ESE's works engine tuner

[lodgernz]

Frits numbers for the Aprilia of course make the assumption that you are able to develop EVERY aspect of the engine whole , to be able to use those ports
at that level of finesse - be careful, or should I say err on the side of caution.

Understood. Thanks Wobbly

[TZ350]

Page 980 ....

[fatbastd]

...and apologies if it should be elsewhere, though the 'brains trust' seems to look in here most often..

Anyway, a mate's son in the UK is at the sharp end of some mini-bike/pit-bike racing championship and keen to win it. Obviously. They are currently running pump Shell V-Power unleaded gas (the best pump available there these days, with no added ethanol). They are making 11hp in an air-cooled 39cc two stroke. They want to avoid an engine-induced DNF. They also need more off-corner grunt and are keen to try exotic racing fuels to achieve this. e.g.VP12 or 14 of some Elf rocket fuel. They are keen to go leaded.

Now, I've asked Wobbly this via email and he had some pointers, though I thought I'd pose the question here as to which fuel they might want to try - they are sceptical of all the makers claims. They don't want to up the compression (though I suspect that's the best option with better fuels) for fear of a DNF. Ignition is some nasty thing with all the adjustment you can get from the slack in the holes on the stator held in by 2 x 5mm screws. There's been no mention of other instrumentation.

Power loss after a few laps is a frustration, for which they are running a touch richer than best power on the dyno, costing 0.5hp. Oil is some Bardhal brew that seems to work and has not been beaten for power on the dyno by other brands. I've passed on the recent oil recommendations discussed here recently. In fact they are running the Bardhal at 25:1, though will be going richer, as the only effect of leaner was greater wear rates. The scuttlebutt in these circles is that some adventurous fools are running down at 15:1 with good results..where have I heard all that before! (Oh, it was me reading Jennings and running a two-stroke air-cooled twin at 15 or 16:1 on veggie oil and finding jennings was right about the effects).

Enough rambling. I was rather hoping someone in the 50 brigade (or any other thinker) might have some useful suggestions for the effects of better fuels on mid-range power, where little else is changed, or a fuel recommendation (not that these fuels are in use in buckets..

Thanks for reading this far.

FB

[F5 Dave]

Yeah
The most obvious one is-is it against the rules to water cool it? That would bring lasting power and aid reliability in spades.

[TZ350]

... a mate's son in the UK is at the sharp end of some mini-bike/pit-bike racing championship and keen to win it. They want to avoid an engine-induced DNF. They also need more off-corner grunt ...

... water cool it? That would bring lasting power and aid reliability in spades.

A simple way to water cool it would be to dribble water into the ducting directing air over the cylinder and head. That way the engine is getting extra cooling from the latent heat of evaporation of the water droplets splashing onto the cylinder and head.

If the rules allow, then some sort of digital ignition like a programmable Ignitec would help for off corner acceleration. But you need a TPS so that at lower rpm the ignition retards back to something more normal when the throttle is closed.

More oil for more power, TZ's could run down at 16 or even 12:1 ... 20:1 is normal. Team ESE runs 20:1 in everything.

[wobbly]

Bottom line here is that as I have stated many times the tuning regime for leaded is completely opposite to that of unleaded pump type gas.
To get ANY benefit from a good leaded fuel they need to increase the com, back out the timing and run lean as hell.
NFG at all without an egt.
Get some super well proven A747 to run with it at 20:1, but if they are so gun shy of the thing that they wont do the dyno time and do proper back to backs then
its probably not going to be much use simply changing fuel and jack shit else.

[koba]

Is more power going to be the best way to ensure a good finish in the championship?
It's possibly sacrilege to say so in here but I've noticed many will do better in the long run by keeping this stable and being consistent...

All depends on the situation of course but often the best change is none at all.

[TZ350]

Is more power going to be the best way to ensure a good finish in the championship?

Agreed .... consistency is a good thing and more hp may not help much.

[richban]

To get ANY benefit from a good leaded fuel they need to increase the com, back out the timing and run lean as hell.
NFG at all without an egt.

Yeah it seams the 300 loves running lean. egt was hitting close to 1300F but man she was angry and fast. I am running Motul @ 30:1 Gunna switch to elf or 747.


It will be interesting to play around with the ratios on the dyno. Do you think I could run the 300 that low. 20:1 that is? Its running straight Avgas with 15:1 comp. ignitech of course.

[wobbly]

1300 is too hot.
Means that the ignition is ramping out too much timing past peak power.
But just as likely that the com is a bit low at 15:1.
Try some more advance past peak, ie flat line it at say 10* ( depends upon what the peak power timing is - it should be around 15* )
then depending upon the result, chuck it some extra com up closer to 16:1.
Both things will reduce the temp at high rpm , without having to go richer to stop it.

20:1 is fine for best engine protection.
Only issue is that Elf 909 will settle out quite quickly in AvGas, but as we used to do in the old days with Castrol R just add a little Acetone
and that problem goes away.
I havnt actually tried Motul Kart without the Acetone, so that may be OK in AvGas.
A747 is fine in AvGas.

[fatbastd]

Thanks for the thoughts...Wobbly's right, again - I doubt changing the fuel won't achieve much, unless the setup wasn't right in the first place. The water-cooling idea is a lateral option, which may or may not be legal/feasible. Will mention it. They do the dyno time, but not sure how effective it is or how willing they are to change things, so all it might be telling them is what they've got.

No free lunch then.

[jasonu]

Is more power going to be the best way to ensure a good finish in the championship?
It's possibly sacrilege to say so in here but I've noticed many will do better in the long run by keeping this stable and being consistent....

Yep just ask any of the 30+hp bucketeers...

[richban]

1300 is too hot.
Means that the ignition is ramping out too much timing past peak power.
But just as likely that the com is a bit low at 15:1.
Try some more advance past peak, ie flat line it at say 10* ( depends upon what the peak power timing is - it should be around 15* )
then depending upon the result, chuck it some extra com up closer to 16:1.
Both things will reduce the temp at high rpm , without having to go richer to stop it.

20:1 is fine for best engine protection.
Only issue is that Elf 909 will settle out quite quickly in AvGas, but as we used to do in the old days with Castrol R just add a little Acetone
and that problem goes away.
I havnt actually tried Motul Kart without the Acetone, so that may be OK in AvGas.
A747 is fine in AvGas.

Nice one. I was wanting to try some more inserts.

It would be a shame to blow it up. She's looking rather swish.

[timg]

Nice one. I was wanting to try some more inserts.

It would be a shame to blow it up. She's looking rather swish.

Very swish indeed. Nice

[chrisc]

Interesting read from Luc Foekema on spark energy and timing as posted on facebook:
https://www.facebook.com/notes/4223470164094/

Conclusion:
More top power as shown in the graph [from decreasing spare energy to 50% from 11K rpm], indicates a not good combination of setup and the exhaustpipe. The setup is optimal for a higher rpm then the exhaustpipe is made for. Just to lower the sparkenergy, more heat will be available for the exhaustpipe, resulting in a higher rpm and in this case a higher power output.

Conclusion "when there is a gain in toppower by reducing spark energy, the temperature in the exhaustpipe is too low or the exhaustpipe is too long, otherwise a gain in toppower would be impossible".