Efficient Engine Design ???

[pgfpro]

Originally Posted by Tygen1

How much boost are you running at these low load crusing rpm's while lean burning? You'd think a turbo big enough to make 450hp at 30psi wouldn't do much at under 2000 rpm...Is the Turbo just helping to reduce pumping loss in these conditions?

Not much boost at my low load level cruising rpm's. But it is helping a ton as far as pumping losses. I'm running a Holset 351 diesel turbo.

[Christ]

Bot...

[bestclimb]

What has been your limit on how lean you can get? I understand that once the mix is lean enough it does not really support combustion and that it drops off steep (both on the lean and rich sides) How even is the mix across all 4 cylinders?

[NeilBlanchard]

Have you folks studied engines like the Revetec?

Revetec Homepage revetec.com

Or, new rotary designs like this one?

Green Car Congress: UK LowCVP Launches ?Technology Challenge? to Accelerate Low Carbon Vehicle Innovation; Libralato Engines First Registrant

[pgfpro]

Originally Posted by bestclimb

What has been your limit on how lean you can get? I understand that once the mix is lean enough it does not really support combustion and that it drops off steep (both on the lean and rich sides) How even is the mix across all 4 cylinders?

The leanest has been 30:1

At 22:1 up the load increases a lot. My best FE has been at 22:1 so far.

I want to run it at 30:1 for NOx reasons.

The mix across all four cylinders has been good. I'm still messing with individual fuel controls and feel I haven't dialed it in yet.

[greasemonkee]

Too bad that's not a dual cam. I'd be interested to see the effects of a late intake valve closing on that setup.

[Christ]

Originally Posted by pgfpro

The leanest has been 30:1

At 22:1 up the load increases a lot. My best FE has been at 22:1 so far.

I want to run it at 30:1 for NOx reasons.

The mix across all four cylinders has been good. I'm still messing with individual fuel controls and feel I haven't dialed it in yet.

30:1 with shorter gearing or smaller tires will put you back in the zone where you're making optimal power to not overload the engine. There will be more wear on internal components due to engine speed, but meh.

[pgfpro]

Originally Posted by greasemonkee

Too bad that's not a dual cam. I'd be interested to see the effects of a late intake valve closing on that setup.

I would love a chance at testing this. There would be a ton more adjustment

[bestclimb]

Originally Posted by pgfpro

The leanest has been 30:1

At 22:1 up the load increases a lot. My best FE has been at 22:1 so far.

I want to run it at 30:1 for NOx reasons.

The mix across all four cylinders has been good. I'm still messing with individual fuel controls and feel I haven't dialed it in yet.

Thats pretty cool. Speeking of cool your exaust temps must be pretty low.

What ideas do you have to get timing back to where you are getting peak pressure with the crank 90 past tdc?

When I was thinking about using a carb to get lean for my rig with a vernier type prop knob attached to the distributor and adjust to best power once as lean as I could go.

[pgfpro]

Originally Posted by bestclimb

Thats pretty cool. Speeking of cool your exaust temps must be pretty low.

What ideas do you have to get timing back to where you are getting peak pressure with the crank 90 past tdc?

When I was thinking about using a carb to get lean for my rig with a vernier type prop knob attached to the distributor and adjust to best power once as lean as I could go.

Yes the exhaust temps are very low during lean burn

What ideas do you have to get timing back to where you are getting peak pressure with the crank 90 past tdc?

This is a issue I'm working on. At anything above 20:1 A/F my timing for max power at light load is in around 40* BTDC. I have a way to control the flame kernel in the prechamber to help this but I ran out of time this last year.
Lean burn is pain in so many ways.

I'm trying to get over a 30:1 A/F ratio to help with NOx but in doing so my BSFC numbers increase drastically. Not good.

If I use my new EGR systems to help NOx I lose power and need more air/fuel to over come it. Not good.

If I drop the A/F ratio down to 22:1 I'm sure I can get 80mpg(before the aero mods) at 55mph with more tweaking with the timing advance,flame kernel adjustment, and pulling more vacuum on the crankcase,but it won't pass emissions on gasoline with these settings and I would have to cheat the system by running two different tuning maps.