Working on a project on an LS2 Corvette.  (this is our 7th trail vehicle (we have had a few major failures) ).

The new method / design we are using eliminates Exhaust Gas reversion while increasing volumetric efficiency and effective compression ratio. This time it is working really well, so far (1000 miles).

 We do it with newly designed intake valves. These intake valves, along with their normal functions, also act as check valves against reversion on the intake cycle (during valve overlap) and also compression reversion on the compression cycle.

On the Dyno @ stoichiometric (perhaps a bit richer) we have significant increase in low end torque. 300 ft.lbs at 1000 RPM and it goes up quickly at 1500 RPM to 400 ft. lbs of toque and stays there until 5250 and starts to peel off slowly , it does not fall off a cliff. These are significant increase in torque.   Max spark advance 19 degrees.  Exhaust temperatures 800 F range.  87 octane gasoline.  The engine has a medium range after market cam.


We are playing with the Air Fuel ratios and today we have it running with very good performance at 24 to 1 A/F (that is as high as our wide band A/F meter goes), it idles at 300 RPM (not all that stable,needs more flyweight).  At cruise, 70 MPH @1600 RPM up a 6 degree grade, with exhaust temps 1100 to 1150 degrees F. (these temps have turned the corner, they were hotter at about 19 to 1 AF)  Throttle position is 45 percent, performance is acceptable.

Questions,
How can I check the NOX?

Is there any reason to believe that the NOX emission may be low?

We plan on going further lean until the exhaust temperatures drop to 800 or 900 degrees(if the performance continues to stay acceptable) , with the throttle pretty much open and then control speed with fuel, via fuel pressure.  Why?  Not sure just trying out some new things.  I would love to hear comments as too what the NOX emission will be????

How about adding, diesel fuel 5% at a time, to see what effect that has on performance and NOX. 

Dynamometer testing with exhaust gas analysis - same as used for regulatory periodic emission testing - can tell you the NOx without having to guess.

Ordinarily, NOx peaks just slightly lean of stoichiometric and then starts dropping off, but the big problem is that conventional 3-way catalytic converters cannot process NOx (at all) in an exhaust stream that is overall lean. The dropoff in NOx when running lean of stoichiometric is ordinarily nowhere near enough to compensate for the inability of the 3-way catalyst to take care of it.

Several old Honda models, including the Civic HF and the old (2-seat) Insight, used a lean-burn mode under some operating conditions, and I've heard they could get into twentysomething air/fuel also. But, Honda has given up on that because the emissions couldn't be kept low enough to meet the latest round of standards.

I'm interested to know how you are getting reliable ignition at such lean operating ratios. The Honda engines did it by playing around with injection timing and flow patterns to create a stratified-charge effect in the cylinder. The mixture at the spark plug was not as lean as that in the cylinder as a whole.

The gasoline engines that I've had the chance to play with, both carbureted and EFI, start getting misfire somewhere near 18:1, even with iridium spark plugs, and less than that when the engine is cold.

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