Hello everyone.



To start off, I would like to begin with a disclaimer:

I have done this all myself, in the dirt next to the garage (too tall, doesn't fit) with a heavy hand on the welder and a "wing it" attitude.

I have done my best to modify things in an intelligent manner, and have researched across forums for topics and past builds to try and answer my questions as best as possible. However, as one might expect, not many applications really are similar enough to gain all the relevant information I need.



I would also like to apologize for how much I write. I tend to do that a lot. But I can promise that if you spare a few minutes at nothing else, you might get a good laugh and I can guarantee that this is going to be one of the strangest builds that you have seen.



***[Head to the bottom of the post if you want to bypass details and just read my problem]



So here goes the details:

1988 Dodge Caravan body

1990 W250 Non-intercooled 12v, and the running gear from said W250 (along with a heavily chopped and modified frame to fit)

GVWR: ~8400lbs with some tools and me the driver



Transmission: NV4500HD with upgraded input shaft, fixed 5th gear, and SBC dual disk clutch with hydraulics (should hold way more power than ill ever make)

Everything beyond this point is homebrew.



New engine build: (sorry if this is more information that desired, just want to put it all out there)

Stock block, bored 20 over.

Stock Non-intercooled cam (slightly longer duration and higher lift than intercooled cam if I am correct) with bronze cam retainer.

Billet oil squirters (instead of those plastic ones).

Stock crank.

Higher output oil pump.

20 over MARINE pistons (a poor choice, more on that later).

20 over cummins head gasket.

2nd gen (oops, more on that later) new (thicker cast) cylinder head, O-ringed.

ARP 2000 head studs.

Hamilton hardened tappets, heavy duty pushrods, 110# valve springs.

Billet freeze plugs all around.

Rear cylinder coolant bypass kit (Homebrew, surprise).



Fuel system:

Injection pump: Bosch VE Rotary Style Injection Pump (Yes, intentionally not a p-pump, though perhaps misguided).

Pump mods: All adjustments fiddled with, max fuel up a bit, BD fuel pin and 3200 GSK.

Injectors: 1990 Non-intercooled stock injector bodies and internals, with tips from Bosch 370 Marine Injectors (more on this later too).

Timing: Gear skipped one tooth (~10deg advance) and pump rotated to head.

Fuel supply: Stock lift pump fed by locally adjacent surge tank primed with Racor P510MAM Multipass fuel polisher drawing from twin 15gal fuel cells



AEM water-methanol injection system with single-port injection right before the intake manifold.



Air system:

BHAF (donaldson filter element)

Emergency Air Shutoff Valve (backwards 102mm Mustang throttlebody)

4" intake piping from filter to atmospheric turbo

Borg Warner S472 Atmospheric Turbo

3" charge piping to Turbonetics 61mm T3 high pressure turbo.

Gigantic Russian made 200psi pressure tested Water-Air intercooler core unit. Uses Meziere inline water pump and stock caravan radiator for heat exchanger

Turbonetics Evolution 38mm wastegate to bypass high pressure turbo

Twin Synchronic Synapse Blow Off Valves hooked to throttle switch + solenoid system (currently disabled for testing/leaks)

4" exhaust with 36" FTE resonator and 36" MBRP resonator, less than 8' of pipe from turbine to exit



Gauges:

Low pressure boost

High pressure boost

Low pressure turbo drive pressure (exhaust)

High pressure turbo drive pressure (exhaust)

Water temperature

Intake Air Temperature

Oil Pressure

Fuel Pressure

Voltage

Exhaust Gas Temperature



Drivetrain:

NV4500 HD as stated above

NP205 transfer case, twin-sticked with interlock pins removed

Stock front driveshaft

Shortened rear driveshaft

Gearing: 3.07 (I think, supposedly that was on the 1st gen non-intercooled automatic equipped trucks, which is what I cannibalized)

35" (more or less-315/75/R16) Goodyear Duratrac tires

A pair of ARB air lockers (sitting in their boxes on my workbench...nobody has enough time to do everything)

RedHead steering box relocated with modified drag link, sporting dual steering stabilizers.

