Alex. A

Yep I talked to Ross in the end and they recommended a spec of .004-.0045" They have quite a barrel shape on the skirts and I believe we measured them .200" from the bottom of the skirt when we honed my block at work. I was just suprised when I received the pistons at work they came with no paperwork..

Hey all, just fitted a plaz engine bay mounted surge tank with a bosch 413 motorsport pump Ro my fg ute. Just have a question regarding the feed and return hoses on the surge tank. Is the upper line on the surge the return to the fuel tank? Thanks all

Yeah very loud.. do you know what you recommended piston clearance was with them? I inquired with Ross and the recommended. 006" for small bore turbo applications.... sweet jesus that's some clearance.

Howdy guys, Just curious if anyone here is using ross forgies in their xr6t? After first hand experience with noise etc? Due to them being a 2168 type forging and requiring more ptw clearance then 4032 pistons.. curious if there is any cold noise and if they get a little better once up to temp? Was listening to a mates built barra with Ross slugs and u could hear them. Cheers fellas

Although this is within oem spec, its lower then I would like to see in a brand new motor running a 15w40 oil.. considering it was over 30pis hot with thinner oil before the rebuild...

Correct mate and you can buy .001" undersized also. This is just so you can tailor your clearances so suit the specific use and clearance required. Some cranks vary a few tenths as do main tunnels and rod bores.. with stack tolerances you can end up quite far away from the desired clearance.. which is then when you mix and match std and hx bearing shells to get the clearamce wanted. Its also interesting how much different manufacturers bearings change in clearance.. we generally find acl is on average .0005" looser then clevite for the same part bearings.. Looks like I might just try dropping the clearance down and see how it goes. My hot pressure was 15psi to 19psi roughly and 750rpm.. not horrible bit compared to the 30psi minimum it had before with worn out std bearings I was just a bit suprised.

Thanks for the reply mate, The aftermarket parts don't really come with a specified bearing clearance as such.. Bit of a long winded reply here so excuse if it gets boring haha I build engines for a living at a shop here in Brisbane, however every motor we build has a dry sump set up with an external oil pump so we send the bearings quite loose to survive... I don't build many street motors anymore and this is my first xr6 I have built. The usual rule for bearing clearance is .001" per 1" of journal diameter(add .0005 for extreme boost/no2 applications).. this is accepted pretty generally... This would put the barra mains somewhere around The .0025-.0026" and the big ends around the .0021".0022" for a std motor using this Formula. looking at the barra workshop manual, they specify Min/max clearance for the mains and big ends at .0007"-.0015"... that's insanely tight for a boosted application With the journal sizes it has!! Is there a different workshop manual for boosted barra motors? I initially built the motor and set the bearings at .0023-.0025" for the mains and the big ends set a little looser at .0025-0026". However once started, the motors hot idle oil pressure was drastically reduced from the Pre rebuild pressures.. I guessed it was due to the extra bearing clearance and the oem oil pump just can't keep up with the extra leaks. Cruise pressure seemed acceptable, however idle pressure had halved.. So I have torn it back down and will re do my bearings... I was really more curious at to what other barra engines builders are sending their clearances at... Thanks again guys.

Hey guys, Long-time lurker first time poster.. I'm rebuilding my fg xr6 turbo atm.. just curious as what other ppl and sending their main and big end clearances at? I have the factory specifications which are super tight compared to what I send motors at usually. Any info would be fantastic. Thanks guys