Which block to rebuild EJ207 or EJ20G
 

I recently just spun a bearing in my WRX and need to rebuild. I figure what the hell i'll make things a bit more interesting. So I'm going to rebuild using a new block. I had the EJ205 block before and want to hold some power. Ultimately I'd like to run a GT2871R or a GT30R. So I want to put the following in a new block using STI heads (so far undetermined which version)

RCMS Omega pistons 9:1 CR .25 overbore
RCMS Arrow H-beam rods
ACL bearings
ARP head studs
79mm crank

Which crank will depend on what block I go with. The EJ20G sounds very solid since it's a fully closed deck block. But I wonder if it is overkill and it's mid thrusted bearing is of the old school design vs. the EJ207 which is semi closed and rear thrusted. Should I be concerned with either block? Does one have an inherent advantage over the other?

cheers

garrett

You can have the closed deck block machined to except the rear end thrust, The advantage of this block is the strength over the semi and based on your above list it would make for a good set up.

Rcms will do the machine work on the block halves for you iirc £295 ish, if you get that done then you can run the sti9 crank or save your money and use the EJ207

I think the price comes out to about the same amount of money either way. I might save more money by going with the EJ20G block tho, even if I have it machined to accept the the STI 9 crank.

cheers

garrett

OK So how big a deal is it to have a rear thrusted motor vs the mid thrusted design? Is the mid thrusted motor not going to last as long? How much better is the rear thrusted design and why?

cheers

The Closed Deck Block gets my vote for strength,fit some ACL Race Series
Mains and Big Ends with your V9 crank,the V9 bolted rods are an improvement over the earlier nut/stud type but you could also fit ARP Con Rod bolts to your V9 Rods for extra piece of mind.
The liners on the CDB are more ridgid under high boost and a lot of people fit ARP Head Studs/Nuts for better clamping force with the steel head gaskets.

Have a read below about the rear thrust block - mainly changed to reduce the NVH into the inside of the vehicle.
(save pic and zoom in)


Attachment 49736


:thumb:

So i might be safe with just using a 79mm Phase one crank with ACL bearings? I'm not worried about noise. Car is going to be fitted with a lot of noise making parts. :)

cheers

V9 crank is Nitrided and the mains are Cross-drilled,so if you can afford to have the CDB machined to take the V9 - you will have a good strong block.
The CDB also has Bore Squirters fitted to the Main Bearing Saddles to cool the underside of the Pistons - another Bonus.

Mick