Modify O2 sensors

[SVOboy]

Indeed. Something the VX and HX have are vtec-e, which promotes swirling, especially in the VX with its bowled pistons that were designed to inhance the swirling created by having only one intake valve open.

[omgwtfbyobbq]

Yup, reminds me of the long tuned intake runners, and heads ported for swirl in the old vw TDs. Now gasoline cars are using direction injection, and diesels are coming with ~16:1 compression ratios, I suppose they'll converge with HCCI multifuel engines.

[SVOboy]

Woot for long tuned intake runners. I wish someone would tell me what's best on the exhaust side for FE, but I can't figure it out. I suck!

[omgwtfbyobbq]

I don't think exhaust tuning won't help much with FE because your limiting factor is pumping losses, which is related to rpm and gearing. Generally, manufacturers will tune an exhaust so that they can get a scavenging effect near peak hp, that way they can get the equivalent of a few extra psi of boost w/o a turbo. In order to do this you have to tune the exhaust based on each exhaust wave (acoustics, they travel at something like 800ft/s) so it will pull the exhaust gasses out of the piston near peak power, and allow even more air than normal to enter, and ultimately more fuel/power. I think this is why the drop off in torque/hp after peak isn't symmetrical compared to the increase...

[krousdb]

Originally Posted by omgwtfbyobbq

Found something that says controlling swirl allows for stable combustion and better lean burn. Which makes sense, because hot spots in a cylinder could lead to pre-ignition, so controlling how the intake charge combusts (even combustion/heat distribution) is critical to being able to run lean without pre-ignition. Running an a/f ratio of 25:1 compared to 14.7:1 supposedly reduces fuel consumption by ~20% over the Japanese test cycle.

Can you point me to your source of info please?

[omgwtfbyobbq]

Here ya go.