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Discussion Starter · #1 ·
i want to start out with 5 psi of boost and i plan to get a 12:1 FMU. now if i raise the boost, i'd have to get bigger injectors and a A-FPR. if i keep the 12:1 FMU, what size injectors should i get and from what car will fit in the SEFI motor?

also, i know 8 psi is the max with stock ignition but if i had somethin to retard the timing, what's the max boost limit i could go for with the right injectors for the above question?

BTW, i have been searchin but i'm just a little confused.
 

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juggalo said:
if i keep the 12:1 FMU, what size injectors should i get
You cant really use larger injectors with a 12:1.
Here's why, it will make the fuel pressure come on too fast for any thing much larger then stock.

For every 1psi of boost, your adding 12psi of fuel pressure. Your FPR leaves off at around 40psi, so at 1lb of boost your at 52psi, at 2psi your at 64psi, at 3psi your seeing 76psi, at 4psi your at 88psi, at 5psi your at 100psi.
Your fuel pump stop's making pressure around 100psi, so any thing past that your not adding any more fuel.

With larger injectors, you want a lower ratio FMU.

juggalo said:
i know 8 psi is the max with stock ignition but if i had somethin to retard the timing, what's the max boost limit i could go
Depends on fuel octane, intercooling and how much hot air the turbo is pumping.
Also keep in mind, the more timing you pull, the hotter your EGT get and the less efficient your motor get's at making power.
 

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Discussion Starter · #3 ·
thanks jeff
 
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