Ease of Tuning evo3 16G with 550's vs 650's Using S-AFC2

[Ski Bum]

I have read many different oppinions on which injectors would better suit an evo3 16g. Some say 550's are plenty while others say that 650's will offer more room to maximize the potential of the turbo. Another point brought up was ease of tuning with the S-AFC2. I have heard that 550's are quite easy to tune while the 650's tend to be more difficult.

For background info the supporting mods will be: walbro 255 with FPR, evo3 16g, FMIC and the rest of the no-brainer supporting mods. As far as boost levels go I would like to run around 18psi daily on 91 octaine and occasionally hit 20-21 psi (or as high I can go) with 100 octane fuel. I will only be using a datalogger, AFR gauge, EGT and a S-AFC2 to tune (non-eprom ecu).

 

[dsm-onster]

Minimum cycle time for most pintle types is 2.0 Ms. for P&H and 2.5 for saturated units. The Disc will cycle as low as 1.0 Ms., pulse width, in P&H and .2.0 Ms. for the sat. Unit. (The Lucas Disc weighs only .4 Grams. and the Bosch / Nippon -Denso pintle is at 3.9 to 4 Grams. --- Ten times heavier) The reduced inertial loading of the disc, allows the disc to overcome the hydro- static load at excitation quicker and return to it's seat faster, providing quicker response times and more consistent cycle-to-cycle values. Because disc injectors are soo much lighter (especially the Lucas), their standard service life is more than a pintle type.

This makes much more sense. . . than the route I was taking to understand the longer service life

IDCs are not always logged with 100% accuracy. Some injectors are actually flowing about 83% of rating when the actual duty-cycle (as seen by the ECU) is at 90%. Some people commonly report logged IDCs of over 100% but this is not possible. Most injectors go static (open all the time) around the 93-96% range, so figures can be skewed a little when comparing one setup to another.

This is what I thought was the case as well. It would be near impossible for an injector that was open for 90% if the cycle to close and open in time for the next cycle. Since that is the case, the injector doesn't close completely and it is on the entire cycle... So, thought ecu can calculate the required time for charge to excite the injector to a high precision, the injecotr can not precisly open and close when it is resting for under 10% of the time.

 

[Ski Bum]

Well this would depend on what you see as limited. Limited on getting the most power out of a 16G setup? Or limited to bigger options down the road?

I plan on sticking with and maximizing a 16G setup as much as I can.

DSM-Link will definitley allow you to make more power than the SAFC and will grant you infinite expandibility. The question is, how much power will you be satisfied with? Do you ever see yourself going bigger?

No, cams are definitley not uselss without DSM-Link. No 650 will not be too dificult to tune with on the SAFC. You can expect around 300whp on good pumpgas tune.

300whp is my goal. If/when I reach that I'm sure it will be difficult to resist the urge for more, that we all have. At the same time, I am setting a goal that is reasonable, streetable and not overly stressful to the car that is/will be my daily driver for quite a while.

My ECU does not have an Eprom which is one of the reasons I chose the S-AFC2 route.

I went ahead and ordered a set of FIC 650's (they are on special for $269 shipped!) Will I be able to run them with the stock fuel pump (I have rewired it) and I do not yet have a S-AFC2?

 

[MyBeatGSX]

Do you have a wideband in your car MyBeatGSX? are you converting narrowband voltages? Im am just curious is all.

No never. All my tuning is done on a dynojet with a built in wideband logger. It draws the AFR right along with the chart so it makes everything very easy to see and adjust.