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ST170 - Silvertop - Blacktop Conumdrum
Nosey - 22/12/19 at 11:30 AM

Hi all, I'll try make this brief!

I have a Focus ST170 track day car, fairly well sorted with suspension/brakes/LSD in a 5 speed box/stripped out etc, but with standard engine.

I also have a good silvertop Zetec in a RWD Fiesta rally car, that's currently sitting up. A genuine 210bhp with a lot of head work but standard bottom end except for pocketed pistons.

I also have a standard 2ltr blacktop Zetec from a donor car.

So, I want more power in the Focus but don't want to spend much money! The ST170 seems to be a bit of a dead end due to the VVT without a decent budget for cams/ECU. I'm willing to use the silvertop but this won't bolt into the Focus due to the engine mount position. What do you think are my options? Put the silvertop head on the ST170 block (will this bolt together OK?). Put the silvertop head on the blacktop block with the pocketed silvertop pistons? Use the carbs/ECU form the silvertop on the blacktop and get some headwork/cams and use this, thereby keeping my ST170 and silvertop intact? Does anyone know for sure the compatibility of the parts?

Thanks in advance for opinions/advice!


big_wasa - 22/12/19 at 08:40 PM

I wouldn’t butcher one for the other. Besides it won’t be as easy as swapping the head.

The st is a better engine than the blacktop. Either way it will take some coin to get it over 200bhp but at around 200 you shouldn’t need cams or head work for the st, Just free up the inlet and aftermarket management.