# Building a VW Aero-Engine

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#### Chucker

##### Member
Supporting Member
Pops, just an idea...

Since the exhaust valves are somewhat of a limiting factor in the life of our VW engines and because heat kills... I'm looking at a way to get more cool oil directly to those little critters.

Whether we have a dual relief case or a single relief case, we all have the same oil control valve at the pulley end of our engines. When the pressure is low, that piston stays closed and all the oil passes through the oil cooler gallery and oil cooler then back down to the main gallery. When the pressure is high enough, the control valve piston opens and the oil begins to bypass the oil cooler gallery directly to the main gallery. If the pressure is really high, the control valve in a single relief becomes a relief valve and dumps oil back to the sump. In a dual relief case, the pressure relief valve (on the flywheel side) opens and accomplishes the same job. Of course you know all this...I'm just getting everyone onboard before introducing my idea.

My plan is to tap off of the main gallery plug below the oil control piston and route that oil to drippers or sprayers above the exhaust valves. When the revs are low and/or the oil pressure is low, the oil control piston is closed and no oil is diverted. At high RPM we get more oil pressure and the piston begins to open. That is when we start to heat up the exhaust valves and could use more cooling. One might be concerned with losing oil pressure in the main gallery. However, the piston opening depends on pressure above the piston, which means pressure in the upper gallery, which means pressure in the main gallery. However, all the excess oil (everyone has a 21mm pump or bigger, right?), rather than being dumped back into the sump, would go do some good by gathering heat from the exhaust valves.

Thoughts?

#### Flyguyeddy

##### Well-Known Member
Supporting Member
Pops, just an idea...

Since the exhaust valves are somewhat of a limiting factor in the life of our VW engines and because heat kills... I'm looking at a way to get more cool oil directly to those little critters.

Whether we have a dual relief case or a single relief case, we all have the same oil control valve at the pulley end of our engines. When the pressure is low, that piston stays closed and all the oil passes through the oil cooler gallery and oil cooler then back down to the main gallery. When the pressure is high enough, the control valve piston opens and the oil begins to bypass the oil cooler gallery directly to the main gallery. If the pressure is really high, the control valve in a single relief becomes a relief valve and dumps oil back to the sump. In a dual relief case, the pressure relief valve (on the flywheel side) opens and accomplishes the same job. Of course you know all this...I'm just getting everyone onboard before introducing my idea.

My plan is to tap off of the main gallery plug below the oil control piston and route that oil to drippers or sprayers above the exhaust valves. When the revs are low and/or the oil pressure is low, the oil control piston is closed and no oil is diverted. At high RPM we get more oil pressure and the piston begins to open. That is when we start to heat up the exhaust valves and could use more cooling. One might be concerned with losing oil pressure in the main gallery. However, the piston opening depends on pressure above the piston, which means pressure in the upper gallery, which means pressure in the main gallery. However, all the excess oil (everyone has a 21mm pump or bigger, right?), rather than being dumped back into the sump, would go do some good by gathering heat from the exhaust valves.

Thoughts?

Isnt this basically what the hvx mods do?

#### Pops

##### Well-Known Member
Supporting Member
Isnt this basically what the hvx mods do?
Yes , doing the hvx mods gets extra oil to the exhaust valve guides and valve stems helping with the cooling. Also the best valve cover pan to use for cooling is the stock VW black thin stamped steel covers and also the the stock rolled steel black push rod tubes. Just like saving weight, all the little details in cooling add up.
My little 1835 tends to run to cool if the OAT's are below 70 deg F. And on a 100 deg day I can climb as long as I want at WOT and CHT's don't get hot.

#### Chucker

##### Member
Supporting Member
Looking at the size of the passageways in the rockers and the swivel-ball feet, I don't see how you could get a significant quantity of oil to the valve stems. But if it keeps the exhaust valves cool, the HVX mods are definitely cleaner than exterior plumbing. One of the reasons I use a top mount cooler is to minimize any pressurized oil outside the case.

I'm still looking at options for feeding a manifold heater (like Pop's) with low pressure oil. I thought about tapping off the main gallery (as suggested above) with the return oil going to a valve cover but there would be zero flow at the time you need the most heat (idle descent).

