flywheel or flexplate

[tahitijet]

what is prefered? My olds had a flywheel but i'm switching to a BBC. Also should I spend the extra money for an SFI approved unit.
thanks

[Oldsquirt]

My old Tahiti/Olds ran a flywheel. In my current Eliminator/BBC I am running a flexplate. This decision was made with the help of my engine builder who is a long time drag boat racer. He was particularly happy when he saw I had chosen an SFI-approved flexplate. The one I am using is a CSI unit purchased thru Summit. Cost a lot more than a stocker, but it was worth it for the peace of mind.

[Moneypitt]

In my opinion stock flexplates are useable in a jet boat. What does it have to do? Start the engine! Thats it. no torque transfer, no converter to shake it, just turn the engine over. I've never had any failures with the stockers, after all, how hard can you turn a jet boat engine? As long as the starter ring stays put, it'll turn the engine.... Moneypitt.......(ultra high rpm applications are a different story)

[wsuwrhr]

Link to my post (http://forums.***boat.net/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=8;t=002971)
I posted on this subject a few days ago. Just figured it was the same type of problem.
Brian

[Duane HTP]

Definitely go with the better CFI flexplate. The stock one may cause early starter problems because they partially depend on the torque converter to help make them solid. With no torque converter they do just what the name implies. They flex.

[Chris J]

I asked this question a few months back and to summerize the info I got back. A flex plate has less rotating mass and is what you want to run on a motor that spinning a jet. If you are turning over 5000rpm I would definatly go for an SFI flexplate. A cracked flexplate on a jet could still shatter at high rpm.
Shatter flex plate = hole in boat eek!