1/2 VW conversions

[flydog]

Hey all
  Have the Milholland plans and just ordered the Great Plains conversion plans.
How does the Great Plains conversion differ (or the same ) compared to the Cassler/Hummel conversion?
Or the plans by Wm. J. Spring in Canada?

 Tnx
 Phil

[Steve]

Each of the plans offer a conversion perspective and some unique elements or emphasis... You cannot learn too much about the conversion... Some just leave it to the Pro's and buy a ready to go Casler Hummel engine... There are what I call 3 levels of conversion - V1 (buy a crank from DeMello plus all the reclaimed and new parts you need for a build - works best on the 69x92 engine) V2 buy or build from parts supplied by GPAS or Scott Casler/Hummel (use the advanced balance method developed by Hummel) - V3 buy reciprocating bottom end assembly from Joe Engelman or Chris Kleman (this uses the Scat or Empi counter-weighted cranks with Chevy journals)... Make the list of parts offered in Joe Engelman's shop notes (oil filter & motor mount bolts for sure) found in his sub directory in the Yahoo Group Files -  access that info here:

[flydog]

Thanks Steve for the info on where people source parts. I was looking for the differences, or similarities, in the conversions( i.e. are Cassler and Spring plans the same so no need to buy both?) Millholand machines the cut end of the crank to controll end play and Spring uses the 3rd(?) bearing for end play controll, etc. How are the cut case versions different?
  Phil

[Steve]

Phil:
The best plans ever for the cut-case 1/2 VW were put out by Bill Bronson (an engineer that could write for the novice converter with a willingness for [work])... The plans cost $75 were worth every penny of it... Bill's website is down and I hope he is Ok... Here's where you might contact him by snail mail:
"Bronson, Bill of 2540 Hillcrest, High Ridge, Missouri 63049, phone (314) 677-4047, sells narrative and plans for building the "Smooth1/2 VW". He also answers questions about 1/2 VW conversions in the "Power On" section of the EAA Sport Pilot & Light Sport Aircraft magazine (SP), which was called the EAA Experimenter magazine prior to the 4/04 issue. SP4/94 and classified ads in SP1994-present. "

Re; The Spring plans you can contact me direct and for your question, at the time Bill Spring did his plans the Hummel plans were a text nightmare and have been significantly improved since by Scott Casler... It's been a while but IIRC the Hummel & Spring plans of that vintage tell the same story for the most part... I have not seen the plans Scott Casler puts out these days but am sure they have been constantly improved - I do wonder what he is doing with the "V3 crank process" Bronson had embraced it before his site went silent...

Good Luck with your venture,
Steve

[flydog]

Got my Great Plains, and Casller plans on the same day right after Xmas. ; )
Thinking about ordering a MOFOCO head. Which one is best for our purpose ?
Big diameter exaughtst is not good for "normal" RPMs right? So do I avoid the O50 head?not that I can afford it.
Would I even notice a difference between the O40 and O41?
O42?

[flydog]

Forgot to ask.
I see many 1.2 VW with a 92 bore. Bigger is better.
Why is the 94 not more common?

[Sam Buchanan]

Forgot to ask.
I see many 1.2 VW with a 92 bore. Bigger is better.
Why is the 94 not more common?

It's more common than it used to be but probably only on the Hummel 45hp engine which has only been available for a few years. I don't know that bigger is always better. To get the full benefit of the 94 bore you need a huge stroker crank like the 86 in the 45hp. The combination of 94 bore and 86 stroke take the VW out to its extreme with the cylinder bore practically touching the cylinder studs and the case clearanced to within a few millimeters of punching a hole. This is just a bit more radical and more $$$'s than most 1/2 VW builders have wanted to go in the past. We're talking the equivalent of a 2400cc four cylinder which is double the size of the old 40hp Beetle engine.

Another factor may be that aluminum 94 cylinders have not been common until recently. I've heard the huge iron cylinders have issues with heat dissipation.

[Steve]

Read your plans for the head recommendations - the MOFOCO heads are good products - I have a new Brazilian 041 that is a junk product - I used Mexican 043 heads (more meat for dual plugs) seen here:  LE #33 Heads



Try and look at case & heads that have been sized for the 94cc jugs - you may settle on 92's...

[leshoman]

I am running the cast iron 94mm cyl with a scoop to move air down the back side.  Have flown on 105 plus days with no problems

[Dan_]

94s in the cars would go square on you if you got them too hot...  (go out of round where the case studs are)  Same for 4 banger airplanes.

92s leave more meat on the cylinders and the case.   92s will of course do the same, but are said to leave a little more margin..

You must use case savers,  there is scant any aluminum left where the case savers are after the cylinder bores are opened up .  

Don't run it hot, and check the torque on the case studs when you do the 25 hr maintenance...

94s have been available in the long (stroker version) for a long time now.  I think the nickies have always been stroker ready... This makes shim plates unnecessary when setting the deck height.  You just calculate the deck height you need for the compression ratio you desire and machine the jug down to that length...

[flydog]

Well, right or wrong I ordered the Mofoco 041 head today. Added stainless valves and a 94 bore.
Now I'm supposed to wait patiently? Ha !

Next question. Case savers....just VWspeak for Helicoil ?

[Dan_]

Same idea.  Special made though...  Read this

[nheistand]

I am using the plans from Simplex Aero. I am doing the full case conversion. With the intake, exhaust, ignition, and fuel pump my engine weighs about 90 lb. The half heads are made from a dual port head cut in half to make two half heads. I used a bolt tapped into the end of the rocker shaft to set in a groove on the head cover flange. So I have a single rocker shaft mount stud. I added a piece of aluminum stock to the side of the half head using #10 bolts and epoxy. Then I tapped to install a second stud so my intake port is the original port and has the same stud configuration as the exhaust ports.

I have the 94mm cylinders and an 82mm stroker crank. I did the main bearings per the plans. I had to grind a little metal off the corner of the rods to clear the camshaft. This might be avoided by using the Chevy rods or having the cam machined down a little. I use two exhaust stubs as my intake manifold and have a single Mikuni carb on the top of the engine. I am using .180 of shims under the cylinders to get about 7.4 to 1 compression to burn auto gas. The 94 x 82 is about the maximum this engine can do. I ordered the engine case with the bore and stroke machining already done. I expect about 40hp from this engine. My engine will be running real soon now. 

Norm Heistand  my .02