just measured s5 turbo rear iron factory bracing (pics)
 

Just in case anyone was curious...

Depending on how you measure it, the extra bracing at the oil filter pedestal is ~13mm wide. I just compared my 88 rear iron with an s5 turbo jspec motor. Here are some crappy cell phone camera pics:

S4 iron

https://www.rx7club.com/attachment.p...1&d=1224621185

S5 iron, extra bracing circled

https://www.rx7club.com/attachment.p...1&d=1224621185

How much thicker is the actual dowel casting compared to the s4?

~32mm wide on the s4 vs ~38mm wide on the s5, so something like 19% thicker

Is this the "normal" S5 TII iron, or the "super beefy" style?? Looks normal from these pics

^ hell if i know. you can't draw many conclusions from such shoddy pics though. I think it's from a 91 engine, not positive though.

^^^
Yeah, I'm no expert. I've never seen both S5 rear irons in person, only on Kevin's site. He has a pic of the differences here
http://www.rotaryresurrection.com/2n...ron_break.html
It seems that the super burly casting is pretty uncommon, but it would still be cool to find the specs on both.

I have seen those pics before, but looking at them again, I think that I may have the "super beefy" casting. You can't see it well in that pic, but the back side of the oil filter pedestel is significantly thicker than my s4 iron. It's more than just the triangle shaped reinforcement. I think that means I have the best one, with similar casting to the FD rear iron.

and for the record, that s4 casting you are looking at has got to be some kind of factory freak. I have detonated the living daylights out of it and it never cracked. I'm talking superlean mixture at with advanced timing at 21psi (faulty MAP sensor reading), overboosting on stock turbo, all sorts of crap. Also overheated the thing.

I think the bust happens more when the motor is putting out very high hp/torque numbers, ie: J-Rat's old motor

it made 386/297 , which isn't a ton of power but it's getting up there for an s4 block