headwork aka port & polishing info

[russianvr4]

Question: was the chamber modified or is that bmw factory machine work marks on it?

[bsinclair]

Originally Posted by russianvr4

Question: was the chamber modified or is that bmw factory machine work marks on it?

thats a factory cnc'd bmw chamber...

[russianvr4]

badass! are the ports cnc'd from the factory or just raw casting?

[bsinclair]

Originally Posted by russianvr4

badass! are the ports cnc'd from the factory or just raw casting?

the ports are just cast... on the first page it shows a pic of where he started porting and you can see the cast finish..

[RansomT]

Originally Posted by russianvr4

Really long forward to dyno results on this. I hope you're not doing any other mods at the same time so we can have a good comparison.

Second that!

[russianvr4]

Interesting that they machined the chamber but not the ports like on their m cars

[bsinclair]

Originally Posted by russianvr4

Interesting that they machined the chamber but not the ports like on their m cars

i would guess it was done to keep the cost down and improved flow wasn't needed to make the 193 advertized hp. i was also told back in 2009 they changed the port size and cams in effort to reduce horsepower as the pre-production models made 15-20hp more. who really knows the actual truth to it all. when Nigel was alive he let me in on a lot of insider info that wasn't discussed.

[usrodeo4]

Do the decked heads run okay on 93 octane (10% of it being that **** they call ethanol)? What is the compression ratio?

[bsinclair]

Yes , decking the head and pump gas is ok. I plan to run pump gas with a decked head and a thinner head gasket.

[Nomad]

Any update on final dyno numbers for this build?