what CR do i need?

[wyrmrider]

you may only lose 5 top end hp but it costs more down low torque
if you are a tuner go fo 10
if not 9 is safer with a tank of bad gas

 

[Bobby Sixkiller]

It does suck not having good gas around. 87 only here. Have to drive couple towns over for 91. I buy lots of 104+.

 

[joemish]

Hello all hope your keeping safe Im building a 440 for a street driven Dart automatic . I have purchased Edelbrock Performer RPM heads #60929 (84cc). The Lunati cam and kit I purchased #(771977PR-16) has these specs
Advertised duration (int/ext) 268/276
[email protected] (int/ext) 226/234
Gross Valve Lift 494/513
LSA/ICL (110/106)
RPM Range (1800-6200)
My question is What compression should i be aiming for to use these parts?
Thank you very much for any help Sabre67

with that mild cam 10:1 would be fine.

 

[AJ/FormS]

Has anybody asked what elevation you intend to drive this thing at?
Sealevel to 5000 or more is a big big change.
With that cam you might be flirting with detonation at 200 ft and 10/1. But by 5000 you'd need 11.2 for the same pressure.
Flipping that around; 11.2 might be the right Scr for 5000ft, but coming down to 200ft will be a disaster.

 

[beanhead]

Has anybody asked what elevation you intend to drive this thing at? Sealevel to 5000 or more is a big big change.

Absolutely AJ. (I think it's been mentioned but not answered..)

See post #15-
https://www.forbbodiesonly.com/moparforum/threads/440-505-stroker-advice.55880/#post-909915941

 

[AJ/FormS]

That's right; mentioned but not answered.
Elevation is a key ingredient and it impossible to recommend a CR in the first place not knowing the specifics of the build, never mind not knowing the elevation either. Not knowing these, you could build a lazy pos slug of an engine, or a detonation-prone pos;
Both at the same CR.
CR by itself is just about meaningless. It is just a tool we use to "ballpark" the Dcr, which will determine the cylinder pressure which will determine whether or not your engine will run WOT on pumpgas.
At other than WOT;
the higher the pressure the better
until you hit the detonation wall; then you gotta back up a lil.

OP asked "what CR do I need". This is an impossible to answer question in it's present form.