Thread: Making A Small Block 350 As Fast As It Can Be

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Henry/Jack,

I gave up that option to avoid one more electrical connection and I am hoping there is still some slack in adjusting the shift points, I won't know until I get it on the road.

Don Shillady
Retired Scientist/teen rodder

"or maybe a bolt-on huffer with an air conditioner clutch at only 6 psi boost"

Don, you've been watching too many Australian movies. There is no clutch currently available that would control a currently available huffer.

Originally Posted by techinspector1

"or maybe a bolt-on huffer with an air conditioner clutch at only 6 psi boost"

Don, you've been watching too many Australian movies. There is no clutch currently available that would control a currently available huffer.

Don,a few years ago I was very up on supercharged applications and at that point and time there was no "clutch" available for a supercharger.
If you have ever driven a supercharged car with out a belt it really is no fun.

I don't know why you're worried about your motor, the throttle response will be fantastic and it will pull like Jack the Bear.

Tech1, I have great respect for your technical knowledge, but I am pretty sure this has already been done by several folks; should I mention old posts by Streets who claimed he had such a setup? What was that movie about a cross country race where they had such a set up on a Dodge or Duster? As DennyW says this may have already been done commercially as well. However, it is a moot point and at least $3000 over the horizon for me but as I see it there would be several problems which could be solved:

1. air & fuel have to pass through the blower when the clutch is not engaged and it is not clear that the roots rotors would position themselves under a slack pulley to allow the mixture to go through the blower; my guess is that this could happen due to engine vacuum with a short duration cam but on the other hand the rotors might just stop in a position that would block most of the intake. Still with twisted rotors it seems unlikely to me that the intake would be totally blocked, but it might be necessary for the rotors to turn slowly due to engine vacuum if the rotors seal as well as they are supposed to. I think there is a better chance of this working with a clearanced roots type blower than it would with a vane-type blower which probably seals better.

2. As you imply the clutch would have to be pretty hefty to handle that big pulley on the snout of the blower.

3. Probably some expensive custom machining would be needed to adapt the clutch to the pulley. On the other hand round stuff is pretty easy to treat on a lathe.

4. Maybe an alternative is to have a variable ratio pulley so that the rotors would always be turning, but at different speeds according to the ratio on some sort of cone the way that some cart racer transmissions work. Just a wild idea, thanks for putting up with me! Some people have been working on variable ratio transmissions for a long time (I'll bet DennyW can find that too!) but they involve belts and slip too much for a main transmission but maybe here is the perfect application for a belt-drive variable ratio pulley?

Thanks for the prediction of a snappy 350, I can't hardly wait. Maybe I will be so pleased with the performance that I will not care about a blower. My only other experience with positive displacement supercharging was a little Judson vane-type blower on a VW 1300 and it really got hot to the point of melting a piston, but of course until the piston melted it really made that beetle think it was a Porsche! Gee I really want that engine to run but there are so many details on a total build that I don't think I will get it on the road until next summer. Boy DennyW can really dig out the research data in a hurry, thanks for your thoughts.

Don Shillady
Retired Scientist/teen rodder

DennyW, that is a good idea but what is the answer regarding fuel-air when the clutch is not engaged? The Mercedes design you mention apparently had a carb open when the blower is off. It looks to me that a chainsaw clutch would be about the right size, but maybe not strong enough. Someone mentioned on another post that a roots blower may take as much as 32 HP to drive it so that means the clutch needs to be pretty tough. Probably a cart clutch would be better. This is sort of a stall-torque converter idea but we are back to Tech1's objection in that one would need something commercially available so maybe a cart clutch or a chainsaw clutch from the biggest available chainsaw might work. Maybe we are back to the older design of a McCullough centrifugal supercharger or just a turbo charger so maybe we have come full circle and a turbocharger is the best answer since it allows flow at low engine speed. Most of the turbocharger setups I have seen for V8 engines are dual turbos, but the old 215 Buick-Pontiac-Olds engines had a single turbo with a waste gate. It might be possible to find a 215 setup in a junk yard somewhere but unlikely. Maybe this exercise just leads to another search on available turbo kits for SBC engines? I looked over your search on variable transmisions and you can see that inventors have been working on that idea for quite a while but not many of those designs have made it to practicality. Since I have my hands full anyway, I'll let you off the hook and in the background I'll keep my open for SBC turbo kits, but I don't really want to go to a dual turbo setup to keep things under a small '29 hood. Another problem comes up with a turbo in that you have to merge the exhaust mainfolds for a single turbo. If I had a Y-block the heads there are perfect for dual turbos. Obviously the roots-type bolt on blower looks like a simpler setup regarding the exhaust but then we are back to the clutch problem. What channel are those Australian movie on?

Don Shillady
Retired Scientist/teen rodder

Remember Mad Max?

He had a button on the shifter that clutched in the blower

All Bull Cookies for Hollywood of course ............

No doubt you could come up with something though .............

Kitz

Erik, I went back to an old post from when I joined the Forum and found it was still there but condensed to only active members as of now and edited quite a bit with three pages repeated so it looks like the comments from Streets are gone due to a combination of his departure, and changeover of the Forum software. Nevertheless, Streets claimed he once had a T-bucket with a 350 that had a huffer on it with an airconditioning clutch on the blower pulley and he could turn it off and on. The discussion was about mpg and he claimed he could run a 2.73 rear gear with the huffer on for traffic light fun and then turn it off for highway use. He mentioned this several times in posts so there is a good chance he actually solved this problem and got it to work. Probably he is on some other site but I do not know how to reach him to check on this. Anyway I need to work on the car today since this is the end of Summer for me and the Fall schedule will have less time for the car so I need to work on it NOW! Saturday I will go to the Richmond NSRA National at the RIR Fairgraounds which is only a few miles from where I live and yesterday and today has seen a parade of rods coming in on I-95 (300 yards from my home) and I-64 and here I am with only a garage car. I hope I can make to the Richmond National next year with a running car. Does this Forum have any representative or contact person at such NSRA events?

