FPR and KRKTE

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golfputtputt

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	FPR and KRKTE « on: February 08, 2016, 11:33:11 AM »

Ultra noob question here.

1.8t AWP me7.5

Have 3 bar FPR, changing to 4 bar

If injector on time = ('roughly') Load*KRKTE*req_lambda

I would lower KRKTE correct? it's currently something like .11564...some numbers, I don't remember. .11 is correct though, ms/%
How much would I lower it by? What do you gauge this scale by? (difference of amount to dial back for 4 bar as opposed to 5 bar) I assume when logging, I would change this and check injector on time and IDC. Anything else?

When upgrading FPR, does anything else need to be changed other than KRKTE?

sorry if this is a repetitive question that every noob asks.... Cry


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fknbrkn

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	Re: FPR and KRKTE « Reply #1 on: February 08, 2016, 11:36:59 AM »

krkte & kvb
iirc 0.0854 & 341


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nyet

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	Re: FPR and KRKTE « Reply #2 on: February 08, 2016, 11:37:50 AM »

krkte * 3/4

Did you bother reading the s4wiki page?

http://s4wiki.com/wiki/Fuel_injectors

And the tuning page

http://s4wiki.com/wiki/Tuning#Primary

which links here
http://nefariousmotorsports.com/forum/index.php/topic,320.msg6774.html#msg6774

which says:
KRKTE = 50.2624*(Liters/Cylinder)/(operating flow rate in cc/min * .684 constant )


« Last Edit: February 08, 2016, 11:41:14 AM by nyet »	Logged

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golfputtputt

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	Re: FPR and KRKTE « Reply #3 on: February 08, 2016, 11:49:12 AM »

Whoa, alright, I didn't know about the first and last pages, I didn't know they existed. my bad.

2nd link: I did know about that one but I wasn't sure if it applied from a 2.7t to a 1.8t and I also didn't really understand how to convert ms/% to cc/min. wasn't sure if it was cc/min/%.....
The info kinda tripped me up.

Yea i dunno, I guess my ability to find this information is pretty sub par. I'm tryin' here. I'll read all that info. my bad dudes.


« Last Edit: February 08, 2016, 11:57:02 AM by golfputtputt »	Logged

nyet

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	Re: FPR and KRKTE « Reply #4 on: February 08, 2016, 12:09:59 PM »

Quote from: golfputtputt on February 08, 2016, 11:49:12 AM

convert ms/% to cc/min

If you are good at dimensional analysis you can do this from first principles.

ms->min is easy.

1 minute = 60 * 1000 milliseconds.

100% = 100% load = how much fuel to go with one cylinder full of air at STP.. so figure out how much air mass is in a full cyl of air at STP, then divide by 14.7 etc... in grams. Then convert that to cc (density of gasoline).

I would go through the whole calc but if you are bored you can try for it.

converting cc/min to different values based on spec pressure vs actual fuel pressure is covered in the injector page.


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golfputtputt

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	Re: FPR and KRKTE « Reply #5 on: February 09, 2016, 11:32:08 AM »

Did the calculations and am posting here mainly to show ya'll that I'm not dumb Tongue

found info on my injectors and needed to scale the flow up for 4 bar FPR. I'm sure others have posted this before but whatever. If anyone else has these injectors:

2002-2004 AWP 180 317cc 3bar 06A 906 031 BA 0 280 156 061 EV6

using equation from s4wiki:

365.925=(√(58.0/43.5))*316.9

316.9cc @ 3 bar
365.9cc @ 4 bar

50.2624*0.4452/ (317*.684)=
50.2624*0.4452/ 216.828=
22.3768205/ 216.828=
.10320079 - old KRKTE (.10301 in bin)

50.2624*0.4452/ (365.9*.684)=
50.2624*0.4452/ 250.2756=
22.37682048/ 250.2756=
.0894087177 - new KRKTE

someone confirm my math?

Also, not sure if anyone has this document for ev12 and 6 injectors but info for EV12s and 6s are not on the wiki (not sure if they pertain to s4's) attached.


« Last Edit: February 09, 2016, 12:54:13 PM by golfputtputt »	Logged

SB_GLI

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	Re: FPR and KRKTE « Reply #6 on: February 09, 2016, 02:27:11 PM »

lots of people over-complicate this. Here's my approach.

1) find your increase in flow due to new injectors or FPR

1 - (316.9 / 365.9) = .134 flow increase

2) subtract from current constant based on flow increase

.10329978 - (.10329978 * .134) = .089458

That should get you darn close. Go for a drive and note the partial load LTFT afterward. Increase or decrease KRKTE based on LTFT. Rinse and repeat in needed.


« Last Edit: February 09, 2016, 02:31:26 PM by SB_GLI »	Logged

nyet

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	Re: FPR and KRKTE « Reply #7 on: February 09, 2016, 02:45:26 PM »

Quote from: SB_GLI on February 09, 2016, 02:27:11 PM

x - (x * (1 - k)) = x*k

You can just .10329978 * (316.9/365.9) dude.


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SB_GLI

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	Re: FPR and KRKTE « Reply #8 on: February 09, 2016, 05:45:42 PM »

hooray math Grin


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golfputtputt

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	Re: FPR and KRKTE « Reply #9 on: February 10, 2016, 10:44:06 AM »

how sensitive is this?
to the
.00000 degree?
.0000 degree?
.000 degree?
.00 degree?
.0 degree?

meaning, at what placement should I begin my adjustments if needed?


« Last Edit: February 10, 2016, 10:45:56 AM by golfputtputt »	Logged

SB_GLI

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	Re: FPR and KRKTE « Reply #10 on: February 10, 2016, 12:57:19 PM »

thousandths


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nyet

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	Re: FPR and KRKTE « Reply #11 on: February 10, 2016, 07:00:50 PM »

Quote from: golfputtputt on February 10, 2016, 10:44:06 AM

how sensitive is this?
to the
.00000 degree?
.0000 degree?
.000 degree?
.00 degree?
.0 degree?

meaning, at what placement should I begin my adjustments if needed?

Generally, 3 or 4 sig figs.

So
XXXX
XXX.X
XX.XX
X.XXX
0.XXXX
0.0XXXX
0.00XXXX

https://en.wikipedia.org/wiki/Significant_figures


« Last Edit: February 10, 2016, 07:02:57 PM by nyet »	Logged

nyet

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	Re: FPR and KRKTE « Reply #12 on: February 10, 2016, 07:03:38 PM »

Quote from: SB_GLI on February 10, 2016, 12:57:19 PM

thousandths

at 0.0XX that is only 2 sigfigs... not good enough, IMO.


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