Air / Fuel Tuning works like a champ on 2IS
I'll post dyno results as soon as I'm satisfied with the air / fuel results. I've already been to the dyno once, and did 3 before, and 4 after pulls. The results were only about 3 HP, which isn't enough to post IMHO. It was also just a couple days after I had it working (poorly). My software datalogs acceleration, and gives a psuedo-torque curve from rate of acceleration. I will use that to figure out the "sweet spot" for AFR, then go back to the dyno.
It runs really lean below 3200 because it's functionally a stratified charge. Conventional wisdom doesn't apply in stratified charge engines. They're in a different world for a/f ratio because they can bypass a lot of the issues with running lean under load. There was a whole lot of engineering that went into this solution, and obviously it's working well.
This is why the comments about just slapping a set of low compression pistons in the engine and applying boost don't make sense. The whole combustion chamber is optimised to produce a rich cloud around the plug with a lean cloud in the rest of the chamber when it's time to ignite. It's going to be quite the trick to get this to happen with a different piston design.
Lexus have a really cool video on TIS showing exactly how all this works. It's in the new model training section for the '06.
This is why the comments about just slapping a set of low compression pistons in the engine and applying boost don't make sense. The whole combustion chamber is optimised to produce a rich cloud around the plug with a lean cloud in the rest of the chamber when it's time to ignite. It's going to be quite the trick to get this to happen with a different piston design.
Lexus have a really cool video on TIS showing exactly how all this works. It's in the new model training section for the '06.
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It runs really lean below 3200 because it's functionally a stratified charge. Conventional wisdom doesn't apply in stratified charge engines. They're in a different world for a/f ratio because they can bypass a lot of the issues with running lean under load. There was a whole lot of engineering that went into this solution, and obviously it's working well.
This is why the comments about just slapping a set of low compression pistons in the engine and applying boost don't make sense. The whole combustion chamber is optimised to produce a rich cloud around the plug with a lean cloud in the rest of the chamber when it's time to ignite. It's going to be quite the trick to get this to happen with a different piston design.
Lexus have a really cool video on TIS showing exactly how all this works. It's in the new model training section for the '06.
This is why the comments about just slapping a set of low compression pistons in the engine and applying boost don't make sense. The whole combustion chamber is optimised to produce a rich cloud around the plug with a lean cloud in the rest of the chamber when it's time to ignite. It's going to be quite the trick to get this to happen with a different piston design.
Lexus have a really cool video on TIS showing exactly how all this works. It's in the new model training section for the '06.
Here is a chart of stock rate of accel (yellow) and tuned to 13.5 (blue). The Y axis is a psuedo-unitless value, and the X axis is RPM / 100. I'm just calculating change in MPH per time and plotting it. It looks a lot like a torque curve to me.
BTW, the stock and tuned graphs above were done within 15 minutes of each other from the same spot on the road in the same direction with about 1.5 miles of cool down at 60 MPH between runs.
If the numbers from the graph in post 24 can be used to calculate torque, then it looks like I'm gaining between 3 and 6 ft-lbs from 4K to redline. The 6 ft-lbs would be from 6300 to redline, which would be about 7.5 hp.
I hope to go into production with a "black box" in the future. However, I'm still quite far from a production unit, as you can see in the picture above. All the components I'm using are "off the shelf", so I would need to spec out custom hardware that has everything needed in one package, and figure out how to finance a first run. 