umm I am yet to put a boost gauge in this car, but I would say about 7 or 8 psi, maybe as much as 10.

 

My compression ratio is a mystery, this is a dead standard mostly stuffed 4K :)

 

I use Ultimate 98, or Optimax, I assume by 91 you mean 91 octane fuel? If you do, then obviously that is why it pings....Mine would too.

 

On the higher octane fuel it doesn't ping at all.

 

yea flat tops on a 4k would be sweet with boost but flat tops in a 5k with boost will have massive compression because there isn't much chamber in the 5k head.

 

i normally always run 98 but was broke the other week and put 91 in... and yea its fine on 98 only gone upto 12psi so far... motor is now dead tho :) and i put a 5k in yesterday :)

 

hey felix.. would 2k pushrods be better than3k ones? (were 3k ones on the end of there adjustment?)

a few of the guys in nz that race k series motors tell me to block the oil feed to the lifters if i was gonna use solids... weird

thanks everyone the infos been great, ive settled on the 5k block with the light rods because i have them and don't intend to go over 8thou. rpm (boring of me hey) standard dish pistons closed chamber 4k head, hollow out the standard 5k lifters and use the 3k push rods standard cam so hi lift wont be a problem, lighten the flywheel, extractors, 2 inch exaust, and bolt on the 4age something something supercharger thats somewhere in freight as i type

its not the most exciting motor but i think it should pull quickly to good usable revs and have enough tork for the hill climbs