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5sfeturbo.com
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Discussion Starter #1
Hi guys,

What is the max safe boost to run on forged 8.5:1 forged pistons?

I'm running supra pump and 550 injectors with an aeromotive fpr.

Thanks
 

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i have this diagram showing approximate boost pressure allowable for varying fuel octanes and engine compression ration

8.5:1 boost octane
8psi 92
14psi 100octane


but another major factor would be the intercooler efficiency
for example

on a ratio of 8.1:1 with 10% intercooler efficiency you can boost safe7psi
but with 90% intercooler efficiency 15PSI safe.

what is your desired boost pressure anyway? what turbo do u have?
 

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There is no hard fast rule. It's dependent on air temperature, A/F ratio, timing, intercoolling, turbo efficiency, fuel octane, ...
 

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patR1 said:
i have this diagram showing approximate boost pressure allowable for varying fuel octanes and engine compression ration

8.5:1 boost octane
8psi 92
14psi 100octane
Wow.. that info is ridiculous by itself.

There is no way anyone can tell how much boost the OP can run and be accurate about it without a myriad of other info. And even then, it won't be completely accurate due to his specific engine condition.

I'm assuming the OP is running a 20b since it's part of his name, and even then, he shouldn't need 550cc injectors. Very few people have pushed the CT20b past 300whp without cams (that he didn't mention).

I'm confused about the whole post. Your compression ratio should be the last of your concerns. Your A/F ratio and knock response should be your primary concerns.
 
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