thumbs

Hey let me ask you guy's this question.

What were (or are) your boost numbers on a stone stock truck with both 18 and 21 cm turbo's?

Could you give me something that I can try on my truck like
rpm, pyro,speed and boost at those numbers?

Thanks againfor the help

wannadiesel

I can't give you real world numbers, but according to my Cummins manual CPL 1579, which is the late '92 and '93 motor should develop between 15 and 19 psi out of its 18 cm housing. Unfortunately my manual doesn't list CPL 1351, which is the infamous 21 cm equipped engine. My truck had this motor swapped in at some point, and it was a bog monster. I would bet it can't make more than 15 psi on a good day. I don't think your 10 psi unloaded sounds too far off.

thumbs

Thanks for the help. I guess I must have a 21cm but don't know for sure. I guess if I change it out to a 16 it would make a big difference

Craig93

With my 18cm housing the most boost I have been able to get out of her on one of the few short hills around here is 16psi, that is with no weight in the back....virgin pump, post turbo pyro hits around 600-650 degrees..@ 60mph.

Alec

With the 21 housing before I tweaked the pump, I got up to maybe 12 psi MAX. Normally I felt good if it got up to 6. After maxing out the AFC eccentric it would hit 16 or so, and maybe 950 degrees post turbo.

Now with the 12 housing I run up to about 23 psi, and haven't gotten her over 950 pre-turbo . . . But I haven't had enough of a load to really check it out with the new housing.

furious70

stone stock pump and 21cm i got about 10 empty, probably 12-13 loaded. with the pump turned up and the 21 i got 15. with the pump up and the 16cm i get 21 or so empty, and 23psi loaded @ 900*, I've never really got hotter than 950, even pulling up 6% grades

Lil Dog

With stock settings I had about 14-15 psi max boost /900-950° pre turbo with the stock 18cm housing.

Now after multiple tweaks to the pump run about 23-24 psi max boost and about 1100° pre turbo. I am unsure how much a 16 cm housing would gain, but from a 21 to 16 would be night and day.

J-eh

wannadiesel

You want to see night and day, go from a 21 to a 12! ;D

Lil Dog

I'd bet....I've been toying with getting a 14, but it would probably be easier to get a 12..

J-eh

PumpDaddy

Stock boost before playing with the pump was 15 psi, after playing have seen 23-24, but backed fuel down, and now 19-20 at wot, worst egt I've seen is 1250, up hill, better than 4000# in the bed, now is about 1150 nailed and pulling

Blowndodge

13-14lbs stock on my 93. 1.1mm timing. Now with stock injectors, 1.7mm timing, 2 turns on the full fuel screw. k&N, full pin travel, 2900 rpms, 23-24lbs. 50k after mods and no problems. Stock was pretty pathetic.

Monty

My stock numbers with the 21 were on average of 15-16psi WOT unloaded. Now the poor ole H1C is seeing 36psi.


Lil Dog,

That 12 is real nice at the low end, just dont hurt yourself by going to it and losing the top end and gaining EGT's. I guess a 14 or a 12 is okay for a mildly bombed rig, but anything more and you will be going to a 16 eventually.

thumbs

I don't get anywhere near those numbers. I am stone stock with a 21cm. Best I can get unloaded up a hill wot is 10psi. I do get 2-4 while excellerating normaly+ a little at around 2000 rpm.

I am thinkin maybe it depends on the way they come from the factory. I do remember I had a recall on the original pump. They replaced it. It may have been even more detuned than the original pump.

Monty

I have found that the VE pumps are like women. They have a mind of there own and there moods change like the season.

Just a little FYI...on a VE equipped B model, Cummins issued a service bulletin that stated if the owner complained of low power, the procedure for the tech was to take the starwheel in 12 clicks.

Thumbs, go over your intercooler boots real good, check for tightness. Also check the small boost line that runs from the intake manifold to the VE pumps diapraghm head. Alot of trucks that I have seen had the brass fitting loose at the intake.

thumbs

Ok thanks. I'll check it out. When I took the flang bolts out and removed the turbo I also moved the hoses goin to the intercooler. I though maybe I had a leak there. I duck taped the connections with no success. I will try the brass fitting in the morning. It was real good to hear Cummins had a bullin on the matter and oked the bump up. Thanks