Factory front brakes, disc conversion on rear axle with k20 front calipers.

Hydroboost braking unit with in-line cooler.

Bonus: Smittybilt X20 17,500lb winch that mounts on front or back of vehicle.



Electrical system is all done by me, and is more complicated than i'd like to share, but everything works spectacularly on the electrical side. There is no room in the engine bay for batteries, so there are 3x Northstar AGM batteries in a sub-floor box behind the rear axle.



Entire vehicle has an altogether too overbuilt structural roll-cage throughout to prevent pop-can-like crushing in any sort of rollover mishap.





Phew. Alright, I think that is everything important. If I have left anything out, or if there is anything you need clarification on, please just ask.

I know this is a very strange thing to build, but I have strange tastes and a rather unfortunate amount of perseverance.



Also, the goal for this vehicle is not BIG POWER. It is more in the mind of the best fuel economy I can get, while still having enough power to zip around, occasionally pull my little car hauler trailer, and do a burnout if the need arises. Though ultimately it is "supposed" to be an adventure vehicle to drive around the country and play in the dirt.

 

***ON TO THE PROBLEMS. [If you skipped the above, please start reading here:]

While there are numerous little issues that I have run into, this vehicle has been roadworthy and covered around 7,000 miles so far, though none of them in a particularly spectacular fashion.



At 5,000 miles, the head gasket went and I found a cracked cylinder head, which is when the entire engine rebuild happened. So there are a few more than 2,000 miles on the rebuild.



3 Main problems I have:

1. Smoke

2. Power (might be tied to #1)

3. Cooling

4. Transmission



1. SMOKE. Since the rebuild, I have traded black smoke for white smoke (unburnt fuel) and lots of it. On any type of colder start, it billows white smoke that burns the lungs of diesel (not healthy) and does not clear up until I can get to about 170 degrees of engine temp, and even once it is fully up to operating temp, at idle it still smokes white, just not as much.



I have a feeling this is due mostly to my bad choice in marine pistons and oversized head gasket, lowering my compression to somewhere near 15 or so. That being said, the cobbled half and half injectors probably aren't helping, and I may have a tad too much timing.



In addition, though it runs somewhat happily, since the build my fuel economy has dropped A LOT. Prior to the engine rebuild running the same turbos and more stock engine bits, I was getting around 20mpg on the highway. Now, after the build, I am down to 12-13mpg, and that is really unacceptable.



If you have any input on this, I would really appreciate it. Because currently the only thing I can think of is to yank the whole new motor, tear it apart, and put stock pistons and a stock thickness head gasket in it to raise the compression back up and revive fuel economy while reducing unburnt diesel smoke. This is obviously not a desirable option as it takes a bit of time, and despite my build, I am about as poor as it gets currently so new pistons would take some saving up.





2. POWER. As mentioned earlier, I feel that this is likely related somewhat to problem #1. Though I believe I have enough fuel/timing/air and parts, I cannot exceed 25psi of boost at the high pressure side under nearly any conditions. Occasionally in 3rd if I stab it right, I can get 30psi, but only if I am lucky and on a hill. While the engine should be able to hold 80psi, I dont need or want to be anywhere near there, but at least 50psi would be nice, and I think not too much to ask for. I have the wastegate diverting air from the high pressure 61mm turbonetics at around 15ish psi, but even so, I can rarely see more than 8 or 10psi at the low pressure pipe, so I think that my 72mm low pressure turbo is barely if at all even spooling. This one is clearly and obviously a huge disappointment seeing the amount of time in the build, to be not any faster than a stock truck. I am sure the setup is capable of so much more, but I am at my end as to what to tinker with to make it happen.



