Compression
06-03-2008, 09:27 AM
#1
TECH Enthusiast
Thread Starter
iTrader: (5)
Join Date: Jul 2004
Location: cali
Posts: 610
Likes: 0
Received 0 Likes
on
0 Posts
Compression to make a long story short i blew my short 408ci twice now 
It spun a bearing both times this time around I'm changing to new moroso oil pan and everything. heres the deal when i first got the engine it was a 11:1 compression ( it had -8cc pistons) , when i first blew the motor i had to bore it out more because the cylinders got slightly scratch so went 40 over and with a -2cc piston, i also got a new cam from FMS 250/255 630/645 (when i ordered it i had told them that my compression would be close to 12:1 but in reality I'm not sure what compression i ended up with the new pistons)which made good power on my m6. Ok so now once again I'm getting the engine build and once again I need to bore again so I'm going to hav ea 4.060 piston and wanted to get gas ported pistons and higher compression maybe 12:1 to 13:1. I'm having second thoughts on it because I'm not sure if this cam will perform like it has with that much compression and also haveing to run high octane all the time is really not something I'm looking for. Any suggestions i have to make up my mind today because I'm going to pay half of the labor today and their ordering the custom piston today also??
It spun a bearing both times this time around I'm changing to new moroso oil pan and everything. heres the deal when i first got the engine it was a 11:1 compression ( it had -8cc pistons) , when i first blew the motor i had to bore it out more because the cylinders got slightly scratch so went 40 over and with a -2cc piston, i also got a new cam from FMS 250/255 630/645 (when i ordered it i had told them that my compression would be close to 12:1 but in reality I'm not sure what compression i ended up with the new pistons)which made good power on my m6. Ok so now once again I'm getting the engine build and once again I need to bore again so I'm going to hav ea 4.060 piston and wanted to get gas ported pistons and higher compression maybe 12:1 to 13:1. I'm having second thoughts on it because I'm not sure if this cam will perform like it has with that much compression and also haveing to run high octane all the time is really not something I'm looking for. Any suggestions i have to make up my mind today because I'm going to pay half of the labor today and their ordering the custom piston today also?? 
06-03-2008, 01:41 PM
#4
TECH Enthusiast
Thread Starter
iTrader: (5)
Join Date: Jul 2004
Location: cali
Posts: 610
Likes: 0
Received 0 Likes
on
0 Posts
TTT..
talked to diamond briefly because I'm getting custom pistons and they suggested not to go to high in compression because its harder to tune and besides then you get in high octane gas. They said thats why engines builders usually stay around 11:1 because they already spend the time and money figuring out whats more efficient.. well thats what i understod of what he said so what do you gusy think I'm not sure what compression i was at before i spun the bearing but the set up seemed good i mean i 568/537 n/a out of it with the cam so i guess it wasnt that bad..
talked to diamond briefly because I'm getting custom pistons and they suggested not to go to high in compression because its harder to tune and besides then you get in high octane gas. They said thats why engines builders usually stay around 11:1 because they already spend the time and money figuring out whats more efficient.. well thats what i understod of what he said so what do you gusy think I'm not sure what compression i was at before i spun the bearing but the set up seemed good i mean i 568/537 n/a out of it with the cam so i guess it wasnt that bad..