What should I be looking for in a flexplate for the TH400 on my LT1? This is primarily a race application, so I want something that's 1.) strong and 2.) helps performance if at all possible. I've seen ads for billet flexplates, some heavier, some lighter, all saying that they're what I want. Do I want normal weight, or heavier/lighter? What are you guys using in a high HP application? Will be 383 w/ Vortech YSi, mid-high 9 sec car initially. Will turn up the boost and get a real camshaft once I've gotten all the bugs worked out and the chassis set up, and will be a *****-to-the-wall setup at that point, save for the air/air intercooler. I wanna get a flexplate once and not hafta worry about it again.

 

I have a ATI steel flex plate now and it is sfi approved. I'm looking to go to a billet aluminum from reactor products T

 

Thanks, anyone else?

 

I run the B&M part # 20238. SfI-rated, external balance, 153-tooth ring gear. Engine is 800HP/800lb-ft at the flywheel.

 

Same here.

 

My engine is internally balanced, wouldn't I want flexplate labeled "internal balance"?

I have a B&M flexplate right now (I think that one), and with my old engine it vibrated some over 50mph, and that engine was internally balanced according to the previous owner. I want it smooth.

 

Welllll.... now you've added new info. If your engine was internally balanced, with a neutral balanced flex-plate in place, you need to replace it with the same. It would definitely vibrate with an external balance plate on it.

 

I'm running a Scat SFI approved piece. It was less than $50 from my machine shop. Been abusing it for over a year with north of 700 fwhp. I just milled off the balance weight and had everything checked on a Hines Balancer for good measure.


http://www.rpmmachine.com/scat-flexplates.shtml