Note in edit mode: Erik I read you post after I submitted mine. Yes, you have pointed out the main problem as how to get the engine to breath when the blower clutch is not engaged. I am already gettirng weary of this idea due to it's difficulty but since one might only want to run a 6 psi boost or even as low as 4 psi, maybe the blower case could be "over-clearanced" so it would leak better when the rotors are not turning but still provide some boost when the clutch is engaged. Still it would be a gamble to possibly waste a $2500 blower case.

Don Shillady
Retired Scientist/teen rodder

Originally Posted by Don Shillady

DennyW, that is a good idea but what is the answer regarding fuel-air when the clutch is not engaged? The Mercedes design you mention apparently had a carb open when the blower is off. It looks to me that a chainsaw clutch would be about the right size, but maybe not strong enough. Someone mentioned on another post that a roots blower may take as much as 32 HP to drive it so that means the clutch needs to be pretty tough. Probably a cart clutch would be better. This is sort of a stall-torque converter idea but we are back to Tech1's objection in that one would need something commercially available so maybe a cart clutch or a chainsaw clutch from the biggest available chainsaw might work. Maybe we are back to the older design of a McCullough centrifugal supercharger or just a turbo charger so maybe we have come full circle and a turbocharger is the best answer since it allows flow at low engine speed. Most of the turbocharger setups I have seen for V8 engines are dual turbos, but the old 215 Buick-Pontiac-Olds engines had a single turbo with a waste gate. It might be possible to find a 215 setup in a junk yard somewhere but unlikely. Maybe this exercise just leads to another search on available turbo kits for SBC engines? I looked over your search on variable transmisions and you can see that inventors have been working on that idea for quite a while but not many of those designs have made it to practicality. Since I have my hands full anyway, I'll let you off the hook and in the background I'll keep my open for SBC turbo kits, but I don't really want to go to a dual turbo setup to keep things under a small '29 hood. Another problem comes up with a turbo in that you have to merge the exhaust mainfolds for a single turbo. If I had a Y-block the heads there are perfect for dual turbos. Obviously the roots-type bolt on blower looks like a simpler setup regarding the exhaust but then we are back to the clutch problem. What channel are those Australian movie on?

Don Shillady
Retired Scientist/teen rodder

He is refering to a Mel Gibson film called the "Road Warrior".In which Mel had a cable he would pull to engage the clutch on the 6-71 on top of his 351 Cleveland in his Aussie Ford.
The point I was trying to make when I said it was no fun to drive a "blown engine" with out a belt was to get you to think about the "air fuel" ratio in general the air and the fuel which has to sneak by the rotors since it is not being forced by them with boost.

Don,

You wouldn't have to worry about the air going around the rotors. The rotors wouldn't be static with the clutch disengaged. The Roots-Connersville type lobed impeller blower is also used as a meter in natural gas applications. The natural gas flowing through the impellers turns them over and the impellers are geared to an index to measure gas consumption. The pressure drop across the impellers is very small. If there were a clutch on the front of the engine, the impellers would not be locked in place, but would rotate because of the intake requirements of the engine. I can't answer whether it would be too restrictive or not, but I believe a properly designed clutch would work . . . and I'm sure the Mad Max had one.

Huffer on huffer off ,is real easy for air to get thru.Basically a pipe,since said huffer is not gunna sit on top of intake,none of the oem style on off huffers sit on the intake,thats for the movies,the real ones are crank driven.I am not sure of the correct name of this valve is ,but heres how it works. You have a 4 inch pipe with a spring operated door{diverter} which opens under low pressure{no boost}apply the boost and the pressure in the pipe forces the trap door closed which seals the system and you are boosted,cut the boost trap door opens allowing fresh air thru the trap door into the carb.with the boost off there is no draw thru the huffer to worry about.picture a drain trap and a cross over pipe on the top .the top is where fresh air goes in unboosted.hit the boost and the top pipe is sealed via the trap door and then the huffer sucks the air thru the bottom of the the drain{instead of the top} around to the same spot only thru the huffer this time

Originally Posted by shawnlee28

Huffer on huffer off ,is real easy for air to get thru.Basically a pipe,since said huffer is not gunna sit on top of intake,none of the oem style on off huffers sit on the intake,thats for the movies,the real ones are crank driven.I am not sure of the correct name of this valve is ,but heres how it works. You have a 4 inch pipe with a spring operated door{diverter} which opens under low pressure{no boost}apply the boost and the pressure in the pipe forces the trap door closed which seals the system and you are boosted,cut the boost trap door opens allowing fresh air thru the trap door into the carb.with the boost off there is no draw thru the huffer to worry about.picture a drain trap and a cross over pipe on the top .the top is where fresh air goes in unboosted.hit the boost and the top pipe is sealed via the trap door and then the huffer sucks the air thru the bottom of the the drain{instead of the top} around to the same spot only thru the huffer this time

What???OH MY!!!!

sounds cool .like a blower on demand. i really thing it would work crappy. it would be a lot of work to find and make a pulley set up and aE clutch that could take and drive a 3 inch belt and take the shock when in engaged ?? at any speed and deal with the blower mass and if the blower is rotors are lined then it would suck big time to get any air / fuel .i would think it would be very unresponsive with the drive belt not engaged . so i would think it is a mad max only thing

Herre is how it was done in 1918 ,I am sure it can be improved upon.crude picture at best,but this is the crank ,gear,driven set -up.This diagram only shows the on off air flow of said huffer and route

it would be a blow thru