Making the AU rev :)

The Monty · 24-09-2012, 07:01 PM

What parts would be required in the bottom end AND head, to be able to get the AU6 to rev to 7k comfortably? I know we've all spoken about it before, and I have spun to 6600RPM before (

)but just want to know what I would need to ensure that it was reliable at that kind of level.
If Im going to do it again, Ill do it properly this time......

B&D Racing · 24-09-2012, 09:34 PM

Hey Ralph

New timing chain tensioners for one and good heavy duty springs and retainers..

mik · 25-09-2012, 01:06 AM

hmmm dunno Monty, i would imagine some strong rods would be high in the list there , crank girdle perhaps? better head bolts? race balancer, blue print and a balance of rotating mass.

The Monty · 25-09-2012, 05:21 AM

I was thinking girdle, h/d oil pump and harmonic balancer. Already have the springs and retainers.

Sox · 25-09-2012, 07:27 AM

AU 6 pots have a main stud girdle standard, and the cast sump forms an integral part of the bottom end, bolting to the side of the main caps.
It's very solid and won't need anything else IMO.

It really depends on how long and often you plan to sit at those revs, but at a guess, for short durations on the drag strip, it would likely do it in standard trim.

The head will just need the appropriate springs/retainers.

You might want to talk to an engine builder who has had a lot of experience with AU 6 about rods and pistons for bulletproof reliability.

T4ME · 25-09-2012, 07:49 AM

Id de-stroke it for those revs.

Maka · 25-09-2012, 12:31 PM

Quote:

Originally Posted by T4ME

Id de-stroke it for those revs.

I would too lol! Cost though?.... Even getting a stock crank and modifying it (lightened & balanced) would go a long way towards your motor revving to 7000rpm reliably.
Depending on how much $$$$ youve got, crank & rods should be a priority.

Good luck with it & good to see you back- looking foward to your new AU journey!

cheers,Maka

FGII-XR6 · 25-09-2012, 08:03 AM

rods would be a priority and a balance

madmelon · 25-09-2012, 08:51 AM

Lighter pistons with a good set of rings and new stronger rods. A long stroke engine such as this has massive piston speeds and accelerations at those revs and rods and ring lands are put under extreme stress. I've also read somewhere that the BA engine has a nasty crank harmonic at about 7000rpm, this may or may not be true for the AU also.

xr8ute · 25-09-2012, 12:39 PM

Surely you would need to spend more time modifying the valve train than the bottom end?

The bottom end just needs to hold together, and stay lubricated. What are the rod bolts like in the I6?

The top end needs to keep the valves in control. What are the hydraulic lash adjusters like above 6k rpm? Can you replace these with a solid?

Sox · 25-09-2012, 06:27 PM

Quote:

Originally Posted by xr8ute

Surely you would need to spend more time modifying the valve train than the bottom end?

The top end is pretty bulletproof, aside from the usual springs/retainers.

Quote:

The bottom end just needs to hold together, and stay lubricated. What are the rod bolts like in the I6?

If only, piston speed is the big problem with the Ford I6 as it's very undersquare.

Quote:

The top end needs to keep the valves in control. What are the hydraulic lash adjusters like above 6k rpm? Can you replace these with a solid?

7k is nothing for a top end design like the I6.

The Monty · 25-09-2012, 06:29 PM

My old limiter was 6200ish, I took it too that from cold every morning, everyday of its life, and it didnt care at all. That was with the big cam, and JMM valve springs and retainers, nothing else.
My first AU I took to 6600rpm about 5 times, standard everything under the rocker cover, no wobbles, no worries, no anything.
I think if its just for the drags, it would be fine. Set it at 7000rpm, use it if I want to, dont if I dont. If it blows, tow it and throw in another bottom end...