The Sam James cowl is a very desirable modification for RV-6's, 7 & 8's. I purchased this cowl before they were "officially" released for production and general sale. I expect that many RV-10 builders will opt for this modification once there are planes flying with round inlets.

I am fortunate that my build started as kit # 570 as early builders had to assemble to exact plans due to very few aftermarket products for the RV-10 market. Because of the early sales & performance success there are many small vendors creating aftermarket items specifically for the -10 market.

I choose the SJ Cowl and Plenum based on it's significant benefit in both aerodynamics and engine cooling characters experienced on the 6's, 7's & 8's. Plus the cowls look so much cooler than the Vans factory cowl. To date there is no empirical evidence that this cowl is an improvement however I am sure adding the SJ Plenum will be a big help in controlling cylinder head & exhaust gas temperatures (CHT/EGT). If you take a close look at Cirrus, Columbia and even the yet to be released Cessna 210 replacement they all use round air inlets vs. the oval/rectangle that Vans still employs. I don't know if there is anything sexier than a SJ Cowl on a military painted RV-8 with a 3 blade prop. Next project???
The James Cowl was not a particularly good fitting piece of fiberglass especially when assembled in conjunction with the James Plenum as the inlet openings to the plenum do not align with the cowl openings. Additionally there was absolutely no way to get the lower cowl to fit as is. We could get the front & right to fit but not the left. Or the left & front to fit but not the right. We fussed with it for 2 days with no luck. When all else fails pull out the saw! We split the lower cowl on the centerline of the cowl starting from the exhaust outlet (nose wheel leg slot) and ending up 5-6 inches from the scoop. This large split allowed us to easily fit all sides and give the cowl enough “relief” to attach without any tension. 2 hours total time once we chose this path. All that was left to do was patch the “V” void and the cowl fit perfectly (photos of the patch are on the Air Box page)

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