Greg Amy

Anyone know the relative injector K-values for the stock US-spec DE and the stock JDM SR20VE?

__________________
Kakashi Racing
2006 ARRC/NARRC/NERCC, 2008 NARRC/NERCC ITA Champions!
1993 VE-Powered Electric Blue NX2000 (street rod)

Calum

It depends on the maf.

Greg Amy

DE MAF.

Here's what I'm trying to do, Calum: I don't want to go to the dyno yet to fine-tune the VE program, I'm waiting patiently () for the next-gen CalumSult box to ship before I do. In the interim, I'm running my VE on the street without solenoid activation. As such, I want to try my dyno-tuned race-engine BIN (.040 pistons, 10:1 compression) on the street VE - itself a derivation from the stock DE program - see if it has better driveability (I've got probs with mid-range, part-throttle surging, lean running).

I'm running the stock VE injectors, B14 TB, stock DE MAF, cold air intake. All I want to do short-term is upload my race-engine program with a change appropriate for the different VE injectors.

GA

Greg Amy

Bump...?

Calum

Its a little complicated, because your taking one program developed for one injector and wanting to use it on a different injector. Your leaving the stock 330s in the VE right? If so, then you need to leave the k-value alone (thats like a global fuel trim, and is affected by injector size). Did you adjust the k-value on your 10:1 program?

Your load scales (TP- Theoretical Pulsewidth) will be different for programs for different sized injectors. But in this case what your probably really interested in is the WOT performance, so we can cheat and just change the 3 right most columns in your fuel and timing maps. Note if they have a different RPM scale in the two programs (in Tuner Pro do a comparison on the RPM scales and check, it won't show this if you just do a comparison on the Fuel or Timing map as a whole) you will need to do a little manual sorting to do this. Just break out the pencil and paper and write out at X RPM I've got Y timing, then punch those numbers into your VE program.

Make sense?

Greg Amy

Uuuhh, 42?

Kinda. So you're saying that even though all the fuel injection components are the same as the DE that was in the car - except for the injectors - it's not as simple as changing the K-factor to accommodate the larger injectors? Just to be clear, I'm using whatever injectors came on the VE engine.

Would I be better off changing to my DE injectors? I can't imagine that this engine is going to flow THAT much more air than my race engine?

I'm actually really interested in partial-throttle, highway cruising driveability. The engine makes good torque down low, but seems to be running fat in most places, but lean at very light throttle. Plus, fuel economy seems a lot less than I'd expect (26-28 mpg average; I consistently got over 30 with the original DE).

What I'm really looking for is factory-like driveability with excellent WOT performance; it's really two completely different mindsets, but most certainly attainable. Since I spend the VAST majority of my time at partial throttle and low revs, I want to get that nailed down first, then we can hit a dyno to optimize top end.

What are the current crop of VE programs based on, and how were they modified?

Greg

Benito Malito

Basically you have to match the VQ table and the injector K value up so the MAF and injectors play nicely. Load up the various programs on TP and compare. You'll see what to do.

__________________
1992 SuperBlack VVL SE-R
1994 P10 KL0
2004 Forester XT SGM

Calum

Yes. The problem is that the ecu uses 'TP' (Theoretical Pulsewidth) as the calculated load. This is your load axis on maps that are referenced by load (like the fuel and timing maps). TP is the pulsewidth needed for whatever maf and rpm the engine is currently running at needed ideally to achieve 14.7:1 AFR. So if your injector size changes, all the load axis should be changed too.

Your K-value is what scales the calculation for TP. Its a ratio of the injector size to the peak reading of the MAF sensor. So the k-value changes as the injector size changes, and also if the MAF is changed. In practice, you can think of the k-value like your fuel pressure regulator- adjustments to it make global changes to your AFR.