Need Advice and help with small torque converter

Ok here is the deal: I am currently working on a 20's Miller 91' front drive racing car. This is one of the early blower setups for the 91'. Here is the layout. The engine faces backwards in the front of the chasis. The basic layour is an inline 8 cylinder twin cam motor. It is supercharged with a centrifugal blower through a step up gear box. The car i am working on has an 8" impeller,the drive being taken off the drive end of the cams. This drive setup was problimatic as there was little ability to dampen any shock loads into or out of the step up gearbox. With the impeller driven to around 35,000 RPM at peak engine RPM (6500) there are high loads when accelerating the engine trying to make the impeller accelerate. And of course the opposite happens when the accelerator is lifted for a gear change as the impeller inertia tries to twist everything in reverse.
Later motors used a large bull gear off the flywheel to eliminate some of the torque issues. A system of springs or rubber was also tried in the early setup with limited success. The saving part of this original design is that the cars were originally built to run on oval tracks at a relatively constant speed. Trouble is that today the only venue to run one of these cars is on a road course and that means shifting and lots of it...

I believe that a fluid coupling or torque converter might be the answer to the shock and high loadings of the original setup. I have pressure oil avaliable in the cams (in line with the imput shaft to teh gearbox) The space is limited, the existing cam cover and front timing housing allow an outside housing for a converter or coupling of about 2.625" od. The avaliable length is around 2" long. The imput and output are in line with each other and the imput drive would have to be a bolted flange of about 1.875" OD. The driven shaft to the gearbox is splined.

Basic question is the sizr of a converter a limiter..i mean is ther a point where a converter just stops to work due to limited size, or does a converter scale well?

Anyone have any expirence in this area in general? I am thinking tht making one (actually 2) is my only real option..did some searching and everything i find seems pretty large.
Will two identical converters driven one off each cam share the load or will one try to do all the work and thus over stress the drive on that side?

Am i insane for thinking about this? Just completed making a new impeller (one that came with the car was made in England as a part of a restoration and the impeller was way too heavy and crude)
Want to try to give this the best chance to live. Good customer who enjoys his cars..In general cost is not the issue.

This is not my first Miller blower job. Several years ago i built a rear drive Miller 122' that was also blown. That car had the blower drive done off the ends of the camshafts. This was also a problem in the day. The long cam shafts would twist and change the valve timing from the fromt to the rear of the motor. My solution for this motor was to make cams that were hollow. Inside the cams is fitted long quill drive shafts that take the drive from the front of the cam to the rear where the step up gearbox fits up. The quill shafts were made from 300M and have proven quite succesful having logged time on a number road courses.

Thanks in advance for any help.
Cheers Ross

Ok here is the deal: I am currently working on a 20's Miller 91' front drive racing car. This is one of the early blower setups for the 91'. Here is the layout. The engine faces backwards in the front of the chasis. The basic layour is an inline 8 cylinder twin cam motor. It is supercharged with a centrifugal blower through a step up gear box. The car i am working on has an 8" impeller,the drive being taken off the drive end of the cams. This drive setup was problimatic as there was little ability to dampen any shock loads into or out of the step up gearbox. With the impeller driven to around 35,000 RPM at peak engine RPM (6500) there are high loads when accelerating the engine trying to make the impeller accelerate. And of course the opposite happens when the accelerator is lifted for a gear change as the impeller inertia tries to twist everything in reverse.
Later motors used a large bull gear off the flywheel to eliminate some of the torque issues. A system of springs or rubber was also tried in the early setup with limited success. The saving part of this original design is that the cars were originally built to run on oval tracks at a relatively constant speed. Trouble is that today the only venue to run one of these cars is on a road course and that means shifting and lots of it...