3. COOLING. A problem that I have, mostly on hills on the highway, though occasionally around town too, is my engine temp. I like to think I have done everything I can to help the engine run cool, but it has different ideas I guess. Ive got twin electric fans on the radiator, the coolant bypass from the back of the engine, the methanol injection, and the gigantic water to air intercooler. The intercooler can drop my intake temps by 80 degrees in almost any conditions, but it is still not enough to keep the coolant under control. Cruising up a steep grade, say a 6% grade on the highway maintaining 70-80mph, my EGT's will get above 1250 if I don't pay attention and slow down, and if it lasts for more than 5-10 minutes, my coolant temp will creep up past 220. I usually slow way down or pull over if it gets above 220 because I am afraid of damaging things. But either way, unloaded cruising at highway speeds with the intercooler and meth, it shouldn't get that hot that quick. Even on forest service roads, in the snow in winter, with the fans on, I cant drive uphill for more than 15 minutes.



The only thing that I can definitively point to for this is my radiator. It is a new and clean aluminum BeCool unit, but it is smaller in terms of surface area than a stock cummins radiator, but i got it because it is the biggest that fit. The car obviously drives, but with temp problems like this, I couldn't even hope to tow my trailer anywhere unloaded, let alone with a car on it, or up a hill. That's a huge bummer for me. The only solution I have for this is to buy a wider radiator, cut it in half to the proper height, and tig it together with my current one merging the end tanks and making it a dual pass to utilize everything, making it a 4/6 core radiator instead of a 2 core. I am extremely limited on space, but that doesn't matter if I can't drive it, so I am willing to cut and re-weld almost anything, though hopefully not the frame.



If you strongly believe that perhaps my cooling could be due to tuning and fueling, please let me know so I don't have to take such drastic measures as fabricating another radiator. That takes time and money that I do not currently have, but will make if needed.





4. TRANSMISSION. This was also a big problem until recently. The clutch pedal requires a left leg squat power of probably at least 100lbs, but I dont really care about that, its just amusing to have other people try to shift gears. The transmission was "supposedly" freshly built when I got it. New stronger 1 3/8 10 spline input shaft, 5th gear fixed, and filled with liquid gold $$$ Amsoil which I have read mixed reviews on, though mostly positive throughout the community. When the car is off, the transmission shifts through the gears like butter. But as soon as the rotating mass is spinning, even with double clutching, it is really hard to shift into any gear. Usually it takes a few hard pushes/smacks to shove into a gear, which is a bit concerning. Also, in 4th gear and only 4th gear, under any load the whole vehicle shakes and growls. I have recently diagnosed this as a bad front bearing on the direct drive shaft, but am not positive.



As I said at the top, this has been a problem until recently. By recently I mean yesterday. While just driving around town at low speeds to go fix a friend's car, 3rd gear spontaneously decided it didn't need all its teeth, and shattered. I was able to limp it the last two or three blocks in 2nd gear with no problems, but any time spent shifting into or driving on 3rd gear sounded very, very bad. So, nothing is fixed, but its definitely broken, so when I get time I guess I will be pulling the tranny and putting in new gears. Yay.



Since the tranny is coming out, I am really thinking of taking the opportunity to pull out the motor I JUST FINISHED BUILDING and tearing it down for new pistons and HG. So if anyone has any ideas about problem #1, and #2, please let me know because I really don't want to tear it apart, but if it's the only way I guess I will just have to suck it up and do it. Also, theres several feet of snow at my house, and that makes everything "more fun".





Once more, I know this is weird, and probably not everything has been done the best way, but please try to refrain from telling me I am overly stupid or simply did such a bad job it's hopeless. I am already telling myself that so your bit there wouldn't help much.



However, if you have any advice or something constructive, I welcome and appreciate all opinions.

PLEASE HELP ME.

And thank you very much for all of your time.

 

***ON TO THE PROBLEMS. [If you skipped the above, please start reading here:]

While there are numerous little issues that I have run into, this vehicle has been roadworthy and covered around 7,000 miles so far, though none of them in a particularly spectacular fashion.



