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383 BUILD DCR RATIO


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ZFAN, my current setup yields 7.74 DCR with a .045 quench. Thats with 5cc flat tops. When I go to the 383 it yields 8.38 with the 5cc flat tops and 8.14 with 7cc. Do you know the cc size of those probes? Just curious....

 

My deck hieght is .005 since I had it decked.

 

Terry

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Guest zfan

Terry,

 

The Probe forged 4 valve relief flat tops are 4cc total. What size cc are your AFR 190's? 68cc? If you have 68's then your compression will be between 10.20 and 10.44 depending on deck heigth and gasket thickness/quench!

 

My 383 has 4cc Probe flat tops and zero deck with 65cc chambers and 41k gaskets. This gives me 11.18 to 1 :shock: sucks to be me. Actually I have run 93 super and 38 degrees timing in cool weather with no problem but retarded back to 32 degrees with warmer weather to come.

 

When I race I give her a sip of 114. 2 gallons to 4 of 93 gas.

 

Mike

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Kevin, the DCR calculations but I think it will be around 8.3 or so according the numbers I input

 

3.75 Stroke

5.7 ROD

4.040 BORE

4.060 GASKET BORE

.040 GASKET THICKNESS

4CC Piston

.015 DECK HEIGHT

282/288 CAM

110 Lobe Sep

106 Center Line

Chambers 68CC

 

Terry

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Kevin' date=' the DCR calculations but I think it will be around 8.3 or so according the numbers I input

 

3.75 Stroke

5.7 ROD

4.040 BORE

4.060 GASKET BORE

.040 GASKET THICKNESS

4CC Piston

.015 DECK HEIGHT

282/288 CAM

110 Lobe Sep

106 Center Line

Chambers 68CC

 

Terry[/quote']

 

Terry,

 

With a 4.040" Bore x Stroke of 3.75" = 385.57 cu. in.

385.57 / 8 = 48.20 cu in x 16.387 = 789.79cc Cylinder Vol in cc's

 

Your cam indicates Valve Events (my calculations) are:

 

Intake: 35*/67*

Exhaust: 78*/30*

 

This gives you 65* Overlap

 

This cam when combined with your engine's...,

Con Rods = 5.703

Stroke = 3.750

Piston Compression Height = 1.432

(NOTE: Your Piston Compression Height is assumed based on your Block having a 9.025" Block Deck Height & using your .015" Deck Clearance)

 

.., gives a Crank Angle Chart that indicates your IVC of 35* has consumed .767" of your stroke. This leaves your remaining stroke at:

 

3.75 x .767 = 2.876" This would give you a cylinder displacement of:

 

4.040 x 2.876 x .7854 = 36.867 converted to cc's would be:

36.87 x 16.387 = 604.15cc Cylinder Displacement

 

Now add up your Total Chamber Volume:

Gasket Volume = 8.49cc

Deck Clearance = 3.15cc

Ring Land Volume = 1.5 (Assumed)

Piston Valve Relief = 4cc

Combustion Chamber = 68cc

 

Total Chamber Volume = 8.49 + 3.15 + 1.5 + 4 + 68 = 85.14cc

 

DCR = (604.15 + 85.14) / 85.14 = 8.10:1

SCR = (789.79 + 85.14) / 85.14 = 10.28:1

 

With this DCR to SCR relationship with 65* Cam Overlap, Aluminum Heads, Aluminum Intake-your engine should yield an excellant H/O Street Engine...just be sure you use 93 Octane for those hot summers.

 

With your 190cc port AFR's your airflow velocity should be high enough at low rpms that you probably won't have to worry about steeper gearing. Your AFR 190's with that engine combo should yield a peak HP, at the flywheel, in the 490-535 hp range: all depending on your engine's VE%.

 

Are you just putting together your paper engine at this point-or is this engine already a done deal?

 

Kevin,

(Yea,Still an Inliner)

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Kevin, thanks for the info! Well I already have the engine together minus the 400 crank and assembly. I have the 350 crank in there now with full Hydraulic roller retro fit. I am adding the balanced 383 stroker kit in a couple of months using my AFR 190s, Victor Jr. Single Plane, 1 5/8 block huggers and Proform 750 DP, with the XR282HR cam.

 

Thanks again...Im excited about the build and looks like it will yield great DCR and SCR... :D

 

11s are definately coming soon to a raceway near me... :wink: I hate those damn Camaro SS cars. They talk so much trash. Theres one that runs a 11.7 here but I have something in store for those guys.... :-D

 

Terry

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