Putting a FocusSport/Cosworth Head on a Zetec...

[slngsht]

Al, another thing you may want to consider is getting your current head bench flow tested, so you know what you have. Of course, that means taking the head off, so your car will be out of commission until you decide to put it back on, or get a different head.

[Al N.]

I'm going to do this project in the "off season"...so pulling the head shouldn't be an issue. My car sits from Nov to March.

 

Cody got back to me with some info...I may try the Ford Racing head with Kent Focus 2s...still not crazy $$, especially if someone takes my current head, which it seems like I have a few takers for.

[Cherik]

one other thing to consider is if you plan to race in a particular class - i.e. modifications: valve sizes, porting etc are limited in certain classes.

I'd check to see which classes these heads are allowed in.

 

As far as a build-up, used ZX3's are not expensive, a short block costs much less ($300...$750) than all the parts you're going to add.

It's a lot more fun to take your time building the new engine that way and not have your car out of commission.

 

 

Cherik

 

[Al N.]

Tx for the tips Cherik...your build site is a great read, btw.

 

Hey, can you tell me which of the heads (Cosworth vs. Ford Racing) has better flow from the numbers? I can't tell and didn't quite understand your explanation of the inches of water...(forgive my ignorance).

 

In the end the bare head is about the same price...so I'll go with whatever has best flow (I do know that the Ford Racing head has slightly larger valves than the stock head...don't know what the focus sport head valve size is yet.

[Cherik]

Al,

glad you enjoyed the site.

 

The "water pressure" depression is a measure of the vacuum. 394" H2O is 100% vacuum. More vacuum (50") is more flow.

However, it's not linear.... can't just multiply the numbers with 50/28 and come up with the matching flow.

All I meant to say is, a fair comparison is a bit obscured by using different vacuum levels. But it looks they are actually very similar.

Ignore the lifts >.4". You'll find most cams doing around 9.75mm lift.

 

However, I recall from when we recently put a new head on Graeme's engine, he compared the two heads you are looking at and we found that the cossy head uses stock size valves, whereas the Focus sport head uses 2mm larger valves and will thus flow more because of that ( at the same pressures) He decided for the Focus Sport head. (as you pointed out - similar price).

 

The Focus head was not skimmed however, so that had to be done separately at a local engine shop (approx $70), but we had to do the "cleanup" afterwards.

 

Cherik