Hi guys, I've never looked into forced induction before, but it's starting to intrigue me. I'm building a 420 and was planning on a 10.5 C/R, N/A. The thought occurred to me if I held the compression ratio down a bit, I might be able to go with a blower later on. It's just a possibility to go forced induction mind you, so I want to keep decent VE if I don't.
Any suggestions or comments? Should I make a clear cut decision one way or the other before I settle in on the C/R? If I absolutely have to do that, I'll probably just skip the blower. The bottom end is going to be top drawer anyway, as I'm thinking around 550# torque +/- at the flywheel, so that's not an issue. Thanks for any input or suggestions! :cheers:

Tim

 

Not enough information. Since some blowers make more heat than others C/R must be based on what type blower how much boost. Will it be intercooled if so what size and kind of intercooler. The only thing that I can tell you from info above is that no blower will work very well at 10.5 boost would have to be kept to very low level. Most street engines are in the 9-1 range this allows reasonable boost with intercooler but still runs nearly as strong at low rpm low boost as a high c/r engine CHP magazine did a dyno test and on a sbc the difference between 9,1 and 10.1 was less than 10lbs. of torque and that was at maximum torque.

 

if you're serious about doing a stuffer on the motor, i would not spend the dough for the custom 420" and stick with the 350" or 383". there is a "replacement for displacement" in the form of PSI. even if you decided to do the blower later, with the 420" set up, you are going to have a heck of a time finding pistons that will give you lower compression with out having to have some made. depending on the cc's of your head chambers that might leave you with a piston that looks like a bowl{not good for flame travel}. black bart sums it up good to the fact that there are many factors in answering your question. depending on your emission reqiurements will also limit some of your choices for superchargers. intercooling is always a good idea in any forced induction system and can dramaticly reduce your chances of detonation. bottomline= if you plan to make 650 to 700 hp don't go over 8to 1 comp even if its intercooled. i am currently fitting a 6-71 into my c4 with a custom drive system. looks pretty bad butt and i'm sure i'm the only one on the block that has tried it in a c4. the old jimmy style 6-71 are not as eficient as the new styles so it creates more heat, there fore my comp ratio is 7.8 to 1 but i will run it at 11-12 psi. on the big jimmy thats good for 700 so i hear :cool: :steering:

 

Humm, thanks guys :cheers: I think I'll stick to motor only on this one.
Now, if I get that little '23 bucket goin........??????? :D