Heads with 3 angle valve job and new valves. Then what?

[rreinicherr]

Shave them some and port? Anyone know how much you can shave to still run 93 octane? Can't afford anything too radical. (Like Rockers) This is for a NA truck.

THANKS!

 

[bigike]

Stock CR is 9.6 to 1, low by any means................

 

[rreinicherr]

Compression?

Anyone know how much you can shave off the heads to get more compression but still run 93 octane. Isn't the limit about 10.2 to 1?


THANKS!

 

[Bone]

With current 93-octane fuel, it is possible to run as much as 11.2:1, but the safety margin is small. Plus, on a hot day, it may not make it.

Plus, varies engine to engine. Cam also becomes a player.

http://www.popularhotrodding.com/tech/0311_phr_compression_ratio_tech/index.html
http://www.faqs.org/faqs/autos/gasoline-faq/part3/section-1.html

octane ratings
n-octane -10
n-heptane 0
2-methylheptane 23
n-hexane 25
2-methylhexane 44
Hydrogen* >50
1-heptene 60
n-pentane 62
1-pentene 84
n-butane 91
cyclohexane 97
iso-octane 100
benzene 101
E85 Ethanol 105
Methane 107
Ethane 108
Methanol 113
Toluene 114
Ethanol 116
Xylene 117

 

[rreinicherr]

THANKS!