over speed on a non gated turbo??

[Clb]

So all my turbo experiance is in 18 wheelers .
88 250 c 6 4.10's loaded down 9k on the hitch...pushing low gear at about 2-2500 it pulls smooth just before i went for 2nd it fell flat on its face kind of felt like the oil stopped running. it will pull drive at 3k. so my question is did i over spool it due to the tourque converter multiplication or is something else going on?
thanx in advance, cb

 

[justinray]

I don't see how you could overspeed a turbo in low... Its difficult for me to even build pressure in first, with a tiny wastegated turbo.

 

[RLDSL]

Most of the time you dont start building any real serious boost till around 2k so if you were at 2500 when it kicked into 2nd you were basically dropping back down below boost level, so this is just normal behavior . you dont have the exhauxt pressure needed when the rpms drop down too far unless you have your foot steady in it and the boost pressure has had a chance to build. Now , if you have a good load on and have been climbing for a bit, you can build up a REAL nice boost level even at 1750 rpms and just tool on up the hill, its simply a matter of getting used to how that turbo likes to be fed. If you are running empty or lightly loaded, dont plan on seeing much boost, it is very load dependent. It rolls on when you need it most, and when you do , you will have all that you need, provided that your pump is set correctly. Now, if your timing is retarded or pump turned down too far, then you may have issues

 

[Clb]

Thanx.. from a dead stop 9k on the hitch before the 1-2 shift it puked... aint timed it or verified the inj./ pump match yet.
Its only getting 8 mpg at 50% towing... looks like ip and inj. time but why would it puke at the powerband +- 500 rpm?
Thanx cb

 

[Kevin 007]

That mileage doesn't surprise me with a C6 and 4.10s towing. But if thats and average...thats pretty low. What kinda smoke do you see upon acceleration? Any light blueish??? that would indicate that the timing is slightly retarded

 

[Clb]

Just a touch at the first responce of heavy throttle input. i need to find a timming instrument and see if it is off...
the p.o. had no clue.(fed. Nailbanger)
And I have a licence so dont get mad .
thanx for the input. will follow thru on this

 

[icanfixall]

So did you just buy this... What injection pump is on the truck... You might have the low rpm injection pump. Most all the pumps will fit our engines but the ones designed for the big dump trucks and many uhaul moveing box trucks have a injection pump with a governer speed set to around 2700 rpm. Our pickup truck pumps rpm limit at 3800 rpm... Makes a big differance.

 

[Clb]

thanx,,, I just got this been thrashing it to get it back up to parr. it seems to have the correct ip cording to the part # from what may be the first one (grey paint and in the bed when i got it) and the one on it now both are listed for an 88, current one is the #1 superseded part #
current # db2831 588032 4703 j 18091 121c 92
old grey unit d9 db2831 4732 j 6396 123 161350c91
these look correct ?
and how does one id what hp the pump is? as the parts list just gives years I have looked into the oem site with no help!she seems to run well ,if a tad hard to start (imho) under 30 sec usually idles smooth don't see much smoke a first puff at start up bluish/white, and at first stab of the throttle when hot is will puff about the same color/amount, looks like an over adjusted enricher or accelerator pump onna gasser.
thanx for the input guys