After what turned out to be a very long frustrating development period...FINALLY!! I had been thinking about this thing for years-3 aluminum prototypes and 2 more 3D printed prototypes later and its ready for longer term testing. Preliminary testing with the previous prototype was extremely encouraging- without the rollers on and the belt set loose enough to cause a roughly 1/2" deflection as it exited the crank pulley, with the rollers on it was difficult to see any deflection, and the common "belt riding up the idler pulley" phenomenon that is seen with aluminum pulleys seemed to have disappeared. Other neat things observed were that the belt seemed to have gotten calmed down quite a bit as it left the idler on the way to the fan pulley. Long term testing begins today!!

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car
Test Start#2 [www.youtube.com]

Most cool! If you're looking for a guinea pig, I'm your huckleberry!

Daniel Atkinson
Tacoma, WA
65 Turbocharged Corsa

Vairy cool!

Dean F. Gemberling
Columbus, Georgia
Heart of Georgia Corvair Club Webmaster
Springfest Webmaster

1963 Rampside w/305 V8 - Built by Ken Arnold in 1998
1965 Monza Coupe - Converting from Drag Race Car to Nice Street Car - 63 Buick 215 V8

Right on Daniel!! I have plenty of guinea pigs lined up already, including 2 racers for the limited supply that I have right now, although once I've got more testing in, it will be fairly easy and quick to get more of them done. You are officially on the next batch list

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car
Test Start#2 [www.youtube.com]

Vairy nice!

Enjoy the Corvair!

Paul Sergeant
CORSA Central Division Director / CORSA Treasurer
Lee's Summit, MO
CORSA since 1975
Member – HACOA, Corvair Minnesota, CORSA, Little Indians, POCI

---

Thank you! Will any of the testers be using it with the Robson Idler?

Daniel Atkinson
Tacoma, WA
65 Turbocharged Corsa

I don’t think you’ll need the Robson idler with this , very cool !

1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1998 Honda Prelude Dirt track car
1967 Crown V8 under construction
Mike Levine
Cumming Georgia
North of Atlanta

Well, I put the first 20 miles on the roller system tonight and had the belt set
loose enough to normally cause belt control problems, especially when running a bell mouth. Especially when the bell has really small notches. Past experience with the bells showed that the belt cutouts had to be fairly big to avoid belt strikes and the bell tested today had notches considerably smaller than what I've found to work. I kept hitting it harder and harder, after 10 miles I checked the bell for strike marks and not finding any, decided to be a lot more mean with it on the way back home. The toughest attempt so far was the last one and involved hammering it in second gear going down a hill in order to get the rev rate as high as possible then backed off at 6000 rpm. When I have done this in the past with the belt that loose, it usually resulted in a belt roll, and another belt strike mark on the bell. This time, nothing happened... no rolled belt no strike marks. Woo hoo!!
Future testing is to see what happens with a stupidly tight belt- this is actually the worst of the 2 conditions related to belt tension because it can happen at any time the belt is shocked hard enough to get scarey tight. Even when the belt was originally set fairly loose. In an experiment some time ago, I did tighten the belt scary tight and then started the car, heard this weird thrumming noise coming from the engine compartment. I checked it out and the noise was the belt vibrating side to side between the idler and crank pulley. I estimated the total deflection at around 1". I went back to look at the rpm, it was at 1000rpm. Then I went back to watch the belt vibrations again and was suprised to find that now there was an equally large vibration between the fan pulley and idler as well as the original vibration between the crank and idler.
Then shut the engine off and set the belt a hell of a lot looser than that and called it good. This scary vibration is what that roller guide is meant to stop... if it can do that then its probably then end of belt tossing if everything else is lined up well.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car
Test Start#2 [www.youtube.com]

do you think that with the belt tight the vibrations were actual crank pulse at 1000 rpm ?

Roger R
Madison Wi
63 greenbriar
65intercooled 180 4sp,autocrosser
62 Rampy

Vairy interesting Kevin, as usual.

Rocco
65 EFI Turbo Corsa
YS113
Barboursville, Va

Put me on the list! Looking great!

