2nd crank keyways for blower engines

[SupStk]

Oh Yeah Bill thanks for the tip... haven't tried the carbide woodruff cutter yet. When it met a hard crank, the HS cutter lasted about 2 revolutions before it gave up.

[Ron C.]

What is necessary for additional keys and keyways for the centrifugal blowers and is that any different than when using an all out roots type blower like on a top alcohol dragster?

Your original question above, I've been flogging a F3R ProCharger on a 565 Big Chief all out dragster application. The centrifical is much more efficient than the roots type blowers and require considerable less hp to drive. Our centrifical is mounted directly in front of the engine and is crank/gear driven using one of The SuperCharger Stores drive units. After discussions with ATI on the drive hub, we installed a 1/4 and 3/16 key way. On the dyno we have made "easly" 1900hp on gasoline (C-16) and no intercooler at only 28 psi.
This blow thru carb deal is going to catch on big.....in my opinion.

Personally, I'm having a problem transfering the engine from the dyno to the race track. After lifting the intake system off "none voluntary" the car several times in track testing, I think I have to much area volume between the carbs and intake valves to control the dynamics under race track conditions.

Away, hope the info helps........

[bill jones]

-are you increasing the intake valve spring pressure to compensate the 28# of boost times the valves square inch area?

[Ron C.]

Didn't have to in this case. I ran the motor as a 632 nitrous motor before. Just shortened the crank a half inch and redesigned the pistons. But the cam is significantly less harsh than the nitrous cam I ran before. Still running the same springs, which are a little over kill. But to much is better than not enough.

[bill jones]

-what did you mean with your comment about lifting the manifold?
-I would take that to mean you had some sort of explosion in the intake tract.
-Assuning that, what rpm did this lifting of the manifold happen?
-What makes you think there's too much volume?

[airflowdevelop]

Ron,
sounds like you are coughing out the intake. This is fairly common on blow thru installs. The volume is a non-issue. Generally on a SC application, the more plenum the better.

Why not try EFI? I have been around the blow thru centrifigual stuff for a long time...and have never seen it work perfectly...The motor will be a completely different animal at the track, then on the dyno.

Bill,
Most guys seem to get ~100 to cut the hub and 60-70 to cut the crank. But...like you I have not been very impressed by the quality of work. I just received a pair of double keyed balancers from a high dollar company. It looks like they cut it with a bastard file stuck to the end of a sawzall. Spinning the hub on the bigger centrifigual stuff (specifically SBC) is common.

Thanks
Dennis

[bill jones]

-I don't have a dividing head yet so it takes a slightly different method.
--------------------------------
-I charged this guy $50 to cut the keyway in the 350 cast crank snout and $20 to slot the hub.
-I would probably charge $100 to cut the keyway groove in a 60rockwell crank snout.

[RRBD]

A rotary table is handy, but totally unnecessay for cutting an extra keyway.
Heres how I would do it:
Set the crank up in v-blocks on the main bearing journals((buy the cast iron v-blocks(cheap) and key them to the table so they are dailed in when you set them in the t-slots))

Put your Woodruff cutter in the spindle and touch off the crankshaft & move the cutter down 1/2 the diameter of the crank snout(1" dia crank snout moove .500) plus 1/2 the width of the Woodruff cutter (3/16" cutter move .09375)

Now, crank your machine close to the stock keyway and rotate the crank while turning your handwheels until the cutter will go nicely into the keyway. Do not move your "z"-axis during all of this.
Now you can lightly clamp the crank down and move the cutter out of the slot and go to the other side and cut the keyway.

As far as making a broaching sleeve for the hub, turn it to desired size, and centerdrill/drill one or two holes the same size as the keyway through the sleeve and then mill your slot for the broach. When you are done, drive in a couple of short roll pins to use for alignment. This is all vice work, you should always avoid having to do set ups where possible.

Another tip is to permanently attach stout risers to the V-blocks, so you can straddle an opened vice with your crankshaft. This will eliminate tearing down the vise set up as often...........

Just my two cents.

Scott

[bill jones]

-basically I do the same exact thing with one extra step.
-once I get the woodruff key set into the original keyway and I snug down the crank, double check the math from the top of the snouty down to 1/2 way---I make a "jack" that sits on the mill table and I install a crowned headed bolt and I adjust that up against the bottom of the rod journal.
-Then when I rotate the crank I move this jack to the other side and use it as stop for the rod journal.

[SupStk]

I would consider Scott's method sound. Clamping the crank in V-blocks is a better setup and faster than using the dividing head. My reference to the dividing head was for slotting the broaching hub. In my opinion rotating the crank takes more time and increases the risk for error. I'd rather just come in from the other side. My 2 cents too.

[Ron C.]

[quote="airflowdevelop"]Ron,
sounds like you are coughing out the intake. This is fairly common on blow thru installs. The volume is a non-issue. Generally on a SC application, the more plenum the better.

Why not try EFI? I have been around the blow thru centrifigual stuff for a long time...and have never seen it work perfectly...The motor will be a completely different animal at the track, then on the dyno.

.Yes, it was a back fire. EFI would be great if my budget could handle it. But like most racers it's not an option currently.

To much plenum is just a thought reasoning. No absolute proof. Still trying to work out some issues. In this case it did not like being back pedeled (on & off the throttle to correct the car). My thought is, this must send a shock wave disrupting the fuel curve matching the air curve. The fuel pressure is related to the boost pressure which the fuel regulator manages. That fuel curve one would think would lag behind in such a quick change in air stream. The larger volume between the carb and valve would seem to be more difficult to control or maintain proper mixture. I'm actually running a CFE tunnel sheet metal manifold/duel carb. It worked fine on the 632 nitrous application, but I'm getting to think smaller would be easier to manage the dynamics going on in there.
That's my thought's anyway.....

[RMFheaders]

The reason its backfiring is when you blow through a carburator. There
is a point where nothing is moving.Its when the carb.makes the transition from vacuum to pressure.At first the fuel is being drawn in from vacuum.as it starts getting boost the manifold gos from having a vacuum to having manifold pressure.But in the middle of the two,For a micro sec.it becomes inert.Which means no fuel is being sucked in by the vacuum or siphoned in from the boost. The only way to get rid of the stumble is to be fat on the bottom.Then it will carrie it through with out popping back .I have messed with lots of ski race boats and offshore boats that would blow the intercooler right into the lake.Making the plenum smaller will just make a smaller bomb. EFI is the way to go .
And when you peddle it ,If you have a blow off it goes past the neutral spot more than once.thats when she leans out the most.

[Ron C.]

Thanks for the comments and suggestions. I certainly appreciate them. Were continuing to work on some ideas. And EFI might be an option for next year.