St 170 Bottom End

[Guest chrispine]

Hi,

as this is a strong crank and presumably rods, does anyone know if the crank and rods will fit into either a 2.3 Galaxy/Scorpio block or 16v RS 2000/DOHC 8v block? Some cheap on Ebay but don't want to find out the expensive way,

 

Chris

[ibrooks]

Almost certainly not - the ST170 is a Zetec with a trick cylinder head and some uprated bottom end bits. The FWD RS2000/Scorpio/Galaxy 2.3 is an I4 - all the same family as the 2.0DOHC that went into the Sierra.

 

That said the DOHC is often very underrated because of the lack of tuning bits for it. It's a strong old lump. Turbo Technics did boost them and I think got around 230BHP without much in the way of engine modifications. But you were looking at close to Cosworth money without the snob value of the badge so it wasn't a popular option.

 

A 2.3 block with the late Scorpio 16v cylinder head, the catalysts dumped and decent management tends to get towards 200BHP and makes nearly as much torque as the 2.9 V6.

 

Iain

[Guest chrispine]

Thanks Iain, got a Scorpio/Galaxy 2.3 in at the moment, have read on the internet (so it must be true!) that you can supercharge this engine in standard form to 12 psi which will give a reliable 300 ish bhp, slowly putting it together at the moment, used the DOHC sump so no heavy balance shafts, also used the RS cams and 44mm Suzuki TB's, the reason for the 2ltr bottom end is a shorter stroke needed to use Calibra Turbo pistons (higher comp height), I have both the dohc and rs 2000 engines in the garage for parts if needed, I bought a spare 2.3 engine cheap on Ebay a couple of weeks ago as it was close to where I live, just wondering how much the standard bottom end will take, bearing in mind standard power was 145 bhp. As the engines are cheap, maybe next year I can give a good idea of what it will take just before it goes bang lol.

 

Chris

[ibrooks]

They are brutally strong so I'd bet the pistons will melt long before you find the limits of crank/rods/journals.

 

Some kicking around of numbers on the Sierra Owners Club did come up with the theory that a 2.3 block and pistons with 2.0 crank and rods (I think) would give a 2.2 engine with a compression ratio around the 8:1 mark and should all bolt together with no fancy work beyond bunging up the hole where the chain drive goes through to the balance rods. It should make a good basis for a boosted engine with serious power potential.

 

Not sure if anyone went as far as building it though as they all seemed to stick with 2.3's with Sierra 8v or Scorpio 16v heads and natural aspiration.

 

Iain