Lotus Elan

HypoJets and O-tubes on the way...

PostPost by: simonknee » Thu Sep 06, 2012 10:41 am

MickG wrote:Simon It's OK; I think I found it in the photo's section


That's probably it but the pics folder I see doesn't show how how to improve the p-spring.
One way is to pull out the p-spring and use a single turn snipped out from a spring of suitable diameter.

I found my old thread (msg 3342) from 2010 and to quote me:

"Modded the aux p-spring. In my case the recommended snippet of spring was to big
to allow it to fit at all. The next size down was too sloppy. But the next size
down fitted inside the P - stiffened it up nicely. Very tight fit. How do you
get them out?"

Not removed them since so I still don't know the answer to that last question :D
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PostPost by: simonknee » Thu Sep 06, 2012 11:53 am

Ah, the photo album with the springs is called "Weber Upgrades", hopefully you found this one too Mick.
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PostPost by: lotocone » Fri Sep 07, 2012 9:20 pm

simonknee wrote:
So lets go a bit richer, H223:
H223-12.0.png


I left the idle mix screws the same and this resulted in an AFR at idle of 12.
This was only a short run as I wanted to get back to watch the Opening Ceremony (go Hawking!)
However the graph immediately looks smoother with no nasty lean spikes.
Felt good too!

So this morning I leaned the mix back a bit for the run to work:
H223-12.4.png

Ended up with an idle AFR of 12.4
Ooooo look at that!
No nasty lean spikes and much more tightly bunched around the ideal afr.
Feels smoother to drive and easier to move off too.



Simon, Thanks again for all of this info. It condenses a lot from the Yahoo group.

I don't have an AFM (air fuel meter), but I ended up using an H222 Hypojet (.022" on second largest air hole in jacket out of 4 holes available). So we are very close. When I set the idle mixtures screws, I used a Colortune. Do you have any idea how this compares with the use of an AFM? I wonder if I am close to the idle AFR of 12.4 that you have.

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PostPost by: StressCraxx » Sat Sep 08, 2012 2:33 am

lotocone wrote:
simonknee wrote:
So lets go a bit richer, H223:
H223-12.0.png


I left the idle mix screws the same and this resulted in an AFR at idle of 12.
This was only a short run as I wanted to get back to watch the Opening Ceremony (go Hawking!)
However the graph immediately looks smoother with no nasty lean spikes.
Felt good too!

So this morning I leaned the mix back a bit for the run to work:
H223-12.4.png

Ended up with an idle AFR of 12.4
Ooooo look at that!
No nasty lean spikes and much more tightly bunched around the ideal afr.
Feels smoother to drive and easier to move off too.



Simon, Thanks again for all of this info. It condenses a lot from the Yahoo group.

I don't have an AFM (air fuel meter), but I ended up using an H222 Hypojet (.022" on second largest air hole in jacket out of 4 holes available). So we are very close. When I set the idle mixtures screws, I used a Colortune. Do you have any idea how this compares with the use of an AFM? I wonder if I am close to the idle AFR of 12.4 that you have.

Bob


Hello Bob,

When you tuned the idle mix screws with the colortune, did you set them for a "bunsen blue" color or did you back the screw out to a yellow flame?

Thanks,
Dan Wise
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PostPost by: lotocone » Sat Sep 08, 2012 1:05 pm

Hi Dan, My settings are for bunsen blue but close to yellow (too rich). Maybe by being at the rich end of the blue zone I'm at 12 something AFR. On one cylinder I think I had to start getting into yellow to avoid popping from the tailpipe.

Bob
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PostPost by: simonknee » Mon Sep 10, 2012 8:01 am

My brother has a colour tune so if I remember to get hold of it I will see what the afr meter makes of the different colours. You definitely want to be at the yellow end of blue when at idle. However whether that is just blue or just yellow perhaps I can divine. Thinking about this I may have use for it to check the idle mix balance between the carbs. At present I go by feel and plug cuts which is not as scientific as I would like.

No data for the last few days as it was my stag weekend and I probably had more alcohol in me than a Californian gas station :D
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PostPost by: simonknee » Mon Sep 10, 2012 8:56 am

Ah I forgot I do have some data from last Thursday.

I went to Aylesbury to get my exhaust modded. So the A41 provided a nice testing ground. Unfortunately you have to hit save on the logger before you stop the engine (it cuts the power) or the data file gets corrupt. So I do not have the run up, just the run back. A shame as I was experiment with "clocking" the new E-tubes. "Clocking" you say, "now what is he on about". Keiths E-tubes have only a few air holes, my O3 e-tubes have 3, spaced evenly at 120deg around the tube (O2 has 2 holes, O4 has four at 90deg, etc). You have the option of clocking (i.e. positioning) the tubes with a hole facing the auxillary venturi passage or no hole facing the passage. If a hole faces the passage then this "reduces the fuel pumping effect" and creates the equivalent of an O2.5 (I put the quotes as these are Keith's words to me and I am not quite sure what he means but expect it to be in his next white paper).

