guess I will get back in touch with him and see if he is willing to try replacing the boost gauge.

 

[doghead]

If the seller is proud of 30psi boost, I would look elsewhere.

 

[gimpyrobb]

Yeah, the life expectancy of that motor is very suspect. I'd move on.

 

[FMJ]

Boom !!!!!!!!!!

 

[Badlatitude]

Thats for the heads up guys. Moving on for sure.

 

[usmctopgun]

Yeah that seems about 2 times what it should be. I suspect its just a bad gauge though, that motor wouldn't hold together at 30psi very long. My .02

 

[m-35tom]

30lb not possible, bad gauge

 

[tm america]

30lb not possible, bad gauge

Tom 30psi is definitely possible. My truck will hit 30psi.this IV verified with three different gauges.problem 30psi is around 1500 egt. But they will do it.it won't last long at full throttle at 30psi with that high egt.

 

[Billy Bobbed]

I have my fuel turned up all the way with the FDC still intact,and I have alot of smoke comming out.I cant amagine how much smoke is comming out at 30 lbs of boost and the EGTs at 1500.The highest I have had my EGTs is 1450 by not paying attention to the gauge.We were comming back from Haspin with are intercom on and I couldnt here the engine that well when I was shifting from 4th to 5th.Didnt get to look at the boost gauge in time.As far as I know I have never seen more than 17 lbs of boost on mine.30 lbs of boost sounds real bad for these engines,but why not try and say you did.Then dont do it again.

 

[Badlatitude]

Its a mute point as we decided to pass on the truck anyway.

 

[JCole]

the current owner says the boost gauge pegs at 30PSI. That sounded off the rictor scale for a big diesel.

Perhaps for this particular motor, but 30psi is nothing for most medium duty motors. 40psi is factory spec for my Hino 3.8L, and my DOHC Cummins makes 40psi for 45 minutes solid on a few hills I have to climb. There is a Twin Turbo Cat at work that makes just under 50 psi, factory trim.

 

[Badlatitude]

Sorry I never had a small diesel like the 3.8 in your hino. I was going by the four macks we had at the const company and an yanmar in my boat. They all were inline 6s boost was in the 15 to 20 lb range. on thoose engines. From what I can tell in this thread it seems 30 lbs is indeed way to high for the multi fuel engine in the deuce and a half.

 

[ken]

30 PSI? Holy cow!! Ive done alot of expermenting and have never gotten a set of head gaskets to survive more than 24PSI. No matter what style of gasket i used. I can't see a "C" turbo pulling this off. But a "D" could if provided enough heat. I've done it on the flow bench. Not to mention i'm suprised the compressor wheel hasen't slung it's self apart. It has to be well beond overspeeding. Good call on passing on that truck. If they ran it that hard there is probally a good reason they are getting rid of it.

 

[JCole]

Sorry I never had a small diesel like the 3.8 in your hino. I was going by the four macks we had at the const company and an yanmar in my boat. They all were inline 6s boost was in the 15 to 20 lb range. on thoose engines. From what I can tell in this thread it seems 30 lbs is indeed way to high for the multi fuel engine in the deuce and a half.

Yeah all of our 14, 15 and 16L motors in the kenworths and petes go to 40psi with the exception of the weird twin turbo cat. EGT's climb to around 1000 degrees. This is pulling Super B's up steep long hills. 140,000lbs plus. I think that the multifuel motor could be set up for that sort of boost too. Not sure what it would take, beefy head studs, better turbo, intercooler. 40psi with 18:1 compression is pretty common with larger diesels.

 

[Badlatitude]

Thats Awesome Jcole. The Macks we ran were older mech motor one 237, two 300s and two 350s. The Yanmar in the commercial boat was a 315. I've never mad any contact with high HP big power diesels. What king of longevity do you get out of the engines slammed out with that much boost. The 79 mach with the 237 and the two stick went 22-23 years before it needed a major. Working 5-6 days a week.

 

[jimk]

30psi and 22:1 is one marriage that won't be pleasant.