DCR Combinations That Have Worked

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..............- DCR Combinations That Have Worked -

........................................................--- For Big Blocks ---

The purpose of these pages is to helpfully show what DCR (Dynamic Compression Ratios) and SCR (Static Compression Ratios) have worked with what Octane gas.

You have to realize that there is more to this than just the DCR. Other things that will effect the octane you can run are altitude, load, quench, timing, combustion chamber shape, piston top shape, etc.. So use the following as a guide for what has worked for others and go from there.

If you know your combination and would like to share it please e-mail me your information (see this page for e-mail address). Use the examples below to compile your data. The more we have the better it will be.

Note: Here is a link to a DCR & SCR Calculator. Please try and use this calculator so we are comparing apples to apples. If you use a different one please let me know. Also if you can fill in all of the fields then we can double check each others calculations.

...........................(I'll try and keep these in order of lowest DCR to highest DCR)

(Note: I'm not very familiar with big blocks, so help me out with the bore/stroke/rod length of your combinations.)

cruzn65impala -- Troy (on http://www.chevytalk.org/): Runs fine on 91, but really wakes up if I add 5 gal of F&L 111 octane then top off with 91 octane.

DCR = 8.11 SCR = 10.26 Octane = 91

Heads early closed chamber oval ports (casting 206) 99 cc Chambers

Polished Lobe Separation 110 Lobe Centerline 106

Cam Comp 280 Magnum hyd
230/230
@ .050 Lift =.520/.520

1.7 rockers Advertised Duration

Pistons TRW L2240NF pistons 21cc dome

402 cu. inches Bore 4.124"

bored .030 Stroke 3.76

(396/427) Rods 6.135 Headers

Piston to Deck Head Gasket
.041 thick,

4.540 bore Initial Timing
16* Total Timing
34* Induction
650 dbl pumper (Proform main body - 780cfm?)
RPM intake

Put your combination here...................

DCR = SCR = Octane =

Heads cc Chambers Lobe Separation Lobe Centerline

Cam

@ .050 Lift = Advertised Duration

Pistons cc

355 cu. inches Bore 4.030 Stroke 3.48 Rods 5.7 inch Headers

Piston to Deck Head Gasket Initial Timing Total Timing Induction

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DCR = 8.11	SCR = 10.26	Octane = 91
Heads	early closed chamber oval ports (casting 206)	99 cc Chambers Polished	Lobe Separation 110	Lobe Centerline 106
Cam	Comp 280 Magnum hyd	230/230 @ .050	Lift =.520/.520 1.7 rockers	Advertised Duration
Pistons	TRW L2240NF pistons			21cc dome
402 cu. inches	Bore 4.124" bored .030	Stroke 3.76 (396/427)	Rods 6.135	Headers
Piston to Deck	Head Gasket .041 thick, 4.540 bore	Initial Timing 16*	Total Timing 34*	Induction 650 dbl pumper (Proform main body - 780cfm?) RPM intake

DCR =	SCR =	Octane =
Heads		cc Chambers	Lobe Separation	Lobe Centerline
Cam		@ .050	Lift =	Advertised Duration
Pistons				cc
355 cu. inches	Bore 4.030	Stroke 3.48	Rods 5.7 inch	Headers
Piston to Deck	Head Gasket	Initial Timing	Total Timing	Induction