fg engine rebuild

[4321]

Its time for a rebuild. I've just picked up a NA fg engine (9k so it's like new) I'm happy with 400kw (at the moment!) so I would like your opinions on A : pistons. looking at a spool kit but I want the engine to be quite, on the manley site it was talking about the wrist pins being offset (like original) & this will make the pistons quite (especially when cold) I don't want a 'rattler' like GHP ended up with. I thought the noise was from excessive piston to bore clearance's?  Atomic sell cosworth pistons which don't need as much clearance & should be quiter but is it worth $1400 more? Do I need another balancer as I don't intend to raise the rpm limit. A new set of billet gears for the stock oil pump & a yella terra flex plate. B:  With the head do I put better exhaust valves & plaz. springs (with retainers or just springs?) or atomic sell a head ported with springs for $2600? I'm going to use all the other valve train components from the NA engine as it's nearly new (and genuine) The cars already got KPM injectors, 460 walbro pump, 3582 turbo with a 11 blade wheel, flapper mod, 3 1/2 x force turbo back etc.. which will be transferred to the new engine. I'm open to other opinions on this build but I'm not after a dyno queen as its a weekend car that has to have good manners. I can buy spool rods for around $600 for H beams or$700 for I beams (which I don't think I need) I hope somebody can point me in the right direction especially regarding the pistons 

[JETURBO]

Piston selection is a crucial balancing act and definitely something to ponder but there’s loads of them out there 

 

Yes spool is a cheaper option and yes they aren’t as quite as others so that’s the trade right there 

 

cosworth is arguably the best piston money can buy for this engine platform and exclusively built for Brad at atomic 

 

you get everything here ( quiet/massive HP capacity ) but cost is the offset 

 

Manley have a decent piston with skirt coatings for a reasonable dollar and a pretty decent all round offering 

 

Mahale have the FGF6 piston that’s a semi forged item, super cheap super quiet but imho rated to 25psi absolutely maximum on E85 probably 22psi on 98 as the ringlands ( on stock ring gap )and technology within the piston isn’t there for a mass production offering 

 

Mahale also offer a range of other pistons to suit the falcon XR6T with very good manners and costs 

 

any piston that’s a semi forged will be cold quieter than forged 

 

full forged has bigger power capacity 

 

cast pistons are the cheapest and quietest 

 

now here’s where it gets funky..... the cast pistons in the FG Xr6t are (IMHO) better at bigger power than the FG F6 semi forged Mahale piston ( weird I know ) 

the ringlands on cast pistons have more “flex” than semi or full forged ( on stock ring gap ) 

 

getting a new set of FG pistons/rings but say a spool Rod will happily crank out 550rwkw with an appropriate ring gap to suit the target boost/fuel with factory PTB clearance 

 

sooooo many ways to skin a cat 

 

on a budget as above , got some coin and want to push it go Cosworth with a 0.50 over and hone and line boar the block to suit with a torque plate on to the stud pressure you’re going to run 

 

basically how fast can your wallet go ?

 

yes get a new balancer as the Atomic street balancer is miles better than factory and sub $300 

 

dont just get the gears, go a full pump assembly as there’s more than just gears in that puppy  again full assembly is sub $1300 

 

swop the yellaterra plate for the Atomic HD plate, one look any you’ll know where every cent went again sub $600 

 

clean the FG head up ( cold tank ) and skim the deck 0.002 of an * 

new exhaust valves for turbo are around $30ea from ford 

 

Plazmaman springs are the new spec and really good ( all retainers/locks are generic across turbo/NA so don’t worry about new retainers ) just under $400 a set 

 

I cannot stress enough to change the chain/tensioner/guides/lower sprocketand pivot guide  at the same time as the factory stuff isn’t great at maintaining pressure against the tensioner under fast fluctuations obviously Atomic again 

all of this stuff and a pump assembly and HD street balancer is $2460 inc gst and postage ( I had this exact package priced up this morning for another member ) 

 

I can supply all of the part above and make it much better than RRP if you want  

 

I can even get all the valves/gaskets/seals and odds n sods for you if you need 

 

shout out happy to help 

Edited 11/04/18 04:38 AM by JETURBO

[arronm]

Perfect advice.

 

And if you are running E85 , get the high comp cosworth pistons. that's what the nizpro car has. Will be a BEAST on E85..

[4321]

Thanks for the replys. I did not even consider the stock pistons but that's something I will seriously consider. I discounted main studs & girdle as unnecessary for my power goal (or am I wrong?) I was going to keep the chain & guides but that's out the window now! I do intend to run head studs (12mm) Stock rings or something 'better'?   

[JETURBO]

If keeping it under 550rwkw or 23ish psi you don’t have to girdle but studs on the mains definitely are a must do 

 

I’d go an ACL ring vs a stock ring and depending how far you go I would loosen up the ring by another bit   ( that was technical but #enginebuildingsecrets lol ) 

 

IF by some miracle and possible with only 9k the boars are straight you could go a factory piston/ring no worries if budget is really on your side but again a smidge off final fit on ring vs stock 

 

Atomic 12mm headstuds and factory gasket no worries, match it up with a 28mm OS washer and you’re peaches to 120ft/lb 

[4321]

Thank you for this information it's invaluable!

[k31th]

he is one helpful ({}) sometimes haha.

[4321]

Ordered the exhaust valves & head gasket but the pistons $242.00 each list! Are they worth it? capa via fleabay has diamond piston, Par rods & total seal rings for $2245 is this comparable? Or am I muddying the waters & should just wake up to myself & go with what Jet suggested? Who do you recommend in Sydney to do the machining? ( I'm in NW Sydney)

[JETURBO]

Sheettt, yeh that’s up there for a $30 piston lol 

 

ummm I wouldn’t go the CAPA package as Diamond pistons are a bit undesirable ...

 

Atomic do a cheaper  superleggra/streettorque 550kw kit that might be what will suit you 

 

I’m not super familiar with what’s on offer in NSW but you need to understand that final fit of parts typically requires balancing and material take off, rings need to be filed to suit and the list goes on, so a knowledgeable machine shop with experience in setting a barra up can definitely be the difference between good and not so good. Atomic is in NSW and Brad does offer full machine facilities....

 

might be worth deciding now how far you want to go as its a slippery slope once you get into it 

[HI PSI]

Dollar for dollar, JE are probable the best value pistons for a stout Barra. I've built three engines using them (Sold two short engines). They're extremely high quality alloy that have minimal expansion. Therefore you can tighten up the clearances, which results in a very quiet engine. 

 

Btw, I agree with 99% of what Jet stated...