Planeta 5 ja Jupiter 4 paremaks.

[riksx]

Eks ennem tuleb kodutöö ära teha, kui keevitama ja lõikama kukun.

Gordon Jennings räägib silindri pea ja kompressiooni kohta nii:
"Maximum power will be obtained at cranking pressures somewhere between
135 and 165 psi. Going higher with compression, in a conventional motorcycle engine,
can give a neat boost in low speed torque, but the thermal repercussions of higher
cranking pressures will surely limit maximum output."

Teine lause on aga selline
"But if you want to use a true (measured from exhaust-closing) compression ratio
much over 6.5:1, on a high-output engine, combustion control beyond that afforded by a
non-squish cylinder head will be necessary. Considerable variation is possible, but a
good rule to follow is to make the cylinder head's squish band about 50-percent of the
cylinder bore area. "

Hetkel on efektiivne surveaste ₅,9. Enamik kaasaegsed mootorid on ₈,0....8,5. Kui minna üle 6,5, siis squishi peaks olema. Nii palju kui olen arusaanud selle squishi mõttest, siis see aitab ära hoida detonatsiooni, mis silindri servas võib tekkida. Ma päris täpselt pole ära mõõtnud ja see 50% väljaütlemine oli ennatlik. Aga kindlasti tahan teha neid nurkasi leebemaks, et nad ei oleks nii teravad ja ei tekitaks uut "silindrit" põlemis kambrisse

Samas aga

"Coincidentally, that compression ratio (5.91:l) is very nearly all a non-squish
combustion chamber will permit in an otherwise fully-developed two-stroke engine.
With small-bore engines you may push the compression ratio up to perhaps 6.5:l without
serious consequences, using a non-squish cylinder head, but that is very near the limit.
Good squish-band cylinder heads, on the other hand, permit compression ratios up to as
much as 9.5:l in motocross engines with exhaust systems that provide a wide boost
without any substantial peaks, but for road racing engines I cannot recommend anything
above 8.5:l, even when unit cylinder size is only 125cc."

Squishi ja kolvi vaheline kaugus. Hetkel on see 1,5mm + tihendi paksus, ehk seda tuleks/võiks ka kärpida, sest kõik cm3 mis jäävad sinna vahele tegelikult jõudu juurde ei anna ja kogu gaasi mahust hoopis vähendab.

"The clearance space between piston and cylinder head must be enough to avoid
contact at high engine speeds, yet close enough to keep the mixture held there cooled
during the combustion process. This vertical clearance between squish band and piston
should not be greater than 0.060-inch (1.5mm), and it is my opinion that the minimum
should be only barely enough to prevent contact - usually about 0.015-inch in small
engines (with tight bearings and cylinder/rod combinations that do not grow, with heat,
disproportionately) and up to about 0.045-inch in big engines. "

Kui Macdizzy't loed, saad teada, mis on deck height, squish angle, squish clearance, squish area, MSV (maximum squish velocity) jms. Sõltub loomulikult, kui peeneks asja ajada tahad.
Aga enne surveastmega tegelemist peaks kõik need paigas olema, põlemiskambri töötlus on mootori tuunimisel praktiliselt kõige viimane asi.
Põlemiskambri südamikud pole õhkjahutuse puhul eriti teemaks, sest soojuse äravool on suuresti takistatud.