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PostPosted: Mon Jul 16, 2018 8:12 pm 
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Rob has a good post coming that we have spoke about tonite .
When you are on boost you are basically pouring fuel in .
Wait for it as a holley or weber has no tapered needle


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PostPosted: Mon Jul 16, 2018 8:15 pm 
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Where will that post be, Ian...in this thread? I'm interested to read it.

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PostPosted: Mon Jul 16, 2018 8:26 pm 
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Ian_B wrote:
Rob has a good post coming that we have spoke about tonite .
When you are on boost you are basically pouring fuel in .
Wait for it as a holley or weber has no tapered needle

I believe at the top end you are trying to pour the fuel in ,if your needle ends up as a thin needle point it might not as well be there I would try shortening it so there is no restriction and get maximum fuel


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PostPosted: Mon Jul 16, 2018 9:19 pm 
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Hmmm...possibly, not sure. If you look at the AFR traces, when there is sudden WOT it leans right out, then gradually gets richer back into the right window. Suggesting to me it's the transitional period that's problematic, and that steady state WOT fueling is fine. I haven't put any 3rd or 4th gear traces in this thread to show that, and I haven't tested that recently. I should do a 3rd and 4th sustained pull to see where it's at.

I'll keep it in mind though, if I reach a ceiling effect I'll consider something drastic like what you suggest. I've just taken off a bit more off slightly higher up (towards the pointy end) to grow that trend of improvements I've had so far. as shown in the scatter plots I posts earlier tonight. I'm doing it very conservatively/gradually.

Edit:

Out of interest I went back to pick a needle that visually looks like a match for what I need. I landed on BCA needle, it is in colour blue below and looks like it is richer than the existing BCF needle in the right sections. See below

Image

I'm going to give this needle a go, partly because it might work better, but also just for the experience of comparing what I've done to the BCF needle - for educational purposes basically.

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PostPosted: Mon Jul 16, 2018 9:53 pm 
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998cc
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If you need more accelerator pump action then you need thicker oil basically resistance.
The spring is resistance too.
If you cant get rich enough up top make the hole bigger Or a combination .
To me its a balance of taper and resistance to piston lifting.
Mikunis on bikes look at main jet diameter right up top.They still have a taper needle for mid and they have a pilot jet.That does the down low stuff.
Mine dont run oil and I believe they are a great beast.
The needle can be moved up and down to vary the mid.
I think they are better than SUs where a needle does all and there are hundreds of em and ya still need to sand em.
Ive got quad 36mm but no manifold and lacking skills


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PostPosted: Mon Jul 23, 2018 6:50 pm 
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Here's the latest sudden WOT.

Image

The AFR is getting more in hand. Still over 15:1 in the example posted there, but an improvement. The AFR is quickly coming back into the proper target AFR after that initial lean spike on sudden WOT too.

The XY scatterplot below shows that for manifold pressures of 4psi or greater, the maximum AFR it sees is 16:1. Again that's higher than I want, but it is an improvement. Well actually that holds true for the AFR at any positive manifold pressure. But 4 to 5psi is what the pressure initially hits in the manifold upon sudden WOT as you can see from the trace above - and as implied in the scatter plot below.

Image

Now AFR at idle is fine, my stable WOT AFR is fine. The two remaining areas to improve is one particular partial throttle AFR section and sudden WOT AFR. In order to drill down on this exact spot, I think I do need to observe the needle at those circumstances. So endoscope or some other means as you suggest. I think (hope) that the two circumstances that need enrichment will turn out to fall on the exact same section of the needle. If so, I should get this pretty close. [If not, it means that I am already compromising and that in order to get the sudden WOT AFR rich enough I would have to over-richen some part of the cruising AFR].

I bought and tried another needle as I alluded to above [edit: by this I mean as I mentioned in a previous post] , but it was way too lean, even though it is meant to be a richer needle. Which suggests that my existing needle wasn't stock and was already altered by the dyno tuner when setting this up originally.

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Last edited by Morbo28 on Mon Jul 23, 2018 8:31 pm, edited 1 time in total.

