'Red' - '89 RC, 6BT/518 - (...at home in Virginia...)

[jungle]

Did you put the OD button on the end of the shifter?
Jim

[Mad Max]

it's not 'finished' but yes it's at...actually it's taped on to the shifter.  It's pretty primitive but it workie just right 

[blueduster]

man do i hear you on the wiring. tedious and time consuming.

so far so good.  I had to readjust the pressure switch that controls the on-off for the overdrive but other than that it works great .  I'll do another fuel mileage test once I fill it up.  I'm hoping a correct trans and higher stall net a bit better fuel mileage.  Then I'm planning to finally bolt up the newer turbo and collar to get both a bit more boost and a bit less turbo lag.

I'm still trying to figure out what the deal is with the steering column wiring.  Wiring, my least favorite part of any project.

[jungle]

it's not 'finished' but yes it's at...actually it's taped on to the shifter.  It's pretty primitive but it workie just right 

I just got the 2nd gen one & installed on the 92 column that will go into the 88 RC. It's really easy to install.
Jim

[MoabION]

well no not 'the' ultimate truck , but for what I need a truck for on a daily/weekend basis, and for what I think I will need in the future, and all things considered, then I'd have to say I'm leaning that way, ja. 

In basic order of priority, the list of requirements for my daily-driver include, but is not limited to -

- Dodge
- Full-size
- No monthly payment
- 4-wheel drive
- All-weather/all-year capable
- Cummins-powered
- Reliable/easy to maintain
- Good fuel economy (20+ hwy ideally)
- Hold 4 full-size adults minimum
- Cruise, delay wipers, tilt

A 3/4-ton 4x4 Cummins RC does all of that easily.  Now the 'nice-to-haves' include:

- 4-doors (ideally)
- Tailgate

I like this list Sam, after driving my beast across country and across trail, I agree, 600ft lb 6bt, 35's 3.54's, and OD (mine with the 5spd) are a great combination. Add AC to the list.  Not perfect for any one thing, but a good compromise and bulletproof.  I would love to have 4 doors and a short bed or a Subummins. I was getting just under 20 mpg before the Detroit and new tires.

[Mad Max]

...so I filled up today, first after the tranny rebuild -  still getting ~18.2 mpg.  Okay, so I'm thinking it should be better, and I start to think of other things that I've changed recently, besides the usual things like an engine and tranny swap...and we recently did tires, so I begin to wonder about tire pressure.  So, I check the tires and....hmmm, wow, these say 80 psi cold - okay these are load range E so that jibes...check the pressure and....well dang - they're at ~45-50 psi - all of 'em.  Hmmm - well that can certainly affect mileage, especially when they're 30 psi under where they're supposed to be.  So, upped the pressure to the recommended 80 psi, and we'll see how much further I get.

And yah the tranny feels friggin fantastic

[jungle]

Glad the trans feels great this time!!!
JIm

[blueduster]

i'd actually try 65-70 psi sam. that 80psi is meant for max when carring a load. at 80, you may get some loose fillings. may not be as noticable in a RC but in a p/u it is a rough ride. 

...so I filled up today, first after the tranny rebuild -  still getting ~18.2 mpg.  Okay, so I'm thinking it should be better, and I start to think of other things that I've changed recently, besides the usual things like an engine and tranny swap...and we recently did tires, so I begin to wonder about tire pressure.  So, I check the tires and....hmmm, wow, these say 80 psi cold - okay these are load range E so that jibes...check the pressure and....well dang - they're at ~45-50 psi - all of 'em.  Hmmm - well that can certainly affect mileage, especially when they're 30 psi under where they're supposed to be.  So, upped the pressure to the recommended 80 psi, and we'll see how much further I get.

And yah the tranny feels friggin fantastic

[Mad Max]

i'd actually try 65-70 psi sam. that 80psi is meant for max when carring a load. at 80, you may get some loose fillings. may not be as noticable in a RC but in a p/u it is a rough ride. 

  rog - I did notice it a bit more 'bumpy' this morning, but not too aweful.  Figured I'd give it a couple days and adjust from there.  I guess that was the same idea the tire shop had when they mounted 'em, but 50 seemed just too low.  I dunno, we'll see if it 'adds up'.  Good 'experiment' opportunities tho.

