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H.A.P.I.

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Chucker

Well-Known Member
Supporting Member
Joined
Nov 1, 2013
Messages
894
Location
Prescott Valley
Does anyone have any history on H.A.P.I. engines or the company that built them?

I have an 1835 HAPI engine (built in Feb. 1983) that I bought 5 years ago just because I wanted the accessory case. HAPI used the Continental mounting system and that is exactly what my project airframe was designed to accept. I have no history on this particular engine but it was obviously mounted and running at some point. Now that I am finally digging into this engine, I find myself impressed with the quality.

I'm just wondering what happened to the company and if they had any chronic problems with their engines and/or components. This engine sports a Slick 4216 Magneto and electronic secondary ignition. It has an aluminum flywheel with a steel starter ring. It contains a 12-pole rotor and stator combination. The dual ignition goes to single-port heads and the engine uses a side-draft Zenith carb to meter fuel.

ATB,
Chucker
 
Does anyone have any history on H.A.P.I. engines or the company that built them?

I have an 1835 HAPI engine (built in Feb. 1983) that I bought 5 years ago just because I wanted the accessory case. HAPI used the Continental mounting system and that is exactly what my project airframe was designed to accept. I have no history on this particular engine but it was obviously mounted and running at some point. Now that I am finally digging into this engine, I find myself impressed with the quality.

I'm just wondering what happened to the company and if they had any chronic problems with their engines and/or components. This engine sports a Slick 4216 Magneto and electronic secondary ignition. It has an aluminum flywheel with a steel starter ring. It contains a 12-pole rotor and stator combination. The dual ignition goes to single-port heads and the engine uses a side-draft Zenith carb to meter fuel.

ATB,
Chucker
Hi chucker
I have a Hapi 2165 cc engie on my sonerai 2 LT. Mine has dual electronic ignition and 2 plug modified skat individual heads with 82 HP. I had to replace the flywheel and alternator with a Great Planes steel flywheel and alternator. The Hapi alternator did not have clrarance enough and the stator and rotor bound up and stalled the engine luckly on the ground while doing runups. When Hapi went to larger cc engines they had crank shafts break. They recalled the engines sent out a retrofit package with heavier cranks and larger #4 main bearing. I have one of those tetrofited engines. Hapi later sold out to Mosler in early 1990s.Mosler stopped supporting the engines a few years later.
Sonerai-1369Z
 
Chucker,

I got a HAPI 1835 motor with the S2L project I acquired last August which forced me to do a little research on the company. HAPI was founded by Rex Taylor (I believe in the late 1970s) and was one of the better VW aero conversions in the early to mid 1980s. I have an original log book for a HAPI 1835 that was signed by Patrick Taylor. Patrick was Rex's son and built many of the customer engines. Rex wrote a good book on VW aero conversions "How to Build a Reliable VW Aero Engine" (I was lucky enough to get a copy when I purchased my S2 project) that is informative and still relevant today. Rex also wrote a 10 part series on aero VW conversions for Sport Aviation which ran in the December 1979 through September 1980 issues.

AFAIK, all of the early factory build HAPIs used a 3 degree tapered bolt on prop flange on a forged VW 69mm crank that had the nose turned to a 3 degree taper. A large bolt holds the flange to the crank and is secured by a cotter pin. Rex claimed the 3 degree taper flange was superior to the press fit flange of that era because itwas much easier to remove (simple gear puller) without damaging anything and much less prone to slip.

The caveat for both press fit and 3 degree flange hub conversions on stock crankcases is that they should only be used with simple, light weight fixed pitch wooden props. Composite props, ground adjustable wooden props and metal props all put too much stress on the stock VW crankcase and its small 4th bearing. HAPI and Rex ran into difficulties (late 1980s?) when they introduced a 2L+ stroker motor without an additional 5th bearing. Numerous crank failures on stroker motors essentially put HAPI out of business. 78-82mm cranks, even with a wood prop, don't seem to last in a stock 4 bearing crankcase. All modern stroker VW aero engines seem to use the Force One type 5th bearing hub conversion or a variant thereof.

That nothwithstanding, the early 1835cc and lower displacement HAPI built motors seem to be pretty stout: New crankcases, magafluxed OEM VW forged 69mm cranks (limited to .010 under), forged rods, forged aftermarket pistons, Seal power rings, fully internally balanced, aftermarket high volume, high pressure oil pump and professionally assembled. HAPI deliberately used single intake port head vs. dual port heads to ease intake plumbing on aircraft. It's uncertain if dual port heads would make more power on a 1835 motor with an aero cam that only runs 3,400 rpm in cruise.

Let me know if you need the wiring diagram or operating instructions for the HAPI secondary dual ignition, I've got it. The Slick 4216 Mag has an impulse coupler to retard timing when starting, the HAPI ignition has fixed timing and is not used when starting the engine. BTW, does your 1835 have a Brazilian case too?

Mitch
 
Thanks, Mitch! Great info.

