Quantcast

Psru bellhousing

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

slociviccoupe

Well-Known Member
Joined
Apr 1, 2011
Messages
362
Location
Palm Bay Fl.
I assume the bad info comes from eggenfeller engines. Probably few nsi and some maxwell engines before they got it sorted out. I get same thing from everyone that hears im putging subaru in a plane. No one has real life experiances but has a friend or someone they know with a subaru sitting in a hanger.

Trust me few things ive ran into almost make me want to give up and put a honda in it. But my issues are through reading on forums. Not real life examples.

Right now just trying to get this bellhousing redesigned so i can move on with other things.
 

slociviccoupe

Well-Known Member
Joined
Apr 1, 2011
Messages
362
Location
Palm Bay Fl.
We do have a new turbo Honda powered RV on VAF which seems to be working pretty well with about 60 flight hours so far.
Id be going different honda engine just because i know it well and have one sitting around. And everything in it from factory is forged.

Im still giving subaru a chance.
 

slociviccoupe

Well-Known Member
Joined
Apr 1, 2011
Messages
362
Location
Palm Bay Fl.
Found a drag race company that makes bellhousings that would stamp me one out of titanium or aluminum. Havent got price yet on either. But its sfi rated and doesnt need a scatter shield. So im assuming it would be up to the task. Everything from 400hp race cars to 10,000 hp top fuel dragsters use them.

Its prety much a formed can with a lip. Id have to do an adapter from subaru bellhousing pattern to a round pattern. The bellhousing would just bolt yo the round bolt pattern and gearbox would mount to the front via studs.
Staryer pocket would be fabricated.
Probably tripple the cost of aluminum but it will be stronger and same weight or lighter. And its weldable and dont have to worry about the fatigue that aluminum has especially if welded.
 

slociviccoupe

Well-Known Member
Joined
Apr 1, 2011
Messages
362
Location
Palm Bay Fl.
Was thinking forced air via a hose to the back of the block where subaru has the cover. And leaving the bottom open. Also inspection hole or cover on side to check coupler during pre flight.
 

Protech Racing

Well-Known Member
Joined
Jul 10, 2020
Messages
355
When you get it together, make notes as to how far you can rotate the prop each direction before the engine moves. Write it on the gear box. Be precise with degrees or MM.
Comes in handy for preflight and service history. IMHO.
 

Puggo1

Member
Joined
May 19, 2020
Messages
8
Hi all,

the easiest method to make a PSRU bellhousing or direct drive shaft support is to use an automatic transmission bellhousing (torque converter housing). Wittman V8 and Beachner v8 direct drives conversions used them and they can be obtained from wreckers at minimal cost. On these parts there's a ring surface which is very accurately aligned to the engine centreline (usually within 0.001 inch). For a direct drive installation, the only loads to the bellhousing would be the propeller vibration and gyroscopic loads, so they could be lighten by grinding away unnecessary ribbing. On a PRSU conversion (gear or belt with offset shafts), when the PSRU is bolted to the bellhousing, a cantilever load is applied to the bellhousing. It may justify adding some weld ribs to withstand this loading. Each installation will be different and should be carefully considered. Losing a PSRU or housing in flight will probably cause the aircraft to crash, so best to be avoided by good engineering and manufacture of the PSRU.

happy designing and building
Puggo
 

pfarber

Well-Known Member
HBA Supporter
Joined
Feb 21, 2019
Messages
711
Location
Pennsylvania
Hi all,

the easiest method to make a PSRU bellhousing or direct drive shaft support is to use an automatic transmission bellhousing (torque converter housing). Wittman V8 and Beachner v8 direct drives conversions used them and they can be obtained from wreckers at minimal cost. On these parts there's a ring surface which is very accurately aligned to the engine centreline (usually within 0.001 inch). For a direct drive installation, the only loads to the bellhousing would be the propeller vibration and gyroscopic loads, so they could be lighten by grinding away unnecessary ribbing. On a PRSU conversion (gear or belt with offset shafts), when the PSRU is bolted to the bellhousing, a cantilever load is applied to the bellhousing. It may justify adding some weld ribs to withstand this loading. Each installation will be different and should be carefully considered. Losing a PSRU or housing in flight will probably cause the aircraft to crash, so best to be avoided by good engineering and manufacture of the PSRU.

happy designing and building
Puggo

I though of this but usually a PSRU input drive shaft/coupler is much shorter than a torque converter. I guess you could extend via a shaft but now you have even more critical alignment issues.

I don't think a stamped shell would be a solution, not rigid enough. You would want some sort of rib or embossed section to add strength to the sides. A car transmission won't see anything but torque and the engine and transmission are bolted to the frame at fairly long moment arms from each other.
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
7,645
Location
Saline Michigan
The bell housing from a car is convenient, but probably longer than needed, even with putting in a torsional isolator of some sort. Bigger than needed usually means more weight too. Ugh.
 

pfarber

Well-Known Member
HBA Supporter
Joined
Feb 21, 2019
Messages
711
Location
Pennsylvania
The bell housing from a car is convenient, but probably longer than needed, even with putting in a torsional isolator of some sort. Bigger than needed usually means more weight too. Ugh.
These days? Engines are mostly front or AWD that means integrated casting (aka no bellhousing). If you get into the RWD motors the bellhousing is also usually cast as part of the tranny as there is almost no service required on torque converters that require a bellhousing to offer removable access.

Watching a few tranny swap videos they are able to butcher bellhousings, but they also start with aftermarket kits and then just make an adapter plate.
 
Top