[rob904x4]

hey sam i have been in the tire buisness 12 year everywhere from installing to whole sale to retail if i was you i would run 60 in the front and 40 in the rear  that whats i run in my 2 cummins rigs 80 would only apply to a full load in the rear only there is no reason to run 80psi in the front unless you have a very heavy front brush gaurd and even then there is no reason for 80 in the front

[Bogie]

The best way I have found to check for proper psi in the tires is easy but will take a little time all you will need is a press gauge,a piece of chalk,and a straight and level roadway.Start by chalking the tread area of the tire then drive straight for a few feet till the tire makes at least 1 full revolution,then ck the chalk pattern adjust till you get even ware.

[cragdweller]

I get the best tire wear on my diesel with about 45 in the front and 40 in the back.  Handles fine too...

[Mad Max]

thanks for all the replies on tire pressure felals.  I'm sure I'll air down a bit soon - right now it's more of a science project to see how much, if any, affect it will have on fuel mileage.  Might not be any - I'll know in a few days.

[Mad Max]

...my science project continues - "Operation 'Light-Weight' " is in effect.  I'm gonna put Red on a diet  

To that end, I'm 'searching' for a D44/9.25 set from a RC or Ram, with 3.21 gears.  When I find those, the Dana 61/71 combo under Red now will be for sale.  Trades (+/- cash) certainly considered.

Also going to replace the 205 with a 241.  Be good for a few pounds.  Fiberglass hood...etc.

I am also looking for a 4bt - good running and complete, of course.  

...I'm just sayin...  

- Sam

  

[jungle]

That would make a sweet combo. You can defiantly get a lot of power out of the 4BT if you try. Should be plenty for the RC, You won't be able to pull any super tankers but it would still be a lot of fun!!!
Jim

[Mad Max]

what's cool is with this truck I don't 'need' a lot of power - just enough to get to work.  A 4bt will do that easily, and when it isn't accelerating (traffic driving, etc) it'll just be loafing along same as the 6bt does now, only with 2 less cylinders to feed.  Should work out pretty good, and if I can keep the truck light enough then it shouldn't have to work very hard.  Could be a colossal mistake too - could be too-underpowered, but I won't be selling the 'spare' 6bt, soooo......

[jungle]

You could crank up the pump, Install a set of 55lpm injectors & a good turbo & Hang ON!!!!
Jim

[RVA RC]

Aww man a Mad Max built 4bt RC? I'm definitly keeping an eye on this! That's the RC I want to build! All I need is the 4bt, and *cough* the *cough* RC. Oh well. I guess I have to keep saving my pennies and living vicariously through you and all the other RCC'ers.

And to think, when you started this 4 pages ago it was all "KISS" and stuff. 

[Mad Max]

Aww man a Mad Max built 4bt RC? I'm definitly keeping an eye on this! That's the RC I want to build! All I need is the 4bt, and *cough* the *cough* RC. Oh well. I guess I have to keep saving my pennies and living vicariously through you and all the other RCC'ers.

And to think, when you started this 4 pages ago it was all "KISS" and stuff. 

...well....so far...for this truck I haven't fabricated anything - everything has bolted right in   , so technically I'm still keepin' it simple.  I didn't say anything about not having fun experimenting!

[Mad Max]

okay, so after yesterdays fill-up, pumping up the tires had no change in fuel economy.  So, where'd my mileage go?  Here's my thoughts -

Assuming the 'new' engine and the 'old' engine are otherwise equal, and with a good tranny, and with fresh tires, the only thing that I am doing differently...is driving faster.  Before the overdrive I'd cruise along at a happy 60 mph, wheras now I can easily do 70+, but, my thoughts are that the increased aero drag is sucking down my economy, pure and simple. 

So, the next couple hundred miles I'll cruise along at 60 mph again, and check mileage again.  If it's back up in the 20 mpg range, then I'll have confirmed my suspicions, and at that point I'll have to decide between 70 mph @ 18 mpg and 60 mph @ 20 mpg.

Now granted, my mileage numbers are an 'average' - city and highway, and I'm thinkin' 18 average is pretty good for a full size.  I have a short trip planned and it's mostly highway, so I'll likely cruise it at 70 mph and see what my highway mileage is.  I'm near certain it'll be at/over 20, but my goal is 20+ mpg 'average'.

