Hi Perry
I want you to take this post in the manner its offered...as help, not criticism..
I have run a lot of Blowers....you may have noticed them on top of top fuel engines lol
What I think you are doing with that blower is...hmmm how shall I describe this...a little like throwing damp sticks of dynamite into a bonfire and hoping one doesnt dry out and explode...
What I am trying to explain is that you cannot just ramp up a blower and hope all will be fine (and the car faster)
It will and in your case HAS worked so far....
But not for long......
You are already coming across some of the problems that we had in top fuel.... like heat sink upwards to the blower
In my day (80s) we had no cooling at all on a t/f engine and the heat was basically dealt with in two ways...
1, it was transferred into the oil which was a straight 70 weight and dropped after every run and a rather nice bright green colour it was as well lol (due to the Nitromethane forced past the pistons into the oil)
2, we were only running the engine including the run for as few seconds as possible.... and a LOT less than you are...
And yes we put a fan on it afterwards but it didnt help much
You are also about to come across another problem we had.... that is shifting enough fuel for the blower....and that means a BIG pump...we used to have to shift around 6 to 8 GALLONS PER RUN!
Now you are not at that stage yet but you really really need to think about a pump that WILL shift as much fuel as you THINK you need , then double it...
Now back to what I said to start with....
If you get ANY of the above wrong and you WILL (take my word), not through any real fault of yours, but just through bad luck or a small error, then you WILL lose an engine or 10....
As long as you are prepared for that then fine, but I dont mean a holed piston or two, I mean a crank or a couple of pistons blowing big holes in your blocks...
My best advice to you would be that IF you must, run a blower only engine until you understand its limitations (and your block and cranks and pistons limitations ( thats a polite way of waiting for it to go bang - as it will)
Then back off a few psi and THEN try a LITTLE nitrous and go on like that..until you lose another engine and so on....
I am amazed that mixing and matching you have not lost an engine so far, you must be extremely lucky (or maybe you have all of Richards luck as well lol)
Anyway, hopefully this may help you or not lol...
We will see ........
All the best Brett