Anyway I only have the O3 data not the O2.5 which is a bit of a shame.

On with the graphs...

WOT-3rd-redline.png and


This is a WOT (wide open throttle) pull as the red trace shows (it says 90% rather than 100% as I need to accurately calibrate the TPS). I was in third and the black trace shows I got from 2100rpm to 6120rpm in 12secs. Given that I think I have a semi-wide box with a 3.7 diff that equates to 25mph to 75mph. Pretty pleased with the nice clean pull. The black line shows no dead spots. The afr is going a bit rich to 11.5 rather than 12.5 so there is improvement to be made here. Interesting that it doesn't head south until a couple of seconds in but this may be a product of my less than perfect initial application of throttle.

Keith says that if the mix is too fat up at the redline when WOT then you need bigger chokes to lean it out. I will tweak further with the parts I have but seems like I need to order a set of 33 or 34 chokes too.
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PostPost by: simonknee » Mon Sep 10, 2012 10:04 am

Here's how to clock the hole so it lines up with the passage.
clocking-O3.jpg and

The one screwed in has a marker pointing to 9 o'clock.
The one that is out has a marker that will end up at 3 o'clock.
Note the alignment of the hole half way down the tube.
The main jet carrier will grip the tube enough that the positioning is retained.
A small squeeze with the pliers will encourage a tighter grip from the carrier.
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PostPost by: simonknee » Mon Sep 10, 2012 10:14 am

The previous posts also demonstrate a really cool thing about Keith's parts.
He is designing in tunability where previously you had to obtain more parts from weber.
You can obtain half-sizes with this clocking technique.
If you drill small things confidently you can add extra holes to the e-tube and turn it into an O4 or O5.
Alternatively you can seal up some holes with epoxy or the end of a cocktail stick.

Hopefully he will soon release his white paper that explains what is really going on in the emulsion tubes.
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PostPost by: simonknee » Mon Sep 10, 2012 6:20 pm

So Keith's take on that WOT pull is as follows...

The strange bit at the begin is normal as you would not normally go WOT in that gear at that rpm.
Interesting he says that the wilder the cam the more prolonged the section will be - demonstrating the difficulty running hot cams at low rpm.

Other than that I am obviously rich and actually for non-ethanol fuel I should be pegging 13 AFR as the magic number.
12.5 AFR is for the gasohol that some of you have to put up with.
So (edit) Paul's engine with it's mapped fuel injection is pretty much spot-on.

Pretty sure I will need larger chokes, just waiting to hear if Keith thinks 33mm or 34mm...
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PostPost by: simonknee » Mon Sep 10, 2012 9:10 pm

Here's a bit more info of the sort Bill was asking for.
Rather than get the afr spread for a whole run you want to split the data into different sessions.
Bill suggested:

1. idle
2. slow acceleration over the driving range
3. moderate accleration over the driving range
4. low speed cruise
5. high speed cruise
6. max acceleration, perhaps over different rpm ranges

The Logworks software lets you search with criteria such as:
RPM > 2000 AND RPM < 3000 AND TPS >10
In words this means include all data between 2000 and 3000 rpm except any where the throttle is closed.
2-3K.JPG and


Bill you are correct in this tends to remove the spurious out lying points.
(note that the telemetry in the screen grab is only a portion of that which makes up the AFR spread chart)

The same again but for 3000 to 4000 rpm
3-4K.JPG and


And again for 4000 and up
4K-up.JPG and


The limitation here is that is does not differentiate between cruising and accelerating. I do need to do some controlled driving but that is easier said than done without a test track. However it is giving a fairly clear picture that I am getting richer the higher the rpm.
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PostPost by: ericbushby » Tue Sep 11, 2012 7:55 pm

Simon,
Please see PM regarding chokes
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PostPost by: simonknee » Tue Sep 11, 2012 9:17 pm

PM replied to.
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PostPost by: Johnfm » Thu Sep 26, 2013 8:20 am

So

Does Keith, or anyone else, have a handy guide that lists which hypojets and o-tubes etc to buy for a stock (ie non big valve) engine running DCOE2 carbs?

No doubt it would be ideal to have all the afr logging etc, but I am not going to do that.

It would be nice to know which bits to order, price them up and order them.
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PostPost by: john.p.clegg » Thu Sep 26, 2013 11:44 am

John
This is where Keith lives now...

http://autos.groups.yahoo.com/group/sidedraft_central/

John :wink:
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