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PostPosted: Mon Jul 23, 2018 7:26 pm 
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I'd actually interpret the difference between the two needles above as the blue one being "leaner" than the brown - the basic shape of it is the same apart from the first few stations, meaning that if you set them both for the same AFR at WOT, the blue one would be leaner at idle & cruise :D

morbo wrote:
I think (hope) that the two circumstances that need enrichment will turn out to fall on the exact same section of the needle. If so, I should get this pretty close. [If not, it means that I am already compromising and that in order to get the sudden WOT AFR rich enough I would have to over-richen some part of the cruising AFR].


keep trying, but I reckon you'll find that there is no needle profile you can either buy or make that will give you everything you want in every circumstance... The HIF44 on my NA motor has really nice AFRs all the way from idle to WOT at 7000rpm, but I still see the needle flash to 16:1 if I nail the throttle at 2500 rpm in 2nd gear. It doesn't hesitate, and accelerates strongly. The only way I know it goes lean is because I have a gauge that shows me. If I didn't have the gauge, I'd think it was perfect and move on with my life

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PostPosted: Mon Jul 23, 2018 8:28 pm 
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simon k wrote:
I'd actually interpret the difference between the two needles above as the blue one being "leaner" than the brown - the basic shape of it is the same apart from the first few stations, meaning that if you set them both for the same AFR at WOT, the blue one would be leaner at idle & cruise :D

I think I just need to clarify, in my last post, the image is of data all running the same needle. There are two "lanes" of traces:
* the top "lane" which has two traces in the same lane is a plot of Manifold Pressure (light blue) and Engine Speed (red/brown)
* and the lane showing just one trace is AFR.
Check the legend in the top right of each lane.
The lanes all line up by time too - if you look vertically up and down the traces in ALL of the lanes, this represents data from the same moment in time. If you look right up the top of the image you will see time stamps.
morbo wrote:
I think (hope) that the two circumstances that need enrichment will turn out to fall on the exact same section of the needle. If so, I should get this pretty close. [If not, it means that I am already compromising and that in order to get the sudden WOT AFR rich enough I would have to over-richen some part of the cruising AFR].

simon k wrote:
keep trying, but I reckon you'll find that there is no needle profile you can either buy or make that will give you everything you want in every circumstance... The HIF44 on my NA motor has really nice AFRs all the way from idle to WOT at 7000rpm, but I still see the needle flash to 16:1 if I nail the throttle at 2500 rpm in 2nd gear. It doesn't hesitate, and accelerates strongly. The only way I know it goes lean is because I have a gauge that shows me. If I didn't have the gauge, I'd think it was perfect and move on with my life

I think you're right on both counts...I don't think I'll be able to eliminate the sudden WOT lean condition and I may already have reached the best case scenario, but I'll see if I can tweak it further using the endoscope to figure out the exact part of the needle to alter. And I have no hesitation on pinning the throttle most of the time either (theres no longer any hesitation and it used to happen only under very specific circumstances). I wouldn't think there was an AFR problem at all if I didn't have the gauge.

Given it's forced induction though, I feel like I have to play it quite safe. But I don't really know...perhaps even for a boosted engine it is quite acceptable to have those spikes? Any advice is very welcome. My natural thought is boost + WOT + lean is bad and should be ironed out but maybe I'm being too anal about it?

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Last edited by Morbo28 on Mon Jul 23, 2018 9:08 pm, edited 2 times in total.

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PostPosted: Mon Jul 23, 2018 8:46 pm 
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I should also add that the reason I'm trying to perfect this is because...so far the engine timing has only been tuned for use WITHOUT water/meth.

The water meth injection is currently operating, providing knock resistance and lower inlet/combustion temperatures. BUT the timing has not been advanced to take advantage of any extra power made available due to the effects of the water meth. I am currently assessing if it is a good idea to advance the timing when the water/meth is spraying. I would do this on the dyno.

In my build thread I've detailed the way I'd do this. The timing will only advance if the following criteria are met:
* Water meth spraying (it comes on above x PSI)
* No error from the AFR failsafe gauge (it gives an error signal if it is leaner than a specified amount at a specified manifold pressure)
* No error from the water/meth failsafe (it gives an error signal if any one of several errors are detected )

(I am also thinking of a further criteria - only allowing timing to advance above x RPM)

But if the lean condition means it's too dangerous to try to dial in more advance, I may not do it. If too risky, I might just use the water/meth for the other benefits without trying to eek out more power. It's not like it's short on power for me anyway...

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