Fan belt roller guide demonstration

[Nashfan]

Heres a video sent to me from a Nashfan customer- Its a video of his fanbelt on his racecar on the track, and he has one of my "beta" roller guides installed. Theres a picture of the unit at the start of the video, but because of the camera angle, cant be seen, but the result of the sweet belt control can! Hes on a 1.8 mile course, his peak speeds are over 100 mi/hr, his peak boost is 18psi, and this is 250hp on his engine. The rpms are between 3600 and 6200 and hes out on the course 4 laps at a time, for a total of 20 laps. He's running a Nashfan, special guidevane bell and 1.58:1 airflow pulley. His head temps never exceeded 450, and while this isnt that great, his manifold air temps were up around 200. Apparently the difference between his heads running at 450 and 350 at this boost level comes down to adding thermal barriers in the combustion chamber and exhaust ports, and adding blocking baffles for the cylinders, which divert more air to the heads, but will cause oil temperatures to rise...
Heres the video

[Nashfan]

Heres a neat demonstration of the guide roller that was sent to me by one of the testers.

[Allan Lacki]

Impressive!

[Nashfan]

Right on! Thanks Alan!! testing is still ongoing but has been seriously fun so far!

[chris]

Kevin, it's always cool to see the new things you are coming up with. I'll be honest, when I saw that using the bellmouth required removal of the belt guide up top, I was a bit concerned. However, you're on top of it (no pun intended)!

[joelsplace]

When can I buy some?

[davemotohead]

Wonder how well this will work with the stock Corvair fans? Also what kind of bearings are in the rollers and their expected life? can the rollers bearings be replaced easily?

[Nashfan]

When can I buy some?

Hopefully, late this spring, if not somewhat earlier. I'm working with a local machine shop to get more mounts done, but have some more testingto do before theres a lot more of these.

[Nashfan]

Wonder how well this will work with the stock Corvair fans? Also what king of bearings are in the rollers and their expected life? can the rollers bearings be replaced easily?

Yes, one of the beta tester's is running a mag fan... he has been thrilled with how it has worked out. He has a 140 powerglide with a 3.89:1 ring and pinion and really likes to piss wind it! Hes put 1000 miles on his set with revs between 5000 and 6000 rpm, using GM recommended belt tensions!! as in 55 lbs strand tension. Those kind of tensions and rpms are usually a good recipe for tossing belts and he had certainly had some problems with that prior to testing the guide running a super tight belt.
Because of these elevated rpms he's been very instrumental in accelerated reliability testing, and found all of the stupid mistakes I had made in the initial beta test units. All of the screw ups have been fixed on his unit, and has been sent back to him. The roller bearings are "hybrid" steel race/ceramic balls with a speed rating of 60000 rpm and equates to an engine rpm of around 7000. They are very easy to replace, and are set-up with the inner seals removed so can be oiled by removing the shoulder bolt and adding a drop of oil into the hole.
The reliability so far is not up to my expectations, as my reliability tester did manage to ruin one of the 4 bearings after 1000 miles of high rpm punishment, but because of the goofy mistakes I made, is not indicative of the reliability of the bearings. His revised set will give a much truer indication of reliability, thus the need for extra testing. Heres a summary of the mistakes- Both rollers were supposed to be intermittently loaded instead of being in constant contact, but what ended up happening was that the left roller was in constant contact, and ended up with considerable preload on it when the engine got hot. Also, these units were originally set-up with no inner support tube/separator so if there was any in and out vibration, it would HAMMER the inner races. Worse than that, the mount being made out of aluminum is going to try and assume the temperature of the thing its mounted on and of course tighten up the end play on the bearings. This is the direction that roller bearings cant handle very well, and its made much worse without the races being locked together with the support tube.
Also, the bearings as delivered to me may not have been pre-oiled, if they were, it did not seem like it was enough to matter. I will know a lot more about the real reliability in a few months.

[kmart356]

For reference, take a look at the fan belt dance (especially during shifts) in this video found on youtube.
.

[davemotohead]

Boy that vid sure shows how much the drive train moves while cornering! My car has semi solid mounts and the drive train only moves a little bit.

[joelsplace]

It doesn't show how crazy the belt can get. I've seen videos where is was really amazing that it stayed on.

[Nashfan]

Yes, heres how bad it can REALLY get. I especially like how the belt squirms out from under the idler guide at one point!

[davemotohead]

Hey Kevin, do you have the Vid of the fan belt breaking and whipping around beating things up? I used to have it saved but cannot seem to find it? I think Ray sent it to me a few years back but cant remember for sure? It really show's why rubber fuel lines are not recommended in the engine compartment!

[Nashfan]

Hey Kevin, do you have the Vid of the fan belt breaking and whipping around beating things up? I used to have it saved but cannot seem to find it? I think Ray sent it to me a few years back but cant remember for sure? It really show's why rubber fuel lines are not recommended in the engine compartment!

I have never seen or heard of that one! It would be cool to see!

[flamencoracer]

Kevin,

I've said it before, but I'll say it again. I'm super excited to being able to get one of these roller guides on my racecar when I get it completed this summer. Since I intend to keep my redline at 7k rpm, the bearings should be fine, and since it's for a racecar, extended longevity or not shouldn't be an issue.