Well folk we found the limit to the gasket. Although not the limit for how much boost the motor can take!
We did some testing this last Sat. at SIR in Tucson. Kelly's first pass was a head gasket blowing 12.34@102. The gasket let go about the 1000' make with a lot of "smoke" coming out of the engine compartment. At least from my view from the starting line that's what it looked like.
Turns out that the top radiator hose blew off and soaked the motor. "No big deal", I thought, "just hook the hose back on and refill the rad." Well then I started thinking....."why did the hose blow off?" Then I had Kelly start the motor. Sure enough water was coming out between the head and block right behind #6 cyl. and steam was coming out of the rad. in a rythmic pattern. The gasket was blown between #6 cyl. and the water jacket at the rear of the motor.
The reason for the blown head gasket was the greedy crew chief! I increased the timing by 3* total. This increased the boost because of the increase in cylinder pressure. So now during that pass Kelly said that it registered 18lbs. of boost! She also noted some pinging then the gasket let go!
No problem though. We just happened to have an extra gasket along with us! So we tore it down and had it back up and running in less than 2hrs.
Kelly then made two more runs that day. The first was a "detuned" 12.81@104 at only 12lbs. of boost. Then we turned up boost to the 15-16lbs. level and she did a 12.31@109. Not bad for having the motor apart an hour earlier!
Sorry for the long post! Just though you'd like to know that the Inline six can handle some abuse! BTW the cast pistons looked great!
Also if we correct this 12.31 to sea level.....it's a 11.85@114. SIR in Tucson is at 3075'.
Later,
Will
We did some testing this last Sat. at SIR in Tucson. Kelly's first pass was a head gasket blowing 12.34@102. The gasket let go about the 1000' make with a lot of "smoke" coming out of the engine compartment. At least from my view from the starting line that's what it looked like.
Turns out that the top radiator hose blew off and soaked the motor. "No big deal", I thought, "just hook the hose back on and refill the rad." Well then I started thinking....."why did the hose blow off?" Then I had Kelly start the motor. Sure enough water was coming out between the head and block right behind #6 cyl. and steam was coming out of the rad. in a rythmic pattern. The gasket was blown between #6 cyl. and the water jacket at the rear of the motor.
The reason for the blown head gasket was the greedy crew chief! I increased the timing by 3* total. This increased the boost because of the increase in cylinder pressure. So now during that pass Kelly said that it registered 18lbs. of boost! She also noted some pinging then the gasket let go!
No problem though. We just happened to have an extra gasket along with us! So we tore it down and had it back up and running in less than 2hrs.
Kelly then made two more runs that day. The first was a "detuned" 12.81@104 at only 12lbs. of boost. Then we turned up boost to the 15-16lbs. level and she did a 12.31@109. Not bad for having the motor apart an hour earlier!
Sorry for the long post! Just though you'd like to know that the Inline six can handle some abuse! BTW the cast pistons looked great!
Also if we correct this 12.31 to sea level.....it's a 11.85@114. SIR in Tucson is at 3075'.
Later,
Will