99 s10 2.2 with t3 all homemade
11-21-2011, 03:33 PM
#11
0.0 BAR
Thread Starter
Join Date: Nov 2011
Posts: 27
at wot it is open loop. this is all very basic stuff. ive done all of it for long enuf to know that all the scary stuff u read on the internet is just internet chatter. the speed of the timing change is within 1 revolution of the engine in a coil pack engine. the water in the line cant even run out fast enuf to cause damage. its almost instantaneous, and the sensitivity is very high. if u damage an engine like this from detonation, it is because u pushed it outside its limits. at 5psi, i can ride around all day with my foot on the floor and it will be fine. fmu or not. it wont make any power, but it wont hurt it either 
like i said, i have a wideband ill put in it if i want to push it. but for now, if the narrow reads rich at 5psi, its golden. and you need to remember that with water injection, u dont want to run it rich. peak torque is made at 13.1afr. those rich mixtures are for keeping pre-ignition down, but do nothing for power or economy. water lets you run 13-13.5afr's and factory or even advanced timing in boost. optimal timing and mixture is where the power is. richening and retarding is sacrificing power to keep it alive
like i said, i have a wideband ill put in it if i want to push it. but for now, if the narrow reads rich at 5psi, its golden. and you need to remember that with water injection, u dont want to run it rich. peak torque is made at 13.1afr. those rich mixtures are for keeping pre-ignition down, but do nothing for power or economy. water lets you run 13-13.5afr's and factory or even advanced timing in boost. optimal timing and mixture is where the power is. richening and retarding is sacrificing power to keep it alive
Last edited by pork chop; 11-21-2011 at 03:42 PM.
11-21-2011, 03:41 PM
#12
1.5 BAR
Join Date: Oct 2009
Location: CHICAGO
Posts: 935
ok....the stock fpr doesnt know what atmospheric is. it is a simple diaphram that reacts to the pressure on one side, to restrict fuel flow on the other. i say pressure because there really is no such thing as vacuum. theres 14psi of pressure all around me. a 2.2 has 55-60 psi of fuel pressure at wot. the fpr lowers that into the 40's when the vacuum in the manifold pulls the diaphram in the fpr. when i add 5psi of boost, the fuel pressure raises 5psi also. so when my boost gauge reads +5, the fuel pressure gauge reads 65psi. i know this, not only because i know how it works, but also because im sitting there watching the pressure gauge 
the fmu is not even necessary on a fuel system like this one, but at a low ratio like 4:1 or 3:1, it is easier to tune for wot. my small factory injectors can easily handle 100+psi . even at 10psi boost, they will never see that tho, because of diminishing returns. they may see 85psi, which is fine because its more than needed. with a reliable water/meth injection system coming on at +2psi, good gas, and the stock fpr raising it 1:1, the factory computer and injectors have plenty of leeway to keep it stoich.
im not changing the tune or any of the injectors. i believe 2.2's have 17lb'ers, and if i find a set of 19's i may put them in, but the computer will stay stock and the o2 will correct the mixture for me. that small of a change is within the reach of factory stuff. and with the 19's, no fmu would be needed at all as in open loop, it would run richer.
anyway, im running it at 5psi so none of this really matters. a squirt of water and it will run 5psi with nothing else done to it. its doing it now without the water, but it pulls timing out. i can feel it step the timing back.
the fmu is not even necessary on a fuel system like this one, but at a low ratio like 4:1 or 3:1, it is easier to tune for wot. my small factory injectors can easily handle 100+psi . even at 10psi boost, they will never see that tho, because of diminishing returns. they may see 85psi, which is fine because its more than needed. with a reliable water/meth injection system coming on at +2psi, good gas, and the stock fpr raising it 1:1, the factory computer and injectors have plenty of leeway to keep it stoich. im not changing the tune or any of the injectors. i believe 2.2's have 17lb'ers, and if i find a set of 19's i may put them in, but the computer will stay stock and the o2 will correct the mixture for me. that small of a change is within the reach of factory stuff. and with the 19's, no fmu would be needed at all as in open loop, it would run richer.
anyway, im running it at 5psi so none of this really matters. a squirt of water and it will run 5psi with nothing else done to it. its doing it now without the water, but it pulls timing out. i can feel it step the timing back.
the o2 will not correct the mixture under boost. the ecm is trying to keep the afr at stoich under boost. the ideal afr under boost needs to be 12-125:1 for the most power. the richest you want to go is 11.5:1.
how would you run richer under open loop? under open loop the o2 sensor is out of the equation. there is no 2.5 bar map sensor for the ecm to read so its not going to know its boosting and its going to lean out.
you know its pulling the timing so you know you are running too lean. adding water and it now pulling timing just confirms that its knocking. cant make power with water. add more fuel or your going to pop the motor. the top compression ring land to the top of the cast piston is very small. maybe 1/4" and they will break from lean conditions or knock.
