desired Piston clearance?

[360duster]

Hi Guys,

what clearance should a Hypereutectic Piston (KB) in a 4.030" bore have? Is it best to look for what KB says: .0015" to .0020" for normally aspirated cars or is there something better for performance use? The car is usually street driven, will see some track time for sure (goal is 12 s).

Maybe you can give me some input based on your experience.

Thanks!

Michael

 

[moper]

No, the .0015-.002 is right. They are supposed to be run tight (comparatively speaking). What you will NEED to do is make sure the rings are filed to fit as those pistons must have a much wider top ring gap due to design and material than others. Instructions are in the box or on the website.

 

[daredevil]

And a little looser if you are ever gonna spray it

 

[360duster]

Thank you guys for the information!

regards Michael

 

[Supershafts]

Use another piston if you are going to spray it.....

 

[SGBARRACUDA]

You can get away with a 100 shot, maybe 150 with this piston.

 

[rumblefish360]

Very true, Hypers should be treated like a stock cast piston for saftey sake even though there stronger, there still cast.
Go to the KB website and look at the notes on the pistons. They have a page for clearances.

 

[Supershafts]

You can get away with a 100 shot, maybe 150 with this piston.

You can.....but there even more fragile with a mistake and unforgiving then a factory cast....

Might as well bite the bullet now and get a better piston, and might as well tell em you want to hit it with 500hp...

 

[360duster]

Hey Guys,

never thought about using nitrous. Engine should be powerful enough for my application. This is the first engine i build completely by myself and i have a tight budget - maybe next time go with forged internals.

Thanks, Michael

 

[1wild&crazyguy]

I run .003, but I buzz the snot outta it.

I would do them at .002

and a .026 top ring gap will work fine.

 

[360duster]

I run .003, but I buzz the snot outta it.

I would do them at .002

and a .026 top ring gap will work fine.

i wonder about the other rings - is there any information about the gap at second ring / Oil ring? Do i have to file them to fit with a special gap too?

thanks for any information, Michael

 

[70aarcuda]

only the top ring gap on the KB hyper need the additional clearance due to being higher on the piston...the second ring is normal gap..

 

[1wild&crazyguy]

standard gaps on the second ring, just stick the oil rings on and don't do anything to them.

 

[360duster]

standard or normal gap at second ring means what? Wich size should the second ring gap have?

Sorry, but i don´t have a clue about this at the moment. Thanks for input!

regards Michael

 

[Petzschler]

second ring gap isn't crutial.. set it to whatever you want. as long as the gap don't butt together.

 

[360duster]

ok, so i´ll set it at .026" like the top ring. Thanks!

Michael