At 5,000 miles, the head gasket went and I found a cracked cylinder head, which is when the entire engine rebuild happened. So there are a few more than 2,000 miles on the rebuild.



3 Main problems I have:

1. Smoke

2. Power (might be tied to #1)

3. Cooling

4. Transmission



1. SMOKE. Since the rebuild, I have traded black smoke for white smoke (unburnt fuel) and lots of it. On any type of colder start, it billows white smoke that burns the lungs of diesel (not healthy) and does not clear up until I can get to about 170 degrees of engine temp, and even once it is fully up to operating temp, at idle it still smokes white, just not as much.



I have a feeling this is due mostly to my bad choice in marine pistons and oversized head gasket, lowering my compression to somewhere near 15 or so. That being said, the cobbled half and half injectors probably aren't helping, and I may have a tad too much timing.



In addition, though it runs somewhat happily, since the build my fuel economy has dropped A LOT. Prior to the engine rebuild running the same turbos and more stock engine bits, I was getting around 20mpg on the highway. Now, after the build, I am down to 12-13mpg, and that is really unacceptable.



If you have any input on this, I would really appreciate it. Because currently the only thing I can think of is to yank the whole new motor, tear it apart, and put stock pistons and a stock thickness head gasket in it to raise the compression back up and revive fuel economy while reducing unburnt diesel smoke. This is obviously not a desirable option as it takes a bit of time, and despite my build, I am about as poor as it gets currently so new pistons would take some saving up.





2. POWER. As mentioned earlier, I feel that this is likely related somewhat to problem #1. Though I believe I have enough fuel/timing/air and parts, I cannot exceed 25psi of boost at the high pressure side under nearly any conditions. Occasionally in 3rd if I stab it right, I can get 30psi, but only if I am lucky and on a hill. While the engine should be able to hold 80psi, I dont need or want to be anywhere near there, but at least 50psi would be nice, and I think not too much to ask for. I have the wastegate diverting air from the high pressure 61mm turbonetics at around 15ish psi, but even so, I can rarely see more than 8 or 10psi at the low pressure pipe, so I think that my 72mm low pressure turbo is barely if at all even spooling. This one is clearly and obviously a huge disappointment seeing the amount of time in the build, to be not any faster than a stock truck. I am sure the setup is capable of so much more, but I am at my end as to what to tinker with to make it happen.



3. COOLING. A problem that I have, mostly on hills on the highway, though occasionally around town too, is my engine temp. I like to think I have done everything I can to help the engine run cool, but it has different ideas I guess. Ive got twin electric fans on the radiator, the coolant bypass from the back of the engine, the methanol injection, and the gigantic water to air intercooler. The intercooler can drop my intake temps by 80 degrees in almost any conditions, but it is still not enough to keep the coolant under control. Cruising up a steep grade, say a 6% grade on the highway maintaining 70-80mph, my EGT's will get above 1250 if I don't pay attention and slow down, and if it lasts for more than 5-10 minutes, my coolant temp will creep up past 220. I usually slow way down or pull over if it gets above 220 because I am afraid of damaging things. But either way, unloaded cruising at highway speeds with the intercooler and meth, it shouldn't get that hot that quick. Even on forest service roads, in the snow in winter, with the fans on, I cant drive uphill for more than 15 minutes.



The only thing that I can definitively point to for this is my radiator. It is a new and clean aluminum BeCool unit, but it is smaller in terms of surface area than a stock cummins radiator, but i got it because it is the biggest that fit. The car obviously drives, but with temp problems like this, I couldn't even hope to tow my trailer anywhere unloaded, let alone with a car on it, or up a hill. That's a huge bummer for me. The only solution I have for this is to buy a wider radiator, cut it in half to the proper height, and tig it together with my current one merging the end tanks and making it a dual pass to utilize everything, making it a 4/6 core radiator instead of a 2 core. I am extremely limited on space, but that doesn't matter if I can't drive it, so I am willing to cut and re-weld almost anything, though hopefully not the frame.



