my '83 camaro has a vette 1980 L48 350 engine in it. the problem is that im trying to find out the stock compresion on that engine. any help would be great

 

okay i found out that it was 8.1 to 1. im not very mechanically minded but am eager to learn more so could anyone explain what the compression ratio means please

 

The CR is the ratio of how big the cyl is when the piston is at the bottom, to how big it is when it's at the top. It's determined primarily by the piston design and the head chamber shape, and also by the head gasket thickness and various machining tolerances. The higher the CR is, the more efficient the engine is at extracting the heat energy from the combustion process, and turning it into mechanical work.

That's one of the reasons those 70s smogger motors are so weak.

A more ideal CR for a hot-running street motor that has to run on pump gasoline, would be around 9½:1 - 10:1. That one simple change, all by itself, would produce an increase in power output of around 15%, if all else about the motor was equal.

The higher the CR, the less improvement it makes as it gets increased. For example, if it was 7:1, then to go from 7:1 to 8:1 would probably produce 12% more power; but to go from 11:1 to 12:1 would yield only 3-5%.

 

thanks RB83L69. im trying to learn as i go but its difficult to take so much in. i removed my engine this week, that was fun and games, and i am now eager to improve it. i think i might go for one of the edelbrock power packages as it takes the guess work out of it. I'm trying to read up as much as possible but am still in no mechanical position to start working out what i need on my own.. dont know what i would do without this forum and guys like you

oh well the engine is out now and im in no rush to get it back in so hopefully with a bit of time and loads of reading up i should be able to create a little mover of an engine. i hope to do most of the work myself, maybe not a great idea but money is tight and its the only way im going to learn, so patience is the order of the day . thanks again

 

okay so i spoke to a guy at edelbrock about using the RPM package on my L48 350 engine. he said that a compression ratio of 9.1 is needed for that package. so what would be the problem with using the package with a 8.1 CR and am i looking at this from the wrong angle i.e would this route end up causing more hassle than its worth ?

am i p*ssing in the wind trying to make a good engine out of a smogger L48 ?

 

The RPM package isn't a really good way to go, for ANY engine.

The heads and intake are OK, but the cam is terrible; and the carb isn't the best, as far as power output; although it's OK as a street kind of one.

The problem with that sort of thing, is that a big cam bleeds off lots of cyl pressure at low RPMs; which results in very low torque at RPMs below wherever the cam "turns on"; which makes the motor feel completely gutless.

If you want a good strong-running combo without tearing into the short block, you could use the RPM heads and intake; a Comp Cams XE262 cam; the Comp 1416 1.6 ratio roller-tip rockers; and the carb of your choice (personally, I'd use the RPM Q-Jet and a Holley 6210 spreadbore carb). The Edelbrock headers (TES) would work well with the rest of that combo too.

 

would the XE262 be a direct replacment for my stock cam ? i presume that as my engine was built in '80 my stock cam wouldn't be of the roller variety , would it be a flat tappet type,. please excuse me if im talking rubbish but im trying hard to learn fast