Help Support Homebuilt Aircraft & Kit Plane Forum:

Pops

Well-Known Member
HBA Supporter
Log Member
What I am finding for information so far is saying the VW heads are good for around 200 flight hrs, does this sound about right?

So if you invest in an extra set of heads when you build the engine, to insure they are all matched, it will likely be many years before you actually need them (25hrs to 50hrs a year is typically a lot). It will be an effort to keep them from corroding in that amount of time. What do you do, keep them submerged in a container of oil?

So only wooden props? Has anyone had any success with other kinds of props, or it is just the way it is?
Wooden props only except for the Revmaster engine.

Vigilant1

Well-Known Member
What I am finding for information so far is saying the VW heads are good for around 200 flight hrs, does this sound about right?
It is highly variable, and the main factor is heat. High CHTs lead to cracking (esp in heads with large valves or dual plugs) and erosion of the exhaust valves or exhaust valve seats. I imagine if a head was kept below 350 degrees all the time (e.g. in a 1600cc stock engine) that the heads might last a very long time. In the Sonex community (2180cc engines, typically 7:1 or 8:1 CR, run at WOT for TO and climbout with pretty good baffling/tin, 375deg or more not uncommon on climbout) I'd guess about 200 hours is typical. By aviation standards, VW parts are dirt cheap. A $500 brand new head includes all valves, valve guides, all springs, new valve seats, freshly bored holes for 2 plugs per cyl, etc. A single new Lycoming exhaust valve is$270.

I don't know how to keep a stored head pristine. Maybe seal it in a mylar bag with an oxygen absorber? A little bit of surface oxidation isn't the end of the world.

So only wooden props? Has anyone had any success with other kinds of props, or it is just the way it is?
The only manufacturer that allows non-wood props is Revmaster. Their engines are even plumbed for the oil passage to allow use of a oil-pressure activated adjustable prop (they used to sell a two-position adjustable prop, too).

Last edited:

Vigilant1

Well-Known Member
I am wondering if it wouldn't be a good idea to run a 2180cc with stock cam and 6 1/2 to 1 compression? You could pull maybe 65hp at a lower RPM than the 1815cc pulls 60hp? Maybe a prop a few inches longer dia. because of the lower RPM? Lower CR, lower RPM's, maybe lower CHT?
Or, just build the 2180cc with 7.0:1 CR and go easy on the throttle--same reduced RPM, reduced CHT as you'd get with a lower CR, but you'd have 75 HP available if you need it. Things happen, and having surplus power to get yourself out of a spot can be a significant safety factor. If you lose all power from one cylinder someday, having 57 HP left would be better than having 45HP.

blane.c

Well-Known Member
HBA Supporter
94mm cylinder x 78.8mm crank approx. = 2180cc (2187)

92mm cylinder x 82mm crank = 2180cc

When you are saying 2180cc engine you are talking about 92mm cylinders and 82mm crank?

Vigilant1

Well-Known Member
94mm cylinder x 78.8mm crank approx. = 2180cc (2187)

92mm cylinder x 82mm crank = 2180cc

When you are saying 2180cc engine you are talking about 92mm cylinders and 82mm crank?
92mm bore, 82mm stroke =the standard 2180cc VW configuration.

pictsidhe

Well-Known Member
Keep it dry and it will last longer than any of us.
Seal the head in a bag with something to absorb moisture. I have taken to using blocks of sheetrock. Bake it in the oven at 230F for a few hours to drive off the water of hydration. You'll see a weight difference. I wrap it in paper to stop dust leaking over everything. I write the normal and dry weights on so I can check it with decent kitchen scales. Rebake if needed. A well sealed bag and you should be able to forget stuff for years.

Well-Known Member
HBA Supporter
Yes, 92 x 82. As you can see from a chart of bore/stroke/displacement, you can put together all kinds of different combinations!

Pops

Well-Known Member
HBA Supporter
Log Member
Or, just build the 2180cc with 7.0:1 CR and go easy on the throttle--same reduced RPM, reduced CHT as you'd get with a lower CR, but you'd have 75 HP available if you need it. Things happen, and having surplus power to get yourself out of a spot can be a significant safety factor. If you lose all power from one cylinder someday, having 57 HP left would be better than having 45HP.
And put it in a light airframe that doesn't required a lot of HP and you have a winner. My SSSC can climb at 600 fpm at the cruise rpm of 2700 , 1200+ ROC at 3150/3200 rpm at WOT. Never seen the CHT's above 290 and cruise at ( see picture).

Attachments

• 56.7 KB Views: 23
Last edited:

blane.c

Well-Known Member
HBA Supporter
Are the cases the same or what cases are the same (1200cc, 1300cc, 1600cc etc.) in respect to the idea that they are going to be machined for bigger cylinders and cranks anyway?

