TeamRealtreeHD Posted June 22, 2009 Author Report Posted June 22, 2009 We tested mine on a buddy's and my guage and got a difference of 10 PSI... so I know first hand right there that guages differ and such. Quote
rubberneck Posted June 22, 2009 Report Posted June 22, 2009 So what i would like to know because you guys obviously are deep into this. What is the best way to figure fuel octane requirements. Everybody on here always talks about kicking compression but as has already been stated, that can drastically change based on port heights. it doesn't make sense to me that kicking compression is the best way. Is uncorrected compression ratio what you use? Quote
mopar1rules Posted June 22, 2009 Report Posted June 22, 2009 bore - 70 mm stroke - 70 mm rod - 125 mm exh opens at 104 deg atdc eng speed - 5000 revs/min trapped compression ratio 7.0 squish area ratio 0.5 (i.e 50%) squish clearance - 1.2 mm If you could throw a screen dump of output in your post would be much appreciated. forgot to say, that the exh port opening in deg or mm, must be ATDC and minus the deck height. also what is the deck height? give me the deck height and the dimension in mm from the cylinder deck to the exh port roof, and i will do the math/rest of it. i'm @ work right now, but when i get home i'll run your figures. Quote
stroker_2 Posted June 22, 2009 Report Posted June 22, 2009 bore - 70 mm stroke - 70 mm rod - 125 mm exh opens at 104 deg atdc eng speed - 5000 revs/min trapped compression ratio 7.0 squish area ratio 0.5 (i.e 50%) squish clearance - 1.2 mm If you could throw a screen dump of output in your post would be much appreciated. forgot to say, that the exh port opening in deg or mm, must be ATDC and minus the deck height. also what is the deck height? give me the deck height and the dimension in mm from the cylinder deck to the exh port roof, and i will do the math/rest of it. i'm @ work right now, but when i get home i'll run your figures. No problem. I assumed the exhaust port data needed to be ATDC hence I have quoted it that way (104 deg atdc). Therefore deckheight has already been accounted for. Should the programme require deckheight for onscreen drawing sure just put in zero. Quote
mopar1rules Posted June 22, 2009 Report Posted June 22, 2009 (edited) i'm assuming the head type is "central".....meaning the spark plug is directly in the center of the head?? if so, max squish velocity is 20.9 MSV and that is produced @ 10 deg BTDC. i didn't even see right away that you had said ATDC for 104 deg. i've just been in a daze today. also, i can't get the computer screen to post up....sorry. Edited June 22, 2009 by mopar1rules Quote
the boris Posted January 4, 2021 Report Posted January 4, 2021 That's some deep thinking Sent from my VOG-L29 using Tapatalk Quote
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