---------------------------------------------------------- RV8-List Digest Archive --- Total Messages Posted Wed 01/08/03: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:45 PM - Re: Vertical or horizontal induction (richard martin) ________________________________ Message 1 _____________________________________ Time: 09:45:53 PM PST US From: "richard martin" Subject: Re: RV8-List: Vertical or horizontal induction --> RV8-List message posted by: "richard martin" Shane, Neither cowl version will give you much of a speed improvement. If you wish to go faster, consider the Sam James Cowl aka "holy cowl or NACA cowl" with a plenum chamber also from Sam James. Use a fuel injected engine with a forward facing horizontal induction. This combination will yield a minimum speed increase of 10 mph and also a boost in manifold pressure of 1 to 2 inches depending on temperature and altitude. Also, this combo will substantially improve both oil cooling and CHTs. Oil cooler should be intalled on the rear of #3 cylinder tilted down approx 25 degrees. DO NOT USE a Positech oil cooler on this installation. I tried one and had very bad results. (inadequate cooling). I used a NIAGARA 10 row cooler. If you are using the 180 hp version, the 9 row cooler should be large enough. I would also suggest that you seriously consider a Lightspeed electronic ignition. It will save you up ;to 5% in fuel consumption, and will give you a boost in power. HOT starts are a non event with a Lightspeed. Go Faster. Dick Martin RV8 N233M the fast one > >Dear friends, > >My Father and building partner are clipping along on our fuselage and >have ordered our finish kit recently. We have not yet bought a motor >but we are considering the superior xp360 injected version. It is a >parallel valve with a vertical induction. My question is how much >drag does the chin scoop create with the vertical induction? >Does the slight boost from the ram air on a chin scoop version outweigh >the lack of drag from a non chin scoop cowl that is used with horizontal >induction? Does anyone have any hard numbers to compare the 2 cowl >versions?. I think the xp360 can be converted to a horizontal draft >induction but is it worth the bother? Any comments would be >appreciated. The bottom line is given the same motor which cowl is >faster, chin scoop or non chin scoop? >Shane Summerhays >Salt Lake City Utah >Flying rv6 >Fuse rv8 > >