-Tom


63' Monza Spyder Convertable (in process) MY Build Thread
62' Wagon rebuild MY Build Thread
65' Monza MY Build Thread
73' NovaSS 454 Big block (Sold)
86' BMW 325es
67' UltraVan 211 "Violet"
NFCC, UMCC
Grand Island, NY

roger65180 Wrote:
-------------------------------------------------------
> do you think that with the belt tight the vibrations were actual crank pulse at 1000 rpm ?

That one, I dont know, but I'm sure it had something to do with it. What I think is happening is that the tension is causing the belt to sink into the groove enough for it to stick and then try to follow the crank rotation, sending it to the left and then "twangs" to the right as it un sticks. Someone else that is running a bell mouth and airflow pulley with a mag fan and lower shouds off has had the same issue with super tight belt tensions. He noticed that as long as the rpms were at 4000 his head temperatures would stay at 300, but then at around 4250 the heads would get alot hotter quick. I told him this was belt slippage, so then he kept going tighter on it and then managed to keep the heads to 300 all the way out to 5000 for 2mins. Apparently he'd broke a few cheap belts attempting this! Then he told me about the weird thrumming noise that was happening at lower rpms. I told him about a then recent experiment that I had done that resulted in the same noise, and then he knew that he couldnt run the belt as tight as he had it! My own personal experience with belt tossing being caused by a really tight belt came a few days after becoming a Corvair owner. The guy that had sold us the car made a point to show me how tight to set the fan belt, which was roughly 1/2" of slack. I thought to myself that cant possibly be right because the belt should slip when its that loose. Then I went ahead and tightened the heck out of it, and was probably as tight as the shop manual used to recommend for the early steel fans. The belt popped off later that day after revving it out to around 6500 rpm, and never did it that way again.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car
Test Start#2 [www.youtube.com]

jazzworkerbee Wrote:
-------------------------------------------------------
> Thank you! Will any of the testers be using it with the Robson Idler?

No- this particular version of the roller guide wont work with that without some modifications to either the idler or the mount. I've always really liked the concept of the spring loaded idler because it can keep a constant tension on the belt. I bought one of these to see what it would take to mount the guide rollers on it and decided to not go there just yet.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car
Test Start#2 [www.youtube.com]

I’ve got a few extra belts laying around if you need them for testing purposes Kevin? However, it sounds as if you’ve already accomplished what you set out to do! I guess I’ll just have to order one of these along with a Nash fan for the new 65 Corsa 140
Come on over for a visit when the inter island is running. It’s been a while and I’m sure we can load you up with some extra parts

San Juan Islands, WA

1966 Corsa Coupe 180/4 Marina Blue/Blue

1965 Corsa Coupe 140/4 Glacier Gray/Black

63turbo Wrote:
-------------------------------------------------------
> roger65180 Wrote:
> -------------------------------------------------------
> > do you think that with the belt tight the vibrations were actual crank pulse at 1000 rpm ?
>
> That one, I dont know, but I'm sure it had something to do with it. What I think is happening is that the tension is causing the belt to sink into the groove enough for it to stick and then try to follow the crank rotation, sending it to the left and then "twangs" to the right as it un sticks. Someone else that is running a bell mouth and airflow pulley with a mag fan and lower shouds off has had the same issue with super tight belt tensions. He noticed that as long as the rpms were at 4000 his head temperatures would stay at 300, but then at around 4250 the heads would get alot hotter quick. I told him this was belt slippage, so then he kept going tighter on it and then managed to keep the heads to 300 all the way out to 5000 for 2mins. Apparently he'd broke a few cheap belts attempting this! Then he told me about the weird thrumming noise that was happening at lower rpms. I told him about a then recent experiment that I had done that resulted in the same noise, and then he knew that he couldnt run the belt as tight as he had it! My own personal experience with belt tossing being caused by a really tight belt came a few days after becoming a Corvair owner. The guy that had sold us the car made a point to show me how tight to set the fan belt, which was roughly 1/2" of slack. I thought to myself that cant possibly be right because the belt should slip when its that loose. Then I went ahead and tightened the heck out of it, and was probably as tight as the shop manual used to recommend for the early steel fans. The belt popped off later that day after revving it out to around 6500 rpm, and never did it that way again.

I am a little confused about the high RPM issue. I thought your calculations were that your fan used less power at higher RPMs than a stock blower. Why would it slip?

