I guess we will wait and see. Hopefully its somewhere in the middle
At this stage I would look to resleeving and then reboring it. And with the other parts I mentioned above, it *should* hold 400-420 atw I would say.
The weakness in any ej block in my opinion is the cylinder walls and the load they cop due to a bad angle on the stock crank. My block fixes that with thicker cylinders from factory.
That being said, of course there are other stress points in the engine (pistons, crank, oiling system etc) which can be fixed with some reverse engineering / thinking.
I'm actually going to speak to serge this week or robin from perfourmance Motorsports to see what they can do for a grb ej207 block in the way of sleeving. I'm not a fan of close decking alone, as the close deck cradle only stiffens the top of the block / cylinders. My theory is the stress point in these engines is further down the cylinder, about 2/3 of the way, which is the focal point of the top of the rod at tdc, so at peak torque, the load this spot in the cylinder cops is the most concerning. This is made even worse by the bad rod angle and rod ratio of the 2.5 crank, compared to the 2.0 or 2.2 crank which is alot more conducive to power and revs. So when you combine that with thinner side walls and bad piston to bore clearances, you can see why I don't really like most 2.5 builds.
Therefore if I can strengthen the "already stronger than any 2.5 litre" block, then that would be a positive. Machining would have to be spot on. And I wasn't necessarily having a crack at all machinists in the USA, but more their theory of what works and doesn't. For sure there will be guys there that know their shit, but most of them don't post their secrets on the Internet I would say
but that's just a hunch We've now moved beyond discussing the inadequacy of stock piston materials (such as the stock ej205/255/257 pistons). Instead I'm calling out the positioning of the crown, the ringlands position respective to the top of the piston, the piston skirting length and thickness, the gudgeon pin location and its effect on piston inertia at higher revs/ load, and the design and strength of the cylinder within which this piston sits.
Then you have the rod itself - the length and design is better than the equivalent 2.5 rod. But I would be getting custom rods to suit the rod ratio I wanted, and they would be better than or at least equal to the pauter I beam rods material.
The crank I've covered already. Same with headstuds and headwork.
If I do this build, I will have addressed these things one by one - and I would like to think I would be pretty close when it comes to the weak points in the stock design, but of course only time will tell.
Mick