I believe that a fluid coupling or torque converter might be the answer to the shock and high loadings of the original setup. I have pressure oil avaliable in the cams (in line with the imput shaft to teh gearbox) The space is limited, the existing cam cover and front timing housing allow an outside housing for a converter or coupling of about 2.625" od. The avaliable length is around 2" long. The imput and output are in line with each other and the imput drive would have to be a bolted flange of about 1.875" OD. The driven shaft to the gearbox is splined.

Basic question is the sizr of a converter a limiter..i mean is ther a point where a converter just stops to work due to limited size, or does a converter scale well?

Anyone have any expirence in this area in general? I am thinking tht making one (actually 2) is my only real option..did some searching and everything i find seems pretty large.
Will two identical converters driven one off each cam share the load or will one try to do all the work and thus over stress the drive on that side?

Am i insane for thinking about this? Just completed making a new impeller (one that came with the car was made in England as a part of a restoration and the impeller was way too heavy and crude)
Want to try to give this the best chance to live. Good customer who enjoys his cars..In general cost is not the issue.

This is not my first Miller blower job. Several years ago i built a rear drive Miller 122' that was also blown. That car had the blower drive done off the ends of the camshafts. This was also a problem in the day. The long cam shafts would twist and change the valve timing from the fromt to the rear of the motor. My solution for this motor was to make cams that were hollow. Inside the cams is fitted long quill drive shafts that take the drive from the front of the cam to the rear where the step up gearbox fits up. The quill shafts were made from 300M and have proven quite succesful having logged time on a number road courses.

Thanks in advance for any help.
Cheers Ross

Ok here is the deal: I am currently working on a 20's Miller 91' front drive racing car. This is one of the early blower setups for the 91'. Here is the layout. The engine faces backwards in the front of the chasis. The basic layour is an inline 8 cylinder twin cam motor. It is supercharged with a centrifugal blower through a step up gear box. The car i am working on has an 8" impeller,the drive being taken off the drive end of the cams. This drive setup was problimatic as there was little ability to dampen any shock loads into or out of the step up gearbox. With the impeller driven to around 35,000 RPM at peak engine RPM (6500) there are high loads when accelerating the engine trying to make the impeller accelerate. And of course the opposite happens when the accelerator is lifted for a gear change as the impeller inertia tries to twist everything in reverse.
Later motors used a large bull gear off the flywheel to eliminate some of the torque issues. A system of springs or rubber was also tried in the early setup with limited success. The saving part of this original design is that the cars were originally built to run on oval tracks at a relatively constant speed. Trouble is that today the only venue to run one of these cars is on a road course and that means shifting and lots of it...

I believe that a fluid coupling or torque converter might be the answer to the shock and high loadings of the original setup. I have pressure oil avaliable in the cams (in line with the imput shaft to teh gearbox) The space is limited, the existing cam cover and front timing housing allow an outside housing for a converter or coupling of about 2.625" od. The avaliable length is around 2" long. The imput and output are in line with each other and the imput drive would have to be a bolted flange of about 1.875" OD. The driven shaft to the gearbox is splined.

Basic question is the sizr of a converter a limiter..i mean is ther a point where a converter just stops to work due to limited size, or does a converter scale well?

Anyone have any expirence in this area in general? I am thinking tht making one (actually 2) is my only real option..did some searching and everything i find seems pretty large.
Will two identical converters driven one off each cam share the load or will one try to do all the work and thus over stress the drive on that side?

Am i insane for thinking about this? Just completed making a new impeller (one that came with the car was made in England as a part of a restoration and the impeller was way too heavy and crude)
Want to try to give this the best chance to live. Good customer who enjoys his cars..In general cost is not the issue.

This is not my first Miller blower job. Several years ago i built a rear drive Miller 122' that was also blown. That car had the blower drive done off the ends of the camshafts. This was also a problem in the day. The long cam shafts would twist and change the valve timing from the fromt to the rear of the motor. My solution for this motor was to make cams that were hollow. Inside the cams is fitted long quill drive shafts that take the drive from the front of the cam to the rear where the step up gearbox fits up. The quill shafts were made from 300M and have proven quite succesful having logged time on a number road courses.

Thanks in advance for any help.
Cheers Ross

I'm not sure what the peak torque loads would be for your blower drive, but if you can estimate the level of shock load they would need to absorb, their are what I believe might be better solutions available than torque converters. Some industrial equipment suppliers carry types of mechanical couplings that absorb or dampen rotational shock loads. Look in the "power transmission" section of their catalogs.
I've seen some of these in use, but don't remember what they're called.
sounds like a fun project.

I'm not sure what the peak torque loads would be for your blower drive, but if you can estimate the level of shock load they would need to absorb, their are what I believe might be better solutions available than torque converters. Some industrial equipment suppliers carry types of mechanical couplings that absorb or dampen rotational shock loads. Look in the "power transmission" section of their catalogs.
I've seen some of these in use, but don't remember what they're called.
sounds like a fun project.

I'm not sure what the peak torque loads would be for your blower drive, but if you can estimate the level of shock load they would need to absorb, their are what I believe might be better solutions available than torque converters. Some industrial equipment suppliers carry types of mechanical couplings that absorb or dampen rotational shock loads. Look in the "power transmission" section of their catalogs.
I've seen some of these in use, but don't remember what they're called.
sounds like a fun project.

Sounds like poor engineering from the get go since the cam shafts turn at half the crank speed and then having to gear it back up.
A lot of lawn equipment is using Hydrostatic drives. It would be smaller in size and you could possibly get enough parts to fab what you need. The only difference between torque converters and hydrostat is hydrostat bleeds off pressure to control. Block off the bleed circuit and you have a torque converter.
You might look into a centrifical clutch like used on go carts too. Would definately ease the loading.

Sounds like poor engineering from the get go since the cam shafts turn at half the crank speed and then having to gear it back up.
A lot of lawn equipment is using Hydrostatic drives. It would be smaller in size and you could possibly get enough parts to fab what you need. The only difference between torque converters and hydrostat is hydrostat bleeds off pressure to control. Block off the bleed circuit and you have a torque converter.
You might look into a centrifical clutch like used on go carts too. Would definately ease the loading.

Sounds like poor engineering from the get go since the cam shafts turn at half the crank speed and then having to gear it back up.
A lot of lawn equipment is using Hydrostatic drives. It would be smaller in size and you could possibly get enough parts to fab what you need. The only difference between torque converters and hydrostat is hydrostat bleeds off pressure to control. Block off the bleed circuit and you have a torque converter.
You might look into a centrifical clutch like used on go carts too. Would definately ease the loading.

I don't know enough of the engineering theory of torque convertors to authenticate this opinion, but I don't think they will work. Convertors work on the velocity of the oil moving, the smaller the diameter the higher the rpm needed for them to function. I'm pretty sure 2.625" dia and 3250 RPM isn't going to even turn the impeller, let alone drive it at the correct speed. Someone please correct me if I'm wrong.

Some thoughts here, for what they are worth - #1 - Would a sprag clutch work? It would be possible to fit one in the area described and would allow the supercharger drive to over run the engine speed when the engine slowed and would at least isolate the drive from the loads experienced on deceleration.

#2 - Could you build a small multi plate overload clutch to fit in that area similar to the overload clutch seen on some lathes' feed shafts? I'm thinking of using small motorcycle/atv clutch frictions and steels in a small housing with an adjustable static spring load calculated to just barely hold the load of the supercharger at full speed/full boost, and will slip with any additional load or shock applied. Such devices are common on commercial mowers, farm machines, etc. maybe there's something small available commercially you could apply with modifications. Perhaps a combination of the sprag and the overload clutch?

#3 - Fan clutches use a labyrinth of passages between two plates, filled with silicone fluid to drive the fan. I wonder if you could pack enough contact area into the space you describe to make this concept work for that kind of power to be transmitted.