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2023 KIA K5 GT/GT1 turbo-AKA ZIPPY II (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Vairy interesting... and vairy interested...following.

"A sign of great intelligence is being able to say 'I don't know'"
1966 Corsa Turbo Coupe
Now Located in Oswego,NY

Put me down.m

Jimc
1965 Corsa Coupe, two owner history


HACOA Member
CORSA 2017 Concours Senior Gold Award
AACA 2015 Award

jjohnsonjo Wrote:
-------------------------------------------------------
> 63turbo Wrote:
> -------------------------------------------------------
> > roger65180 Wrote:
> > -------------------------------------------------------
> > > do you think that with the belt tight the vibrations were actual crank pulse at 1000 rpm ?
> >
> > That one, I dont know, but I'm sure it had something to do with it. What I think is happening is that the tension is causing the belt to sink into the groove enough for it to stick and then try to follow the crank rotation, sending it to the left and then "twangs" to the right as it un sticks. Someone else that is running a bell mouth and airflow pulley with a mag fan and lower shouds off has had the same issue with super tight belt tensions. He noticed that as long as the rpms were at 4000 his head temperatures would stay at 300, but then at around 4250 the heads would get alot hotter quick. I told him this was belt slippage, so then he kept going tighter on it and then managed to keep the heads to 300 all the way out to 5000 for 2mins. Apparently he'd broke a few cheap belts attempting this! Then he told me about the weird thrumming noise that was happening at lower rpms. I told him about a then recent experiment that I had done that resulted in the same noise, and then he knew that he couldnt run the belt as tight as he had it! My own personal experience with belt tossing being caused by a really tight belt came a few days after becoming a Corvair owner. The guy that had sold us the car made a point to show me how tight to set the fan belt, which was roughly 1/2" of slack. I thought to myself that cant possibly be right because the belt should slip when its that loose. Then I went ahead and tightened the heck out of it, and was probably as tight as the shop manual used to recommend for the early steel fans. The belt popped off later that day after revving it out to around 6500 rpm, and never did it that way again.
>
> I am a little confused about the high RPM issue. I thought your calculations were that your fan used less power at higher RPMs than a stock blower. Why would it slip?

The above was from a person using a stock mag fan with a guide vane bell and later with an airflow pulley, with the lower shrouds off... It uses a whole bunch more power than the stock set-up, because it is flowing a whole bunch more than the stock set-up, mostly because he had the lower shrouds off. I kind of wanted him to try it with the lower shrouds on but he hasnt done it yet.
What I was talking about with my personal experience with a tight belt and high revs was also with the stock fan.
The Nashfan horsepower consumption is indeed very low. All tests that I've done both with the prototype and now the production fan agree with each other well in the sense that the multiple tests with the proto agree with each other, and the same extra tests done with the production fan agree with each other. Particularly cool for me was a double check that I did where I tried to predict the power consumption of the production fan based on the output change that I had made. It was supposed to be a proportional change in output and also a proportional change in power consumption, and this prediction also agreed nearly exactly with the experimental results. What Im getting at here is that the hp consumption is so low that the belt will not slip from driving the fan in steady state even with a "loose" belt but for belt control reasons should be a little more snug than is required to drive it. But now this can cause some pretty severe shock loading and pop the belt for that reason. Best solution is to NOT use tension to control the belt. Limit the deflection in all directions with a roller guide and set the tension in a way that will let the belt slip from acceleration and not steady state hp.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car
Test Start#2 [www.youtube.com]

OK, thanks Kevin, that makes perfect sense, I worked on some electronic equipment that used a squirrel cage blower with a large HEPA filter. They would for weeks on end, no problem, but if you ran them without the filter the increased load would pop the thermal breaker in no time.

Or you could just hold your hand over the business end of a leaf blower and hear it rev up.

BTW I made a similar device for my big lawn tractor with a mule drive. It didn't throw the belts but they would get into crazy mode and slapped a stationary part of the frame and fray the back. Also went to Kevlar belts and never looked back. OT, but I did find a Kevlar belt that crossed to a Vair, but never ordered it.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2023 KIA K5 GT/GT1 turbo-AKA ZIPPY II (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa