Efficient Engine Design ???

[pgfpro]

Originally Posted by maxc

For your EGR valve just condense some of the exhaust and use the water. They did it on some WW2 planes off the wing heater systems.

So you run the exhaust gas through a condenser and route it back into the intake?

Sounds interesting.

[maxc]

Water can speed up the overall combustion process. http://www.not2fast.com/NACA/naca-report-531.pdf
Heat reflective coatings on the pistons and head.
Very high compression with the right heat range of spark plug, very finely controlled water vapor flow, and strong long duration spark.

[Christ]

I second the higher compression. Once you get so lean, you actually need compression and hotter plugs to get the mixture hot enough to ignite. Ignition temperature goes up the leaner you get, after a certain point.

Have you considered setting the engine up to make enough power normally to do what you want, but using a second program (similar to going open loop on WOT) to get power when you really need it?

Shave that head, and study your cam profile to see where you can keep dynamic compression numbers up. Consider your RPM range, and make note of the max RPM that you ever use, and keep in mind where your turbo will be most helpful. Also, keep in mind that the more you lean your mixture, the less your turbo will want to spool, and the higher compression you'll have to have to get a similar effect from the turbocharger.

Longer stroke will get you more low-end. You can use a D17 crank in your engine, but you must also use the D17's oil pump and dipstick tube, I believe.

Attempt to defeat parasitic losses in your engine by pulling vacuum on the block, to the tune of ~15 inches, IIRC. You'll want to pull it from the valve cover area, to lessen the amount of oil you get in the stream. You'll also want an oil catch can/separator.

Also, consider dyno tuning, if you have access to a dyno without too much cost, and tune your accessories to load the engine to put it in a more efficient area of the BSFC map if you're not quite able to get it there under normal operating conditions. Sometimes, adding just a little bit more load will get you "over the hill", I think, so the net effect is a gain.

If you've got the cash, re-cast your pistons so they fit the combustion chamber better. Larry says (Widmer, you know him.) that the ideal combustion pattern is a football-esque shape with the largest concentration of fuel/air stratified about the spark plug, and making sure that there is no extraneous pocket of mixture anywhere. That means fitting the piston as tightly to the head's design as you feel comfortable.

Speeding up your swirl (staggered intake events) should also help dramatically with increased detonation resistance, according to Widmer's research. If you have the means, consider staggering the intake valve opening events of the same cylinder a few degrees apart from each other, so that as the air really picks up velocity on one valve, the other is starting to open, which should induce high-speed swirl, as the second flow will influence the first one.

[pgfpro]

Originally Posted by maxc

Water can speed up the overall combustion process. http://www.not2fast.com/NACA/naca-report-531.pdf
Heat reflective coatings on the pistons and head.
Very high compression with the right heat range of spark plug, very finely controlled water vapor flow, and strong long duration spark.

Thanks for the link I will read over the material.

[pgfpro]

Originally Posted by Christ

I second the higher compression. Once you get so lean, you actually need compression and hotter plugs to get the mixture hot enough to ignite. Ignition temperature goes up the leaner you get, after a certain point. I will be building a second engine this winter with a higher compression ratio and will be testing to see if I can get substantial gains from a increase in compression. This low compression engine actually does better with the prechamber then a stock JDM 10:1 engine.

Have you considered setting the engine up to make enough power normally to do what you want, but using a second program (similar to going open loop on WOT) to get power when you really need it? Its running in open loop all the time now. If I understand you right its doing this right now? The lean burn mode is load dependent based off the fuel and timing cells in my software that I setup. It uses three cells y and two x for 6 total. The only time it hits these cells is when I'm on the freeway in 5th gear at 55mph to 65 mph.

Shave that head, and study your cam profile to see where you can keep dynamic compression numbers up. Consider your RPM range, and make note of the max RPM that you ever use, and keep in mind where your turbo will be most helpful. Also, keep in mind that the more you lean your mixture, the less your turbo will want to spool, and the higher compression you'll have to have to get a similar effect from the turbocharger. I can't change to much of this due to my lean burn combustion chamber.

Longer stroke will get you more low-end. You can use a D17 crank in your engine, but you must also use the D17's oil pump and dipstick tube, I believe.
It has a ton of low end torque now even in lean burn mode. More then the stock D16 VTEC.

Attempt to defeat parasitic losses in your engine by pulling vacuum on the block, to the tune of ~15 inches, IIRC. You'll want to pull it from the valve cover area, to lessen the amount of oil you get in the stream. You'll also want an oil catch can/separator.This is what i have been working on now and I should have it ready for the next time out.

Also, consider dyno tuning, if you have access to a dyno without too much cost, and tune your accessories to load the engine to put it in a more efficient area of the BSFC map if you're not quite able to get it there under normal operating conditions. Sometimes, adding just a little bit more load will get you "over the hill", I think, so the net effect is a gain. I have free dyno tuning available so I will take advantage of this.

If you've got the cash, re-cast your pistons so they fit the combustion chamber better. Larry says (Widmer, you know him.) that the ideal combustion pattern is a football-esque shape with the largest concentration of fuel/air stratified about the spark plug, and making sure that there is no extraneous pocket of mixture anywhere. That means fitting the piston as tightly to the head's design as you feel comfortable. My pistons are highly modified to work with the prechamber. I haven't ever seen anyone with this design. But what you describe is what I'm doing but with a whole unique shape.

Speeding up your swirl (staggered intake events) should also help dramatically with increased detonation resistance, according to Widmer's research. If you have the means, consider staggering the intake valve opening events of the same cylinder a few degrees apart from each other, so that as the air really picks up velocity on one valve, the other is starting to open, which should induce high-speed swirl, as the second flow will influence the first one.You just gave me a new idea. Thanks

Thanks again for all the input. Much appreciated.

[greasemonkee]

Shave down 4 of your intake cam lobes? - If you have a 20 lobe cam.

If it doesn't work swap the cam.

[pgfpro]

Originally Posted by greasemonkee

shave down 4 of your intake cam lobes? - if you have a 20 lobe cam.

If it doesn't work swap the cam.

I think I might try this I have a few extra cams laying around

[greasemonkee]

Also I forgot to mention that I had ran some tests on Basjoo's old engine before replacing it. I applied various levels of vacuum via an external source to the crankcase and recorded the data at various rpm and vacuum levels (no load) using his supermid injector duration reading. I saw no difference at all on the vacuum vs no vacuum that was noticeable on the readings.

At 7"hg of vac the seals began to sing and it became worse with increasing vacuum. Not sure how one would get around that unless they kept less than 5" of vac.

[Christ]

I think my vacuum number was incorrect. At 15", it becomes a requirement to reverse the direction of the seals to hold the vacuum, since at that level, the oil simply can't get out.

I actually believe that you want to keep the number under 3 inches, preferably close to equilibrium.

The point of the vacuum system is to provide a higher pressure differential across the face of the piston during combustion, and to aide with ring sealing, preventing cross contamination of the combustion chamber and oil. There is also an apparent benefit to the valve seals.

[dcb]

also there is less air mass to shuffle around in the crankcase, when one piston is going down and another moves up, air has to move, less dense air is less mass to reciprocate, but I don't know how much it matters.