Well Regan is pretty in it too but I think so.
Don't you look at my accountant.
He's the only one I've got.
Depends largely on the end use and the bmep capability of the engine.
The defining factor is the dynamic compression - this is created by the addition of the static com and that created by the combination of trapping efficiency and the delivery ratio.
The higher the trapping and delivery efficiencies are then the max static com that can be tolerated short of detonation ,is reduced.
But a good example is a conversion I did to a brand new TM KZ10 kart engine.
This was designed to run in open class and has a 60mm piston giving 152cc.
The regulations only allow unleaded pump gas, and initially it was run with the standard straight line ignition.
I played with a few combinations of com and static advance with a det sensor bolted to a head stud.
This engine would have state of the art trapping and delivery numbers , especially with a VF3 and 36mm carb in place of the 30mm regulated unit.
Thus a fairly low com was needed to get the right combination of peak power and overev capability when pushing up against the over advance created by the non retarding ignition.
It ended up with 13.2:1 full stroke and this setup was right back at the original numbers of 15* advance and 1180*F - the lower egt caused by the excessive advance.
Any lower on the com and the peak dropped ( 58Hp crank @ 12800 ) but any higher and the peak remained constant but it detoed in the overev at 14400 +.
This deto could be suppressed by going richer, but then the power suffered everywhere.
With a proper ignition I would guess at 13.8 :1 and an egt up at 1280 as unleaded burns alot faster than AvGas and added to the extra retard able to be dialled in with a digital.
Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.
I am now starting to make some headway with tuning the Beast and I am beginning to enjoy using the Ecotrons small engine EFI kit for two strokes and its 2T tuning softaware.
Recorded some RPM and TPS data along with the Lambda O2 sensor.
This is an expanded section of the recorded data with TPS at the top, RPM in the middle and Lambda at the bottom. The curser shows the Lambda is 0.86, rpm 6.5k and TPS 99%.
Exported the Alpha-N map to Excel. Using a spreed sheet makes it easy to manipulate the map and keep the steps between cells smooth.
The thick blue line is the Lambda and its max lean where its flat on top and the bottom of the dips is Lambda 0.8 - 0.88 ish. The red line is TPS and thin blue is RPM.
By printing out the Alpha-N map and studying the Lambda-RPM-TPS data I can see where to make changes in the table.
Its starting to feel like progress but I have not got so far as to have a worthwhile dyno graph to show off yet.
.
..... just realized that I have done the whole evenings tuning work without the battery charger hooked up to the battery so as to have a stable EFI supply voltage.
How many more ways can I find to make mistakes with this thing ......![]()
Keep going TeeZee - they say that what doesn't kill you makes you stronger.
Thank you for re-posting your ignition curve, I loaded it into my Ignitech for Taumarunui and the bike ran great ( apart from a carb flooding issue ) much better drive at low-mid Rpm and plenty of over-rev as well.
This may be of no use or you may already know. In Excel if you plot a set of data points (ie xy scatter graph) if you put the mouse on a data point you can click and drag it and it will update the raw data. This might be of use for tweaking your maps
A thought for 2015s project..would it be possible to make an adaptor to convert a single cylinder crankcase to a V configuration allowing the use of a wider variety of available 50cc cylinders.I remember seeing that higher BMEPs were possible with smaller engines as well.Certainly it would seem the cylinders would be mostly reed as I don't envision the common intake flowing enough nor would it seem possible as an RV unless a twingle.
Why make an adaptor, cast a new one, that way you get exatly what you want.
I've held 2 RG50 cases together and pondered that. Would be legal too. But still easy with a single to get a raceable package.
Don't you look at my accountant.
He's the only one I've got.
Yesterday was brilliantly fine, today its raining, that's New Zealand for you. Strangely not many NZers bother with rain coats.
Taumaranui a grade race 1, the other A grade races can be seen here:- http://www.kiwibiker.co.nz/forums/sh...post1130659210
With Lambda at 0.76 its a little rich at 11.6K rpm, the Lambda (bottom line) hovers mostly around 0.9 - 1.0 so a little lean for best power every where else.
But look at the Lambda line, there is no big peaks and hollows now, Ecotrons recorded data and data analyzer software is sure a big help with sorting out the fueling.
Flettner,watching you guys cast complex forms is like magic to me.I can machine simple forms manually or even program CNC but your work is an art.Ideally I'd like to incorporate everything that has been shared in one motor but my other limitation is the wallet.Off the (ebay)shelf parts and sweat equity it is.
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