My only criteria for all this testing is fuel economy, testing different things out to see what does what and what doesn't do squat.  Chassis changes, different gears, tire changes, engine swaps, overdrives - I'm learning all kinds of good info, and in the end I'm hoping to have a very reliable, efficient, daily-driver RC that I can take the wife and dogs fishin' in, maybe pull a small bass boat behind.  I'm near certain a "1/2-ton" RC with a 4bt and 518, with 3.21 gears and a nice 31" tire, will do what I want with ease.

If I wanna go 4-wheelin...well I got the other toy for that , and a rig to haul the toys around with.  While it has taken many, many years to get 'here', I'm pretty certain I am on the downhill side of knowing what I need, to do what I want, how I want.

- Sam

[KansasCrewCab76]

Double M,
For your consideration:
My all stock 93 D250 will get 24 highway with 65-70 psi in the tires at 65 mph on the highway. One thing I have always tried to stick with is 1800 rpm no matter. I run around in town and 1800 rpm is 45 mph, perfect for all the city streets, it will get 20-21 mph in town.

Just some input. I have tried this 1800 rpm on 5 different CTD's and the results are the same. I also do not ahve a heavy right foot.

Now I know mine isn't a 4wd, but it is a 5spd with the .77 OD ratio, but your 518 4wd has a OD ratio of .69. So the difference has to be wind resistance (your higher vehicle height vs. mine)

Just rambling...sorry.

[blueduster]

i don't think the aero is as much to blame as you think. i think our kansas brother is right. haven't owned a ctd but been around them a lot at the dealership and friends. the 1800rpm seems to  be a common area they like. every engine has it's happy zone. my 5.0 stang liked 2000rpm/75mph and got 24 mpg early in it's life, 21 after 200,000 miles.( think it was the heads needing attention.) my 2 barrel 318 dart liked 2100, got 20mpg even after 100,000. of course both of them, especially the stang, had great aero compared to our trucks. but i don't think the aero of a W250 and RC are dramatically different. my 79 RC gets 12 at 75(about 2000) and at 65(1700). i think it would do better with more gear to get to 2000 at a lower speed. after i get my work done i will have to start new experiments.   

[88_mopar]

but i don't think the aero of a W250 and RC are dramatically different.

Yea but KCC76's D250 probably sits alot lower than Red.

People never believe me when i tell them my RC gets 16-17 mpg. But they never take into consideration that it sits about 6" lower than a stock AW150.

[s ǝoɾ]

i don't think the aero is as much to blame as you think. i think our kansas brother is right. haven't owned a ctd but been around them a lot at the dealership and friends. the 1800rpm seems to  be a common area they like. every engine has it's happy zone. my 5.0 stang liked 2000rpm/75mph and got 24 mpg early in it's life, 21 after 200,000 miles.( think it was the heads needing attention.) my 2 barrel 318 dart liked 2100, got 20mpg even after 100,000. of course both of them, especially the stang, had great aero compared to our trucks. but i don't think the aero of a W250 and RC are dramatically different. my 79 RC gets 12 at 75(about 2000) and at 65(1700). i think it would do better with more gear to get to 2000 at a lower speed. after i get my work done i will have to start new experiments.   

MM and KC are BOTH right.

May sound like a preacher, in the past max had talked about "air plane gears" and running 3.07s/tall tires/overdrive, and I explain in my own experience "it don't work that way". 1800 is a sweet spot A little higher seems ok, not much lower. It will also keep the transmission alive. Somewhere, there is a flow chart showing the GPM of the trans pump. Under those speeds, flow drops off, which means not as much can be pumped through the cooler and still hold everything tight. Double benefit!

