I mentioned in the previous IDIocracy post that I already started driving Snekvan in un-tuned form around. The turbo setup had become fully “closed loop” at that point – meaning, at least, that charge air went into the engine and it didn’t emit oil from everywhere. After putting a few heat cycles and start/stop cycles in, it was time to try and blow it up!
I was only going to put basic and critical instruments on – a boost gauge and an exhaust gas temperature (EGT) gauge. The former measures when the head bolts fall out, and the latter when the pistons begin melting. I gathered that “more fuel” and “more boost” were the only dimensions of “tuning” these old mechanical diesels, with the important exercise being repair what blew up and then adding more of whatever you just did.
Yeah, yeah, you can adjust the timing curve of the injection pump and whatnot inside… I’m aware, I just consider that a black box at the moment.
This thing already has a bunch of holes drilled in it for whatever, what’s one more? I made a pass-through in the “doghouse” compartment towards the driver’s side. A little run of wire loom will be enough for now to prevent the steel edges from breaking anything.
Up top, I changed the tee fitting such that the (mechanical) boost gauge sense hose got its own fitting, and the wastegate hoses were joined together.
The EGT probe occupies (finally!) the small bung I welded onto the Left Snail adapter. I didn’t go for dual EGT probes, even though the Right Snail pipe has one as well. Vantruck will have dual EGT readouts once everything’s all done.
To power the gauge readouts and lights, I stole 12 volts from the fuel cutoff solenoid on the injection pump. This goes hot whenever
the key my rigged toggle switch is in the ON position.
Here’s the EGT cable (silver braided cord), the power cable, and the mechanical boost gauge hose routed through the loom. And that’s it. No tucking, no zip tying, no keeping it even remotely hidden.
Everything goes up top to this generic 2 inch round gauge holder. I got it from Harbor Freight, and it came with the boost gauge, an oil temperature gauge, and a…. ammeter gauge. What a choice of variables to watch, huh? The EGT display is an Amazon special, but fits the same 2 inch universal gauge holder.
With this setup, I was able to get an intial baseline for Snekvan. The “stock” fueling only managed around 5 or so pounds of boost, even at full ham. Not enough to trip the wastegates on the eBay special turbos which are (hopefully) 8 PSI. The EGTs on an open highway were very low, on the order of 180 to 200 celsius, and never exceeded 360C even on extended full throttle pulls. The IDI was tuned to be a reliable workhorse, not a drag racer. There was a lot of room here.
And so we begin. The way to adjust the fuel on this Stanadyne DB-2 injection pump is by taking the little service lid off the right-hand (passenger) side.
The Internet said “A little diesel will spill out”.
By “A little” they meant the entire pump (fully submerged inside and air-free) will drain out of this hole. That’s like a half gallon, I swear.
To access the Secret Set Screw of Fuel Adjustment, turn the engine by hand (breaker bar and a 15/16″ deep socket on the crankshaft) until the front of the injection pump gear reaches high noon o’clock.
The Secret Set Screw of Fuel Adjustment lies within the Rotating Whatever-the-Fuck of Making It Go. on the very posterior of the V-shaped opening.
To get at this screw, you need to use a 5/32″ hex key that has at least ~1.25 inch of depth before it turns, so it’s either a ratchet driver bit or putting a wrench or vise grip on the short end of a regular L-handle. I only had a long-reach ratchet driver for 5/32 and that didn’t fit in the van engine cave, so vise grip it is. This screw is in a distorted thread locking feature and so it takes quite a lot of torque to turn.
The Internet Lore with this procedure is to adjust the screw one “flat” at a time (60 degree increments) and taking note of EGT. I had ascertained through the same Internet that going a half turn right out of the gates (180 degree, 3 flats) was probably fine. So, I did just that.
That was the state of Snekvan when I recorded this driving video:
It was able to hit ~8 PSI on the gauge if I let it rip, but did take some time to build up to that point. It definitely felt like there was more to give, and the EGTs were higher – on the order of 400 celsius maximum, but fell quickly once I let off.
Sagely Old Guy advice on the Internet seemed to converge around 1000-1200F (or around 540-650C) as the maximum safe continuous operating condition for reliability, and I wasn’t anywhere near yet.
That driving video was actually quite long and involved some stops and red-light pulls, but generally speaking there was enough traffic that I could only get a limited amount of wringing done.
Well okay then. Here we go! We’re now going to turn up the boost, after having turned up the fuel!
To adjust the wastegates on these things much higher than 8 PSI, it seems like you actually need to start cutting the actuator rod. I decided to go for 15 PSI, which needed an inch of chopping and using a die to cut more threads onto the rod so the clevis rod end could go back far enough.
