elitesrock2
Well-Known Member
Almost have my 69 dart finished up and ready to run and i'm wondering what octane fuel i should run in it. engine is an odd combo as it was put together when purchased
specs are
.030 over 340 with forged crank, h beam rpm rods and 2618 ross pistons. -12.6 cc dome giving me around 11.43 to 1 compression with a .039 gasket.
Camshaft is a comp RX302S-R6 solid roller. 269/276 at .050 .654/.655 lift 106 lobe separation degreed at 106 pushing some 1.5 ratio Harland sharp rockers.
Cylinder heads are just some smog heads with extreme port work done. exhaust injection ports welded and shut and the hump ground out when ported. they are iron and aluminum is not in the budget.
Fuel and air is a edelbrock super victor intake with an 850 demon
running headers and a 3 inch exhaust 4.56 gears and a early low 1st ball and trunion 4 speed converted to u joint with a vertigate shifter with DOT slicks. cooling system is perfect so i'm not worried about getting it too hot but this car will see the street a bunch. I was thinking i may be able to squeez either 25% race 110 to 75% non ethanol premium or maybe half and half.
Another question i have is referencing hughes engines theory on cylinder pressure. they claim a max of 165 psi and around 200 for iron vs aluminum heads. here are my results shown with the wallace dynamic compression calculator
inputs are 4.070 bore 3.31 stroke, 6.123 rod length, 11.43 static compression, abdc of 77 degrees and 1800 ft of altitude. 0 boost pressure
Static compression ratio of 11.43:1.
Effective stroke is 2.24 inches.
Your dynamic compression ratio is 8.06:1 .
Your dynamic cranking pressure is 152.12 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 7.70 :1.
V/P (Volume to Pressure Index) is 106
specs are
.030 over 340 with forged crank, h beam rpm rods and 2618 ross pistons. -12.6 cc dome giving me around 11.43 to 1 compression with a .039 gasket.
Camshaft is a comp RX302S-R6 solid roller. 269/276 at .050 .654/.655 lift 106 lobe separation degreed at 106 pushing some 1.5 ratio Harland sharp rockers.
Cylinder heads are just some smog heads with extreme port work done. exhaust injection ports welded and shut and the hump ground out when ported. they are iron and aluminum is not in the budget.
Fuel and air is a edelbrock super victor intake with an 850 demon
running headers and a 3 inch exhaust 4.56 gears and a early low 1st ball and trunion 4 speed converted to u joint with a vertigate shifter with DOT slicks. cooling system is perfect so i'm not worried about getting it too hot but this car will see the street a bunch. I was thinking i may be able to squeez either 25% race 110 to 75% non ethanol premium or maybe half and half.
Another question i have is referencing hughes engines theory on cylinder pressure. they claim a max of 165 psi and around 200 for iron vs aluminum heads. here are my results shown with the wallace dynamic compression calculator
inputs are 4.070 bore 3.31 stroke, 6.123 rod length, 11.43 static compression, abdc of 77 degrees and 1800 ft of altitude. 0 boost pressure
Static compression ratio of 11.43:1.
Effective stroke is 2.24 inches.
Your dynamic compression ratio is 8.06:1 .
Your dynamic cranking pressure is 152.12 PSI.
Your effective boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 7.70 :1.
V/P (Volume to Pressure Index) is 106
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