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New injectors = too low req_fuel?
Posted: Thu Jun 15, 2006 9:09 pm
by Jon k
Running a 2.5L inline 6 cyl on a MS-1 V3 with MSnS-E 029Q2.
I am going from 17# to 42# injectors. I want to get my off-boost map working so I can drive the car limped. However, 6 cyl, 6 inj, 42# injectors and 14.7 stoich equals a 6.3ms req_fuel. Too low? Manual says more than 8 less than ~12-15 What can I do? Car need the 42# to make desired HP
Posted: Thu Jun 15, 2006 9:43 pm
by jakobsladderz
The biggest problem will be trying to achieve a stable idle with the available timing resolution. There's not much you can do WRT injector sizing if you have chosen the injectors based on your max fuel requirements. You must be running some serious boost though...
with the high res timing in MSnSE you should not have too many issues with resolution at low pulsewidths.
if you still have hastles another way (which I consider to be a nasty hack) is to use a rising rate fuel reg to allow for the use of smaller, idleable injectors but to provide enough fuel at high power levels. Problem with this and high boost is that there are not too many fuel pumps rated to handle even 3 bar fuel pressure (~standard) plus 1 bar boost (14.5 PSI), and I gather you would be running much more than that.. Injectors also can behave weirdly if the pressure is raised too high.
Posted: Thu Jun 15, 2006 9:46 pm
by Jon k
jakobsladderz wrote:The biggest problem will be trying to achieve a stable idle with the available timing resolution. There's not much you can do WRT injector sizing if you have chosen the injectors based on your max fuel requirements. You must be running some serious boost though...
with the high res timing in MSnSE you should not have too many issues with resolution at low pulsewidths.
if you still have hastles another way (which I consider to be a nasty hack) is to use a rising rate fuel reg to allow for the use of smaller, idleable injectors but to provide enough fuel at high power levels. Problem with this and high boost is that there are not too many fuel pumps rated to handle even 3 bar fuel pressure (~standard) plus 1 bar boost (14.5 PSI), and I gather you would be running much more than that.. Injectors also can behave weirdly if the pressure is raised too high.
Yeah I ran a RRFPR before and I don't like how they react. I think I may just try and up the idle RPM if I have issues - I hope I won't
Posted: Thu Jun 15, 2006 11:14 pm
by keithmac
I run 42lb`es at 4 bar (equates to 500cc injectors), works very well! my req-fuel is 5.9 but I`ve not seen any real drawbacks, idles well enough at 14:1 AFR.
The HiRes code is great, but I`d wait `till its been finalised before running on boost with it.