#### Vigilant1

##### Well-Known Member
Supporting Member
FWIW, I recall reading many years ago about someone who fitted windows to the valve covers so he could see what was happening inside regarding the oil. If I recall correctly, one side remained more than 1/2 full all the time with oil, the other side drained well. IIRC, the theory was that oil was getting pushed /splashed back up into that side via the pushrod tubes.

#### Pops

##### Well-Known Member
Supporting Member
Bob Hoovers mods takes care of one side of the heads getting more oil than the other.

#### Chucker

##### Member
Supporting Member
FWIW, I recall reading many years ago about someone who fitted windows to the valve covers so he could see what was happening inside regarding the oil. If I recall correctly, one side remained more than 1/2 full all the time with oil, the other side drained well. IIRC, the theory was that oil was getting pushed /splashed back up into that side via the pushrod tubes.
Wish I could find that thread again....

#### karmarepair

##### Well-Known Member
Supporting Member
Long discussion about venting valve covers, which includes links to pictures looking into the valve covers.

We don't run at 5000 RPM. IF you MUST vent, make sure it's at the TOP of the valve cover.

Me, I added stainless steel pot scrubbers, and a baffle plate to me AeroVee. Which hasn't flown yet.

A few posts by the Sensei:

#### TFF

##### Well-Known Member
Alfa Romeos and Volvos, 80s and earlier, have wire “scrubbers “ from the factory, buy in the vent lines from the valve covers. Air oil separators. The only issue I have is making sure there isn’t a small piece that can come loose. Airplanes you have to be that much more careful. I don’t know about stuffing them inside the crank case.

#### dave wolfe

##### Well-Known Member
Supporting Member
If I recall correctly, the engine that was filling the head up with oil was consistent with using too big of an oil pump. The extra oil ends up getting shot up a pushrod cover.

#### Pops

##### Well-Known Member
Supporting Member
Reading Bob Hoover's blog on Crankcase Ventilation I see he is venting the crankcase to the airbox. I vent mine to between the airbox and carb intake. Same thing. I had never noticed that before and have read everything about VW's that he wrote. Thanks.

#### Marc W

##### Well-Known Member
Getting ready to order rod and main bearings for my 2180. Do Pops or any of the other experienced VW mechanics have any preference for a bearing brand?

#### Pops

##### Well-Known Member
Supporting Member
I haven't seen any difference in brands of bearing. The last several sets of bearings I used was Silverline. Seems as good as others.
Maybe others has seen some difference ?

#### Marc W

##### Well-Known Member
Thanks. The car guys seem to have preferences but we aren't running at high rpm either.

Looks like main bearing sets are scarce! Several suppliers out of stock. Somebody I looked at had Silverline in stock.

#### Vigilant1

##### Well-Known Member
Supporting Member
Okay, here's something:

A 1:4 scale VW Type 1 plastic engine model. It has 200 parts, it takes a couple of hours to build. 3 AAA batteries turn the crankshaft (you can see the pistons etc go) and LED 'spark plugs' blink at the right time.

See video of it 'running' (the model has a sound module to make the classic VW running music).

. $186 each, and they are sold out. Last edited: #### Vigilant1 ##### Well-Known Member Supporting Member Would be good for 0.36hp And there'd be somebody modifying the lobes on that toothpick camshaft, smoothing out the ports, and shaving that plastic head to make 0.38hp. #### Kamcoman77 ##### Well-Known Member Supporting Member VW Darrin recommends Silverline because the 2-piece, center bearing is steel backed and tends to support the case web a little better than the all aluminum brands. #### fly2kads ##### Well-Known Member Supporting Member Okay, here's something: View attachment 130909 A 1:4 scale VW Type 1 plastic engine model. It has 200 parts, it takes a couple of hours to build. 3 AAA batteries turn the crankshaft (you can see the pistons etc go) and LED 'spark plugs' blink at the right time. See video of it 'running' (the model has a sound module to make the classic VW running music. .$186 each, and they are sold out.
I have had one of these on my wishlist for a while now. I haven't pulled the trigger on it because it's pretty pricey. Hmmm, I do have a birthday coming up....

#### Bill Volcko

##### Active Member
Supporting Member
In looking at the pictures on Hoover's blog, crankcase haves specifically, I see zero porosity on the castings. I have an Aerovee from Sonex, made in Brazil, aluminum, VW branded, lots of porosity. At least i think it's porosity in the casting. Is this normal?

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