JRios

Just a little info for everybody that wants to use a bored maf (53.5mm) with 370cc, you multiply the stock K value by 1.047824.

So that's :

53E3 Hex= 21475 Dec x 1.047824= 22502.0204 Dec

21475 x 1.047824= 22502.0204 Dec

That's 57E6 Hex.

So that would be the new K value 57E6.

__________________
Jorge
1996 SE-R

 

JRios

Does anybody have the flow numbers of 370cc injectors at 4 bar?

Peter

Umm - YES!

Currently running them on emanage, switching to JWT
*soon*, but for the 4-bar 370's, it's 427.24.

Peter

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'02 G20 Sport
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JRios

Thanks!! Now maybe we can figure out the bored maf and 4 bar setup

JRios

Ok, now being that the new K value for 370cc (at 3 bar) and a bored maf is 57E6 Hex and that equals 22502 Dec.

Now 370cc at 4 bar is 427.24

What I did was take the original injector size and divide it be the new one.

376.35 / 427.24= 0.8808867

Then I take the original K value which is 22502 Dec and multiply that by 0.8808867.

22502 x 0.8808867= 19821 Dec which is 4D6D.

New K value= 4D6D

JRios

For those wondering how it is that I got 376.35 as the injector value for 370cc, here's how I did it.

I have a N/A rom bin which the K value is 31206 Dec (79E6 Hex) and I have a U12 DET which has a K value of (53E3 Hex) 21475 (just in case it uses the same MAF as the DE). Now, when I would do the formula of changing injectors, I assumed that the DE uses actual 259cc injectors.

Now when I did 259/370 = 0.7

Now when you multiply (k value) 31206 x 0.7= 21844.2 Dec which is 5554 Hex

Now, this isn't right, because the stock U12 is (53E3 Hex) 21475 Dec.

In order to get the same value I had to use this formula

259/376.35= 0.6881892

Now you take the N/A K value 31206 Dec and multiply it by 0.6881892

31206 x 0.6881892= 21475 Dec and that's 53E3 Hex.

Now, this is all on the assumption that the 259cc are infact 259. This is just me throwing out numbers I would have to actually test this to see how accurate it is. But I think it's a good start. What do you guys think?

JRios

Any suggestions Calum?

Calum

You've got the right idea, but two points.

First, 370s aren't really 370s. I had a set tested and balanced by RC a while back, and while I don't remember what they ended up being it was significantly higher than 370. I don't know how close 259s are to actually being 259s, I've never had a set tested. Its not that big a deal, the ecu can and will adjust up to 20%. After you pick your k number just watch the alpha parameter. It will tell you if you need to go up or down. Adjust the k value to minimze it.

Second, I think you'll find if you use 53E3h in a bluebird rom with a 53.5mm maf, all other things being unchanged, it will run on the lean side. Can you walk through the derivation of your original multiplier, 1.047824 (round it to 1.05, the numbers come out smoother)?

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JRios

Ok, so 21475 x 1.05 = 22548 (5814 Hex).

So now it would be 22548 x x 0.8808867= 19862 (4D96 Hex)

What do you think? I would have to try this out on a car to be accurately correct. Right now, I'm still looking for a donor car, hopefully by the beginning of next year I will have a few cars to play with.

JRios

Ok, so 21475 x 1.05 = 22548 (5814 Hex).

So now it would be 22548 x 0.8808867= 19862 (4D96 Hex)

What do you think? I would have to try this out on a car to be accurately correct. Right now, I'm still looking for a donor car, hopefully by the beginning of next year I will have a few cars to play with.


Edit: Ugh, spelling errors.

Calum

Yea, but how do you come up with the 1.05 in the first place?

JRios

Doh, I thought that you wanted me to use this number instead. Let me get back to figuring this out again then. :P

nite-stalker

Calculated K values are really only good as starting points. You really need to adjust them after running on a wideband o2, etc... from there, keep trimming using the percentage technique. if 10% too rich, lean K value by 10%, etc. keep doing it until it is correct.

however it is not as simple as that, to make things run in harmony, you will have to play with the latency and K value together, if not it will be a new bunch of headache... AF just right at idle, but too rich/lean at WOT, vice versa.

JRios

Very true, I was getting to that part. I was just trying to do it in steps .