Back Into It.....

Buzzliteyear

New Member
Thanks for the site,
I have my own shed now which every guy should be given as a teenager .......:)
anyway building a Bedford J Series with 350 Chevy etc and always enjoy the research side like Dynamic C.R. vs Cam timing vs Octane etc etc

Brett
 

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chromebumpers

solid fixture here in the forum
Staff member
Welcome Brett! Interesting project you have going. Will you be taking photos throughout the restoration and posting for us to watch?
 

B&R Racing

solid fixture here in the forum
Cylinder Head Airflow into the engine and out will net the largest gains into a chosen engine.
Along with Full Race Cylinder Head and Intake Porting work done.
It can be up to +500 Hp more over stock Normal Aspirated.

Pushing right to 8.0:1 Dynamic nets very little power gains Vs Lower Dynamic compression chosen to run on lower octane fuels .
 

Buzzliteyear

New Member
I borrowed a spread sheet and changed it around added imperial etc
in New Zealand out 96 octane is the same as your 91....so based on that all my research is showing no more than 8.3:1 on iron heads
which is what my test engine can achieve with a early closing intake....
 

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B&R Racing

solid fixture here in the forum
I borrowed a spread sheet and changed it around added imperial etc
in New Zealand out 96 octane is the same as your 91....so based on that all my research is showing no more than 8.3:1 on iron heads
which is what my test engine can achieve with a early closing intake....
With cast iron heads on a Small Block Chevy I would not push the Compression static ratio or Dynamic compression ratio unless your using Factory Vortech cast iron heads, GM Fast Burn Cast iron heads that were sold over the parts counter, or a Rare Set of cast iron SBC Dart 18 degree valve inclination heads made for Dirt Track Racing similar to Brodix 18X heads.
I looked at your spreadsheet and I would be satisfied myself with 7.4:1 - 7.7:1 Dynamic compression ratio for 91-93 RM/2 USA inland pump gasoline.

My 1976 Pontiac 455 in my 63 Pontiac Grand Prix has a Static Compression ratio exactly 8.4:1 only and Dynamic compression ratio of 7.7:1 I recall calculated.
It's much more important to match the camshaft duration and LCA lobe centerline and ICA ECA Intake centerline exhaust centerline to the power band of the engine your building.
Retarding ignition timing to avoid detonation with too high of Dynamic compression ratio can cost 40-100 hp and same in Ft/lbs torque output at the Flywheel.
These Dynamic compression ratio calculators are far from optimal perfect does not account for Wet flow any, Fuel shear, different combustion chamber designs, ect.
My 455 Revs up like a $50,000 dollar 410 cubic small block Chevy Dirt Track engine with Crower Titanium lightweight Connecting rods.
No Titanium rods in my engine.
 

B&R Racing

solid fixture here in the forum

Just 8.4:1 static compression ratio with Factory cast iron heads I full Race Ported out myself.
Huge 111 cc combustion chambers.
Heads milled .050" off to get 8.4:1 exactly.
Stock compression ratio advertised was just 8.2:1.
1971 GTO 455 #66 Heads chosen I used.
 
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