(I know I recently thread jacked you, mentioning getting rid of the 3.55s, and going up a good bit, gasoline mopar is better in the 2000-2400 range, dodge built them to run around 2400, but a lil less works fine)

back to diesels and 1800 rpm. You are sitting in massive torque peak at this point. Peak torque and peak fuel efficiency coincide because in order to make the most power, you have to use the fuel the most efficiently. Triple whammy. On flat ground, you might be able to lug an engine and get away with it. Even on the slightest of "rolling hills" (anything outside of florida and nebraska) in order to maintain constant speed you will sometimes have to dig into the throttle. If you are already near peak torque during cruise, when you hammer down (or gently accelerate) you stay in that zone, instead of trying to play catch up. No matter the engine rpm, the truck requires a specific hp to keep it rolling. Lets just say 100hp for a big truck. At 1800rpm it is easier to make this, than say at 1300rpm. Prime example is a stock 426 hemi I dynoed. Put out 430 real hp @ 5500rpm. At 1000rpm, it only made 8hp. Below it's efficiency point it just doesn't make power. In the case of a vehicle going down the road this results in transmission kicking down/engine slowing because it can't make the grade/or torque converter or clutch slipping. (not likely to slip a clutch since you can't make enough power in the first place) Of course that is extreme scenarios, like towing or just under powered (not most diesels)

So ya, the 1800rpm theory is pretty much spot on for these trucks under most conditions. For me around town that just means shutting off the OD or running OD on, on the highway. 33s/3.54 but with slipping trans.

BUT the aero is the absolute most important function here. Cummins factory tests indicate this as well. @60-65mph 60% of your power is absorbed just fighting wind resistance. The other 40 is shared between tire foot print friction, drivetrain losses, weight. Higher mph increases the number even more.

The underneath of a 4x4 is a trainwreck if you are a air molecule in the middle of the road minding your own business. You are getting smashed up against all kinds of drive train parts, caught behind bumpers, ect ect. Your brothers outside of the truck are no better off, they have to climb over a higher roof line, around more exposed wheel wells, ect ect.

I recall reading about efforts to get 30 real mpg out of a ram 2500. It was ALL about the aero. They went so far as to duct tape all exposed body gaps. 2wd doesn't get better mpg so much because of front axle weight, it's the fact they tend to have smaller tire contact patch, sit closer to the ground, have less air snagged under them, and a lower roof line.

You can read around, there are heavy big block fullsize cars with carbs and nasty cams who can still knock down 20mpg+. It's because they slip through the air easier. Any body who has ridden a motorcycle or stuck their hand out the window at 75mph knows exactly what I am talking about. Hold your arm straight out with a 1ftx1ft piece of plywood, then try it while holding a pencil (if you didn't break your arm from the 1st experiment)

[jungle]

Good info Joe!!!
So it might be good to gear & tire size  for 75Mph in OD for the highway correct.
Jim

[blueduster]

theres where i miss read, not realizing kcc76 had a 2wd. so yea, bigger difference than i thought. glad to know 1800rpm is right. good knowledge for all of us.

[s ǝoɾ]

Good info Joe!!!
So it might be good to gear & tire size  for 75Mph in OD for the highway correct.
Jim

That is a very tough call jim. I just made a quick calculator in excel to check this. (for overdrive trucks WITHOUT lockup converter) Oddly enough, the rpm it spit out, coincides with my real world rpm even though I have lockup. That makes sense, because I had suspected my lockup wasn't working properly anyways.

As far as his gears (@75mph), the number it spits out is ~3.26, so 3.23 would have to do. 3.07 and 33 seems to come out to exactly 1800 as well.

Problem is, I'm not convinced that gearing for 75mph will ever net superior fuel economy. I would be more inclined to set it up for a more realistic 65mph and enjoy increased torque in town. That shows up as 3.55 for 33s, and 3.76 (3.73) for 35s. 3.54/35 will still do 75mph at a bit under 2000 rpm. Within reason.

Seems to me, this may indicate it's not so much the gear setup, but rather the operators speed.   Max is on to this though and has indicated considering slowing down.

For the 4BT talk, the best thing I have found matching 31" (according to calculator) would be AAM 3.42s that is 1850 rpm @ 65mph. Of course we (I) do not have any clue if that same rpm range is optimal for the smaller 4BT. Maybe the fuel curve and torque are identical but on a smaller scale, or maybe it likes to "rev" a little more. Since 3.42 is not really available outside of late model dodge or various chevy, I'm not sure which one (3.23 or 3.55) would be better suited. 1920rpm for 3.55, 1740 for 3.23

Just for kicks I will include a few other figures.
1660 for 3.07
1740 for 3.23
1850 for 3.42
1920 for 3.55
2015 for 3.73
2120 for 3.92
2220 for 4.10

[Mad Max]

I've been surfing around on 4bt swaps to find out where a 4bt likes to hum.  I'm not certain I'll be doing the 4bt thing anyway, but I do think a slightly taller gear (3.21) is in my future, but, the other combo I'm messing with is going to 4.10's and a 34" tire.  Just thinkin' out loud here...

