HX-40 = No boost at 70MPH??

[smilliron]

Ok, been stuck playing around town with the new turbo until last night when I hopped on the freeway to go get fuel. Set the cruise about 70mph, and noticed I'm running about 50 - 100* hotter than with the ol' HY, and running NO boost at all. Sounds pretty obvious to be a boost leak right?? Checked every clamp, tightened the snot out of 'em, same thing. Is this to be expected for a bigger turbo?? It will hit a solid 35 pounds boost, not a bit more when using the elbow that came on the turbo.



So, let me know if you guys think this is normal or if I'm blowing boost off somewhere... I don't hear any whistling or anything, but this kinda sucks.



--Sam

 

[Bill Kondolay]

Sam,



Welcome to the world of turbo lag,

Most guys never even notice this, with Stefan's truck on our trip to california last week we had 0 psi boost cruising down the highway unless we hit a small hill or something.



I see this on a lot of the trucks with the big turbos. What is interestng is that while we were in CA , Stefan had some 410 gears installed and we had 2 psi of boost on the way back.



EGT's were down about 50 on the way back compared to on the way down.



I have also noticed that you get lower boost numbers after installing bigger injectors while just cruising.

 

[smilliron]

Thanks again Bill!!

Thanks a lot for the info Bill. As always it is appreciated very much. Next time you guys are in the area you should let me know and I'll have to buy you and Stefan a few cold ones for all your help, and to make up for how much I bug Stefan all the time.



Thanks again,

--Sam

 

[MikeR]

My boost gauge reads from 2psi to 50psi, there is no '0', but with my HX40 the needle sits in the stop pin at the 2psi mark doing 70mph. It instantly comes up to 4 or so onany slight hill.



My cruising egt's did not change what-so-ever. Still cruise at 525-575 at 70mph.



-Mike

 

[KatDiesel]

I got a B1 turbo, and I cruise at 72 to 75mph on normal roads with 7 to 10lbs of boost. I do have 4. 10 tho.

 

[smilliron]

Ok, so I guess that would have been good information too, I'm running right around 700 - 750* EGT at 70MPH. Is this a lot higher than everyone else? As I said before, with the little HY running 10 - 15 pounds boost, my EGTs wer around 650.



Thanks guys,

--Sam

 

[TomGolden]

Sam,



I have about 20K miles now on my totally stock HX40. I have DD 3's, a 4" exhaust and a Comp box. On the flat lands, running between 65 - 75 MPH, I see 0 - 4 PSI of boost, depending if I am accelerating or not, and usually between 550 - 700* EGT.



When I hit hills, it gets up to about 10 PSI of boost if I try to hold 70 - 75 MPH. If it's a fairly long or steep hill, and I hit the go pedal, I can make it pull as much as 30 PSI and climb up to 1000*.



Your experiences sound fairly normal to me.



Tom

 

[John_P]

Sam:



Although I have a 12 valve here are some "reference

numbers" for you on what I see with my truck:

(I have 3. 54 gears and Piers HX-40/16)



(Smooth level asphalt, 10-15 MPH headwind)

Temperature: 70 Humidity: Aprox: 70-75%



Speed RPM Boost EGT



60MPH 1500 0 to 1# 500

70MPH 1750 2 to 3# 625

80MPH 2000 8 to 9# 750



Sam, I am also running 285/75R/16 BFG Tires.

Hope this has helped you some.



----------

John_P

 

[Mopar-muscle]

sam , whats your altitude there ?



i'm near sea level and if i remeber my boost number was lo , turbo is off for the winter , though egt was the same as with my hx35 , this was running with dd3's and an ez

 

[smilliron]

MM,

Elevation is about 2800 ft.



It sounds like my boost is about right, might be just a bit hot though. I Might have to do some more checking to get a better average on temp.