Yes. My HAPI has the Brazilian case, Slick 4216 magneto, and fixed-timing secondary ignition. I can see that the rods were balanced at both ends and the entire rotating mass was balanced as well...including a cast aluminum flywheel with a steel starter ring. The flywheel also has a cast-in rotor that spins around a 12-pole stator. The whole engine is a work of art....and almost everything seems to be as good as new....apparently very few hours but no history or logs.

I have heard bad things about the HAPI stator/rotor combination. However, comparing notes with another HAPI owner, it seems that there was an older version of stator that used fewer poles and a rotor that was fastened to a steel flywheel. The quality of my flywheel and rotor looks very good and I am tempted to run it as-is.

Good to hear about the taper fit hub. I was going to avoid removing it because I thought it might be a shrink fit. I want to inspect all the bearings and replace the sand seal.

Thanks again for the input.

ATB,
Chucker
 
Chucker,

Sounds like you've got your 1835 mostly apart with the exception of removing the prop flange from the nose of the crank. Did you leave the pistons installed on the rods too? Am I correct in assuming that your engine was assembled with teflon buttons retaining the piston pins vs. circlips? Have you examined the ring package on your pistons yet to see if you have Total Seal gapless compression rings? I'm not sure if HAPI ever put these rings on production 60-2 engines but they are listed as an item for sale on page 29 of the 1984/1985 HAPI catalog. Quite interesting, because this was time period when Total Seal was suggesting putting the gapless ring in the second ring position rather than the first position which they had been advocating since the late 1960s. Attached is a link to a YouTube video where Keith Jones from Total Seal explains why normally aspirated engines should run the gapless ring in the first or top ring position:


BTW, did your 1835 come with a starter? Mine did not, I've got the HAPI pn (20-007) for the 3.5lb Bosch starter they sold but I can't cross reference that to any Bosch or VW listing. When I look at standard VW 1600/Type III starters they all have a solenoid attached to the starter whereas the Bosch unit supplied by HAPI did not have a solenoid attached and was triggered by a firewall mounted 1960's Ford style solenoid.

Mitch
 
Mitch,

The rings are standard....not gapless. The wrist pins were held in with circlips. The starter was a standard Bosch product for VW engines. Here is what I can read from the data plate on my engine:

Sammy Falco
Katy, Texas
Model 602P Serial 3909
Mfr. 2-83 Dry Wt. 158
60 hp 3200 RPM IGN TMG. 28 BTDC
FUEL 92 Oct Min Oil Cap. 2.5 qts.

The 602P might be 602D (Dual Ignition). It is hand written and it is hard to tell. There is no dash between the numbers but I assume that means 60(hp)-2P(model 2 P or D???).

Would love to get my hands on a catalog or some of the literature you have found. Any helpful links would be....well, helpful! Thanks.

Chucker
 
I recently bought a S2 midwing has the same set up as y’all’s hapi 1835 ect no starter I live in north Texas after 5 hrs figured out really quick it didn’t like the Texas heat did fine early morn didn’t like it in the afternoon so I rebuilt it added oil cooler 1.5 oil sump duel port heads and went with the compu-fire dis-lx ignition for the secondary still waiting on the diehl case from GP been using the hapi case to get things going so far so good when it gets done if y’all are interested in the hapi stuff that I have let me know pay the shipping and y’all can have it
Charging system worked when I took it all apart can get pics of the hapi this weekend
 

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Thanks, Mitch! Great info.

Yes. My HAPI has the Brazilian case, Slick 4216 magneto, and fixed-timing secondary ignition. I can see that the rods were balanced at both ends and the entire rotating mass was balanced as well...including a cast aluminum flywheel with a steel starter ring. The flywheel also has a cast-in rotor that spins around a 12-pole stator. The whole engine is a work of art....and almost everything seems to be as good as new....apparently very few hours but no history or logs.

I have heard bad things about the HAPI stator/rotor combination. However, comparing notes with another HAPI owner, it seems that there was an older version of stator that used fewer poles and a rotor that was fastened to a steel flywheel. The quality of my flywheel and rotor looks very good and I am tempted to run it as-is.

Good to hear about the taper fit hub. I was going to avoid removing it because I thought it might be a shrink fit. I want to inspect all the bearings and replace the sand seal.

Thanks again for the input.

ATB,
Chucker
The problem with the Original Hapi Flywheel was the aluminum center would fracture. If you flywheel is aluminum change it out! Steve Bennett made a conversion kit to update with the lightweight GP all Steel flywheel this is what I have. Essentially a Hapi case sandwiched between a GP 2276vw and a Slick 4216 magneto. I had to space the magneto out about 2.5mm and lengthen the clamp blocks. My Starter name plate is attached but I cannot run it down.
 

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Mitch,

The rings are standard....not gapless. The wrist pins were held in with circlips. The starter was a standard Bosch product for VW engines. Here is what I can read from the data plate on my engine:

Sammy Falco
Katy, Texas
Model 602P Serial 3909
Mfr. 2-83 Dry Wt. 158
60 hp 3200 RPM IGN TMG. 28 BTDC
FUEL 92 Oct Min Oil Cap. 2.5 qts.

