Tiger Dyno'd

[Bixxer Bob]

Had the old girl dyno'd by a very nice man called Tony.

She's the most powerful Tiger he'd ever had at 102.4 BHP at the rear tyre   :P

He's only ever had one other...  :oops:

Here's the graph:



The run is done in 4th gear: red and blue lines are before / after fuel tweaks; the line going up is power - you can see a 1 bhp increase.  You can also see that there's a flat spot at 80-90mph or 6500-7300rpm.

The other line, going down is fuel air ratio.  The horizontal, dotted line is to show where 13 to 1, or max power is (ideal mix is 14.7 to 1 but no-one really runs that); top of the graph is lean, bottom is rich.  Red is first run, blue is second run after mapping. You can see that on the first run, she's weak almost everywhere, from 40 - 90 mph (3000 - 7300 rpm).  We put a block 10% extra fuel in this area and then added another 10% in the worst, 50 - 70mph area. The blue run shows that the adjustment brought it roughly just lean of best power 45 - 65 mph and then slightly rich 70- 90 mph (where the flat spot is that we accidentally created).  

Armed with this, I can extrapolate the fuel we put in and the impact, work out another map and then take it for another dyno run at some point.


Oh, and the result????  Surging's almost completely cured and the throttle pickup stutter out of corners is totally fixed.   :lol:  :lol:  :lol:

Still burbles nicely on overrun but almost no bangs.... :)

Funny thing is  :roll: dealer said it was running very rich, when the evidence is it was almost dangerously weak.  This was borne out by the plugs, which were nearly white intstead of chocolate brown.

[Sin_Tiger]

That's an excellent result, puts my Vara in the shade by a long way, 87 and that was after LeoVince SBK's and PCIII, that is considered good for a Vara.

First time I'd done a Dyno on a bike, half meter flames after a full load cut is spectacular if a bit scary  :shock:

Agree, it's just the starting point, on the raod is what matters.

[TigerTrax]

I dyno'd my '98 after popping in some Daytona coils & plug wires.

The guy at the Dyno shop ( that's all they do) said every guy walking thru the doors would kill to see a chart like this!. (sorry don't have ). But he was really impressed with the very little drop off between gears.

[Chris Canning]

How come you went all the way to Chesterfield,when you have BSD on your door step

[Bixxer Bob]

Mark Brewin at BSD did my Blackbird.  He did a brilliant job using a Power Commander to release 139bhp at the tyre with stock pre-catalyst exhausts.  However, when I asked about doing the Tiger they said they don't do Tuneboy, so I had to find someone who did - hence going to Tony.

[John Stenhouse]

Did the dyno people do the tuneboy or was that your own set up?

[iansoady]

It would be very interesting to see the A/F map you've ended up with.

[Bixxer Bob]

Did the dyno people do the tuneboy or was that your own set up?

It's my own setup, but they are agents, so - for the price of a software key plus dyno runs, labour etc - they can do it for you.

[Bixxer Bob]

It would be very interesting to see the A/F map you've ended up with.

I can do a screenshot of the current map I'm running which produced the second plotline.  I haven't got round to doing the further tweaking yet because I'm unwell again (second time this year), so won't be doing any serious riding for a few weeks.

[Bixxer Bob]

I pulled these off in 3D view because they're more informative than just rows of numbers.

The axis from left to right is rpm 0-10000 and the axis front to back is throttle position 0-100 %.  The height, for sake of arguement here, is how much fuel added. (It's more complex than that but there's no need to go into it here).

You can see that the top pic, which is the standard Triumph tune for late VIN girlies with aftermarket pipe ie Tune 10173, has a big hole at zero throttle settings and low to mid range revs.

You can see on the second map I've smoothed out a lot of that as well as adding 10-20% across the throttle range from 2500-6500 rpm.  I still have to deal with the dips and peaks on the curve which I'll do when my brain is working a bit better than it does at the moment.

