NefMoto

Just looking to garner another set of eyes on my numbers for calculating KRKTE for new injectors... pretty sure this is all correct in the theoretical sense but doesn't hurt to double check. :)

New injectors: Bosch EV14 52lb/hr (550cc/min)
Target fuel pressure: 4 bar (58.01psi)
Cylinder displacement: 0.44525dm^3 (1.8T)
n-Heptane flow rate for given pressure: 434.436g/min

So, for the given flow rate, pressure, engine size...

KRKTE = 50.2624 * 0.44525 / 434.436
KRKTE = 22.3793 / 44.436
KRKTE = 0.05151

Does this look accurate? Also, as far as actually applying this value... I've been reading that most maps have a "factor" for this value.  What is the purpose of the factor?  Is it a scaling factor?  Should I be adjusting my calculated KRKTE by the factor before inserting it, or just insert what I got and WinOLS/TunerPro will handle the rest?

This looks correct.  This would be your starting value...

OK, just wanted to make sure I wasn't missing something simple.  Thanks!  :)

put that value in and multiply the stock TVUB table by 1.20 on all 5 lines.  the car should start.  then get 100 miles on the trims and in all likelihood you'll just need to raise the TVUB table.  you'll probably need 1.30 or there-abouts, rather than 1.20-ish, but just start slow.

Why should one approach it that way?  Isn't TVUB calculable if you have calibration data for the injectors?

no engine ever works on strictly calculated values since every engine is different. That's why you custom tune all engine to get the most out of them.

I personally wouldn't bother with any theoretical calculation, I would just take stock KRKTE, see how many times is the new injector larger than stock (cc/min) and appropriately scale KRKTE by that value.

TVUB can usually be calculated from spec sheet but it will probably not be spot on since again, engines differ. FPR might be a bit off, etc, etc.

I don't expect that things will be spot on... I'm just trying to learn and also do some prep work on the tune so when I flash it and start logging... I can be as close as possible.  I mean, if you can get within 90 - 95% of the optimal values by doing some theoretical stuff beforehand... why wouldn't you want to? :D

except that you're not within even ball park with the calculations. KRKTE is way off. Stock is almost 0.15 @ 320cc (some say 350cc). 52lbers at 4 bar at 630cc would therefore be around 0.73 or so. That way off the value you theoretically calculated for these injectors by almost 50%...

Heres what i used on my BT 1.8t car way back when, 550cc ev14's at 4bar

my car had slightly increased displacement as i was +1mm on piston size, but its a start i guess if you want.


krkte - .04746
tvub - volts 8, 10, 12, 14, 16
         1.2627,.7586,.4889,.30,.1636

Stock for me is ~0.10, and I'm getting 0.05151 from my calculations.  That's almost half the original ms/% time.  Assuming the stockies are 316cc injectors given the value in KVB, then 550cc injectors at 4 bar is around 635cc.  635 / 2 = ~317.  Almost exactly *two* times more.

How is my calculated KRKTE supposedly so far off? O_o

Sorry. Platform discrepancies, you're obviously calculating for different platform I had in mind  :P

You're good then!

Have you seen anywhere this sheet? I would like to analyze it and include it then into my me7 wizzard ;)

Each manufacturer should disclose it on their spec sheets but this information is like a best kept secret around... There is a site that has spec sheets for a few types of bosch injectors:

http://www.boschdealer.com/specsheets/

Ev14 specific sheet is here but I am afraid that it is inaccurate in multipliers (for fuel pressure) section as they don't make sense seeing how hey jump around when pressure is increased and they should more or less linearly increase :
http://www.boschdealer.com/specsheets/0280158117cs.jpg

He means spec sheet from the manufacturer. Each one will be different.