Well-Known Member
HBA Supporter
http://vwparts.aircooled.net/OEM-VW-Magnesium-Engine-Case-043-101-025OE-p/oem-vw-engine-case.htm
This case can be used for 1300cc on up, although there isn't really much reason to build anything less than 1600cc. This same vendor sells them pre-machined for larger sizes, as well:
http://vwparts.aircooled.net/OEM-Magnesium-Super-Case-p/magsupercase.htm

The 1200cc cases are different (with a couple of variations, to boot), and are not available new.

Vigilant1

Well-Known Member
Are the cases the same or what cases are the same (1200cc, 1300cc, 1600cc etc.) in respect to the idea that they are going to be machined for bigger cylinders and cranks anyway?
Also, if you'll be building an engine of 2180cc or larger, beefing up the front (prop) bearing and using something more substantial than a shrink-fit prop hub is generally advised (though some people do believe a shrink-fit prop hub is okay for 2180cc and a significant number of planes are flying that way). If you'll be using a Force One prop-hub and bearing you can buy a case that is already bored for it, as well as being bored for 92 or 94mm cylinders and already clearanced for longer-than-standard stroke. Here's a GPAS page showing these (at the bottom): http://www.greatplainsas.com/scengcase.html

Well-Known Member
HBA Supporter
Oh, and just to be clear, the standard case is for 1300 and 1600cc motors. Cylinders larger than 85.5mm generally require machining the case spigot opening to a larger size.

There are a couple of 87mm and 88mm "slip-in" cylinders that don't require machining the case, but I haven't seen them used in aircraft. My own opinion is that if you are going to bump up displacement from 1600cc, you might as well go to 1835 (92 x 69).

You didn't ask, but we may as well cover this, too. New cylinder heads are generally sized for 85.5mm barrels. Heads will need to be machined to open them up for larger sizes.

Vigilant1

Well-Known Member
And put it in a light airframe that doesn't required a lot of HP and you have a winner. My SSSC can climb at 600 fpm at the cruise rpm of 2700 , 1200+ ROC at 3150/3200 rpm at WOT. Never seen the CHT's above 290 and cruise at ( see picture).
That's a head that should last a looong time.
Yes, a light airframe works great. I'd guess a heavier plane could be similarly easy on the engine >if< it had a generous wingspan (to generate lift and ability to climb with a smaller induced drag penalty) and was relatively "clean" (to reduce profile drag, important in cruise). It's amazing how little power some motorgliders need, even the heavy ones.

HBA Supporter
Thank you

Pops

Well-Known Member
HBA Supporter
Log Member
The 1300 case is like the 1500-1600 case except the holes for the jugs are for the 77 mm pistons and jugs that is the same size of the 1200 cc, 40 HP. They will have to machined to fit the larger dia 1500-1600 pistons and jugs. Also the 1300 heads are the same as the 1500-1600 except for the smaller bore for the 77mm pistons and jugs, and the valves are smaller size as the 1200 cc, 40 HP. The 1300 cc, 50 HP engine was just sold in the U.S. for the year 1966.

http://vwengineconversion.com/index.php?id=hvx-mods
http://zoomaviation.com/programs/vw_engine_specs_&_formulas/

HBA Supporter
Thank you

blane.c

Well-Known Member
HBA Supporter
So if you should buy new cases, buy stroker crank, buy piston/rods/cylinder sets, buy new cam/lifters, buy new ignition. There isn't much you don't buy new outright? Maybe find a set of single port heads to machine and rebuild?

So what's the use of buying used engine? Is it for the sheet metal (providing you know what tin you need)? Rocker covers? Is it the little ancillary items you are trying to get?

Pops

Well-Known Member
HBA Supporter
Log Member
So if you should buy new cases, buy stroker crank, buy piston/rods/cylinder sets, buy new cam/lifters, buy new ignition. There isn't much you don't buy new outright? Maybe find a set of single port heads to machine and rebuild?

So what's the use of buying used engine? Is it for the sheet metal (providing you know what tin you need)? Rocker covers? Is it the little ancillary items you are trying to get?
Who said buy a used engine? Build from new parts, but there is a lot of new junk parts for VW's out there at the VW hotrod part stores. If you buy the new parts from Great Plains or Hummel you will be getting the better quality parts.

blane.c

Well-Known Member
HBA Supporter
Who said buy a used engine? Build from new parts, but there is a lot of new junk parts for VW's out there at the VW hotrod part stores. If you buy the new parts from Great Plains or Hummel you will be getting the better quality parts.
When you started the thread you show two engines you got for like 25\$ a-piece, which kinda' sets the tone that you use them (whether you do or not) because you lead with them (dance with the one that brought you).

blane.c

Well-Known Member
HBA Supporter
Do you buy stuff like dipsticks/tubes, rocker cover bails etc. or do you recycle that stuff?