Howdy,

Im just in the process of rebuilding my ef xr6 motor, just want to get some opinions about how far to go with the balancing/machining side of things. Basically so far this is what ive got:

- EF Block
- Early EL XR6 Head
- ACL Race Pistons (0.5 oversize)
- ACL Race bearing set, etc.
- ACL Race composite gasket
- Crow Performance cam + valve springs
- Chiptorque computer

Basically Im chasing around 160kw atw with just over 10:1 compression. I am getting a little bit of work done on the ports to open them up a bit.

I need to workout how to acheive the desired compression with decking the block & shaving the head using the ACL high comp pistons, i want to get as much compression of this thing as feasable. Anyone know how much to take off the head/block in this case?

These are the machining options I want to get some opinions on whether they are worth doing for the money for this motor, given the high comp:

- how far to go with the bottom end balancing
- index grind crank
- stroke match
- resize rods
- cc pistons


Anyone who has had a similar type setup, id love to hear how you have done it.


Cheers,
Nic.

if you want compression get AU rods and use the high compression AU ACL race series pistions. They are flat tops compared to the e-series which i think are a 5cc dish. Just make sure you are checking your PV clearance.

You can go as far as you like with the rest of the bottom end, but I would suggest just having the rotating assembly balanced and then check tolerances as you assemble.

I would also go the standard ford AU MLS gasket over the ACL race series.

So the au pistons and rods will be a direct fit?? The compression height is alot different on the au pistons looking at the specs, will this leave enough valve clearance?

How much will I be able to shave the head back if I use these pistons?

Yes they are a direct fit, but you have to use both the au (or ba/bf) rod with the pistons as they are slightly longer. Valve clearance will depend on the cam profile you use. Do a trial assembly and measure the PV clearance and relief the pistons as needed.



How long is a piece of string?

If you use the AU piston/rod combo or the EF one, you need to CC the chambers to work out show much needs to come the head to get the compression you want.

more so if you want to run as much compression as is feasable. you don't want one cylinder slightly higher the rest,
Can you afford to run 98 octane feul all the time?

nmc, how much are you budgeting at your original list?