Great discussions fellas

- Sam

[s ǝoɾ]

I've been surfing around on 4bt swaps to find out where a 4bt likes to hum.  I'm not certain I'll be doing the 4bt thing anyway, but I do think a slightly taller gear (3.21) is in my future, but, the other combo I'm messing with is going to 4.10's and a 34" tire.  Just thinkin' out loud here...

Great discussions fellas

- Sam

Shows a hair over 2000 rpm (2015) assuming slowing down to 65, but 2330 @ 75. 1850 will get you doing 60.

[jungle]

That is a very tough call jim. I just made a quick calculator in excel to check this. (for overdrive trucks WITHOUT lockup converter) Oddly enough, the rpm it spit out, coincides with my real world rpm even though I have lockup. That makes sense, because I had suspected my lockup wasn't working properly anyways.

As far as his gears (@75mph), the number it spits out is ~3.26, so 3.23 would have to do. 3.07 and 33 seems to come out to exactly 1800 as well.

Problem is, I'm not convinced that gearing for 75mph will ever net superior fuel economy. I would be more inclined to set it up for a more realistic 65mph and enjoy increased torque in town. That shows up as 3.55 for 33s, and 3.76 (3.73) for 35s. 3.54/35 will still do 75mph at a bit under 2000 rpm. Within reason.

Seems to me, this may indicate it's not so much the gear setup, but rather the operators speed.   Max is on to this though and has indicated considering slowing down.

For the 4BT talk, the best thing I have found matching 31" (according to calculator) would be AAM 3.42s that is 1850 rpm @ 65mph. Of course we (I) do not have any clue if that same rpm range is optimal for the smaller 4BT. Maybe the fuel curve and torque are identical but on a smaller scale, or maybe it likes to "rev" a little more. Since 3.42 is not really available outside of late model dodge or various chevy, I'm not sure which one (3.23 or 3.55) would be better suited. 1920rpm for 3.55, 1740 for 3.23

Just for kicks I will include a few other figures.
1660 for 3.07
1740 for 3.23
1850 for 3.42
1920 for 3.55
2015 for 3.73
2120 for 3.92
2220 for 4.10

Joe are those #s in OD or 1 to 1?
Jim

[s ǝoɾ]

Joe are those #s in OD or 1 to 1?
Jim

Overdrive with non lock up converter (46RH/518, or a 47RH with blown converter or solenoid)

Lockup would be potentially 150-250rpm lower depending on speed/engine rpm.

Doing it in 1:1 with 33/3.54 will net you about 2500rpms or so. I know this because that is about what I was getting. I don't like it because my governor starts defueling somewhere in the 2300-2500 range. Defueling against the governor while trying to go WOT up a hill with a load is counter productive. 

[powercharger79]

going back to the

ramburban

pic as someone said hell I'd probly use single cab and cut out the back from above the window down bit come to think of it you should find another cab like B.U.D's go from there etheir why sweet.....

[NMike]

on the 4BT, a diesel only uses as much fuel as NEEDED. if the 6BT needs to make X torque to go 65mph, it needs X fuel

the 4BT will still need to make X torque to go 65mph. with less engine, you will have to apply same if not more fuel for the engine to make the power it needs.

beside how much would you have to spend on the swap, and how far would you need to drive to recoup that cost assuming a 2-3mpg gain?

[Mad Max]

beside how much would you have to spend on the swap, and how far would you need to drive to recoup that cost assuming a 2-3mpg gain?

...ahhh, the 'mad' curse I suffer from is I'll spend the $ just to find out of I was correct about something , and then I'll know if it was cost-effective.  I'm willing, and able, to go 'there' just to know if my ridiculous ideas would work or not......like an air-bagged 3 and 4-linked off-road Ramcharger .  If my ideas don't work, well then I know for certain, and I'll try something different....like hacking all the air bag stuff out and installing nice, simple, effective leaf springs. 

But seriously, the 6bt in Red now spends most of its time barely working, in other words it is a lot more engine than the truck needs to maintain speed.  But when accelerating it's 'working', but certainly not hard, and I'm fairly certain the 4bt would be better suited for a driver in a relatively light-weight truck, especially after I pull a few hundred pounds from it.

