The WS7 3 is several years old, if you really like these engines go with the WS9 as it is just like all the WS7 engines you are used to only it has a turbo plug and uses the MES exhaust system that gives it a little more power as well. If you want the most powerful you want the B9 or soon to be B10. The Shark9/Cross10 are basically the same engine and offer almost as much power as a B9/10 with better fuel economy. Any of the other engines are really just sport engines and probably would not satisfy you if you have raced before.

I have not had a chance to use the engine protector yet so if you get it to fit with the Losi clutch I would like to know. As far as runtime, thats a tough question that has a lot of other variables. For me when I go down in nitro I usually get worse gas mileage as I find myself in the throttle more because I am missing some power I am used to. the Shark gets better mileage than the B9 so just add the shim and go with 30% and see how it does. Remember it's going to take a good gallon before it'd fully ready to race and lean out for max performance and mileage.

Hey Chris, the B9 and B10 are the same, they are 5+2 intake ports, and 3 exhaust ports, the Killer 9 is 5+2 exhaust and intake and 1 exhaust port, the Shark 9 is 3 intake and 3 exhaust port,

Yes, B9 and B10 are the same engine with cosmetic changes. The crankcase is now coated like the WS line of engines and the case it's self is reinforced a little around the main bearing. The B10 also has an extra fin on the cooling head. I have honestly never even bothered with a K9.

Also not sure if you were a WS7/9 fan but if you were you may want to pick one up as they are doing away with the entire line of square stroke engines, and replacing them with the Cross10.

Yes, I saw that, I like the WS7 line, to me it's more linear than the C6 line, and more top end, I'm a big fan of the WS7 line, the B9, B10, and the cross 10 seem to be the same as the C6 BBT line. I do like the mileage the C6 line gets. I did see that they have a WS9 engine also.

Hey Chris, have you been able to get any track time on your Shark yet? I am trying to decide on a fresh mill for this season.:tire:

B9 and B10 are really just the old school C5's with updates thru the years, so they went to C5BB, then C6BB then C6BBT and so on. The Cross10 is not the same tho, it is actually the 2010 version of the Shark9. The WS9 is honestly an awesome engine as it's the first time they incorporated the 3 exhaust ports (MES) into that engine line. Unfortunately the ones that have already been made are all that there will be.

Ran it for a few practice tanks in AZ last month, it ran awesome but it was a pretty limited amount of time and still not fully broken in. I think you should get either the Shark or the B9, the WS engines are sweet but you really have to coax some extra bottom end out of them at our altitude.

Finally got some runtime tuning with the Rally 9.
Very nice smooth engine and a whole lot of run time.
In my Hotbodies D8T 15.30min of run time from one
tank. 7mm restrictor, Werks 2013, and Sidewinders World 30%.
Plenty of power and not lacking anywhere.

My race partner with WS7 III with OS 2050 got 13.30min out of his Kyosho MP9 on a full tank. Plenty of power all around. 7mm restrictor and same fuel.

does anyone know how the pros break in there motors, and in details.

Found out the engine protecter dosnt come out until april:(. I well be trying it with a losi clucth and ill let you know when i get it im about 99.9% sure it well work. The shark is waiting on a competition heater and ill start breaking her in Nice and Slow should be ready for late spring i know its going to be a beast. I heat cycle my motors alot and take my time never rush Your motor. I always get a good 10+ gallons from my Rbs with all the power i need. Ill report how everthing going with the shark for you guys. Thanks for the info. Speedyrob

Anyone know where I can find a piston and sleeve for my RB WS7III?
If anyone has anything just shoot me a PM. What plug have you guys ran back in the day with the Ws7? It's a standard plug.

Part number RBD01143-WS7M will work for you and it looks like A-main has it in stock. This is the P/S/R set for the WS9 so it has 2 extra exhaust ports and probably the reason it cost more than the set for WS7.