Brodhead Pietenpol Association

Original Posted By: John Weikel
Subject: Engine choice...GM L4 In regard to the GM L4, How big is the main bearing on whichever endyou plan to hang the propellor on. At least as I understand it one ofthe nice things about the Model A Ford is that the main bearings arerelatively wide and thus are able to handle the stresses imposed whenone changes the orientation of a large gyroscope (propellor). I haveread that this is also true of VW conversions. I don't know how big thebearing is on a corvair but I guess it is big enough. All of theaircraft engine main bearings on the propellor end that I have ever seenwere pretty substantial. Also are the thrust bearings up for the job. Ihaven't settled on what engine I am going to use but a PSRU can be madeto handle most of the loads involved without stressing the enginebearings unduly. My personal favorite is a planetary gear set. I haveoften wondered about adapting as set from a drag racing transmission. Itis a manual transmission with stacked sets of gears and is designed tohandle 1200 + horsepower. This is all of course just my opinion andshould probably be taken with a grain of salt. Matt Kirk________________________________________________________________________________

Original Posted By: Matt Kirk
Matt,I believe that Ross PRSU's use planetary gears from Ford Automatictransmissions.John W -----Original Message-----

Original Posted By: Rcaprd(at)aol.com
In regard to the GM L4, How big is the main bearing on whichever end youplan to hang the propellor on. At least as I understand it one of thenice things about the Model A Ford is that the main bearings arerelatively wide and thus are able to handle the stresses imposed whenone changes the orientation of a large gyroscope (propellor). I haveread that this is also true of VW conversions. I don't know how big thebearing is on a corvair but I guess it is big enough. All of theaircraft engine main bearings on the propellor end that I have ever seenwere pretty substantial. Also are the thrust bearings up for the job. Ihaven't settled on what engine I am going to use but a PSRU can be madeto handle most of the loads involved without stressing the enginebearings unduly. My personal favorite is a planetary gear set. I haveoften wondered about adapting as set from a drag racing transmission. Itis a manual transmission with stacked sets of gears and is designed tohandle 1200 + horsepower. This is all of course just my opinion andshould probably be taken with a grain of salt. Matt KirkIn regard to the GM L4, How big isthe mainbearing on whichever end you plan to hang the propellor on. At least asIunderstand it one of the nice things about the Model A Ford is that themainbearings are relatively wide and thus are able to handle the stressesimposedwhen one changes the orientation of a large gyroscope (propellor). Ihave readthat this is also true of VW conversions. I don't know how big thebearing is ona corvair but I guess it is big enough. All of the aircraft engine mainbearingson the propellor end that I have ever seen were pretty substantial. Alsoare thethrust bearings up for the job. I haven't settled on what engine I amgoing touse but a PSRU can be made to handle most of the loads involved withoutstressing the engine bearings unduly. My personal favorite is aplanetary gearset. I have often wondered about adapting as set from a drag racingtransmission. It is a manual transmission with stacked sets of gears andisdesigned to handle 1200 + horsepower. This is all of course justmyopinion and should probably be taken with a grain of salt.Matt Kirk________________________________________________________________________________