[DevilzTower]

As stated by previous folks ... the hot spot for a 6BT is right at 1800rpm for peak torque ...

I think contrary to what I stated earlier, I'd agree that the truck probably should be geared for 65mph driving with the extra rpm going to extra hp to push the beast along at those speeds to fight wind resistance ...

however ... something else is going on here ... even with a somewhat "off" gearing you should be getting better mileage than that ...

I've heard of numerous reports (KCC76;s included) of std and extended cab trucks getting better mileage pushing much more weight...D's and W's ...

do you have a fuel pressure gauge on that rig yet, or any gauges - I know the last rig had every gauge autometer manufactured, what about Red?

4BT: In theory the answer is most certainly yes about the 4BT being a better match for the weight and pulling characteristics of an RC.  I've seen modified ones making 250hp and 550+ ft*lbs torque, which will be plenty for an RC even when towing.  I'm sure you know of this but www.4BTswaps.com is a source of great info ... a couple of notable RC conversions done over there and W150's good mileage reports as well 22 - 25mpg.

[s ǝoɾ]

on the 4BT, a diesel only uses as much fuel as NEEDED. if the 6BT needs to make X torque to go 65mph, it needs X fuel

the 4BT will still need to make X torque to go 65mph. with less engine, you will have to apply same if not more fuel for the engine to make the power it needs.

beside how much would you have to spend on the swap, and how far would you need to drive to recoup that cost assuming a 2-3mpg gain?

You are forgetting several factors. All is good and well on the highway once warmed up. Probably not a ton of benefit there, although I have seen some high claims.

A benefit you are forgetting about is city/suburban driving. That engine warms up faster and consumes less at idle (stop lights) ect ect. The mixed drive cycle is going to see more of a benefit.

[Mad Max]

do you have a fuel pressure gauge on that rig yet, or any gauges - I know the last rig had every gauge autometer manufactured, what about Red?

Spot on DT.  Red actually has no gauges except the factory dash, and those are so old (300,000 miles+) that I'm curious as to their 'correctness...especially the oil pressure.  For example, Red's original 6bt (the one that dumped the pump and 'prompted' the engine/tranny swap) showed 'low-er' oil pressure on the dash gauge.  But after the engine swap, the new 6bt (the one I had in Nacho, that had great oil pressure) still registers 'low-er' pressure - same-same.  So, to me that means both this and the last 6bt both have good oil pressure but the dash gauge simple registers poorly.

As well, I do plan the full gammot of normal gauges for Red - oil press, water temp, trans temp, pyro, boost, tach - what I call the "basic 6".  The fuel isn't turned up much so I know the pyro isn't pegging past 1200*...but I still want to know for certain.  

I don't have a fuel pressure gauge but that is also a good one - may have to add that.

And yah 4bt swaps is a great site - they have a VE pump rebuild link that's great.

*********************

One thing I'm nearly certain is Red's next upgrade, is axles.  I realized the other day that I have a perfectly good set of dana axles with 3.54 gears in it sitting right inside my shop - the ones from Nacho.  So after some of this and after breaking out the Crown-o-meter...and some more of this I did this and then went to my trusty gear-speed-calculator and plugged in the numbers for a 31" tire and 3.54 gears and overdrive, and discovered that at 65 mph the engine will be doing 1800 rpm, that's with 3.54s - 300 rpm higher than with 3.07s.  At 75 mph the engine will be doing 2000 rpm - and that ain't bad .  This is a snapshot from my G-S-C (I really wish we could figure a simple way to upload this thing to RCC)



So, I'll be swapping out the axles one of these weekends.  Granted the D60 and D70 are "heavier" than a D44 and 9-1/4, but since these axles are right here, and they already have 'traction enhancers'...well it just makes good sense.  Mileage may even go up since most of my driving is city.  I'm not disapointed by having the extra strength either, of course.

After the swap the 3.07 D61/71 combo will be available, and after that I'll scrounge up another front 60 for Bud.  

- Sam

If anyone wants my GSC send me a PM with your e-mail and I'll beam it to you - it's just a simple excell spreadsheet and it's dead accurate.

