What power are you all running with silvertop pistons with arp bolt? You hear so many roumours but what are the actual figures people are running.

 

Power conversions have had their zvh turbo engines up to as much as 280 bhp, they recommend/advise that 200 - 250 is the safe mark but this is only with spot on fuelling, I think mfi would struggle to get this sort of power but efi with the correct injectors would be fine.
Hope that helps

 

i personally wouldnt want to gamble with standard pistons as a slight hicup could cost your engine. Ive heard people using toe rods @ 280hp as rough limits, bud id imagine torque is more what kills them?

 

a friend of mine has been using xe pistons, standard rods and arp bolts on his mfi with fith injector. He got 267bhp at16 psi. It seems to me that 280 would be the max and 250 sensible.

anybody else got good reasults

 

Revs kills rods.

 

That it correct

 

ne pistons are actually mahle forged i believe so alot better than standard zetecs i would say

 

what revs would be recomended? 7000rpm?

 

I know someone has taken standard rods (NON shot peened) past 330bhp.

280-300 was the general advisable limit Ive heard numourous times.

 

Yes, but on a turbocharged engine its the torque that causes the failure typically. Two different types of failure (tensile and compressive)

 

Would shot peening or polishing make much difference?

 

Not on a turbo engine, not really.

 

Yes it would add to the strength - we saw 8300rpm on standard CVH Rods that had been shot peened on my RST!

 

Woah!!! What was the rest of your spec, and did you get any valve float?

 

big head, throttle bodies and long exhaust headers!

 

I am led to believe whilst torque can obviosly kill a rod it is far more likely to be revs, failure occuring at the top of the exhaust stroke! As it has no force pushing down on the piston.

I spent alot of time with Harvey Gibbs sorting a spec for a silver top and he reckons with ARP bolts they are good for 290bhp as per a couple of engines he has done with no failures!

 

My 2.1ZVH ended up at 294bhp at 28 psi with an occasional trip to NOS on arp'd standard rods and it never let go! did a good 15K on that engine, giving it death!

 

same as my 2.1zvh with standard rods was 311bhp and with nitrous used occasionally never had a probelm with the rods it was always something else failing and i was always told revs kills rods and power..

sean

 

Cheers Rick, your quite correct!

 

Always good to know!

 

You have to put it into context though. A rod will break when the torque and speed exceed a maximum figure.. I'm no physics expert, so lets use bananas as a unit. An 8300rpm 140 ft-lb n/a engine may have a sum of 50 bananas, which may be less than a turbo engine with 300 ft-lb @ 6000rpm at 70 bananas.

 

i had 262bhp in full zetec form with cp pistons, arp rod bolts but it let go after 12500 miles but i had efi n will running toooo much boost n it left a nice hole a the front of the block

 

pa_sjo I'd go along with your example - sounds logical enough to me.

Perhaps I should have pointed out it was indeed a turbo'd CVH.