Yes, Tracy's site isn't as current as it used to be. He's still very active in "the scene." Conversion costs could vary a lot depending on how "fancy" you'd like things to be. The Mazda cores themselves are readily available and you'd probably find a good one for very little money. You want to use new (good) apex seals (Mazda brand name ones are among the best). Teflon-encapsulated O-rings are worth the price, and a few other odds and ends. The place you'll have to spend money is the PSRU. As shown on Tracy's site, his are about $3500. They show up on eBay and Barnstormers occasionally (along with abandoned engine projects) so that could be a low-cost way to go. As I mentioned, Paul Lamar and others are working on lower-cost and lighter-weight PSRU designs, but they aren't ready today. The Mazda stock Mazda induction system is much too heavy and big, but you don't have to spend a lot of money to replace it. Tracy produced about 160 HP in his 13b for many years using three simple Mikuni carbs. I think some folks are flying with Holleys with a separate leaning block (for altitude compensation). Tracy makes a very nice engine monitor, but if you want to go the caveman route you don't need it. Okay--so I haven't given you many numbers. If you're willing to scrounge for an engine and wait for a used PSRU, buy used radiators (or use "stock" sizes), etc, but needed to pay for exhaust pipe fabrication, etc, I'd guess you might be able to do everything for $5000-$6000. But it's easy to spend as much as you want! The Bruce Turrentine video is worth buying if you are serious about doing the rebuild yourself. Some people just buy the first old core they find for a few bucks just to experiment with pulling the engine apart and seeing how it works. At the very least they wind up with some useable spare parts for later, parts to practice on (drilling the P-ports, etc), parts to take to their EAA meetings and airshows for demonstrations, etc You may already know this, but here are some other notes: -- PSRU gearing: Although Tracy advertises the 2.17:1 ratio as being good for the RX-7 engines and the 2.85:1 as being best for the Renesis (i.e. RX-8) engines, many people believe the 2.85:1 ratio is also best for the RX-7s. The engines redline at (IIRC) 8000 RPM, so one wouldn't have a problem turning 7000 RPM for takeoff, etc. With a 2.17:1 ratio and a "full size" prop, the tip speeds start to get inefficient at that engine speed. -- As with any auto conversion, doing the details right is key. I'll bet more of these engines fail in aircraft use due to the use of auto-standard rubber hoses, auto-part worm clamps, and non-AN oil fittings than from anything fundamental to the engine. -- P-Port: Fish around Paul Lamar's site for more on drilling out the housings, sealing up the water jacket and the unused side ports, etc. There's a You Tube video on it, I think. -- Ross redrives: These were sold before Tracy got started. They are well made, but have some known issues. AFAIK, they aren't subject to sudden failure, you just need to monitor the gear lash and a few other points. If money is an issue and if you find one for the 13B at a low price, you might consider it. It might not go 2000 hours, but it might be a good "starter" PSRU while other designs mature or you search for one of Tracy's PSRUs at the right price. Stuff to think about . . . "and the Mazda goes Hmmmmmmmmmmm." Mark W.