[DevilzTower]

gauges - ya just mentioned fuel since if the fuel pressure is being sucked down, due to an overworked lift pump or a small fuel line from the tank (I don't believe you've mentioned if it's got factory or larger lines), that the fuel could be cavitating (air in it) and significantly reducing fuel mileage - Nacho's engine had the piston style lift pump on the block, correct?  I can't remember what hp those top out at ...

speaking of factory gauges ... if I remember correctly (RCC correct me if I'm wrong) that the factory gauges of this era are faux gauges ... i.e. that they give the value of what the customer would expect to be normal readings unless they are really out of wack ... basically normalizing the data ...

thought was ... that at the time these vehicles were produced Detroit was first starting to go beyond accepted norms for things like oil pressure and didn't to alarm the customer ...

Axles - ummmm traction enhancing devices already installed - sounds good to me ... and agreed mileage may (should) go up since your axles will be geared better for city driving) still trying to figure out how I'm going to move this RC around in the snow (when it's done) with 1200# of cummins hanging over the front axle without having to keep it in 4wd the whole time ...

D71 - wait a minute ... a 3.07 in a 2wd RC - don't you need a fully built shop/drag truck for ASA modified's?  Red can tow it until Bud is done!

[Mad Max]

D71 - wait a minute ... a 3.07 in a 2wd RC - don't you need a fully built shop/drag truck for ASA modified's?  Red can tow it until Bud is done!

...2wd RC??  Which / who's RC are ya referring to?  On the ASA shop rig - that'd primarily be "Big Mack" - my '93 D250.  That dude is pushing over 300 hp and 650 tq - it does all my towing for me


On the lift pumps, no all three of my rigs have the standard lift pump (Nacho too), but Mack will get the upgrade as it's the only one that has need of it - the others won't need it as they won't be pushing any more power than Mack, and Mack has been doing great with the stock pump.
- Sam

[blueduster]

the rebuilt tranny is still a non lock up right? so add a 100rpm or so for the converter. but still much better than where you are. i wasn't sure if you had plans for those axles or i would have mentioned that a while ago.

Spot on DT.  Red actually has no gauges except the factory dash, and those are so old (300,000 miles+) that I'm curious as to their 'correctness...especially the oil pressure.  For example, Red's original 6bt (the one that dumped the pump and 'prompted' the engine/tranny swap) showed 'low-er' oil pressure on the dash gauge.  But after the engine swap, the new 6bt (the one I had in Nacho, that had great oil pressure) still registers 'low-er' pressure - same-same.  So, to me that means both this and the last 6bt both have good oil pressure but the dash gauge simple registers poorly.

As well, I do plan the full gammot of normal gauges for Red - oil press, water temp, trans temp, pyro, boost, tach - what I call the "basic 6".  The fuel isn't turned up much so I know the pyro isn't pegging past 1200*...but I still want to know for certain.  

I don't have a fuel pressure gauge but that is also a good one - may have to add that.

And yah 4bt swaps is a great site - they have a VE pump rebuild link that's great.

*********************

One thing I'm nearly certain is Red's next upgrade, is axles.  I realized the other day that I have a perfectly good set of dana axles with 3.54 gears in it sitting right inside my shop - the ones from Nacho.  So after some of this and after breaking out the Crown-o-meter...and some more of this I did this and then went to my trusty gear-speed-calculator and plugged in the numbers for a 31" tire and 3.54 gears and overdrive, and discovered that at 65 mph the engine will be doing 1800 rpm, that's with 3.54s - 300 rpm higher than with 3.07s.  At 75 mph the engine will be doing 2000 rpm - and that ain't bad .  This is a snapshot from my G-S-C (I really wish we could figure a simple way to upload this thing to RCC)



So, I'll be swapping out the axles one of these weekends.  Granted the D60 and D70 are "heavier" than a D44 and 9-1/4, but since these axles are right here, and they already have 'traction enhancers'...well it just makes good sense.  Mileage may even go up since most of my driving is city.  I'm not disapointed by having the extra strength either, of course.

After the swap the 3.07 D61/71 combo will be available, and after that I'll scrounge up another front 60 for Bud.  

- Sam

If anyone wants my GSC send me a PM with your e-mail and I'll beam it to you - it's just a simple excell spreadsheet and it's dead accurate.

