what is the most horsepower yall have heard of from a y block. just wondering

 

Well, these seem respectable:

Home May 03

331 cubic inch Y

Y

There is other info there, but no dyno for supercharged engines.

Y-Block Revisited

You can find lots of vids for the Y block:

Bob's 57 Ford Y-block drag racer - YouTube

12.80 @ 108. Not sure how much that thing weighs, but if it weighs 3800lbs, he needs 350-390 hp to do that. I saw a couple references to the stock supercharged 312 as 300hp.

 

About 770hp on a blown dragster motor that was running out of fuel at the high end of the revs during the dyno session. Try that with a stock blocked small block!

The naturally aspirated Engine masters entry a few years ago put out 524 streetable hp and 477ftlbs on 91 octane. It's now in a drag configuration with more compression and a different cam which requires race fuel. I'm not sure of it's current output.

Here's a video
Eaton Balancing Y Block Ford 2010 Engine Masters Challenge - YouTube