H2AD alternator question

[Dugaru]

We got a screaming good deal on a 2000-hour O-320-H2AD that was recently flying on a 172N. The owner is upgrading to an O-360.

We're going to be running a 14 volt system. The easiest alternators to find online (and there aren't many) seem to be stratospherically expensive. What are the best experimental/automotive/cheap alternators for this application?

I found a thread on this question but it was pretty old, so I figured it was worth harassing everyone again. Many thanks!!

 

[blaplante]

As an RV-6A H2AD owner...
The H2AD alternator bracket hangs down too far to fit the cowling, without a bump out.
The stock plane power bracket for o-320 doesn't directly fit the H2AD mounts. I had to make a plate to adapt the plane power bracket to the engine.

Also, the H2AD rear case interferes with the Van's engine mount, so one tube has to be modified. The shop that makes those mounts knows what to do and modified it for me.

There's a couple other installation glitches.

Generally I'm happy with the engine.

 

[RYOUNG]

We got a screaming good deal on a 2000-hour O-320-H2AD that was recently flying on a 172N. The owner is upgrading to an O-360.

We're going to be running a 14 volt system. The easiest alternators to find online (and there aren't many) seem to be stratospherically expensive. What are the best experimental/automotive/cheap alternators for this application?

I found a thread on this question but it was pretty old, so I figured it was worth harassing everyone again. Many thanks!!

I have the same engine in my RV-3B. I have a B&C 40 amp experimental alternator and crowbar voltage regulator. I have had zero issues. Not cheap but worth it to me.

 

[planenutz]

That screaming good deal might cause you a few screaming nights of frustration. As Blaplante mentions the lower cowling will most likely need to be modified with a bump so that it clears the alternator, regardless which one you use. Even with the standard Vans 40A alternator it still requires additional clearance.

Blaplante is also correct when he states you will need to modify the engine mount top brace in order to fit the engine into the mount - which will require you to cut that top tube out and weld in a new piece.

The stock Vans Baffle Kit will not fit the H2AD and you'll need to modify most parts.

You will need to cut the top engine cowling and place bumps on top to clear the two bosses at the frount where the fuel pump bolts on (front left) as the engine hits the cowling at this point.

You will not be able to leave the engine lifting eyes on the engine when fitting the cowling. No great drama there, but whenever you need to remove the engine for some reason you will need to remember where you left those lifting eyes so you can reinstall them. You might laugh - but in 15 years time I bet you won't remember where you left them.

The cut-out for the oil dipstick is higher up on the top cowling than the location provided for on the standard Vans epoxy cowling. Again, not the end of the world... but more work.

Once you commit to the H2AD you will pretty much need to stay with the H2AD as the cost to change everything over in the future to a different engine model is prohibitive. What I mean by this is that you can (reasonably) easily change between most models of engines without major changes to your firewall forward setup, but the H2AD is different in almost every aspect. All your fuel and oil hoses are different lengths too so you can't buy Vans's firewall forward kit and expect anything to fit.

All of that said, the H2AD is an honest 160 HP engine and as long as you look after it you should be right. Be sure to check that camshaft though - after 2,000 hours its likely to need replacement. The good part here is you can take remove the pushrods and followers from the engine without pulling the cylinders off and inspect the cam lobes.

Good luck with the installation.


Cheers,

 

[blaplante]

I was able to fit the alternator without the lower cowl bump.
Also the baffle kit ... the sides work, but as mentioned above the front and rear need extensive work.

Another issue is cylinders... Lycoming is the only source for cylinder assemblies, and they aren't cheap. For the other 320 there's some competition.

 

[hgerhardt]

What's the deal with the H2AD alternator boss? Does it have the same hole pattern as 'standard' engines, just farther away from the crankshaft centerline, or is the bolt pattern different too, whether that's different fore-aft, or hole spacing also?

 

[blaplante]

What's the deal with the H2AD alternator boss? Does it have the same hole pattern as 'standard' engines, just farther away from the crankshaft centerline, or is the bolt pattern different too, whether that's different fore-aft, or hole spacing also?

I don't recall exactly, but I do recall the hole spacing is different and I think was further aft. What I did was make a steel plate that attached to the h2ad bosses (attached with countersunk screws) and bolted the plane power bracket to that plate. I think I was able to use one of the holes in common. Then attach the link to the starter as per usual.

I had bought the proper h2ad original Cessna bracket, which hung the alternator WAY to low.

These days, with lower electrical loads, the 20amp vacuum pad mounted alternator might be an option.