Forged Engine Components & Tolerances

[F6_Tornado]

Yes Ninka I have heard a Few Atomic Diesel 4ltr Turbos (ADT)

I open the work Gate every morning at 5am and it’s very quiet at that time and I have ZERO noise even when standing in front of the bonnet.

Unfortunately the old rule of thumb that you allow so many though per Inch of diameter bore was ok in the eighties but its 2008 now and with plateau honing, Piston material and a dummy head plate that old rule of thumb is planets away from what you can close it down to nowadays.

[mic]

To save opening a new thread, can anyone tell me if all the bf cams are the same in all the turbo models including the phoon and nado ?

[Venom XR6]

Yes they are.

[mic]

Cheers mate.

[turbotrana]

I though Nizpro designed there own and then get them made, they have never said what they used

I actually specified my own piston design with Wiseco then found out Nizpro were buying them.

[ETM]

my bores were plateau honed by southern engine reconditioning, I dont believe that I would have got the same job from joe blo machine shop.

if you want the real deal use cp and get them to do the job. if you want their number pm me

[2MUCHKW]

I actually specified my own piston design with Wiseco then found out Nizpro were buying them.

Yeah mate ... sure Nizpro run your spec design of Wiseco pistons!

Simon @ Nizpro must get to hear some bullsh*t in his line of work :wacko:

[ETM]

you might be surprised that people who wont say what they use may often be using regular off the shelf parts

[Ninka]

the pistons in these engine have a short skirt so as not to hang out the bottom of the bore at bdc, that will always lead to more knock than an engine with a shorter stroke that can use a longer piston skirt.

You're right on the money for the skirt, except there is no reason for all these piston manufacturers to run skirts shorter than stock, which most of them seem to do.

Law of physics dictate that the skirt load with a shorter piston is GREATLY increased, as there is less leverage preventing the piston from turning in the cylinder, and thus more chance of a bent skirt at high hp or detonation.

Mahle is a pretty light piston, and the heavy Atomic 'Fat Rod' combined with a light Mahle piston makes a combination which weighs exactly the same as the stock combination, only it revs much better as this piston is lighter and has less friction than the stock setup.

Another problem is that tolerances given for the pistons are for race engines, which run 100% load for much of the time, and thus has much more thermal expansion margin built into the piston clearances.

I have done a temperature test on the Mahle Piston vs a stock unit, and couldn't see much difference on the micrometer, so clearances for street use can be taken down somewhat compared to recommendations, just how much depends on the size of your balls, as too tight will result in so called 'black death' where the piston 'nips' the cylinder during load, and a hone and new pistons is the result.

Hope this is helpful

Edited 21/07/08 02:49 PM by Ninka

[Nizpro]

I actually specified my own piston design with Wiseco then found out Nizpro were buying them.

I can tell you 100% we have never used a Wiseco piston in in engine that has left this workshop in a Falcon engine, We have used then in RB26 rebuilds as they make a good piston for them, I am afraid you have been given bad information.