FMU what ratio 12to1 10to1 8to1

evanzzr · 1-12-08, 0:58

I am sc my kl03 5psi . 255 pump maybe millenia injectors .which FMU should i buy A 12 to 1 a 10 to 1 a 8 to 1 ? any help would be greatful

**cf_z** · 1-12-08, 9:52

ive got the 12:1 on 4 psi, and i get 10:1 rations in full boost.

i would say 12:1 would be good. anything lower you'll just risk leaning out.

**Trent** · 1-12-08, 11:13

To determine the amount of fuel you can supply with your AFPR or FMU follow this calculation:

Fuel pressure @ rail = Rise x boost + idle pressure
Example: 10 x 5 + 50 = 100psi

So using a 10:1 FMU at 5 psi will yield 100psi at the rails. Generally, you don't want to go over about 100-110 psi, so a 12:1 would be too much according to that calc. Depending on your injectors and ultimate horsepower goal, an 8:1 may be sufficient.

cf_z, have you ever measured your fuel pressure at full boost?

**KING6** · 1-12-08, 13:19

You dont crank up the rail psi that high. People run them at 30-35psi.

**cf_z** · 1-12-08, 18:06

trent- no i havent. i dont even have an afpr

ive got a 6:1 recalbration sitting on my desk, but im positive thats too low.

**BOYZERO** · 1-12-08, 22:56

start with a 10:1 and then test it and determine if you want to go any lower, but @ 5psi, you'll be ok.

refer to this chart in middle of page and read the whole page to get a better understanding of what u are looking to do:

hope it helps. . .

Vortech FMU

**hgallegos915** · 1-13-08, 0:24

12:1 is to much .

Im at 5 psi and under boost im at 10:1 !! I tried doing everything to make it leaner and i cant. I also have millenia injectors. I even lowered by idle pressure at like 15 and im still rich. at idle ill be like 13:1 or something , gradually going richer.

bleh!

megasquirt is the only way to control it right.

isnt like 8:1 fmu richer?

**cf_z** · 1-13-08, 1:42

hgallegos- no, the first number is how many times increases in pressure for one lb of boost.

**hgallegos915** · 1-13-08, 12:52

a ohhh i see !

**KING6** · 1-13-08, 14:03

An fmu shouldnt change your idle or your crusing AFR.. it will only change them when its under boost. Thus you would be really rich under boost, wasteing alot of fuel, not making as much power. Yet staying on the safe side. 12:1 fmu, your probaly running
-10.0 AFR.
Yours is alwase rich because you have the mill S injectors.

1-12-08, 0:58	#1 (permalink)
evanzzr Join Date: May 2006 Location: destin, FL, USA Age: 28 iTrader: (0)	FMU what ratio 12to1 10to1 8to1 I am sc my kl03 5psi . 255 pump maybe millenia injectors .which FMU should i buy A 12 to 1 a 10 to 1 a 8 to 1 ? any help would be greatful

1-12-08, 9:52	#2 (permalink)
cf_z Join Date: Sep 2007 Location: NE Indiana, USA Age: 18 iTrader: (10)	ive got the 12:1 on 4 psi, and i get 10:1 rations in full boost. i would say 12:1 would be good. anything lower you'll just risk leaning out.
	MY SIX, since-day-one. WTB:2g Rear Sway bar & Strut Bar PM me. g-meter'd at 65 HP haller.

1-12-08, 11:13	#3 (permalink)
Trent "Dark Side" of the moon Join Date: Jul 2003 Location: The Mosquito State, LA, USA Age: 25 iTrader: (0)	To determine the amount of fuel you can supply with your AFPR or FMU follow this calculation: Fuel pressure @ rail = Rise x boost + idle pressure Example: 10 x 5 + 50 = 100psi So using a 10:1 FMU at 5 psi will yield 100psi at the rails. Generally, you don't want to go over about 100-110 psi, so a 12:1 would be too much according to that calc. Depending on your injectors and ultimate horsepower goal, an 8:1 may be sufficient. cf_z, have you ever measured your fuel pressure at full boost? Last edited by Trent : 1-12-08 at 11:17.
	'91 Miata: BEGi S2 turbo kit, Megasquirt EMS, 460cc injectors, 6UL's, Tokico Illuminas, Tein S-Tech Springs, 1.8 Brake conversion, 1.8 diff, GS rad, ACT XT clutch/PP, AEM UEGO WB, full 3" exhaust, HDHCDDHT roll bar, etc, etc. '07 Honda CR-V: The daily. '93 MX6 LS-ZE MTX Gone, but not forgotten.

