Lean is less dangerous than rich?

[raz]

Where do you suppose maximum CHT and EGT are on this chart?

My guess is maximum CHT is at about 15:1 and maximum EGT is at about 16:1.

 

Some things to keep in mind are that critical temperature can be considered more related to load than mixture. Also timing has an effect too.

I'd like to see more data!!!

Sooner or later the equivalent of todays UEGOs will be 4-gas with ms response time. I want it now!

 

You lot are right of course. I'll stick to not leaner than 14.7 for now.

 

I'm thinking sensors for CHT and EGT should be fairly cheap stuff, commercial or home built. Don't they measure EGT (at least) at dyno centers? Also, accelerometers are dirt cheap now. They should be usable in some way or the other for road dynoing...

[Guest Phil_P]

Sooner or later the equivalent of todays UEGOs will be 4-gas with ms response time. I want it now!

 

You lot are right of course. I'll stick to not leaner than 14.7 for now.

 

I'm thinking sensors for CHT and EGT should be fairly cheap stuff, commercial or home built. Don't they measure EGT (at least) at dyno centers? Also, accelerometers are dirt cheap now. They should be usable in some way or the other for road dynoing...

 

I've just recently got a 'Beltronics' Vector FX2 which is quite fun. Once you get it calibrated it gives you a power readout, in the meantime it gives you loads of 0-60 or whatever figures plus acceleration in 'G'. I don't think the lateral acceleration figures are much use with the bike, due to leaning though.

[raz]

I've just recently got a 'Beltronics' Vector FX2 which is quite fun. Once you get it calibrated it gives you a power readout, in the meantime it gives you loads of 0-60 or whatever figures plus acceleration in 'G'. I don't think the lateral acceleration figures are much use with the bike, due to leaning though.

Never heard of that, googled it now. Looks pretty interesting and not too expensive. More bang for the bucks than my €200 CF hugger anyway...

[dlaing]

Here are some other interesting charts.

A little hard to read, but worth the effort...

They came from another interesting avionic article, seemingly from the same school of thought as the first article.

http://www.amtonline.com/publication/artic...d=1&id=1171

On our bikes I think we would face two specific problems if we want to optimize for power and efficiency.

One is that our engine is not likely to be well balanced between the cylinders, so it likely won't run smoothly in the lean economy zone.

The other is that unlike an airplane engine, smooth transitions of power and drivability are very important.

The transition from maximum power to maximum economy, while bypassing maximum temperature is not likely to work smoothly, assuming maximum economy is even ridable.

But maybe I am wrong, and it can be done with acceptable smoothness??????

It would be nice to be able to flick a switch and jump to maximum economy for long stretches of highway.

One other thing I noticed browsing for info, is that many people state with authority that maximum EGT occurs at 14.7:1. I believe it occurs much closer to maximum NOx production. Whatever, I'll probably just keep running rich unless I buy an EGT sensor. I still have to get my WBO2 working....

[luhbo]

.... that many people state with authority that maximum EGT occurs at 14.7:1. I believe it occurs much closer to maximum NOx production.....

 

I think I remember that N (from NOx) does react with O² and other elements only under very high pressure and very high temperatures. This would mean optimal combustion at maximum NOx concentration. On the other hand optimal combustion (and) at the right time should not give the highest exhaust gas temperature. In fact it should then be relatively low. Nogbad is the pro on this field, what does he say?

 

Hubert

[luhbo]

Never heard of that, googled it now. Looks pretty interesting and not too expensive. More bang for the bucks than my €200 CF hugger anyway...

 

Anyway, to get an optimised map (spark and fuel) within a fair amount of cycles/tries on the road you'd need a possibility to store acceleration over n and alpha. Otherwise I think the values would just be interesting.

 

Hubert

[raz]

Anyway, to get an optimised map (spark and fuel) within a fair amount of cycles/tries on the road you'd need a possibility to store acceleration over n and alpha. Otherwise I think the values would just be interesting.

 

Hubert

Mm... that don't compile in my head. Too uneducated unfortunately. What is n and alpha? Anyway, I realize that thing won't probably be any real good, but it sure would be real fun.

[raz]

This chart supports the "lean is dangerous" theory Of course, all these diagrams would fall short of a Guzzi twin diagram showing CHT and EGT vs mixture.

[luhbo]

... What is n and alpha? ...

 

RPM and throttle angle. These simple bike ecus we use are called Alpha/n-systems.

[dlaing]

This chart supports the "lean is dangerous" theory Of course, all these diagrams would fall short of a Guzzi twin diagram showing CHT and EGT vs mixture.

The charts also support the lean is cool and will give you good gas mileage theory.

These charts are still missing dimensions n and alpha. I would guess they are discussing a cruising speed at maybe 2/3 of.100)maximum throttle and RPM. But notice they mention a richer mixture (.100) for takeoff.

What would be important to see is the Guzzi twin diagram with CHT, EGT, mixture, rpm, and TP.

And then see the effects of timing and fueling.

[raz]

RPM and throttle angle. These simple bike ecus we use are called Alpha/n-systems.

but of course. Temporary failure in my head. I'm planning to write a simple datalogger for my laptop that logs timestamped ECU output, GPS speed and LC-1 output. If that Beltronics thingy can output to a computer too it would be a cool complement.

 

Actually my Thinkpad laptop contains an accelerometer. Maybe I could use it some way.

[raz]

It seems a common type of CHT sensors for carts or airplanes are replacing the spark plug washer and cost like $20. EGT sensors seem a bit more expensive and you have to weld another bung. I'm not too keen on that. I wonder how inaccurate a sensor epoxied to the outside of the downpipe would be... Of course it wont be as fast and accurate as one inside.

[Skeeve]

I wonder how inaccurate a sensor epoxied to the outside of the downpipe would be... Of course it wont be as fast and accurate as one inside.

 

Make a "temporary" header out of copper pipe? Plenty fast enough for most purposes. Aluminum a little slower, but more?less? resistant to exhaust contents? Don't know about availability of either in the dimensions needed, I'm just sayin'...

[Guest Phil_P]

RPM and throttle angle. These simple bike ecus we use are called Alpha/n-systems.

 

Ah, but the LCD display for the Power Commander can record that data too

[Guest Nogbad]

Gas temperatures are notoriously difficult to measure accurately, especially under dynamic conditions. The temperature of your header is determined by the balance between heat received by convection and radiation from the flowing gases inside, and losses from convection, radiation and conduction to the ambient air and environment and cold cylinder respectively. This balance will alter with speed, gas composition, throttle opening etc etc. To measure EGT accurately you need a thing called a suction pyrometer.