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Half VW build costs?

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Topaz

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How much machining can you do and how much do you have to buy?
Yeah, that's the big question. Half-VW's come in all iterations from plans to cut down your own 4-cyl engine to bolt-together kits. Which one you get depends on your skill with the necessary machine tools (and your access to them).
 

StarJar

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Also ,although about 20 lbs. heavier, there is the "better half" option, where you use the full case, but cut down the heads, cam, and crank.
For either way, be real carefull that the 1/2 crank is professionally done, with someone experienced with "half vw's". It's more than just counterwighted and balanced, there is a special dyanmic involved, that takes extra work. I paid 400 about 10 years ago, for the crank, but that thing ran beautifully.
Also a stock Harley Davidson Carberater worked beautifully, for me.
 
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revkev6

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It's definitely not a cheap option but has anyone ever built a 84mm stroke by 101.6mm bore half vw?? buy a race engine to use as a base for an aircraft engine? you'd get somewhere in the neighborhood of 1350+cc out of a two cylinder. put some shims on the barrels to drop compression and a suitable camshaft. based on other two cylinder manufacturer hp claims (hp per cube) you would be looking at 45hp from a half vw. 90hp if you kept it whole! (these engines made ~300hp at 7500rpm in race trim) they can be had with all kinds of bearing options as well. type 4 mains, sbc rods etc.
 

StarJar

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how much HP did you get with it?
do you still have the plans?
Don't remember the size, but it was a strong engine. You can get some info here www.betterhalfvw.com

revkev6 said:
It's definitely not a cheap option but has anyone ever built a 84mm stroke by 101.6mm bore half vw?? buy a race engine to use as a base for an aircraft engine? you'd get somewhere in the neighborhood of 1350+cc out of a two cylinder. put some shims on the barrels to drop compression and a suitable camshaft. based on other two cylinder manufacturer hp claims (hp per cube) you would be looking at 45hp from a half vw. 90hp if you kept it whole! (these engines made ~300hp at 7500rpm in race trim) they can be had with all kinds of bearing options as well. type 4 mains, sbc rods etc.
This might work well with the full case I mentioned above, because the full case holds more oil, and also disipates more heat.
Also it might work good, since your going for torque, and not high rpm, so you won't be stressing the parts to bad. Plus the slip on hub can handle 45 horses no problem.
 
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revkev6

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the race cases are not stock vw units. they use a modified cylinder bolt pattern in the case to handle the size of a 101.6mm cylinder. they can be had in dry or wet sump (full aerobatic half vw?? lol) almost all of them are 100% aluminum although I did own a 100% magnesium version of a scat case. the stock vw cases are some sort of aluminum/magnesium alloy. with the 100% aluminum cases I think there would be a rather significant weight penalty from keeping a full case twin.

none of these parts are cheap if you want to buy new, the heads bare heads go for $1500 a pair and the cases are about the same. this is why I suggested buying a used complete race motor. cheaper that way, as long as everything is in good shape.
 

Pops

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I built a 1/2 VW a few years ago. If I were to do it again, I would go with the full case 1/2 VW and not cut the case as I did. I bought the counter weights from Scott and welded on and balanced the crank. If You can do all the machine work yourself, great, if you have to hire the machine work, I would just buy the engine from Scott at Hummel. I used to go to the Hummel fly-in's when Scott lived in Ohio, and Scott is a honest stand-up man.
A friend has over a 1K hours on his 1/2 VW in a Mini-Max that he built himself. Half VW's are great little engines.

Dan
 

nheistand

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I am building a low cost half VW at this time. I am using a rebuilt case from WestCoastCore that is bored for 94mm and clearanced for an 82mm stroker. This case is only $515. I am using a new dual port head with 94mm bore from TexasAirCooled that will be cut in two to make two half heads. This head is $236. I took a chrome valve cover and cut it in half to make two half valve covers. I used PVC board and sheet metal screws to fix the cut end of the valve cover. Then silicone sealer inside to prevent leakage. I cut the valve cover bale in half and welded the two pieces back together with my small arc welder.

My piston and cylinder set is 94mm stroker from TexasAirCooled and is $96 (set of 4 divide by 2). My crankshaft is 82mm forged counterweighted stroker from ebay for $234. Rods are rebuilt German from gex for $41 (set of 4 divide by 2). Camshaft is new stock ebay $70. Lifters 4 for $21 TexasAirCooled. Oil pump $30 TexasAirCooled. Pushrods $19 ebay. Pushrod tubes $11 TexasAirCooled.

Etc., Etc. for a grand total of around $1900 for a 82mm by 94mm big bore stroker that will generate about 40hp at 3600rpm. This is about the limit for being able to control the heat at the head and cylinder.

My ignition is a 009 type distributor with electronic ignition inside and a 3 ohm dual output Harley Davidson Sportster coil. So I will run a small sealed lead/acid battery (12v 5ah $20). I am keeping it as simple and low cost as possible without sacrificing reliability. Keeping the full case instead of cutting it is only about a 5 lb penalty since magnesium is very light. I expect this engine to have a 1000 hour TBO if well maintained. Inside the engine the crank is cut, the cam is cut, and oil passages plugged as needed. No oil cooler is used since the full case makes a good oil cooler. 1/8 in aluminum plate for block off plates for all the extra holes in the engine case. Crankcase breather is a PCV valve installed in each valve cover.

The other engine I would like to build is a 1600cc rebuilt long block for about $1460 where I would cut and counterweight the crank then add a small turbo charger to get the 40hp. The price and complexity of this will probably make the big bore stroker preffered.

Norm Heistand my .02
 

sotaro

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Thank you for your detailed post. How is the build going? I am curious about your last paragraph. Do you mean buy a 1600 cc long block and after halving it, turbo to get to 40 hp with 800 cc? Turbocharging is being discussed on another half vw/industrial v twin thread now. Have you had any more thoughts on how to keep the heads alive with the 6-8 psi of boost needed to increase power by 40%? Thanks
 
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