What's the largest throat/thinnest valve seat anyone has ran?

[Mike T]

We know what's ideal but what have you gotten away with in the past? Has anyone ran 90% plus throats, and if so how narrow was the 45?

I read where some A/M heads are up to 91-92% (not Buick) out of the box.

 

[earlbrown]

keep in mind, turbos take a lot of nit-picky head 'tricks' right off the table.


On a slow turning V6 that's supercharged, small nuances to the Nth degree (that cost money) really aren't a good bang for the buck.

 

[Mike T]

My personal heads have higher ratios than I'd like like to see... not going to be a daily driver so we'll see how long the valve job will last.

Fastblackracing did a good write up on heads
Cylinder Head Madness......UPDATE 6/25/2016 and included some throat ratios around 90% on the TA /Champion intakes and as high as 88% on the exhaust.

Mine are 92% on the intake and 93% on the exhaust. Made a few seats on the lathe (just to see what a valve job will look like) based on measurements taken from the heads. The intake will be fine but 93% on the exhaust is really pushing it. I can get a .055 wide 45 at .010 from the margin and about a .020 60 degree. percentages are not as forgiving on the smaller valve.