rocklord 6 Posted November 3, 2016 I'm in an Information gathering mode for my AU 4.0 engine and need some values to calculate the compression ratio if I install the Tickford 94DT head. I found a vendor in the USA (Silvolite) that sells pistons for the Australian 4.0. I've attached a shot of the catalog listing for the 4.0 pistons Silvolite sells. Looking at the piston specifications, the compression height for the 4.0 models varies from 1.208" to 1.394" Three of the pistons identify what engines they go to: Silvolite 3324H - EB-ED 4.0 (CH 1.375"); Silvolite 3325H & 3326H - EF-EL 4.0 (CH 1.375" & 1.394" respectively). Is the 3326H piston with CH 1.394" for LPG? One of the pistons, Silvolite 3333H, is domed with four valve reliefs, so it must be for the BA 4.0 with LPG (CH 1.215"). The last piston in the list, Silvolite 3334HC, has a single valve relief but only a CH of 1.208". Is the Silvolite 3334HC piston for the AU 4.0? Is the compression height for the AU 4.0 piston 1.208"? If not, what is the stock CH of the AU 4.0 piston? And what is the recess volume of the stock AU piston? The other question I have is the stock AU block, or deck height. Doing a search of the forum I came up with a post stating that the deck height is "somewhere" around 9.2-inches. Another website stated the deck height as 9.22-inches. I don't have access to local (Australian) reference material so I can't look it up. So I'm wondering what the stock deck height of the AU block is? If I assume a piston CH of 1.208, a rod length of 6.057, a crank throw of 1.955 (3.91 stroke divided by 2) and a zero piston recess, then the deck height would be 9.22-inches. If any of my assumptions are wrong, then.... Any help is appreciated. Share this post Link to post Share on other sites
351XD_Fairmont 604 Posted November 4, 2016 I had a look at some aftermarket ones and comp height was 30.9mm or 1.217" but you would probably be better off waiting Thom to chime in with his expertise mate Share this post Link to post Share on other sites
SPArKy_Dave 8,876 Posted November 4, 2016 I wonder if those pistons are re-boxed ACL or some other brand? Or if Silvolite actually produce them? I can't imagine there'd be much call for them in the US. Share this post Link to post Share on other sites
351XD_Fairmont 604 Posted November 4, 2016 Maybe they use them in their generators Dave, wasn't it you who found they were using barra's for generators? There was a link to a website on here somewhere where they were advertising them as such, was pretty interesting but no idea where the link is Share this post Link to post Share on other sites
FORD_MAN 1,026 Posted November 5, 2016 Yes in the US, the Barra is listed as a industral engine, http://www.aclperformance.com.au/EU/Ford4.0LIntechCastPistons.htm ACL AU pistons were 1.219" comp height, http://www.precisionintl.com/Engine.aspx?ID=470&EID=11716 Hypertec AU piston is 30.9mm comp height, have 4.4cc dish (3rd down) Not sure on AU block deck height but X-Flow is around 9.44" with around 0.020-0.030" piston to deck clearance, I know the SOHC engines run smaller deck clearance, say 0.010"-0.020" Share this post Link to post Share on other sites
gerg 10,871 Posted November 5, 2016 I think that version is de-rated for an industrial application ie no VCT but a good base to start from.<br /> Share this post Link to post Share on other sites