Quote:
Originally Posted by trainwrex
The problem is the differential heating of the bores especially the areas where the pins are.
CD and sleeving the block and torque hone plating has been shown to be the best way to may a 257 reliable.
I did a huge amount of research into this when i did my build speaking with world renown tuners etc and that was the reason i did what i did to my engine.
Also power comes with the heads so you need to get the heads matched to the outlets.
I was looking at EG33 build back in the day but it was too expensive to do but now guys are turning to H6 or even better EG33 motors to pump out decent power without stressing the engine. Thats what id be doing if i was looking at building up a subaru..
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I think we're both agreeing that a 257 can be made reliable but its expensive to do so.
As I've said many times had my current engine not had the sleeves already done I wouldn't use the EJ257 as a platform again. It would always be a stroked closed deck whether that be a 2.1 or a 2.35 would depend on block availability.
In theory the 257 is great but the reality is some what different.
Sleeves are more likely to drop than they are staying put so you need to budget for several possible rebuilds and block refacing until they settle.
14mm headstuds are an absolute must on a big power 257.
Even if you close deck a stock 257 the cylinder walls are thinner than you'd think.
Here is a dissected ODB 2.0L
Here is a 257 see how thin the factory walls are? They still split even with pins an CDB inserts when you start to use them for big power.
The EJ257 can be made into a good platform but its gets very expensive we've both got the reciepts to show that
I just wouldn't use one as a basis for a big power build again.
With regard to torque plate honing that has nothing to do with strength of the block and has no influence on it whatsoever. It's just a process that simulates the heads being torqued down when cylinder honing so it's more accurate. Although it is something I have done on every build I do whether they be 2.0L, 2.2L or 2.5L blocks.
I also have all my engines centreline honed for the crank too. This latest one was quite a way out according to the machine shop i used.
Heads, obviously polished flowed and ported makes a difference but its not as essential on an FI engine as it is an an NA one.
A good example was my GC8 that was running untouched 2.5 heads castings. They weren't ported or polished I literally just changed the valves, springs and retainers. The cams were OEM 06 WRX AVCS cams.
That car made 600hp and ran 10's. No doubt it would have gone on to make 60-70HP more had it had head work and big cams but that work and expense just isn't necessary until you get to that point. I can't believe people think they need cams before this point. 400whp will be more than enough for most.
Stock STI5 heads will do 400whp easy without being touched. Although I'd always recommend swapping out valves and springs if you wanted to do that.
Bottom line is a modified 257 is good for a mid power build say 400 whp. They can be used beyond that but to make it reliable beyond that gets expensive.
The flat six is an awesome platform as Andy Forrest has proven but lets be realistic here. The cost and work involved to build one is way beyond what's being discussed here.
The OP has asked for opinions on the 207 versus the 257, and despite loving how my own built 257 drives I just cannot agree that its the better option for the OP.
In this case I honestly think the 207 is a better platform.
It's only my humble opinion but that's based on building, using, racing almost every combination of EJ engine there is over the 15 years since i bought my first one. The only ones i've not tried is a destroked 2.5 or a stroked 2.5 and to be fair i've no desire to.
Hopefully Tino you'll see this as a good discussion rather than me trying to be a smart ass which I'm not