[iansoady]

Interesting that you seem to have achieved this by using the fuel map rather than the air/fuel ratio. It's the latter that I changed to eliminate the hunting between 2,000 and 4,000 although I wasn't looking for any more power.

[Bixxer Bob]

Interesting that you seem to have achieved this by using the fuel map rather than the air/fuel ratio. It's the latter that I changed to eliminate the hunting between 2,000 and 4,000 although I wasn't looking for any more power.

Wasn't really looking for more power either. The two tables have a complex relationship, so I want to spend more time on the dyno when I can afford it (the time not the cash).

Ideally, I want to map most of the A/F table to 13 for most power, but leave the area where I cruise most, around 6000rpm on 30%throttle in 6th gear, as lean as I can (probably about 14 rather than the 14.7 stoichiometric value) then remap the fuel values for best running.  I could just change the full load map, but I don't think any of us ride around with the throttle pinned all the time, and the standard maps are all over the place anyway.  Have you looked at the peaks and troughs on the fuel map for a Datona?  Or tried to figure out why the ign map has spikes all over it?

This stuff is rather geeky, but I'm really getting into it.

[GWL]

:icon_scratch

[Bixxer Bob]

:icon_scratch

 :lol: Ok, here's months of learning in a short, simplified form.  

The stoichiometric ratio for burning petrol using oxygen is 14.7 parts oxygen to 1 part petrol by mass.  If you burn it at 14.7 to 1 there's no left over oxygen or hydrocarbons which is peak efficiency.  Anything above 14.7 air to 1 fuel is lean, anything below is rich.  BUT, (remember, we're keeping this simple) this ratio creates a lot of heat under load, and 13 to 1 is best for power, so then real target is usually somewhere between 13 and 14.5 to 1.  The best ratio for any given set of engine conditions is stored in a table known as the Air Fuel table (A/F) in what we all call a "Tune".

Now, in your Tiger fuel rail the fuel is held at a constant pressure by the pump and pressure sensor.  By knowing that pressure and the rating of the fuel injector you can work out exactly how much fuel is passed by the injector for every milisecond it's open. In the case of our Tigers, that's 3430 milligrams of fuel per second.  To work out how many milliseconds to open the injector, the Engine Control Module (ECM) needs to know some information, which it gathers from the sensors.  

First it needs to know the temperature of the air and the barometric pressure (that is the atmospheric pressure - which changes as you go higher up mountains, or if it's a dry or a wet day).  Using those two pieces of information it can work out how much oxygen is in the air being sucked into the engine.  Next, it needs to know how much air is being drawn into the engine at any one time. It knows this by the throttle position which it reads from the throttle position sensor, and the engine revs which it reads from the crankshaft sensor.  Using those two pieces of information, it looks up a number in the Fuel Map which is another of the sets of data in a "Tune".  That number is then multiplied by the mixture ratio  in the A/F map and comes up with a fuel figure.  Since it knows how much fuel passes through an injector per second, it can work out how long to open the injector.

There's a whole load of other stuff about engine load that we won't get into here, but basically, if you change the A/F or Fuel maps, you can tell the ECM to put more or less fuel into the engine and thus affect how it performs.

See,   I told you it was simple....

Oh, there's one other thing that comes out of this... There's a thing called the long term fuel trim stored in your ECM.  The ECM uses this to adjust the whole fuel map if your bike naturally runs rich or weak.  It works by monitoring the oxygen sensor.  If the oxygen sensor is constantly trying to richen the mix, it'll slowly increase the long term value until the oxygen sensor is happy.  You might wonder why it should need to do this; well, it cancels out any difference due to height above sea level and hot or cold, wet or dry weather affecting the amount of oxygen in the air, but the most significant error that this corrects is tiny variations in fuel rail pressure caused by variations in the pressure sensor, fuel pump efficiency etc.

Anyone still awake???

Happy to take comments - I'm certainly not an expert in this area yet  :oops:

[Sin_Tiger]

Good write up Sir, well done, you have more patience than me