Roller cranks!?

[Tom G.]

A friend of mine has broken his rollercrank in the past..,i think it doesn´t function with to much power....
It was a 2276 with FK87 IDA and welded 040 heads 42x37...

Regards
Tom
 

[Roller crankshafts]

Hi again. I have been reading some comments and thought I would put some wrong statements to rest. Rollers for VW and Porsche basicly consist of: Porsche made a 356 SPG and a Hursh. Their 4 cam engine also had a roller but that is another monster all in its self. Just a quick note here the 4 cam engine, one of the most advanced in it's time, ran a roller. Humm..
SPG also made a 40 HP 64 mm 4 dowel, a 69mm 4 dowel, a 69 mm 8 dowel, a 78 mm 8 dowel stroker and a 82 mm 8 dowel stroker. Now, I don't claim to know everything, but in my 30 years of rebuilding and repairing these cranks I have never seen a 74 mm stroker. SPG made 4 different rods for these cranks. All these rods except for the 40 HP are the same length. Right you heard me all the same length! The later style rods have tested to be the strongest. That is the only rod they put on the 82 mm stroker. Personally I prefer the Porsche 356 rod. They have a beefer shank to them. They are kind of rare and are more expensive to use but some of my customers only use them because of their design. The 40 HP roller came with a 20 mm small end and is shorter throw. The later style rods can be put on these cranks. The throw is shorter 64 mm and the crank itself is about 4 pounds lighter. I have some customers building small motors with nitrous claiming to be getting more than 200 HP out of these cranks. Not to bad for a 40 HP design. One thing I advise you if you dabble in these cranks have someone who knows these cranks work on them. All the rod failure and I mean ALL that I have seen could of been prevented if it was not assembled correctly. Balance and straightness is the key and of course cutting the main bearings correctly. Anyway I hope this puts to rest some questions. If all you would like I could post some pictures of rods and such. Also I might add that the SPG roller that is posted on this website, the nice shinny one, is a 69 mm not a 82 mm.
Gary

[Lee.C]

Hey Gary - again thankyou for the interesting info and like I said before its nice to have someone who really know what they are talking about 

I was wondering would you be able to rebuild the 82mm SPG I have found - it is in the states at the moment so I could get it sent straight to you 

I plan on building a replica of Mike Mahaffery's old 2180cc IDA'd motor - Any tips 

[ESH]

Great information. About 8 or 10 years ago I almost bought a 2L aero motor with 8 sparks, a Speedwell oil system and a roller and have always been intrigued by them. Cool stuff.

[Lee.C]

Great information. About 8 or 10 years ago I almost bought a 2L aero motor with 8 sparks, a Speedwell oil system and a roller and have always been intrigued by them. Cool stuff.

Now that sounds like an interesting motor - where did you find that