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CHUGSzilla and The 1544: Testing on March 10, 2024

Blackfoot Tucker

Well-known member
GOLD Site Supporter
Because we took both machines out, and this post makes reference to them individually, I decided to start a new thread. Both other threads and the Testing on Super Bowl Sunday thread will have links to this one.

Another awesome day of testing / operational verification in Utah’s Uinta Mountains! The first weekend in March we got some decent snowfall and although we’ve had some warm days since, there is a solid base. Conditions yesterday were really excellent, and we could go most anywhere we tried. In the Testing on Super Bowl Sunday thread I had discussed the locations we have previously tested at, and said I wanted to avoid Cedar Hollow due to potential paint scratches on CHUGSzilla.

When we took the 1544 to Cedar Hollow a couple weeks ago the experience was epic, and decided we’d go back there. Yes, CHUGSzilla has its new green paint (Note, I didn’t say "pretty" or “beautiful”) and I decided The Infamous WBJ1 isn’t a "pretty boy” anyway, so if his ugly green snowcat had some character scratches… so much the better. To Cedar Hollow we went!

Where Tuckers love to hang out… a gas station.

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We have been putting in some pretty long hours trying to get the radiator upgrade completed and the transmission valve body adjustments made. We also needed to change out the spark plug wires on the 1544, and we finished those tasks late on Saturday afternoon. I really wanted to bring both machines for a few reasons:

- We preach there is no substitute for testing in real world conditions, and though all we did to the 1544 was install new spark plug wires, knowing that the machine worked well in the backcountry means we can say it passed its performance verification, as opposed to saying “we think the problem is solved".

- One never knows if something will go awry, and having a second machine means the chances we’ll have to walk out are a lot slimmer.

- Two machines are more fun!

After unloading at the trailhead there was a fellow who flagged Scott down. He said he got his truck stuck up the trail a bit, and spent hours trying to dig it out. He told Scott he’d hang around and do some X-country skiing while we were testing, and Scott agreed to pull the truck out on our way back.

Here’s the struck GMC truck. What was he thinkin? (When we were headed out he was nowhere to be found, though the hapless GMC was still there.)

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Our usual photo op spot for the obligatory pic.

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So… how did they do?

The 1544 ran well all day long. No, it doesn’t have "LS power", but it performed solidly. Normally, Scott and I will swap machines back and forth during the day. I started in the 1544 and was content to drive it all day long. It really ran well. I can’t compare the Edelbrock ProFlo 4 system to any other aftermarket fuel injection system, but I can say it's a major improvement. Huge, in fact. Some projects are expensive, and there’s a pretty marginal benefit. At the end of the day it’s a “meh” experience. In our opinion the Edelbrock ProFlo 4 system provides significant bang-for-the buck. The engine starts easily, and it runs well. Yes, Scott in CHUGSzilla with its L94 LS engine could pull away from me, but its not like the 1544 ever had to hang its head in shame.

That said, there’s one hill that’s a “tester”. We have never taken a machine to that hill, and conquered the hill. Never! In fairness to all the other days, and the other machines, snow conditions make a huge difference. You really can’t compare results accurately unless they are side-by-side, on the same day. But even so, CHUGSzilla is the undisputed Champion!

The first machine we took to this hill was the Tucker known as the Vail Cat. It did pretty well, making it maybe half way. That Tucker had long tracks in front and mid-length (1500 series) tracks in back). Powertrain was a Chrysler 318 Industrial (carbureted) and New Process 5-speed manual transmission. Here are some pics.

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Of the various snowcats that have passed through our hands, we have more experience operating the 1544 than any other. We’ve tried the hill with the 1544 on multiple occasions (yesterday included) and it's never made it to the top, or even come close. The machine that previously held the record was… wait for it… TUG. But there was significantly less snow that day, and TUG made it a lot further up the hill… backwards, than it did forwards!

(For those that don’t know, TUG was a DMC 1450. A factory, wide track DMC 1450 has tracks that are 84"’ wide. TUG’s tracks were 96” wide. Hence the name - TUG is an acronym: "The Ultra Gimp”. The Infamous WBJ1 gets credit for the name.)

Here's a video of TUG trying to climb the hill... backward. This were shot on March 6, 2021, and you can see how little snow there was. I didn’t “publish” this as public. That means you need the link below to view it.


But today CHUGSzilla made it to the top, and did so without question. Though it's equipped with Eaton E-Lockers in both front and rear axles, the E-Lockers weren’t even needed. I don’t know why but the video of the first attempt did not turn out well. CHUGSzilla made it 98% of the way up... and then spun out. The (successful) video that follows was a different line up the hill. In the second video, going down hill, at the 5 second mark you can see where Scott spun out on the first attempt up the hill.

