What is the maximum cylinder pressure on pump gas

[SOB/RFH]

I remeber seing maximum cranking cylinderpressure numbers from mainly Joe Sherman in Hot Rod Magazine. I don't know if anyone has any opinions/experieance/theory on this subject when it comes to aircooled motors. I think that this could be a way to develop the heat and pinging controll in our little motors so I think it needs to be addressed. I notice that a lot of the motors that were tested in the enginge builder challange had high compression ratios and there must have been a delopment in this area over the last years. I remember when I bumped the CR to more then 11:1 and ran the motor on the street. No one belived it was possible. That was just 8 years ago and the Blue handbooks of that time stating no more than 8:1 ruled.

[Jim Ratto]

Blue handbooks of that time stating no more than 8:1 ruled.

  did you take the Zotz? 

[Rune]

Blue handbooks of that time stating no more than 8:1 ruled.

  did you take the Zotz? 

Man, those are so tasty!! Wish I could get them here in Norway...

[SOB/RFH]

Blue handbooks of that time stating no more than 8:1 ruled.

  did you take the Zotz? 

Did buy the book in Sweden, guess they ate the zotz before I got hold of them!!!

No input on cranking cylinder pressure?

[Svwerker]

No pressure, no Zots.
Bad day! 

[Udo]

I remeber seing maximum cranking cylinderpressure numbers from mainly Joe Sherman in Hot Rod Magazine. I don't know if anyone has any opinions/experieance/theory on this subject when it comes to aircooled motors. I think that this could be a way to develop the heat and pinging controll in our little motors so I think it needs to be addressed. I notice that a lot of the motors that were tested in the enginge builder challange had high compression ratios and there must have been a delopment in this area over the last years. I remember when I bumped the CR to more then 11:1 and ran the motor on the street. No one belived it was possible. That was just 8 years ago and the Blue handbooks of that time stating no more than 8:1 ruled.

It depends on what fuel you have and what cam size. With our german shell V power you can run more than 11:1 

Udo

[SOB/RFH]

We have the V-power over here (not wher I live thou) but I am using Statoil (from Norway of all places) 98 octane RON (Equall to 94 octane US gas). I have run motors with up to 11,8:1 with zero problems like pinging or high temperature. I use cams with 255 to 270 deg duration at .050" lift. My cuestion is what is the maximum cranking pressure. If the pressure reeds high it is i a matter of retarding the cam or go bigger on the cam in my book. So therefor cranking pressure is free of camchioce but gasoline quality is a major factor.

[Udo]

10 bar ?

[SOB/RFH]

I dug out my old copies of Hot Rod Magazine and lo and behold, Joe Sherman (he is located in Huntington Beach) claimed 170 PSI as the maximum cranking pressure on regular gasoline. 170 PSI equalls 11.72 bar. Anyone ever reached that high and ran regular gasoline. I run a rather close lobe ceterline effecting the overlap on my own cam so there is not to mouch of a problem. I need to messure this with my new high torque starter to see if I got  a to good of a messurement with my old (lazy) starter. Rpm of starter could/should effect reading and I recall some guy running Pro Stock stating that cranking pressure should be read at around 1000 rpm.