Although I'm a master-tuner, I'm afraid to try this lean-burn super-advance stuff. Although it makes sense. I want to try it on my daily, then have a look at the pistons in 6-months.

Here is the problem with semi lean burn. When the fuel is injected the combustion starts from the center and leaves a layer of fuel on the outside near the walls. That protects the walls and keeps them cooler. When you're leaning at 16-17 you're using that layer up yet you still have enough power to do dmg. Super lean burn combustion is suppose to exchange that layer near the walls with air however i dont know how much fuel super lean burn is suppose to have. What i have read about it though is you need direct injection so you have a fairly good amount of concentrated fuel in the piston to burn.

It's not the pistons you should be looking at, it's the valves.

If you have an EGT sensor tuning cruise to be as lean as possible is easy, otherwise it's complete guesswork really.

However I've run for 6+ at 16.5:1 years via the following method

Lean out when at steady state until the car starts to surge, then add in a few points of fuel

Do the same with timing

Then revisit the fuel.

Done.

It's better on a dyno as then you can see at what AFR and timing angle picks up the most power. You want as much power with as little throttle position as possible.

EGR is nice if you have that as you can reduce pumping losses by being able to run the same afr/timing fuel PW at larger throttle openings.

Super lean burn in Hondas is like 20 - 30:1. Not possible with the 5 engine period.

Here's some good reading about mixture for you guys:

http://www.avweb.com/news/pelican/182084-1.html

Written from the standpoint of managing aircraft piston engines, but the concepts apply to us too.

Note that this would not apply to the new, direct-injection super lean burn technology being developed now.

To answer the original question, you'd use a solenoid hooked to a tee connected to the atmospheric port on an external waste gate. Trigger the solenoid with the ecu to switch between vacuum and atmospheric. You'd need to run a light wastegate spring to ensure your cruise vacuum can open the waste gate.

It probably won't help, though

electronic wastegate actuater
Seems the newer cars are using these devices in line with the ecu to regulate boost that way.