1-12-08, 13:19	#4 (permalink)
KING6 Join Date: Oct 2002 Location: Central, USA Age: 24 iTrader: (16)	You dont crank up the rail psi that high. People run them at 30-35psi.
	The King OF AFTERMARKET/USED PARTS F/S F/S K6F Radiator support brackets, fuse box covers, egr block offs < 94/LS-T -possibly for sale. B.O

1-12-08, 18:06	#5 (permalink)
cf_z Join Date: Sep 2007 Location: NE Indiana, USA Age: 18 iTrader: (10)	trent- no i havent. i dont even have an afpr ive got a 6:1 recalbration sitting on my desk, but im positive thats too low.
	MY SIX, since-day-one. WTB:2g Rear Sway bar & Strut Bar PM me. g-meter'd at 65 HP haller.

1-12-08, 22:56	#6 (permalink)
BOYZERO Join Date: Sep 2005 Location: , IL, USA Age: 28 iTrader: (1)	start with a 10:1 and then test it and determine if you want to go any lower, but @ 5psi, you'll be ok. refer to this chart in middle of page and read the whole page to get a better understanding of what u are looking to do: hope it helps. . . Vortech FMU
	93 MX6 LS,Xtreme ecu,cai,ze im,port matched phenos,ngk wires/irid plugs,180 stat,udp,ss headers,2.5in exhaust w/hooker aero chamber muffler w/3in tip,S2 clutch,11lb flywhl,strut bars,eibachs,monroes,awr f/r mm,awr sway bar kit,bm shifter w/rr-racing bushings. 1/4=15.0@92.5 http://i215.photobucket.com/albums/c...lipboyzero.jpg-timeslip-stock cat,ecu,clutch/flwhl

1-13-08, 0:24	#7 (permalink)
hgallegos915 Join Date: Sep 2005 Location: EL Paso, TX, USA Age: 27 iTrader: (0)	12:1 is to much . Im at 5 psi and under boost im at 10:1 !! I tried doing everything to make it leaner and i cant. I also have millenia injectors. I even lowered by idle pressure at like 15 and im still rich. at idle ill be like 13:1 or something , gradually going richer. bleh! megasquirt is the only way to control it right. isnt like 8:1 fmu richer?
	KLZE curved neck boosted @ 5 PSI. Millenia s Inj, Cosmo AFPR, Vortech 12:1 fmu. AEM Wideband, sidemount intercooled. ONE FAST little car. ALL DONE PHYSICALLY BY ME.No shops.

1-13-08, 1:42	#8 (permalink)
cf_z Join Date: Sep 2007 Location: NE Indiana, USA Age: 18 iTrader: (10)	hgallegos- no, the first number is how many times increases in pressure for one lb of boost.
	MY SIX, since-day-one. WTB:2g Rear Sway bar & Strut Bar PM me. g-meter'd at 65 HP haller.

1-13-08, 12:52	#9 (permalink)
hgallegos915 Join Date: Sep 2005 Location: EL Paso, TX, USA Age: 27 iTrader: (0)	a ohhh i see !
	KLZE curved neck boosted @ 5 PSI. Millenia s Inj, Cosmo AFPR, Vortech 12:1 fmu. AEM Wideband, sidemount intercooled. ONE FAST little car. ALL DONE PHYSICALLY BY ME.No shops.

1-13-08, 14:03	#10 (permalink)
KING6 Join Date: Oct 2002 Location: Central, USA Age: 24 iTrader: (16)	An fmu shouldnt change your idle or your crusing AFR.. it will only change them when its under boost. Thus you would be really rich under boost, wasteing alot of fuel, not making as much power. Yet staying on the safe side. 12:1 fmu, your probaly running -10.0 AFR. Yours is alwase rich because you have the mill S injectors.
	The King OF AFTERMARKET/USED PARTS F/S F/S K6F Radiator support brackets, fuse box covers, egr block offs < 94/LS-T -possibly for sale. B.O