Hi guys made a start on a engine rebuild an spec is as follows
V9 crank
Steel rods
rcm water pump
rcm oil pump
rcl race bearings
arp bolts and studs
mahle piston rings
All of this is going to a low millage p1 casings with exclent bores and pistons.What would the max bhp of the std sti pistons,only im looking at around the 400 figure and the pistons being forged I would expect them to.The whistler is a hybred gt3078r brand fire new, apexi pfc,fmic,550 injectors.Would like your views about pistons cheers Andy

 

There are forged pistons and then there are FORGED pistons, I would go with the decent ones tbh, otherwise 350ish to be on the safe side.

Tony

 

here we go again, forged and forged!

 

jd5217 what are your views on std sti pistons

 

Yes, forged and forged, design and materials used, doesnt matter if its forged, lower grade materials and bad design make them considerably weaker.

To the OP, there is a reason an STI "forged" piston is considerably cheaper than say a cosworth forged piston

Tony

 

Currently I am running a 04 sti uk on standard internals dynoed at Powerstation to 464bhp & 394lb/ft at 1.5 bar on a MD195S with 10% methanol. Seem to be holding up so far.

 

Tony's got it spot on - if stock STi forged pistons and rods, then keep it to 350/350 IMHO.

If, however, serious after market uprated, pukka FORGED items, then the world's your oyster (within reason, of course)...

 

Can you explain the differences between "forged" and "FORGED"? (apart from CAPS lock).

Can you alos post up comparative costs for the differing pistons.

 

The way I understand it is that the STi rods and pistons, although forged, aren't really 'worthy' of the name.

Presumably, it's a typically mass-produced, cost-cutting 'half-hearted' attempt at doing it.

Contact APIDavid - he'll tell you some interesting stories of STi internals ...

 

Why should I contact API, I have had no running issues with mine for them last 2 years.

GRD are managing to run in excess of 500bhp on standard internals. There appears to be confusion about what pistons are in what model and age.

 

Running 500bhp and running 500bhp reliably are 2 different things, hence why people dont normally exceed 400bhp in the new age cars, on the other hand there was a nice thread not long back with a 500bhp standard internalled JDM MY01/02 plate that quite nicely exploded and quickly burnt out on the motorway when the engine let go catastrophically
Luckily the driver had plently of time to get out, thats what 500bhp does on standard internals

Tony

 

Similar thoughts here. I'm running a 321H - 415bhp and 379lb/ft - on an 03 UK STI, completely standard internals. Engine has clocked up 67,000 miles of which 32,000 racked up on the 321H. Car gets driven hard, runs as sweet as a nut, is totally reliable and burns absolutely no oil My only concession to the increased power is to change the oil and filter every 3-4000 miles or so.

 

400bhp+ has been considered safe on Newage Sti's for quite a while now, four of ours (Including our good friend JD's) have been running in excess of 450hp for over 2 years without issue. The right components, careful mapping and regular servicing have all contributed to this.
My advice has always been that, if you are happy to accept that something could go wrong (Regardless of spec) and just move on from it if it does, then push it and see how for it'll go !

 

What MartynJ say is correct - I've already done over 13k on my new age since I took her over 400 and its is fine.

 

I'm enjoying reading all the 400+ success stories on standard internals (newage)

 

see how far yours will go then chris.

 

Yes I know that new age engines are somewhat stronger, still not indestructable though but thats not the point, its not a new age engine the OP is talking about

Tony

 

but he is planning on using stock STI pistons.

 

Stock classic STI pistons in a classic STI block, slight difference compared to the newage cars (and no I wouldnt run stock classic STI pistons at 400bhp if i wanted to keep my engine in tact! )

Tony