I don't know enough of the engineering theory of torque convertors to authenticate this opinion, but I don't think they will work. Convertors work on the velocity of the oil moving, the smaller the diameter the higher the rpm needed for them to function. I'm pretty sure 2.625" dia and 3250 RPM isn't going to even turn the impeller, let alone drive it at the correct speed. Someone please correct me if I'm wrong.

Some thoughts here, for what they are worth - #1 - Would a sprag clutch work? It would be possible to fit one in the area described and would allow the supercharger drive to over run the engine speed when the engine slowed and would at least isolate the drive from the loads experienced on deceleration.

#2 - Could you build a small multi plate overload clutch to fit in that area similar to the overload clutch seen on some lathes' feed shafts? I'm thinking of using small motorcycle/atv clutch frictions and steels in a small housing with an adjustable static spring load calculated to just barely hold the load of the supercharger at full speed/full boost, and will slip with any additional load or shock applied. Such devices are common on commercial mowers, farm machines, etc. maybe there's something small available commercially you could apply with modifications. Perhaps a combination of the sprag and the overload clutch?

#3 - Fan clutches use a labyrinth of passages between two plates, filled with silicone fluid to drive the fan. I wonder if you could pack enough contact area into the space you describe to make this concept work for that kind of power to be transmitted.

I don't know enough of the engineering theory of torque convertors to authenticate this opinion, but I don't think they will work. Convertors work on the velocity of the oil moving, the smaller the diameter the higher the rpm needed for them to function. I'm pretty sure 2.625" dia and 3250 RPM isn't going to even turn the impeller, let alone drive it at the correct speed. Someone please correct me if I'm wrong.

Some thoughts here, for what they are worth - #1 - Would a sprag clutch work? It would be possible to fit one in the area described and would allow the supercharger drive to over run the engine speed when the engine slowed and would at least isolate the drive from the loads experienced on deceleration.

#2 - Could you build a small multi plate overload clutch to fit in that area similar to the overload clutch seen on some lathes' feed shafts? I'm thinking of using small motorcycle/atv clutch frictions and steels in a small housing with an adjustable static spring load calculated to just barely hold the load of the supercharger at full speed/full boost, and will slip with any additional load or shock applied. Such devices are common on commercial mowers, farm machines, etc. maybe there's something small available commercially you could apply with modifications. Perhaps a combination of the sprag and the overload clutch?

#3 - Fan clutches use a labyrinth of passages between two plates, filled with silicone fluid to drive the fan. I wonder if you could pack enough contact area into the space you describe to make this concept work for that kind of power to be transmitted.

I agree with mudflap's first suggestion of a sprag clutch. Some late model automobile alternators incorporate a sprag clutch inside the drive pulley. The size is definitely in the right range and the mass of the alternator rotor might be comparable to what you need. Max

I agree with mudflap's first suggestion of a sprag clutch. Some late model automobile alternators incorporate a sprag clutch inside the drive pulley. The size is definitely in the right range and the mass of the alternator rotor might be comparable to what you need. Max

I agree with mudflap's first suggestion of a sprag clutch. Some late model automobile alternators incorporate a sprag clutch inside the drive pulley. The size is definitely in the right range and the mass of the alternator rotor might be comparable to what you need. Max

I would vote for mudflaps #2, a fixed pressure clutch set to slip below damaging levels of torque would be simple, low maintenance and the easiest to fabricate.

I would vote for mudflaps #2, a fixed pressure clutch set to slip below damaging levels of torque would be simple, low maintenance and the easiest to fabricate.

I would vote for mudflaps #2, a fixed pressure clutch set to slip below damaging levels of torque would be simple, low maintenance and the easiest to fabricate.

What about the mechkinism in posatrac /limited slip differentl , certinly could handle the power transfer. There are several types used, clutches, varacous, etc. Might even be small enough to fit.

What about the mechkinism in posatrac /limited slip differentl , certinly could handle the power transfer. There are several types used, clutches, varacous, etc. Might even be small enough to fit.