Jaki luz tłok-cylinder 289 Hypereutectic aluminum

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Witam,

Mój blok 289 właśnie wylądował na maszynie u szlifierza i jest pytanie na jaki luz przygotować blok? Z Haynes'a podają 0.045 do 0.066, ale to dla zwykłego fabrycznego tłoku. Jaki luz powinien być dla takich nadwymiarowych tłoków: http://www.summitracing.com/parts/SLP-H273CP30/ Na podstawie tego co podaje Haynes, mój szlifierz chce zrobić na 0.065 do 0.07mm.

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Po rozmowie z Piotrkiem, googlaniu i konsultacji ze szlifierzem ustaliliśmy, że "na moją odpowiedzialność" jedziemy z 0.05mm

Może się komuś przyda więc wklejam dla potomoności:

Piston to Bore Clearance for hypereutectic pistons were Dyno tested at wide open throttle with .0015", .0020", .0035" and .0045" piston to bore clearance. After 7-1/2 hours the pistons were examined and they all looked as new, except the tops had normal deposit color. Even with 320 degrees Fahrenheit oil temperature, the inside of the piston remained shiny silver and completely clean. Excessive clearance has been shown to be safe with hypereutectic pistons. Loose Hypereutectic pistons over .0020" do make noise. As they get up to temperature they still make noise because they have very restricted expansion rate and do not swell up in the bore. The Hypereutectic alloy not only expands 15% less, it insulates the skirts from combustion chamber heat. If the skirt stays cool piston expansion is drastically reduced. Running close clearances is beneficial to piston ring seal and ring life. A small short term HP improvement can be had by running additional piston clearance because friction is reduced. To obtain actual piston diameter, measure the piston from skirt to skirt level with the balance pad.

Źródło: http://racingarticles.com/article_racing-10.html