asht42

hi guys,

I'm new to the site and looking at starting an st170 project, looking to stick with natural aspiration preferably although i realise supercharged and turbocharged engines give better hp gains for the same amount of money.

I've got an idea to increase the stroke of the engine to 2.3l, can anyone tell me the combustion chamber sizes for the 2.0 st170 and the 2.3 duratec engines?

I am open to any other ideas anyone wishes to suggest

AustenW

The first and most important question is:

How deep are your pockets?

Sp3no

iTrader: (1)

N/A Tuning Ł2000 For individual TB's set up with Cams 200-220bhp
Supercharged Ł4000 on the road if you can find a kit in the first place and keep stock internals 290bhp
Turbo Charged Ł6000-Skys the limit 300-600+bhp

I started a ST170 turbo build (which is on hold due to finances) and even considering i can pretty much do all the work myself i needed just shy of Ł4000 for parts to hit 400bhp

asht42

the simple answer is as deep as they need to be lol

I'm more interested in getting high performance figures than how much it costs me to get those figures.

AustenW

If thats the case you can buy my engine off me

https://passionford.com/forum/restor...ling-up-9.html

Chaz888

I would have a good ponder on what you want first whats the target bhp ? what kind of engine character do you want ? how do you want it to rev? do you want the power to be steady or explode in the last few thou of the rev range?

asht42

thank you for the offer but that would sort of defeat the object lol i'm looking to build the engine myself, just out of curiousity how much did you spend and what sort of power figures are we talking?

asht42

really i'm after similar power levels to the mk1 rs focus preferably without having to resort to turbocharging etc.

Chaz888

ok well boreing and strokeing is a good start getting the comp up is also good if poss then larger valve area and a well matched cam and it all balanced and flowed for said setup then maping also cooling and oil pressure and flow poss needs looking at ,not sure if your get your target bhp but you can get a lot out of NA engines ,do have a lot of talks with people that have already maxed out this engine as they will have done most of the hard work for you in finding what works .

AustenW

A friend of mine has 260bhp nasp on an ST170 engine running high comp pistons, rods, ported head with huge cams, jenvey bodies and management

I reckon 4 to Ł5k should do it

asht42

i was hoping that the 2.3 duratec could be mated with the st170 head but from what i have read the st170 is not actually a proper duratec, more of an updated zetec than a full duratec.

I was thinking that this could increase the compression due to the 2.0 probably having smaller combustion chambers, the valves are slightly smaller but the valve lift is better, along with the timing. does this sound like a good idea if it will work?

asht42

obviously some valve work would be required to allow enough flow for it to be worth doing.

mjcapri

Yep the 'Duratec ST' is infact a Zetec I'm afraid so you can put that idea on hold.... Sorry!

hogdog

The head is actually very good on the ST170 so headwork is not absolutely necessary to crack 200bhp N/A, you just need to get it breathing a bit better. That means a better exhaust system from manifold all the way back...It's not as efficient as most people will tell you. It's tuned for mid range torque so swapping it over for a big bore system will give you top end gains and mid range losses. Add some wild cams (delete the VVT) and throttle bodies and you should be cracking 200bhp. High comp pistons will really help and you can go for a larger bore (up to 2070cc) but that's an expensive step and again, not 100% necessary.

Will Pedley is the man to speak to if you're serious about a N/A ST170.