If you strongly believe that perhaps my cooling could be due to tuning and fueling, please let me know so I don't have to take such drastic measures as fabricating another radiator. That takes time and money that I do not currently have, but will make if needed.





4. TRANSMISSION. This was also a big problem until recently. The clutch pedal requires a left leg squat power of probably at least 100lbs, but I dont really care about that, its just amusing to have other people try to shift gears. The transmission was "supposedly" freshly built when I got it. New stronger 1 3/8 10 spline input shaft, 5th gear fixed, and filled with liquid gold $$$ Amsoil which I have read mixed reviews on, though mostly positive throughout the community. When the car is off, the transmission shifts through the gears like butter. But as soon as the rotating mass is spinning, even with double clutching, it is really hard to shift into any gear. Usually it takes a few hard pushes/smacks to shove into a gear, which is a bit concerning. Also, in 4th gear and only 4th gear, under any load the whole vehicle shakes and growls. I have recently diagnosed this as a bad front bearing on the direct drive shaft, but am not positive.



As I said at the top, this has been a problem until recently. By recently I mean yesterday. While just driving around town at low speeds to go fix a friend's car, 3rd gear spontaneously decided it didn't need all its teeth, and shattered. I was able to limp it the last two or three blocks in 2nd gear with no problems, but any time spent shifting into or driving on 3rd gear sounded very, very bad. So, nothing is fixed, but its definitely broken, so when I get time I guess I will be pulling the tranny and putting in new gears. Yay.



Since the tranny is coming out, I am really thinking of taking the opportunity to pull out the motor I JUST FINISHED BUILDING and tearing it down for new pistons and HG. So if anyone has any ideas about problem #1, and #2, please let me know because I really don't want to tear it apart, but if it's the only way I guess I will just have to suck it up and do it. Also, theres several feet of snow at my house, and that makes everything "more fun".





Once more, I know this is weird, and probably not everything has been done the best way, but please try to refrain from telling me I am overly stupid or simply did such a bad job it's hopeless. I am already telling myself that so your bit there wouldn't help much.



However, if you have any advice or something constructive, I welcome and appreciate all opinions.

PLEASE HELP ME.

And thank you very much for all of your time.

 

I've worked on a ton of these 12V cummins engines- but only in stock form (at a dealership in the mid-late 90's). So I can't really speak to the modifications you've made. But I can say the following:

1. A thread like this deserves pictures. We will need to see what a cummins-powered mini-van looks like
2. If I recall correctly, these engines should have something in the neighborhood of 17:1 compression. I dunno how much lower you can go without causing problems... but if you've significantly lowered compression then that could very well be the cause of your white smoke.
3. If an engine has white smoke, that means you have a problem with compression, timing, or fuel delivery. Make sure valves are set correctly. Make sure compression is in spec (sounds like it might not be). Check the pop-off pressure of your injectors- if this is too low then the fuel won't be atomizing properly and can cause hard start, smoke, poor fuel economy. Also just make sure your fuel pressure is in spec and you don't have much (if any) air in the fuel return. As low fuel pressure and/or air in the fuel can cause smoke, low power, etc.
4. Make sure your inj. pump timing is correct. If it's retarded, that can cause hard start, smoke, poor fuel economy, etc.

Based on what you're telling me, I'd start with the basics. Make sure valves are set correctly. Make sure pump timing is correct and injector pop-off pressure is in spec. I don't remember what the spec will be for opening pressure, but I think it was in the neighborhood of 3500 psi for the VE pump engines. Make sure the tips aren't leaking and the spray pattern looks ok.

If all that checks ok, then you are looking at a problem deeper in the engine. Possibly that lowered compression ratio. Maybe a failed piston or rings. Maybe something stupid like cam timing a tooth off so that every single exhaust valve is now bent a little bit. Don't laugh... I've seen it happen. That and much worse. A compression check would be a good start to let you know what's going on before tearing down the engine.