Air / Fuel Tuning works like a champ on 2IS
11-18-06, 04:58 PM
#18
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.
11-19-06, 07:15 AM
#21
11-19-06, 05:17 PM
#23
Tech Info Resource
iTrader: (2)
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.
11-19-06, 06:15 PM
#24
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.
11-19-06, 06:48 PM
#26
Tech Info Resource
iTrader: (2)
Not just a torque curve, but a beautiful one for a street car.
02-13-07, 08:15 PM
#29
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. 