lml@lancaironline.net Mailing List Archive

<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> Thank you for your insights on flowtesting. We have a 600 CFM flowbench, have done quite a bit of flow development on Lyc cylinders, and are always interested in new developments in testing procedure. What we asked about was the FLOATing to which you referred in the following quote: <<..For ex - 360 Lycoming engine that should produce 180HP you put all 4 cylinders on a bench and float them you'll will get about 160-165...>> We don't understand the process of FLOATING. Incidentally, our flowbench doesn't measure power output; it measures the volume-flow capacity of a given item at a specific delta-P across the item. How does yours measure power????? Just wanted to clarify one more misunderstanding. Your claim that: <<..Upon CFM info retrieval you are then able to determine HP..>> This is one of the biggest hoaxes out there. The CFM the heads will flow has NO direct or linear relationship to the HP an engine will produce. There are MANY, MANY other factors which determine the power an engine produces, and airflow capacity only determines a MAXIMUM theoretical value the engine could produce if all the other (interrelated) stuff is right, including, but not limited to cam lift, velocity, acceleration profiles and lobe positioning, intake system acoustic tuning, airflow velocity profiles, airflow separation on the port floor, mixture homogeneity, fuel vaporization issues and SMD particle size, effective cylinder pressure, chamber swirl and tumble, flame-front propagation, and other combustion-quality issues, exhaust system restriction and acoustic tuning, and others. The only way we know of to determine engine power is to measure it on an honest, calibrated dynamometer using controlled testing methodology. There are lots of dynos out there which measure fictional horsepower. In fact, if you'd like to buy an IO-360 which produces 950 HP, just give me two minutes behind the dyno control panel and I can show you those, or any other, numbers you'd like to see. Some of the goofy power claims out there are the product of just such dynos, or worse, the product of overly active imaginations. One of the most ludicrous is the claim that installing 10:1 pistons (LW-11487-S from the HIO-360-D1A) in an angle-valve Lycoming will yield a 20% HP increase over the 8.7:1 pistons. Oh yeah, for sure! BTW, on certain engine programs, we have achieved flow increases in angle-valve Lyc heads as much as 19%, and, in certain cases, sometimes had that actually DECREASE power. Jack Kane EPI, Inc. LML website: http://www.olsusa.com/Users/Mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please send your photos and drawings to marvkaye@olsusa.com.