The 602P might be 602D (Dual Ignition). It is hand written and it is hard to tell. There is no dash between the numbers but I assume that means 60(hp)-2P(model 2 P or D???).

Would love to get my hands on a catalog or some of the literature you have found. Any helpful links would be....well, helpful! Thanks.

Chucker
I have a catalog I was going to give to Robin Taylor this summer. She is the Daughter inlaw of Rex Taylor and was promoting new cases in stock as a 20 year old....
 
Interesting, the starter you have is a Nippondenso (know as "Denso" in the US) from a Japanese vehicle. It also looks like it has an attached solenoid. The Bosch starter HAPI had in the early 1980's catalog (882) and the 84/85 catalog was much smaller, did not have an attached solenoid and weighed only 3.5lbs. In the 84/85 catalog HAPI noted that the Bosch starter was ideal for engines up to 1835cc and that their HI-TORQ II starter (which looks similar to your Nippondenso) was the best choice for high displacement engines. HAPI also noted "Requires minor clearancing of engine case" and listed the weight of the HI_TORQ II at 5.5lbs.

Is Robin Taylor Patrick Taylor's wife?
 
Joe,

Thanks for the PN on the Subby starter. It's under $100 on Amazon but tips the scales at a hefty 8.65lbs. I don't need the power of a gear reduction starter to start my little 1835 so I'll keep looking for the PN for the Bosch 3.5lb starter.

Mitch
 
Interesting, the starter you have is a Nippondenso (know as "Denso" in the US) from a Japanese vehicle. It also looks like it has an attached solenoid. The Bosch starter HAPI had in the early 1980's catalog (882) and the 84/85 catalog was much smaller, did not have an attached solenoid and weighed only 3.5lbs. In the 84/85 catalog HAPI noted that the Bosch starter was ideal for engines up to 1835cc and that their HI-TORQ II starter (which looks similar to your Nippondenso) was the best choice for high displacement engines. HAPI also noted "Requires minor clearancing of engine case" and listed the weight of the HI_TORQ II at 5.5lbs.

Is Robin Taylor Patrick Taylor's wife?
Yes very happily married to Patrick. I think she is the President of Viking Aircraft or at least answers the emails. This spring after I get my LSP ticket I want to fly down to world headquarters for a visit. I will stop in and see Fred's Sonerai at the same time.

http://vikingaircraft.com/
 
Does anyone know if there is an external difference between the 3-degree taper hub and the shrink-fit hub?

I split the cases and the #2 and #3 main bearings look great...as do all the cam bearings. The journal alongside the #4 bearing looks great as well. I would like to pull the prop hub to inspect and clean everything and put all new bearings in the bottom end. However, if my hub is a shrink fit hub.... that may not be the best option.

Of note: There are no grooves in the hub to move the oil back into the case as you see on the GPASC shrink-fit hub. Is that an indication that it is a 3-degree taper hub?
 
Chucker,

My engine has a HAPI 60-2DM data plate on it and looks identical to all the pictures of 60-2DMs in the HAPI catalogs I have. Additionally, the hub is same as those pictured in the catalogs, the Rex Taylor VW book and the Rex Taylor articles from Sport Aviation. AFAIK, HAPI did not install shrink fit hubs on factory built 60-2DMs. I've attached a picture of the front of my engine. Hard to see it, but there is a single bolt inside the hub that bolts to the crankshaft snout and that bolt is safetied with a long cotter pin that passes through both sides of the hub.
 

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Was HAPI the company that started selling watercooled heads for the VW? With turbo options?
Were any ever shipped (water cooled systems)? What happened to the tooling (patterns and fixturing)?

Or am in thinking of a different company/

Thanks!
smt
 
Chucker,

Sounds like you've got your 1835 mostly apart with the exception of removing the prop flange from the nose of the crank. Did you leave the pistons installed on the rods too? Am I correct in assuming that your engine was assembled with teflon buttons retaining the piston pins vs. circlips? Have you examined the ring package on your pistons yet to see if you have Total Seal gapless compression rings? I'm not sure if HAPI ever put these rings on production 60-2 engines but they are listed as an item for sale on page 29 of the 1984/1985 HAPI catalog. Quite interesting, because this was time period when Total Seal was suggesting putting the gapless ring in the second ring position rather than the first position which they had been advocating since the late 1960s. Attached is a link to a YouTube video where Keith Jones from Total Seal explains why normally aspirated engines should run the gapless ring in the first or top ring position:


BTW, did your 1835 come with a starter? Mine did not, I've got the HAPI pn (20-007) for the 3.5lb Bosch starter they sold but I can't cross reference that to any Bosch or VW listing. When I look at standard VW 1600/Type III starters they all have a solenoid attached to the starter whereas the Bosch unit supplied by HAPI did not have a solenoid attached and was triggered by a firewall mounted 1960's Ford style solenoid.

Mitch


I lied about the rings.... On closer inspection, the second compression rings are Total Seal rings.
 
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