[revetec]

Originally Posted by jrobson

Engine response must be quite nice, btw how is response with your sluggish looking bottom end? No offense of course, just saying it "looks" sluggish

You must understand that the "trilobe system" is running at only 1/3 engine speed. This means that the trilobes on acceleration require only 1/3 of the inertia. If you go to our website and look at the videos of the CCE2003 engine, we show the revving response. It revs quite fast and is not sluggish on any of our engines.

Originally Posted by jrobson

My opinion is that if you want to put BSFC figures out, compare it to the industry standard at 100% load and let it be what it is, but of course that is just my personal opinion. If your graph is indeed correct then it looks like your engine is right around the same level as a very good conventional engine, but I could be wrong, perhaps everyone is publishing 75% results and not 100???

100% load is not an industry standard. The common test is to the NED European standard which relates to real driving cycles. And most companies publish their best figure.

Originally Posted by jrobson

Edit: Okay I just looked at your site again and "14.5:1 of 238g/kWh (34.4%)" that looks "pretty much the same" as a decent conventional engine to me at the same ratio. Sorry I was just scanning this forum, though you got 207g/kwh at 14.7:1.

In the comparison note that I designed the heads in 2 weeks with no CFD. The heads are two valve and is a hydraulic lifter push rod design. Our next round of testing will incorporate a higher level of top end technology.

Our engine uses different piston acceleration and piston dwell than a conventional engine, and our engines have always run better on a leaner mixture. Most of the tests were done at 14.5:1 due to the standard required for optimal Catalytic Converter operation. 15.2:1 is like a top limit for a Cat. There are Cats out there that can operate at a leaner mixture so this is not a problem.

We would like to test leaner but in our first test it was not necessary from our results of 207g/kW-h. Normally a conventional engine power drops at 15.2:1 so it is not used under any serious loading, although, many engines these days run up to 17:1 A/F under prolonged cruise.

Finally note the graph you posted with the two valve and four valve engines. Even the four valve engine has the best BSFC at about 75% load.

Hightower99: I've heard many engines knock, and most commonly it occurs at lower RPMs such as accelerating from a standing start or in the transition from cruise speed to a heavy load. Both I would say it is most common in the 2,000-3,000rpm range. I'm not saying it doesn't occur at higher RPM, just from my experience from being an automotive mechanical engineer for 25years and driving thousands of cars, this is where I have mainly heard it.