At that level, too, there felt like not much waste to be gating on that little actuator. It’s already preloaded forwards so far I’m not even sure how much more it can push. For Vantruck, where I want to run 20 pounds and above, I’ll need to investigate using an external biasing spring (imagine a spring threaded over that whole rod) to keep the range of motion available.
The way I determined how much to back up the rod was by using a hacked up Harbor Freight tire filler and slowly pushing the handle to observe at what pressure the cans started moving. Maybe not the most accurate method, but it let me not uninstall both turbos and remove only the canisters, so…
At this point, I decided to take a few good photos of the integration since I had only limited testing I wanted do remaining and I needed to start knocking it down for Operation IDIocracy Increment 2: Rebuild Boogaloo. This is a look from the underside showing the oil drain pump and the awkward U-turn, which will be designed out once I lob this thing in Vantruck.
And here’s the top side! Basically everything is accessible with the shifting of a few hoses, even with the auxiliary rear heater hose stack in place (on the left). Depending on how much more hosiery I want to deal with, there is plenty of space to turn around an intercooler hose there too. All of this with the OEM fuel filter head in place (anterior left of the Chamber of No-Nos shown) and no wiring/cables/hoses routed properly whatsoever.
Now compare this to Spool Bus:
Yup, design goal #1 is already accomplished.
Debugging and Hotfixes
I keep mentioning that I actually drove this thing a lot in the couple weeks it was together in November and December, and it’s true – I put probably 500 to 600 miles on it minimum. I went to a couple of local weekly meetups to show the goods around to the astonishment, disgust, and intrigue of many:
During one of these, I noticed something in the engine bay starting to emit oil everywhere. It wasn’t immediately obvious where it was coming from. My from-turbos oil return fitting that was going into the injection pump timing gear cover was stain-free, and yet every belt and surface underneath was just covered.
It took a little investigating once I got home. Can you see the problem below?
Yes, it seems like the same oil return hose popped free of its crude zip tie ligatures at some point and committed self-die on the alternator belt:
It wasn’t a big gash, but just enough of a leak to slowly slime itself. I don’t think I even noticed an oil level change on the dipstick, but it doesn’t take much to make a mess.
Therefore, one of the first design revisions was to the routing of this oil return hose! It now exits over the top of the engine. I could definitely do with a right-angle fitting here in the future.
The next Monthly Not Cars & Not Coffee was December 2021, so I decided to make this its final public appearance. I had a little fun with the pressure washer the night before as well, as BattleBots was about to premier in January of ’22….? Yes, I meant 2022. I’ll be writing 2020 for the next 3 decades.
The problem is there’s nothing to see, because van. In a galaxy brain moment, I decided to jump a parking island and hang the nose off the front of it. It was well received once people figured out what was happening.
On the way back home, I showed off a little leaving a quick after-meet at the local Instagrammable Asian Food Gallery and pop
Uh oh. Why is this diesel engine pulling a mild vacuum? (For the uninitiated, diesel engines don’t normally throttle air and so should NOT be pulling intake manifold vacuum unlike gas-engine cars). It wasn’t like the boost hoses blew off or anything, because that should expose the intake adapter to atmospheric air pressure. This was a vacuum. The gauge went down if I stepped on it or went faster.
I took the Slinkyhoses out to have a look.
So this was an interesting failure mode. Snekvan’s completely ratted out engine is down on compression and burns or otherwise emits a lot of oil. This comes out of the PCV (CDR) system and is fed into the right-hand intake. Therefore, one of these slinkyhoses has just been getting sprayed down with hot oil, and the neoprene rubber they were made of can’t handle it.
It delaminated from the inside and basically formed a big arterial dissection. I literally had to perform bypass surgery on a van. It’s also interesting to note that the left (driver’s) side hose is completely intact because it doesn’t need to carry Extra Lubricated Air.
I decided to try the silicone variant of the same hose to see if it would fare better. I don’t know how these get made, but I hope the material is overmolded onto itself at high temperatures and cure together as one instead of being adhered together by some intermediate glue. That the neoprene hose disintegrated between layers wasn’t promising.
And with the silicone hose embedded, I decided to turn up the fuel ALL THE WAY – seems like it’s about 1.5 full turns, give or take – and absolutely send it for Snekvan’s last hurrah. I had it recorded by a dude with a camera gimbal who was seated in an open hatchback while his wife drove:
Now this… This was absolutely a beast. It sounded much angrier and was basically the second fastest thing I owned (after the substantially newer 290HP Coronavan). This was a good technical “save point” for the project.
And so ends the saga of Snekvan. This video was filmed the morning of Christmas when all was basically quiet and hung over. I was going to start the teardown that day.