11-21-2011, 03:47 PM
#13
0.0 BAR
Thread Starter
Join Date: Nov 2011
Posts: 27
its not running lean. its running warm air under pressure. afr is not why an engine knocks. it pulls timing because it has too much cylinder pressure and pre-ignites. the proper fix for that is not richening up the mixture, its killing the pre-ignition. when the water goes on it, there wont be anymore timing issues. i dont want 12-12.5 afr because i will be spraying water. its a waste of fuel and power to run it rich
wot open loop=rich. injectors run at the highest duty cycle programmed in the pcm. raising the fuel pressure to them with a fmu is why u get the rich mixture at wot. if you arent in open loop, the fmu is useless since the pcm lowers the duty cycle to fix the mixture and satisfy the o2 sensor circuit. the whole point of an fmu is so u can steal the tuning ability away from the pcm at wot. u dont want the map to know whats going on....only to tell the pcm to stop thinking and spray fuel. then we adjust the fmu to get the afr right....and change nozzles in the water jet to get the quench right. at all other throttle positions, u want the pcm to choose the best settings for the best drivability.
heres a good write up. a little snobby, but they do have their ---- together, so i suppose they can be.
http://www.rbracing-rsr.com/waterinjection.html
wot open loop=rich. injectors run at the highest duty cycle programmed in the pcm. raising the fuel pressure to them with a fmu is why u get the rich mixture at wot. if you arent in open loop, the fmu is useless since the pcm lowers the duty cycle to fix the mixture and satisfy the o2 sensor circuit. the whole point of an fmu is so u can steal the tuning ability away from the pcm at wot. u dont want the map to know whats going on....only to tell the pcm to stop thinking and spray fuel. then we adjust the fmu to get the afr right....and change nozzles in the water jet to get the quench right. at all other throttle positions, u want the pcm to choose the best settings for the best drivability.
heres a good write up. a little snobby, but they do have their ---- together, so i suppose they can be.
http://www.rbracing-rsr.com/waterinjection.html
Last edited by pork chop; 11-21-2011 at 04:02 PM.
11-21-2011, 07:28 PM
#14
0.0 BAR
Join Date: Nov 2010
Location: Louisiana
Posts: 30
I just had this discussion about factory regulators being 1:1 with busa4 the other day. Its a simple diaphragm, and its position changes based on the pressure differential across it. The fpr will eventually saturate at some manifold pressure and stop increasing the fuel pressure, but I have tested them out to 10psig with no signs of saturation.
I ran a walbro 255 ***** out with a 12:1 fmu and 8psi of boost for about 50k miles on my 240sx, back when running an fmu wasn't so taboo. The fuel pump maxed out at around 90psi, it wasn't supplying the theoretical (43+12*8+1*
= 147psi. My injectors with 160k miles didn't mind the excessive pressure for all those miles, and i beat the living **** out of it. It was a mid 13sec car with $1000 in mods.
I have a walbro 190hp fuel pump in my daily driver (89 integra) and the same fmu that I used on my 240sx. It has been boosted for a year at about 7psi and she is still going strong. These injectors have 198k miles on them and they don't mind the high rail pressure either. The afrs are perfect under boost and cruise with the 8:1 disk in the fmu.
You can read about how crappy fmus are all day on the internet. If you keep the boost low, they are a reliable source of fuel enrichment. I know they are not ideal, but they work.
I ran a walbro 255 ***** out with a 12:1 fmu and 8psi of boost for about 50k miles on my 240sx, back when running an fmu wasn't so taboo. The fuel pump maxed out at around 90psi, it wasn't supplying the theoretical (43+12*8+1*
= 147psi. My injectors with 160k miles didn't mind the excessive pressure for all those miles, and i beat the living **** out of it. It was a mid 13sec car with $1000 in mods. I have a walbro 190hp fuel pump in my daily driver (89 integra) and the same fmu that I used on my 240sx. It has been boosted for a year at about 7psi and she is still going strong. These injectors have 198k miles on them and they don't mind the high rail pressure either. The afrs are perfect under boost and cruise with the 8:1 disk in the fmu.
You can read about how crappy fmus are all day on the internet. If you keep the boost low, they are a reliable source of fuel enrichment. I know they are not ideal, but they work.
11-21-2011, 09:24 PM
#15
0.0 BAR
Thread Starter
Join Date: Nov 2011
Posts: 27
ya, injectors have to be pretty big to lock. i suppose a set of old 55's wouldnt like 110psi too much, but 17's are very small and wont mind any pressure i could push on em. if my stocker wont push past 70psi, ill replace it with a new gm unit. i tested a few autozone pumps a few years ago and they all deadheaded less than 70. the gm unit i ended up with deadheaded at 135psi. it wont do that with the flow of a real engine at wot, but 100psi was easy to get with the return line pinched (i went racing with 200shot jets, but lost the fuel jet, so i ran it with my 150 fuel jet and the return line pinched kinda like hilborn injection....super rich sweet smelling at the line, and ripping flames to the 60ft mark!!
fmu's get a bad rap like nitrous or welded spider gears. all of them work awesome for a guy like me....all of them are disastrous for the average high school kid
kinda like hilborn injection....super rich sweet smelling at the line, and ripping flames to the 60ft mark!!fmu's get a bad rap like nitrous or welded spider gears. all of them work awesome for a guy like me....all of them are disastrous for the average high school kid
Last edited by pork chop; 11-21-2011 at 09:31 PM.
