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Old 04-23-2013, 04:16 AM
gearheadslife gearheadslife is offline
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Originally Posted by techinspector1 View Post
I really like putting combos together on the DynoSim, particularly with AFR heads. They use real-world parameters for their flow numbers and I use them AS-PUBLISHED. Some other head manufacturers fudge on the numbers by using larger pipes, so I factor the flow a little to make it real. AFR uses a 4.280" pipe to flow these BBC heads, so I use their flow as published. RHS, for instance, uses a 4.200" pipe to flow SBC heads. Now, you tell me, when's the last time you saw a production SBC block with a 4.200" bore?

Being a contrarian though, I decided to use the tiniest little heads that Air Flow Research makes for this street motor Sim.
The short block is 4.280" by 4.250" with 6.385" rods and 1.270" 18cc pistons, for a stack of 9.780". We will cut the deck 0.010" to arrive at a piston deck height of 0.010". When used with a Fel-Pro 1027 gasket, the squish will be 0.049".
AFR 265's get the nod, part number 3620-1. 2.19"/1.88" valves with 112cc CNC chambers. These little jewels will generate 10.44:1 static compression ratio with the dimensions listed above and should operate smoothly on pump gas with enough camshaft.
Cam will be Comp solid roller, part number 11-772-8, as seen on the cam card in this thread. It will be installed retarded 4 degrees on these 0.050" tappet lift numbers.....
IO (14) BTDC
IC (54) ABDC
EO (57) BBDC
EC (17) ATDC
Intake centerline 110
Exhaust centerline 110
Lobe separation angle 110
Overlap 31 degrees
We'll use an Edelbrock #7164 RPM Q-Jet intake manifold mounting a Cliff Ruggles-prepared 800 CFM Rochester Quadrajet. Fuel pressure at the carb inlet will be dialed in at 5 psi. Large fuel line will be used to facilitate VOLUME, not pressure.


Peak volumetric efficiency 99.3% @5500 rpm's
Peak BMEP 188.3 lbs @5000 rpm's
Dynamic compression ratio is 8.113:1. This motor will easily run on pump gas.
The motor will make another 18 hp and another 15 ft/lbs of torque with a 1050 carb, but driveability and mileage would suffer greatly in my opinion.
one question,, if my 18cc domepistons give 10.2 to 1 with a 118 chamber
how is a 112 chamber only 10.44 to 1.. what am i missing??

and thanks for running that..
if you could, could you flash a rec port through just for giggles(well and that I have a single plane intake for when and if I efi)
thanks again..
my dyno sim, only works with windows 95..
it should be noted that these engine has a cloyds "hex a just" timing set and a 3 piece timing cover to make fine tuning the cam to the engines "wants"
next best thing to a jesel belt system,
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