More power = More heat

AF = EGT & Piston design. How much heat can the ring lands stand? How much heat can the skirt disapate?
You need to think about the combonation of boost with the heat. IAT would also play a much bigger role relating to combustion heat
At what EGT does failure occure for the OE piston & what is a safe power level?
Where would you place the EGT probe? If it were up to me it would be less than 2" from the header flange.

"flying small planes and leaning for best power while running safe EGTs transfers to the Mini but i do not know that EGT number" Bob, this is exactly right. That (say for a 172 or an Archer) exact # might not work for the mini, based on rpm, SC boost, IAT and piston design ( RPM being big - what ever wil happen will happen faster ).

 

I understand the concepts, just thinking what I can do to somewhat negate this. Prior to having the head on there, I was running rich as can be. I wonder if stepping back to a 15 would benefit me for the time being.

 

There is not a whole lot that going to a 15 from a 17 would do. You would still be looking at high EGT. Problem is, what is it? It could be safe but better safe than.........
I'll try to find some #s from my NOS car, coated pistons & non coated. The EGTs were very high along with head temps. This is old style NOS you could dial in the fuel volume via FP. I may have some AFs.

 

I know Alta sells a stock size I could swap on for the time being. Safe is better than sorry.

I need to get back to the dyno, I have since put the cat back on the car and feel it should richen that back up a tad.

 

That would depend on what the upstream O2 sensor sees & the ECU tune.

I found some old specs from the NO2 car ( same as a TR6 piston ):
Forged Jans uncoated pistons were very good at 1250 to 1350 EGT 5 lbs fuel presure, 4 lbs was pretty doable ( worth 80hp ).
With coated Wiseco at 1480 the head temp at the plug was over 400, oil temp 287, water temp 255, toasty, at 2lbs fuel aprox 13.7 AF ( worth close to 100 hp & lots of risk ). No damage what so ever to the pistons. The tops still looked new. Short lengths of time only 10 - 12 seconds max.
The Mini OE piston has much higher & smaller ring lands, so my guess, 1200 might be a good #. This is pure speculation, as I know nothing about the metallurgy of the OE piston nor have I had 1 in my hand.
Measurements were done with http://www.digatronusa.com/ .
EGT can tell you quite a few things, poor AF, poor ign timing, bad fuel, air leaks, just to name a few.
The AF on your sheet could be wrong & the EGT could be fine. There's only 1 way to find out.....

This thread is about Thumper heads & not pistons. No hyjack intended.

 

Its ok, its my post I appreciate the info.

I plan on another dyno run either this weekend or in January before I do any racing.

 

keep it rolling...... sounds good pushing the envelope a bit

 

With a little luck someone will latch onto this thread with some better info before you do the next dyno.

 

TampaMCS.. going to talk to my Dyno Tech at HP Performance tommrow.. I have a copy of your dyno.. and see what he advises.. cool??

Just me......................................

Thumper