Quote Originally Posted by DOHC46 View Post
I just found out you can buy a full built Cosworth 2.5L EJ25. Probably costs twice as much as the 818 kit though.

http://americas.cosworth.com/product...ck-assemblies/

However, if you have the money, and are going to be doing a LOT of track days, I think it'd be worth it.
I had one of those fully built Cosworth 2.6l long blocks. I was actually going to put it into the 818. Sadly it was recently damaged in a fire (the engine didn't catch fire, the garage it was in caught fire).

If you go all out and get the 2.6l kit, billet crank, manifold intake, headers and dry sump, you're looking at spending well over $40,000 on parts, labor and tuning. On top of the engine you'll need a bigger turbo, a new ecu, a new turbo back, and a big FMIC (all included in the $40k). The actual Cosworth supplied block is not very expensive and no different from a standard ej257, what you are paying for when you buy the CS600 shortblock kit are all the forged internals.

HP numbers will vary from dyno to dyno, but you'll be looking at somewhere in the range of 500+ awhp on pump gas (On a conservative Maha dyno I had 630 at the crank on 94 octane pump gas and a "safe" tune). The weak point ends up being the head gasket, you should expect to replace this at least once a year if you push the car regularly (mine was doing laps every week).

I'm not going to rebuild the engine. I'm going to take the insurance money from the engine and build a much tamer ~400hp engine for the 818. An 818 with 600+ hp seems kind of pointless and there are much better places to spend your money if you want to make the car faster (I'm thinking 5-speed sequential gearbox). A 400hp engine will set you back less than $10k, after that it's diminishing returns.