I'm planning on getting a vortech fmu for my 90 turbo civic si. I have 340cc injectors, an adjustable fuel pressure regulator and boosting 9psi. I'm confused on which one I need 12:1 or 10:1 or 8:1. I have a stock fuel pump. I'm not exactly sure I know what those numbers stand for. Just need a little help from you guys. Thanks for any and all replies.

 

Since you have 340cc injectors.. 4:1 or 6:1 would be OK.
Numbers represent how many PSI does it need to increase fuel pressure regarding to each 1PSI of air pressure.
For example with 6:1 ratio:
1PSI boost = (stock fuel pressure)+6PSI (from FMU)
2PSI boost = (stock fuel pressure)+12PSI (from FMU)
and so on...

Just bear in mind that stock fuel pump is *not* good for higher fuel pressures...

 

OK.

Read the Engine Management FAQ at the beginning of this forum.

If you still want to use an FMU after reading that, well, you're on your own.

FMUs are not for "high boost setups". Take the time to do your setup right, and it will provide you with the well earned power. Half *** it, and well, you'll see..

 

You're running 9spi with NO FUEL MANAGEMENT Post pics of the fried ringlands.
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I've rebuilt the motor with hypereutectic pistons and rings, blockgard, arp rod bolts, triple layer metal head gasket. I adjusted the fpr so the car runs really rich. It's only been 1500 miles on the new motor, so the car doesn't see much boost.

 

It shouldn't be seeing any boost. I bet it idles real nice.
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If you really did do all of that to your motor.. why the hell are you half assing your Engine Management.

It's ENGINE MANAGEMENT. It controls your engine, you know, the thing you spent all the money on. Wouldn't you want to protect it? Wouldn't you want to get the most out of your money?

Please, read the FAQ. Change your EM solution.

 

I'm half assing my EM because I don't need it at this point. I don't wrap the car out at all. I've read the FAQ. I've also talked to people that swear by fmu's for higher boost. That's why I'm asking questions. Either way it cost me nothing to build this car because I did all the work myself and and bought everything at wholesale. I wouldn't be that upset if it blows. I've put my money into my turbo Z28 http://www.4redlinemotorsports.com/ls1turbopage.htm

 

Stop talking to those people.


That Z looks nice. It's yours?
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I'll see what my AFR's look like with a fmu and 9psi. I'll run rich at idle if I have to in order to run 12:1 at boost. Yeah, she's mine. My pride and joy. Completely custom job. She doesn't see much boost either, until racing season starts anyway. One thing I like about imports is their gas mileage. I have to run race gas in the Z so it gets a little expensive to drive.