Question on CR with a D1
Question on CR with a D1 Ok I have a 383 with PRC 5.3 2.5 stage heads compression ratio is 11:1, I'm going to go with dual pumps system from lonnie. What can I get away with until and if I change my heads on lbs. can I go 8-10 ? I'm going with a custom cam from Pat G with my current set up, I have heard that more CR you have the less boost you have to make to make power. And the lower your CR the more boost it takes to make power, once again thanks in advance !
Sway
Sway
Being 11:1 static compression ratio isn't as critical as what your dynamic compression is, ie based on how much overlap you have with your cam.
Octane is going to be your friend, as such, I recommend a water/meth injection system. Some say go 100% meth, but the water helps add octane believe it or not, and helps to cool the combustion chambers and piston crowns.
Personally, I wouldn't shoot for that much boost, and I would keep the timing out of it, max I would run is 15-16 degrees of timing. Some will say you can run more, but the more timing, the higher risk of knock.
Octane is going to be your friend, as such, I recommend a water/meth injection system. Some say go 100% meth, but the water helps add octane believe it or not, and helps to cool the combustion chambers and piston crowns.
Personally, I wouldn't shoot for that much boost, and I would keep the timing out of it, max I would run is 15-16 degrees of timing. Some will say you can run more, but the more timing, the higher risk of knock.
With or without meth will change the amount of boost you can run pretty drastically. At 11:1 I'd stay under 6psi intercooled without meth. A big overlap cam will allow you to run more because it's just shooting out the exhaust but it's more of a bandaid.
It is true that less CR allows more boost and in the end more power than less boost and more CR but there is a streetability line. An 8:1 motor can take a ton of boost but will feel like you are driving a chevy conversion van with a 305 double barrel carb out of boost. Bleh. For the street and no meth I think 9.5 is ideal.
What CC are your pistons? -3.2?
It is true that less CR allows more boost and in the end more power than less boost and more CR but there is a streetability line. An 8:1 motor can take a ton of boost but will feel like you are driving a chevy conversion van with a 305 double barrel carb out of boost. Bleh. For the street and no meth I think 9.5 is ideal.
What CC are your pistons? -3.2?
Agree with every point above. From my own experience & the same heads, running exactly 9.5 lbs @ 11.2:1,,,,,, you will love it. it will be responsive & peppy. In my case I was limited to the amount of boost that I could potentially make. (can't fit a bigger roots style in an Fbody). So we chose to raise the compression. I couldn't be happier. As mentioned above, 9.5 lbs is fine. I also suggest that you take advantage of the progressive Alky systems on the market. I believe Devils Own is a sponsor. I'm running 50/50 MOONSHINE ...... For safety rather than gaine. As Alchemist said, it cools the combustion chamber & water has highest octane available. Knock will not be an issue at this level.
