I thought about both the O-290 and O-235 engines but finally have settled on the O-200.
It's been said here that some of the fastest KR's are running the O-200. I am in the process of switching from the Corvair. So, I have been doing alot of research on the O-200 mods. Here a little of what I have found: **************************************************** There are some fairly economical mods which can yield tangible benefits. First, up the compression ratio. The standard CR is 7.8:1 and upping it to 9.5:1 is a quick and easy mod. LyCon sells NFS pistons for about $800 set, http://www.lycon.com/ . Klaus at Lightspeed also sells pistons, http://www.lightspeedengineering.com/ . A slightly less expensive piston mod is to use a C85 piston in the O200. The C85 piston has a bit more crown than the 0200 and your can pick up and easy 8-10 hp. Balancing the crank, rods and pistons is a good mod, but expect to pay about $1000- $1500 for this service. Balancing, in effect, lets the crank spin easier with less resultant stress and helps preserve the bearings. Bumping the ignition timing from 28 to 30-32 degrees is also good for a couple of easy horsepower. When setting up the mags, the internal cam may need to be profiled to ensure that the spark is symmetrical from lobe to lobe. The Slick mags usually have a "cam spread" of a few degrees. For example the mag is set t fire at 28 degrees on cylinder #1, but when the crank is turned to fire the next cylinder, the timing may be at 25 or 33 due to the unequal lift of the cam. Sanding the Slick cam to make it lift evenly will really smooth out the engine. An aftermarket electronic ignition, like Klaus' at Lightspeed will yield some benefits at altitude. The O-200 35 deg stock cam actually works pretty well up through 3200 rpm, but will definitely need to be re-indexed above 3400 rpm. There are probably some exotic cams available, but, given the relative bang for buck ratio, it is hard to beat a stock cam. I think that the C90 cam has a slightly different profile which may give a bit more torque. There is a slight difference between an original 1940's C90 cam and the O200 cam. I think that TCM may now sell the O200 cam as a replacement for the C90. At one point in the past, the C90 was optimized to drive a wood prop, and due to the thickness of the prop, a bit more torque was required. The C-90 and 0-200 both are.410"lift cams. The C-90 is 245 degree duration on both Intake and Exhaust with a 24 degree overlap. The 0-200 is 259 degree duration on both Intake and Exhaust with a 35 degree overlap. The C-90 cam will produce it's peak torque at a lower rpm due to it's shorter duration and overlap. The 0-200 cam will produce more power up top. ******************************************************************** Use a 4 into 4 exhaust. See Jeff Scotts page: http://jscott.comlu.com/KR/exhaust.html It seems to me the O-200 done right is a 100Hp engine and perfect fit for the KR2S. My plan is to use the O-200 and do the following mods to get a solid 100Hp. C-85 pistons, crank balance, vac pump removal, Ellison EFS-3A TBI, timing advance, custom exhaust. The final mod might be a dry nitrous system to add 10% additional power on takeoff. I really am intrigued by possible effects of a mild nitrous boost. Craig www.kr2seafury.com ________________________________ From: Rodger Nicolls <bandenok...@gmail.com> To: kr...@mylist.net Sent: Friday, January 6, 2012 3:18 PM Subject: KR> Opinion on O-290 Netters, What are your opinions on using an O-290-D Lycoming for the KR2-S? (approximately 230-260 lbs dry weight and 125hp at 2600 and 130hp at 2800). The weight is about the same as the Corvair, but the horsepower is a bit more. What do you think? Rodger _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