Thanks,

--Sam

 

[csutton7]

you got no worry's--sometimes with bigger turbo's you may see a slight increase in EGT's on the lower boost levels--they do their work on the high boost end----0 psi is nothing to worry about under this driving condition--it's when you accelerate and you have 0 psi that you should worry----chris

 

[rubberneck]

my egt's went up 50 -100 degrees cruising down the road also and boost went down when i switched from my hx35 to the B1. i would say you have no problems at all. If it runs well, drive it and forget about it.

 

[Briar Hopper]

Keep an eye on your oil, get it analyzed, check for soot content. Less boost down low, with bigger injectors, can lead to extra sooting of oil. It's a particular concern with synthetics as you run them longer, but even with a regular oil like Rotella T, you may want to re-think your oil change intervals and do it more often.

A couple of analysis tests 5000 miles apart will give you a clue.

My stock Hx40 sooted my oil so fast you wouldn't have believed it.

Buy the best oil filters you can, that will help. Fleetguard, Hastings, Amsoil, are all very high quality filters.

 

[JJW_ND]

H

Brian... . How high a soot you get to and how many miles to do it.



I spoke too the lab I use quite abit about soot levels and they said readings less then 1. 0% are nothing to worry about. A level of 1. 5% is Cummins warning level.



The best I could get to was 0. 4%. Oil was as black as coal for the last 10K miles before I dumped.



IMO... . Lots of black smoke out the tail pipe and often WILL increase soot.



jjw

ND

 

[HVAC]

High performance turbos are intended to work at their best under high performance conditions. If you make 850* or 950* at cruise, it doesn't weigh into the picture. Peak boost and egt @ peak boost are what matters, NOT cruise egt.



High performance turbos are going to make high boost with little drive pressure. At cruise you are making the least drive pressure possible. Next to that you go negative when you let off the pedal.

 

[Bigsaint]

I'm still changing my oil at 3,000 mile intervals (Rotella T). I also had concerns with soot, since I have the BD 5's. Insoulables remain at 0. 5 for every analysis.



I have the same experiences with the HX40 as well. Running on flat ground between 55-70 MPH, I see very little (if any) boost on the DiP. gauge. Any incline or increase in throttle will move the needle, anywhere from 10-20 psi's. My egt's are the same as Tom Golden's... normal driving, not hot rodding, typically see between 600-800 pre-turbo.



Scott W.

 

[Briar Hopper]

JJW-ND, it's Briar, with an "r" not Brian with an "n". My soot levels hit . 4 , so I unhooked the bypass filters, dumped the oil, went to an Amsoil SDF-80 oil filter, and 15w-40 Amsoil, changing it every 10K, changing filter at 5k. My soot index is fine, but right now I have the Hx35 on there, pending arrival of Piers' Hx40. No bypass filtration again until I hit the right turbo combination, hopefully this spring.

 

[Idaho CTD]

High temps with HX-40

I too had what I considered high temps with a stock HX-40. I was pulling a trailer home from AZ into a pretty good head wind and was running 1050-1150 up hills that I rarely got above 950 with the stock HX-35. So I put the HX-35 back on and sent the HX-40 to Piers to work his magic on. I did run about 700-750 cruising @75 with 2-3 lbs of boost (unloaded on level ground) with the Hx-40.

What do you guys consider safe sustained temps while towing? There are a few hills I go over that are quite long and I have been trying to keep my temps below 1050 or so if it is for more than 1-2 minutes. Am I worrying for no reason?



Thanks

Nathan

 

[csutton7]

Idaho CTD---you're worrying to much--1299* and below and you have no worries---1300* and above for short periods is ok----chris

 

[Idaho CTD]

Might be a little off the subject but....

I think a lot of people are doing things to try and keep their egt's down on the HO trucks. I was just wondering what has worked the best for you? I know my '01. 5 HO runs a lot hotter than my '99 did and also hotter than my present '02 etc does. That is the reason I went back to the 5sp for my new truck.



Thanks for the input

Nathan