New pulley fits good. No cleaning up the print was necessary this time. It actually does not hit that alternator bolt anymore. I might just start looking for the same bolt with a smaller head. Next up will be some testing. The nylon should be good enough to run with for a little while.

 

Wonder if this style might work. This is on the Summit Racing site. https://www.summitracing.com/parts/b...hoCLOsQAvD_BwE

Ooops! Just noticed it's for body panels so probably not stout enough. Maybe a hex head cap screw with washer.

 

Anything new yet?

 

Not really unfortunately. Since it has gotten cooler I have been wondering if the effects of the pulley would show enough. Thinking about it: theoretically, the thermostat should keep the temperature set point the same as usual except when the cooling system saturates (i.e. when the thermostat is fully open / cooling system can no longer keep up with heat production). Therefore, in cooler ambient temps, with the A/C off, and the overdrive pulley, if the water pump and fan are spinning faster, the thermostat will simply just be more closed than it would be with a normal pulley (because less thermostat opening will be required to maintain the temperature set point if the coolant is being cooled more with faster spinning fan / water pump). The advantages of the overdrive pulley probably won't show until the cooling system is saturated and the thermostat is open all the way. Then, once the thermostat is open all the way, the advantages of the faster spinning water pump/fan will be more apparent. Thus, the more cooling system "headroom".

To get around this, I was thinking about blocking off part of the radiator to force the situation I just described (thermostat open all the way, cooling system saturated) even with a lower ambient temperature, testing with the regular pulley watching the temps with Ultraguage. Then replicate with the overdrive pulley. I think that should give a good idea of the pulley without having the 95F weather.

I am waiting for a friend of mine to test this on his Disco. My Rover V8-powered one is out of commission at the moment.

 

So, a follow-up. It's been a while, but I finally got to test this today. Belt fit and pulley fit was good. The tensioner took up the extra slack as expected. It was cooler out in VA today, but I could still tell the water pump was moving more water. It took a little longer to warm up. The temps settled around 188-190 with a LR low-temp thermostat. I put a few minutes of run time on it. Problem was that after a few minutes, the nylon heated up and bent back a little, which allowed the belt to slip backwards and start squealing. The alternator bolt was a small problem, however I was able to turn it a little and the belt stayed away before it jumped. Overall, I am happy with the performance of this prototype.

I am sort of between two options - option 1 is to recreate a stronger, thicker pulley out of nylon. I was impressed with the strength of the 3D printed nylon pulley. I am sure the nylon would not bend significantly if it was thicker. That option is about $70 for a one-off, but I still wonder about longevity. Option 2 is to CNC the same pulley out of 6061 aluminum, which definitely won't bend. Downside is that it's about $270 for a one-off. On the plus side though, if others wanted them, I could get them produced in bulk for a lot cheaper.

Thoughts?

 

I'd be in for a CNC pulley if you go that route. Probably would be game for a printed one as well but I'm curious how long those would last with the heat cycles in the engine compartment.

 

I am thinking that the aluminum is probably the best idea. I just looked up the glass transition temp for nylon 12 and its around 207 degrees F (not sure about the reliability of the source though). If that's true, then the nylon 12 is good enough for a test run for fitment, but not for an actual part. There is not enough margin if the engine ever did get hot on a steep grade.

For other parts though, like intake hose fittings, etc. I would think the nylon 12 would work good. Even would probably work for other pulleys that don't get as hot.

 

Just putting this out there in case folks weren't aware, not purposefully trying to stomp on the thread. The new FlowKooler water pump reportedly solves all low RPM head pressure and flow issues, and has increased flow throughout the RPM range, for less than $150

 

That FlowKooler pump looks nice, but there are few things I think are advantages of this setup:

1. Easier to install. The whole water pump doesn't have to be replaced, which is a hassle and waste if the one that you have works.
2. It works with any factory pump.
3. Provides more airflow, because the fan also spins faster. It should be better at cooling at idle.

If it works well enough, and a few people want to do a group buy, it could probably be done for less than $100. But I'll have to see how it works first.