So... i'm littering these forums with questions lately and here is another one i'm throwing in.

I have a ZT build going for 250-300bhp on forged pistons but standard st170 rods, guy at the garage said he wouldn't set the limit further back than 6k.. Personally I think that is almost like a diesel, what does everyone else know about the safe limit for these rods..

I would be happy with 6.5 k hard cut, that's a big compromise as it is!

 

I was running these at 8200 rpm on a n/a st170 build. bloke is full of shit! lol

 

standard they are 7200rpm

 

Yes well i know they are good for the 7k mark in N/A form, but this is forced induction, all that extra pressure will be ramming down those rods and pistons! BUT JESUS CHRIST 8200!! lol

 

I ran mine at 6200rpm but that's because the turbo ran out of puff about 5800rpm and there is no point in having a high limiter if the turbo can't flow enough air to use it.
What turbo are you using?

 

my zetec turbo runs 277bhp at 6200 revs on standard zetec rods (cast iron)

 

I wouldn't say he was full of shit haha, Bit harsh, He prob an old school mechanic playin it safe. lol
i.e don't rev the tits off it and it will last longer.

 

Yeah makes sense, I'm using a t34. Bit over kill I know but I have it now!

Thats good mate, what's it like hitting red so early though?

I agree here, it's logical!

 

sorry ive just looked again and the 6200 isnt where the limiter is its where the power tails off on the dyno graph..shift lights come on at 6500 and limit is 6700 i havent actually driven the car at those revs yet

 

What turbine housing mate?

 

I've personally seen 2 ST170's with rod failures. I can only assume they were both engine speed related, as they were from standard cars. Its quite possible that they both could have been put in the wrong gear though.

 

Not sure mate.. it's the standard turbo from the early escort cosworth.. the big one as far as I know lol

Yeah I think I'm gonna play it safe with rev limits. 6700 I think but I'm not gonna take it there too often! Just don't want a massive kick shortly followed by bouncing off the limiter!

 

Ah you'll be on a .48 then, should be nice and responsive.

 

It wont be a .48 if its from a early Escort, .63 as std

Steve

 

ive built and mapped a zetec turbo with a t34.48 running 22psi limiter set at 7100 soft 7200 hard cut he was at central day and managed a 13.1 and spent the day cracking the limiter with no problems

 

forgot to add standard silvertop rods with arp rod bolts

 

Id say 7.5k in short burst and now and again that's with ARP's . Any more than that H section would be needed along with forged pistons to be safe and reliable.

 

i was lucky in my st170 powered fiesta,was in third at 7000 revs,went for 4th and got second... luckily the only damage was to a gear cable...

 

Sorry yes I'm talking shit! lol
It will be a .63 in which case it will make power all the way to the limiter.

 

thats good stuff....

im on stock rods with calibra turbo piston set up, im looking at fitting a t34 with ofam and frs injectors soon but i wanted around 15/16psi boost