Rtek 850cc x 4 injectors - need your opinions/experinces
#1
Senior Member
Thread Starter
850cc x 4 injectors - need your opinions/experinces
ok, in the endless pursuit of more forward Gs, time to upgrade to the 2.1 + more injector while engine is rebuilt.
some say don't do 850's on the primary, some say no problema.
i'm considering these:
http://www.ebay.com/itm/4-Siemens-De...item3cb364afbc
why, thinking tuning would be much simpler than having primary different than secondary.
seller claims these have superior flow characteristics than old design.
i personally dont see idle/response issues specially w/ the fresh rebuilt. i've been running 720's w/the Rtek 1.8 with the idle resistor almost maxed. my multimeter says injector pulse width is over 5ms @ 1000rpm. so going to 850's on a fresh motor (more vacuum) i'd expect pulse width not change much from current. seems to me there will be plenty of room for fine adjusment.
thoughts,experiences, suggestions appreciated.
some say don't do 850's on the primary, some say no problema.
i'm considering these:
http://www.ebay.com/itm/4-Siemens-De...item3cb364afbc
why, thinking tuning would be much simpler than having primary different than secondary.
seller claims these have superior flow characteristics than old design.
i personally dont see idle/response issues specially w/ the fresh rebuilt. i've been running 720's w/the Rtek 1.8 with the idle resistor almost maxed. my multimeter says injector pulse width is over 5ms @ 1000rpm. so going to 850's on a fresh motor (more vacuum) i'd expect pulse width not change much from current. seems to me there will be plenty of room for fine adjusment.
thoughts,experiences, suggestions appreciated.
Last edited by Clubuser; 06-07-12 at 04:25 PM.
#2
rotorhead
iTrader: (3)
Assuming those fit correctly, the issue is that the Rtek 2.1 has presets for 720s but not 850s. So you will be fiddling with fuel correction and such.
Also, make sure you don't get confused with the advice about 850 primaries on FD's. When people do that, they are usually swapping in the OEM side feed 850 (originally designed for the secondary position) and put it into the primary. They don't work well in the primary position on your typical FD running Power FC management.
Also, make sure you don't get confused with the advice about 850 primaries on FD's. When people do that, they are usually swapping in the OEM side feed 850 (originally designed for the secondary position) and put it into the primary. They don't work well in the primary position on your typical FD running Power FC management.
#3
Rotary Revolutionary
iTrader: (16)
There isnt much adjustment available at idle unfortunately. I'm running 4x750 and my variable resistor is at nearly 4 volts to get a smooth idle. I've tried running the N390 afm (cosmo 13b-re) and it wouldn't even try to idle regardless where the variable resister is set. You might have better luck leaning out larger injectors than bumping up the DC on smaller ones, but I doubt it, the variable resistor is pretty limited, and almost worthless in my experience.
#4
Senior Member
Thread Starter
#6
Rotary Revolutionary
iTrader: (16)
That being said, I dont see why you would have a problem getting 850's to run on the stock afm.
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