Going up: https://www.youtube.com/watch?v=1Aj_jpGaijY

Going down:

To take the driver variable out of the equation, Scott made three tries with the 1544. This is the best of the three.


While that was clearly a triumph for CHUGSzilla, the snowcat Gods aren’t done punishing us for defiling it by painting it that hideous shade of green. The previous cooling system issues have pretty much been solved, but there’s a new problem. The alternator ain’t cutting it. We had a problem last fall when we we were doing some work on the machine and one day the battery didn’t have enough juice to start the engine. It should have, and we monkeyed with the alternator a bit and it started charging again. But yesterday It showed its hand when the voltmeter was reading only 11 volts. More monkeying and it started working intermittently. But the low voltage means the radiator fans run slower, and the engine gets hotter... and the fuel pump would run slower, too. CHUGSzilla has a second battery for the winch, so we pressed on knowing we could change out batteries if necessary, and make it back to the trailhead. A new alternator has been ordered from Rock Auto. Due to The Infamous WBJ1’s plethora of LED lights on CHUGSzilla I decided to get the optional higher output alternator. (Knowing him, he’ll take that as inspiration for yet more lights!)

Though there were a disappointing amount of snowmobile tracks, we did find some unmolested fields of untracked snow, and that's just a magical experience when you have great snow, great weather and capable machines! Scott and I have a truly horrific work : fun ratio in terms of hours worked on snowcats compared with hours operating them, but yesterday was really spectacular. We ventured farther than we have, and truth be told, we had an absolute blast!

I tend to be the guy who takes the pics and the videos. This video starts out with some tracks visible. What happened was Scott started down the hill and then backed up and suggested I film him, so I went ahead a bit and stopped. Then I videoed Scott and CHUGSzilla playing in the untracked snow. (At times in all the CHUGSzilla videos you can hear the 1544's engine purring.) When he went behind the trees I stopped, and then started again once CHUGSzilla was in view.



CHUGSzilla also has an issue with OBD code P0102, which is a mass air flow sensor problem. I called the company that re-flashed the computer, and it was suggested we replace the MAF sensor. We did that, and the code is still there. The engine runs pretty well, though and we’re hoping the problem is a minor electrical wiring issue….

But, Sun Valley 2024 is around the corner and poor Thundercat doesn’t even have any tracks installed. The 1544 runs great and CHUGSzilla, PITA that it is, no longer gets to be the prima donna getting the bulk of our attention.
 

YamaDooPolCat

Well-known member
SUPER Site Supporter
What is the max RPM in the green machine? I’m limited to 3,500 by the Vickers pump for the steering.

I wired in an orange light in the dash for alternator offline warning. I installed a 100amp alternator and 100 amp current guage, ( alongside the red light oil pressure warning).

These electric fuel pump engines can run out of juice fast. When I use the electric blade I’ll see 100 amps on the guage. I also have a 130 amp fuse in case something decides to smoke.
And there is a second battery in the back for the winch that charges off the system as a spare. And an electronic jump start power pack.
 

Blackfoot Tucker

Well-known member
GOLD Site Supporter
Man that thing sounds great. How loud is it inside?
DaveNet,

That's a good question. Running the exhaust out the back is definitely quieter than along the right side A-post.

We lined the inside of CHUGSzilla’s cab with sound deadening mat and that makes a big difference. With Thundercat we then used an acoustic foam covered with perforated vinyl as the upholstery material throughout the cab. But WBJ1 opted to go with significantly less expensive indoor-outdoor carpet. It doesn't have the same sound reduction qualities, but it was way less expensive, and much easier to install.
 

Blackfoot Tucker

Well-known member
GOLD Site Supporter
What is the max RPM in the green machine? I’m limited to 3,500 by the Vickers pump for the steering.

I wired in an orange light in the dash for alternator offline warning. I installed a 100amp alternator and 100 amp current guage, ( alongside the red light oil pressure warning).

These electric fuel pump engines can run out of juice fast. When I use the electric blade I’ll see 100 amps on the guage. I also have a 130 amp fuse in case something decides to smoke.
And there is a second battery in the back for the winch that charges off the system as a spare. And an electronic jump start power pack.
YDPC,

I apologize for the long answer, but I wanted to answer your question properly, and there’s a lot of information to cover.

I suspect your Vickers pump setup is the way it left the Tucker factory. This is from memory, so I may be incorrect, but IIRC the drive pulley, mounted to the harmonic balancer, is 6” in diameter and the driven pulley on the Vickers pump is 8” in diameter. That combination “underdrives” the pump; meaning engine RPM is greater than pump RPM by the 8/6 ratio. At 3,500 engine RPM the Vickers pump would be spinning at 2,632 RPM. In the V-belt days, pulleys were bolted to the harmonic balancers, and depending on the accessories installed on the engine, that determined the number of grooves on the various pulleys, and the diameter of the pulleys. The factory Tucker setup uses dual groove pulleys and two V-belts to drive the Vickers pump.

