"Back in the day" we always use to do the 'double key' thing on any mill with a gilmer belt driven 6-71 (or larger) blower. 'Not really sure the 2 keys would be at all necessary on the FGT's v-belt blower setup - at least in the stock configuration. BUT, as you said, you're no longer playing in that ball park.:willy...as well as an additional keyway located 180 from the OEM for a total of two.
John, always great to see you post here... I have 2 questions...The issue with the crank is simple. It is fine in the application it was designed for. Adding a Whipple is outside of that design parameter. Now, that does not mean to call Whipple and complain either. Its simple physics and some good old common sense. The keyway is very small, the factory bolt is torque to yield and that combination just is not made for repeated abuse.
For sure, all of the Whipple applications will have crankshaft issues at some time in the future depending on how much it is driven and how hard its driven.
For example on this particular engine, this engine had 3500 miles and I'd suspect relatively hard miles. The keyway was already damaged to the point that we removed the crank and fixed it. I have pictures to display this. I have fixed several of these over the last year. It can go so far that the end of the crank can break off and who knows where the 20 lb balancer will go. The costs to fix at that point is pretty high.
The best fix available is a billet crank. We designed one that also added material to the front of the crank, bigger threads and a larger face for the cam gears to fit against.
John,For sure, all of the Whipple applications will have crankshaft issues at some time in the future depending on how much it is driven and how hard its driven.
Don't put a whipple with lots of boost on it Ford racing is now putting double key ways in the cobra jet motors after the issues they have with them... I would think that anything less then 20lbs of boost will be fine and anything over 20 a person at somepoint will have problems. Another thing that will help with this is installing either a innovators west alum balencer or a Ati. John uses the Ati i believe. The 07 shelbys also had a ford GT style 20lb balencer and ford replaced those in 08 with a lighter 10lb unit as it was easier on the crankshaft.John,
For those GTs with Whipples, are there any preventative measures one can take that do not require removing the crankshaft?
The difference is the distance between the 6 and 10 rib. Its like .100 closer between the two pulleys on the Gt balencer versus the gt500I wont add any more HP until I can replace the crank. Interesting news about the balancers... ATIs site list a different part number for the GT500 and the GTs. However, the replacement parts (Shell assembly and Hub) share the same part #. It kind of makes you think the only difference is the price they charge the two respective parties.