S58 is what you're looking for unless BMW doesn't want to share it's latest and greatest with Toyota then maybe just the relatively older S55. Worst case (or best case if you got the 2020 MY) is a B58 with a little more boost.
I feel like Toyota would not just simply turn up the boast to make the GRMN version because increased boast will affect the reliability of the engine. I'm sure reliability had a part in the 335 claimed hp whereas the Z4 has 385hp. I know they put it down to some particulate filter but dang, that is some filter to rob that much hp.
BMW isn't interested in Z4M
S55 is proven 1000hp capable, I had a F80 M3. It was a ton of fun. Tons of torque, very little lag.
It's a great motor, I didn't say it was bad.
Itās not as easy as it sounds. Everything would have to be revised. Sensors, emissions, pistons, bearings, headers, turbos, etc. everything would be different and likely worse. Toyota once knew how to build inline 6ās. But with todayās requirements? Not so much.
I spoke to A70. He said the 700hp motor IS the B58. During development they apparently tested it to that level without failure.After putting so much reliability into the B58 and R&D, I think Toyota will go forward with the B58 only.
If they ever go with the CGI block then the B58 can be tuned further up to 700hp i hear. Which should be enough for this chassis.
But i am sure the quarter mile or traffic light racers will want more
Replacing the block with an iron one (if they used it) or stronger internals isn't as easy, at minimum it will probably have a better head, which I'd be fine with, but anything more would be annoying. A bigger turbo and accommodating parts are probable, but you'd change those in either version anyway if you're looking for more power so that shouldn't worry anyone. So, we'll just have to see what will be different.