The engines on both Thundercat and CHUGSzilla use a serpentine belt system to drive the water pump, alternator (and power steering pump on Thundercat for its hydraulic winch). Both machines used a separate serpentine belt for their respective air conditioning system’s compressors, and of course we removed the AC compressors. The harmonic balancers themselves are machined with grooves for the serpentine belts to run directly on the harmonic balancer. On both machines we used the same custom pulley for the Vickers pump designed by a very good friend and made to his specifications. The new pulleys are made for a serpentine belt and are machined from 6061 aluminum alloy and then hard anodized. This also required changing the shaft in the Vickers pump from one using a keyway to a different style that is splined and threaded on the end for a retaining nut. This same friend is very knowledgable about hydraulic systems, and his feeling was that the Vickers pumps were designed to run continuously in industrial applications for extended periods of time. While Vickers makes specific recommendations on maximum pump RPM, he thought it was okay to exceed those limits a bit for short periods of time on occasion.

Because we knew we wanted the engines in both Thundercat and CHUGSzilla to run at higher RPMs than what Tucker did, we designed their systems accordingly, and used greater underdrive ratios than the factory Tucker setup.

GM offered the 8.1 Vortec engine as an option for certain automotive applications, but they also sold the engine as a medium duty truck engine, a marine engine, as an industrial engine, and for use in RVs. I bought a harmonic balancer from a company that installed the marine version of the engine in boats they built, and that balancer was machined to accept auxiliary pulleys that could be bolted to the balancer. The MerCruiser division of Mercury Marine also used the 8.1 engine, and I bought a MerCruiser auxiliary pulley that was appreciably smaller in diameter than the stock automotive harmonic balancer diameter and somewhat smaller than the machined groove diameter of the marine engine’s balancer.

In the case of CHUGSzilla’s L94 engine, we bought an aftermarket harmonic balancer from Summit Racing that was machined to accept an auxiliary pulley. My buddy then designed a special pulley for CHUGSzilla, and it was made by the same firm that made the pulleys for the Vickers pumps. My recollection is 2,500 pump RPM occurs at roughly 4,000 engine RPM on CHUGSzilla, and a little less on Thundercat. Both engines are computer controlled, and needed to have their computers re-programmed, anyway. That allows one the option to set certain parameters where they want. One of those is maximum engine RPM. Whereas the 8.1 engine was designed to produce its power at lower RPMs, the L94 engine in CHUGSzilla is a higher RPM engine. For example, peak torque on the 8.1 is at 3,200 RPM, peak horsepower is at 4,200 RPM, and I think the rev limiter is set to 4,500 RPM. However, the L94 engine's peak torque occurs at 4,300 RPM, and peak horsepower doesn’t happen until 5,700 RPM. That’s way, way too high for the Vickers pump, and the RPM limiter is set at 4,750 RPM. Mathematically, that equates to 2,951 pump RPM. That’s about 18% more than Vickers maximum recommended RPM, but not grossly out of line for short periods of time.

Whereas V-belt tension is typically adjusted by moving the driven accessory within its mounting brackets, serpentine belt systems rigidly mount the accessories and use a separate, spring loaded belt tensioner pulley. That’s the setup on both Thundercat and CHUGszilla. The mounting brackets Scott fabricated are massively strong. I think the one he made for Thundercat has 11 pieces of steel plate welded together and weighs over five pounds.

Pics are always helpful. The stock 8.1 automotive balancer is on the left and the industrial version is on the right. You can see how the industrial balancer is machined to accept an auxiliary pulley.


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Here’s another view. Note the smaller diameter of the machined groove area on the industrial balancer. That means the water pump, alternator and power steering pump run at slower speeds than they would with the automotive balancer.

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Here’s Scott holding the auxiliary pulley in position.

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And here’s the installed setup on Thundercat’s 8.1 engine.

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Here’s the setup on CHUGSzilla.

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YamaDooPolCat

Well-known member
SUPER Site Supporter
DaveNet,

That's a good question. Running the exhaust out the back is definitely quieter than along the right side A-post.

We lined the inside of CHUGSzilla’s cab with sound deadening mat and that makes a big difference. With Thundercat we then used an acoustic foam covered with perforated vinyl as the upholstery material throughout the cab. But WBJ1 opted to go with significantly less expensive indoor-outdoor carpet. It doesn't have the same sound reduction qualities, but it was way less expensive, and much easier to install.

I never drove my Tucker before stripping it down to change a few things. I installed Hush Mat in the floor and doors, but I can’t compare how much this changed the noise factor.
I did drive the Tucker before I changed out the slides for top idler wheels in the track frame, and the noise reduction was massive.
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