running rich and idles very bad 7afte Options

[trd94]

ok i just intalled my new turbo kit and it seems to be running a little rich , my kit includes , t3 turbo in a 60 trim , wastegated at 7 psi , 89 ford probe injectors, 3 in intake pipe& down pipe back is also 3 in, 12:1 fmu , walbros 255 fuel pump, type rs bov,and a costome mount side intercooler, i have all the other little thing for the kit as well, i retarded my timming by 6 degrees and it just wont smooth out what would you guys think the problem is . i thank you for any help

This post has been edited by trd94: Apr 11, 2006 - 2:46 AM

[NuclearHappineS]

Some simple math... example

stock hp = 100hp.... target hp = 400hp
stock injector = 200cc/min ideal injector = 400/100 * 200 = 800cc/min

roughly: cc/min = desired wheel hp *1.5
200whp = 350cc/min
300whp = 450cc/min << the figure most 3sgte guys quote
400whp = 600cc/min

This is all for 4 cylinder cars

Fuel pressure example

stock fuel pressure = 40psi
new fuel pressure = 80psi
fuel pressure ratio = 80/40 = 2.0
flow ratio = square root ( fuel pressure ratio) = square root (2.0) = 1.41

1.41 is 141% so 41% more than stock ...

so if you had 200cc injectors @ 40psi, and you got a new fuel pressure regulator set @ 80psi then you effectively now have 200*1.41 =282cc/min injectors

282cc/min /1.5 = ~188whp worth of fuel

FMU example.

you have 300hp stock, you want to put on a turbo (that according to the compressor map) says that you can make 520hp @ 8psi (according to the chart)

fuel flow ratio = horsepower ratio
fuel flow ratio = 520/300 = 1.7333
fuel pressure ratio = fuel flow ratio ^2 = 3.0044
say your stock fuel pressure is 15psi.
new fuel pressure = 15*3.0044 @ 8psi of boost = 45psi fuel @ 8psi boost

FMU rate = (high pressure - base pressure ) / boost pressure
FMU rate = (45psi - 15psi) / 8psi = 3.75:1 FMU

The max pressure you want to reliably pump through your injectors is 85psi

Domestics run low psi fuel injections (8-20psi sometimes) so FMU's are great for them becuase you can double your fuel flow going from 20 to 80psi ...

but on an import where you already start at ~43psi of fuel pressure at atmoshpere... then you're limited to adding 45% fuel flow with an FMU Setup (or a dry nitrous setup because it works on the same fuel pressure rise concept)...

so with a 12:1 FMU you are limited to 4-5psi while still being considered 'safe'

so that's what i was saying...

@ 8psi , with a 12:1 FMU you run some 124psi fuel pressure
base is ~45psi
pressure ratio = 2.75
flow ratio = 1.65 =+65%

from your injectors
stock injector = 200? cc
new injector = 330cc/min
flow ratio = 330/200 = 1.65 = +65%

so at idle , the FMU isn't active...so you only have the increased fuel from the injector upgrade which is the 50-65% i quoted you at idle...

under boost you have to multiply the flow rates
new flow rate = 1.65*1.65*stock = 2.72 * stock
so 200 * 2.72 = 540cc/min injectors
540cc/min /1.5 = 363 wheel hp worth of fuel

if you're actually making 250 hp instead of 363 then your a/f ratio should be around

250/363* (12:1) = 8.3:1 << rich

-nuke