I'm starting to plan for the engine I'm going to put into my 65. Right now I'm leaning towards a 331 with low compression (8.5 - 9.5). The goal being to have a reliable engine with low compression that I can throw a supercharger on at a later time.

My question for you is: what is the drivability and engine performance of a low compression engine compared to an engine with higher compression? Would I be totally dissatisfied with driving a low compression engine until I get the paxton on it?

I'm thinking about using either Coast High Performance or Smeding for the engine source. Has anyone dealt with either of these shops?

 

A higher compression engine with the right cam/heads etc will perform better than a lower compression engine and have better throttle response. That said the lower compression engine will still run fine, and it's worth it if you're going to put a blower on it.

 

Obviously the higher compression engine will put out morehp when the rest stays the same. With higher comptrssion it wil be crisper to run. A 331 running at about 9:1 is still a lot of fun. Ya. There is improvement but if your plan is to feed her at some stage then yes ya go for it. But I'm not sure at what cr would be best for supercharger plans

 

I run a 331 with ~9.3:1 CR and I think it runs fine. Runs great on 89 octane, even the crappy stuff out here in CA.

 

I personally wouldn't go past 8, maybe 8.5 tops if you will for sure be adding a supercharger. For an NA engine with these compression ratios it will run fine but it won't have any "snap."

You are sort of putting yourself in a box by having to compromise. It would be best to either build the engine from the get go for a blower or build it from scratch for NA. Trying to compromise for both, takes something away from both. Your NA/Blower choice not only dictates CR, but also your optimum camshaft choice.

Best of luck with it.

 

Yep. Plenty of fun. I ran a 302 at 9.2 for years and it ran 12.1's all day long. Then added boost. Keep it about 9.0-1 and when you add boost you can do 450rwhp if you wanted.

 

How much boost also depends on the setup a great deal. An intercooled blow-through carb will handle WAY more boost than a non intercooled EFI setup. It's not uncommon to run non intercooled blow-through carb setups at 15psi of boost or more on 9 or 9.5:1 compression with the right tune. On pump gas. And intercooled blow-through carb blower setup at 8:1 compression will likely break the block/trans/suspension from too much power before it detonates on pump gas, unless you have a race block.

It all depends on what you want to do.

 

Thanks for the input! I'm feeling a bit more confident now. Right now I'm eying the 8.7 compression 400 hp crate engine from CHP (http://www.coasthigh.com/product-p/11938-ps-f331-v.htm). It's pricy but it looks like it might be a quality engine with room for a future paxton upgrade. I'm wondering if it's worth the Dart Block upgrade. I doubt I would ever exceed 500-600 hp even with the paxton. I'm really trying to build a street/strip car. I want performance and fun but I also want the car to be drivable...for those spring time road trips.

 

A stock block will hold about 500-550 at the crank if it's well balanced and tuned right.