[DevilzTower]

...2wd RC??  Which / who's RC are ya referring to?  On the ASA shop rig - that'd primarily be "Big Mack" - my '93 D250.  That dude is pushing over 300 hp and 650 tq - it does all my towing for me

Easy there big fella, I was just busting your chops that you need a NEW project vehicle as a promotional tool for ASA ... that being a fully prep'd drag truck with a 3.07 rear - just seems that everyone is pushing a diesel drag truck or at least that's what "Diesel Power" would have you believe 

[Mad Max]

lookin' for two threads - for the life of me I can't find these two threads where someone grafted the glass and outer frame from a pop-top RC into a non-pop-top RC, and someone else did the same with an early tailgate and glass top hatch.  Anyone know where those threads are?  Before the September Moab trip I'm doing the surgery to Red and I wanted to re-read that procedure.  Pulling the side glass / glass hatch out and getting lots of ventilation during the hot weather is mega nice .

[Grim]

Lemme know when your gonna do that, because I will bring the Reaper out there and we can both do it at the same time.  As long as your willing to trade labor? 

Oh, HI SAM!

[Mad Max]

hey there Josh - 'sup man!  Been a while.  No problem - bring the Reaper on over and we'll do dual surgeries .  Gotta find parts first, and I know a place 

[jungle]

Sam,
In your travels out there have you seen a very good chrome grill shell for the 92ish trucks?
Thanks, Jim

[Mad Max]

no buddy, sorry.  They're available repro but not sure from where exactly.

Just filled up the truck - after driving over 500 miles at/below 60 mph....still ~18 mpg.  So, it seems that aero between 60-70 mph seems to have a negligable effect to fuel mileage. 

So, what else is there?  There's the overall rpm at those speeds.  Witht he currect gears and overdrive engaged, 60 mph = 1400 rpm - obviously not in the 'sweet spot'.  At 70 mph it's still only 1600 rpm.  But, with 3.54s, 65 mph would be just shy of 1800 rpm, and 75 mph would be just shy of 2000 rpm.  Not bad. 

So since I'm planning to swap axles anyway I'll recheck mileage after that and see if a 'gear swap' brings up the numbers.  Either way, interesting case study, and I'm really not complaining about 18.4 mpg.

- Sam

[jungle]

Thanks Sam!!
I might have to get a new unit from Dodge because I want the Dodge name on it. When are you putting the new axles under Red?
jim

[Mad Max]

...dunno exactly....sooner verse later - maybe in a couple weeks.

[88_mopar]

Sam, I have an idea for the removable side windows, I'd build a "U" shaped sheetmetal frame that goes around the edge of the glass, weld hood pins to it aiming inside the vehicle, then drill holes in the pinch weld for the pins to go through. Some universal weatherstriping to seal it up and keep tension on the pins and you're good to go. Hop inside, pull 4 or 5 hairpins and the glass is out.
Edit: Or even just build the frame out of flat stock and glue the glass to it like the factory does.

[Mad Max]

well just a bit of an update -

The recent score of our '93 RC has changed the game a bit - the R&D I've been doing with Red is essentially complete, and I no longer need to swap axles.  Like Nacho, I had to drive the thing to know and feel the changes which guide my ideas for the future, and now I know what I need to know.  

The short term plans are to drive both Red and Oxx for a few months, and, take both to the Moab gig in late September - that's shaping up to be a pretty good event - lots of friends and fun trail riding and some mountain biking.  Afterwards, sometime in October, the hard-core work on Bud will start......and word on the street is Bud wants Nacho's engine and tranny, bad (I've discovered he can be greedy that way) - fortunately I was able to broker an agreement between the two of 'em and Red has agreed to donate his driveline for Bud.  It's like when the SR-71 Decepticon donated his power source to Optimus...or...something.  At that point, Red will become a donor truck for both Bud and Oxx - chassis hardware for Bud, and 'diesel'/electrical components for Oxx's eventual diesel conversion.  

I thought long and hard about selling Red in one form or fashion - putting the original 6bt/727 back in or maybe without an engine/tranny, but I need a lot of the hardware I've been testing for both Bud and Oxx, so it's in my best interest to keep what I need and get Bud built.  Bud's essentially going to 'replace' Red, and that ain't so bad  .  That's a good plan I like that plan...