Jump to content


ken666

BA Turbo oversize bore limits?

Recommended Posts

Hey guys,

I'm about to give my BA mk11 2005 XR6t a full rebuild due to an oil pump gear failure, and would like to know more about the block bore size limits?

I'm not familiar with the do's and don'ts with the Barra 4L engine, as I have always owned and built windsor and cleveland engines.

I do however have a great understanding of engine building, but just need to know how consistent these blocks were cast and whether core shift was a problem like many other "thin walled" castings?

I will be anticipating around 700+, running 21psi boost and don't need to learn about another "weak link" the hard way again!

Also wouldn't mind knowing what deck heights others are running, as the block is going to need a quick skim due to light corrosion around the water jackets.

I think the engine may have been overheated previously, as there was some migration around the gasket and mating surfaces?

Cheers Ken 

Share this post


Link to post
Share on other sites

You will have to get the block sonic tested to verify wall thickness. Every block should be done prior to machining, as number one cylinder suffers from bore shift. I'm currently building a spare and got one good block out of three. The minimum bore thickness we encountered was 0.060", which is obviously very thin. If you have a reasonable block, you can also offset bore individual cylinders to keep as much meat in there as you can. The minimum thickness in this new block is 0.120". I hope that this helps.

 

Cylinder Front Rear Left Right
1 0.155" 0.135" 0.230" 0.220"
2 0.165" 0.135" 0.180" 0.230"
3 0.130" 0.160" 0.180" 0.230"
4 0.130" 0.130" 0.230" 0.245"
5 0.155" 0.130" 0.180" 0.230"
6 0.250" 0.130" 0.170" 0.240"
Edited by HI PSI

Share this post


Link to post
Share on other sites
19 minutes ago, HI PSI said:

The minimum bore thickness we encountered was 0.060", which is obviously very thin.

Wow! that's only 1.5mm. Are all the barra blocks (turbo, N/A, gas etc) the same casting?

Ford were always good at getting the best value out of each casting.

The clevo block was always considered to be seriously compromised if bored anymore than .030'' oversize.

I actually had the block from my XB GT re-sleeved with chromoly siamesed sleeves, then furnace brazed in and together through the welch plug holes.

Maybe its something to consider if block consistency is so varied?

Share this post


Link to post
Share on other sites

he's going for super-high power output, unlike yourself, hence him needing a reasonable wall thickness. The engine will most likely be fine, but as Brad said, sonic-testing is the way to go for peace of mind. The barra isn't widely known to be short on wall thickness for any reasonable street application.

Share this post


Link to post
Share on other sites

I know it's not exactly the way you wanted to go, but what about a atomic long engine (with warranty!) All the R&D's done, brad's done heaps of them, then just concentrate on the bolt on's. answer to the blocks, they are all the same other than the dipstick hole- BA's & BF's at the frount, FG's at the rear, so if you get the wrong block redrill it before you assemble it. I would assume the newer the engine the less corrosion. But get it checked anyway, easier now than after a split bore!

Share this post


Link to post
Share on other sites
3 hours ago, 4321 said:

answer to the blocks, they are all the same other than the dipstick hole

 

The engine mount castings are different and there are different external coolant passages in the side of the block, on some models.

 

I don't know all of the differences but I wouldn't be surprised if there was a "best" or preferred block for very high powered applications.

Share this post


Link to post
Share on other sites

I couldn't find any preferred block for high HP from my research, but I am unsure if anyone has actually had a bunch of blocks tested for RND purposes? Had some people say BA BF Blocks were better (Apparently more nickle content) and some said FG were better both from reputable sources, I would go with what ever has lower KM's.

Share this post


Link to post
Share on other sites

Everything else being equal, I'd choose one that didn't have an extra hole tapped in the side, as that'd be a spot to start cracking and another thing to seal up. 

 

My 85xxxkm na fg gas block was more  out of round than my 160xxx bf turbo block.

 

But yeah, haven't looked into it at all so can't really comment much further.

 

Seems like testing each block for bore thickness is the way to go.

Share this post


Link to post
Share on other sites

Regardless both blocks have been pushed well over 1500hp so unless its a big drag build both would be fine pending sonic testing.

Share this post


Link to post
Share on other sites
On 13/05/2019 at 6:48 PM, 4321 said:

I know it's not exactly the way you wanted to go, but what about a atomic long engine (with warranty!) All the R&D's done, brad's done heaps of them, then just concentrate on the bolt on's. answer to the blocks, they are all the same other than the dipstick hole- BA's & BF's at the frount, FG's at the rear, so if you get the wrong block redrill it before you assemble it. I would assume the newer the engine the less corrosion. But get it checked anyway, easier now than after a split bore!

 

I understand what you are saying, and agree with your philosophy.

But I'm a hands on person and get more satisfaction from the fact that I was the one who put all the pieces together and brought it to life!

I really don't let anyone touch my car with a spanner, It's just the way my father brought me up.

Together we have built many top shelf  cars from the ground up.

And on the one or two occasions that we payed someone (very reputable) we felt that it was second class work, compared with what we knew we could do?

It's an awesome feeling when you get it right and people ask who did the work.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Donation Box

    Please donate to support the community.
    We appreciate all donations!


FordXR6Turbo.com Powered by Invision Community

×
×
  • Create New...