'90 W250--'89/91/92 Ramcharger

[Tacoclaw]

Hopefully Saturday right after work, then I'll have a gun loaded and ready to spray primer on it as soon as it's done and cleaned. I'd like to have it painted done, and out of there by Monday. It keeps the flares from the bosses down.

[Tacoclaw]

Alrighty, boys, once again before I have to risk asking on CompD.

I'm working with the RPMxcid/3456=CFM equation. As you can see in this pic I scribbled all over, you pretty much just drop a zero off the RPM you're at and that's what a 5.9 will want CFM-wise. My question is this, is that what the engine is guaranteed to be pulling at those RPMs? Is that the bare minimum required or is that a best-case scenario number guaranteed to burn all the fuel needed to maintain that RPM?

I'm dealing with this chart, the lower, less steep line is the CFM requirements of a 5.9 at those RPMs. The steeper lines are the blower input(I assume that's also the output since it's a positive displacement pump) CFMs. At 1000rpm, where I need a little pep, it looks like the blower is just putting out the 100 CFM the engine needs. This is with my best case, and expensive, 3.1 drive ratio I've been able to track down. Of course once RPMs ramp up the blower far outpaces the CFM needs of the engine, but that'll drop as the boost comes up.



Thoughts on if this thing, numerically anyways, is going to make any difference at the 1k rpm range?

Like I said, this is all tied into just what that equation is calculating exactly. If my truck would only pull 104CFM at 1k if it's inlet was exactly as big around as the piston, then this isn't an issue.

As an edit, this is all assumed N/A. I figure my turbo starts lighting around 18-2200. I have no real idea since I have no tach, but earballing it that's what I'm going to say. The blower output doesn't amount to much once above that RPM because the turbo starts putting out more CFM than it can pull by that time.

[oldestof11]

Does this help?
http://www.competitiondiesel.com/forums ... p?t=112491

[Tacoclaw]

Kinda.

I know roughly how to read the maps, I'm just wondering about what I've got scribbled down there. Mostly if our engines actually consume 104cfm of air at 1k RPM under normal circumstances. Like I said, if that's some sort of perfect number then I'm not too concerned. Otherwise it seems like this blower will almost become a restriction at speeds below 1krpm since its production line drops so much faster than the Cummins consumption line.

[Tacoclaw]

It's not like any of this matters, I already know I'm going to pulley it as hard as I can and run it no matter what.

Just looking for some insight on if what I'm reading there is true. I'm kinda jealous of everyone knowing the math needed for stuff like this when I don't.

[Tacoclaw]

I am alllllllllmost ready to believe things may work out and this will be painted and ready to come home by Monday.



Still, 3 days is a long time.

[Tacoclaw]

So it starts, progress this far today:

Me actually doing some work. I learned that sanblasting sucks ass.


And various stages of primer.




Fully coated with primer, we're grabbing some food while it dries.


Well, we were grabbing food. Now we're sitting in a parking lot in my painter's car out of gas.

[dazedandconfused]

How much sand did you use? I have the same blaster.

[Tacoclaw]

Like 3-4 1/2 bags. I used this nasty-ass Black Beauty media that we've got a pallet of laying at work. It cuts like crazy but plugs up the tip a lot.

[Tacoclaw]

Dun!

[dazedandconfused]

Chassis savers is some good stuff. Its all I use and hardens like steel.

[PToombs]

It goes a lot faster if you use a real blaster. Where I used to work we had a big one, held 300 lbs of sand, ran off a tow behind compressor with 3/4" hose. That would peel rust like dirt coming off. It would take about 40-50 minutes to do your frame. It was loud and dirty though. Respirator and hearing protection were a must.
Now put it together!

[Tacoclaw]

We used to (still possibly do) have one like you're talking about, even had a tow behind compressor with a screw-type compressor instead of a piston style, but I didn't see any need to look around for it for this job. I'd hate to use anything bigger, I went out there at first with just the hood, some rubber mechanics gloves and a T-shirt. That lasted about 4 seconds, it was like the frame directs every grain of sand right back into my arms.

Grabbed a flannel and just dealt with it after that.


I'm going to assemble the frame brackets and leaf spring stuff, but I'm still planning on making this blower happen while it's still in the Dodge. I just feel like the old girl deserves one last hurrah.

[PToombs]

A flannel? And you still have skin? We usually did it in the winter because there was nothing else going on, it was a nice filler. We'd blast the frame and paint it, then do the body work and paint the truck. Every truck got done on a 2-3 year rotation, plow pickups, 10 wheelers, 6 wheelers, septic truck. We'd wear a coat, coveralls over that, tape the sleeves and pant cuffs, respirator and hearing stuff and the hood over that.
It was fun blasting when it was 10* out. I couldn't feel my fingers, but the frame didn't rust.

[Tacoclaw]

Yup, it wasn't so bad, it was working over my legs worse than anything since I was just wearing blue jeans. I didn't care, I wasn't stopping and risking not getiiing it done today because I wasn't comfortable.

I also had a cut right on the heel of my hand and the glove was holding a big ball of media right on it, rubbing it around every time I moved. I had to pick them all out with a razor blade after I was done.