Engine Compression-Inviting all gear heads?

Question

I'm somewhat competent when it comes to cars and motors. Just was wondering about compression. I understand higher compression engines tend to make more horsepower. What are pros and cons of higher compressed engines (aside from the fact they're less relaible with turbos and superchargers-correct me if I'm wrong). Why do some manufacturers go with higher compressed engines (like corvette and camaro) while others choose lower compressed (like mustang). As I understand, most supercars (ferrari, lamborghini, porsche etc) are highly compressed. Does this correlate to why their so high maintenance and unreliable? Please feel free to correct me if I'm wrong and be as thorough as possible. Thanks in advance...

Answer 1

Not all high compression engines are destined for problems. This depends on the design and quality of parts (pistons, rings, head gaskets and connecting rod bearings.) Diesel engines have far higher compression than gasoline engines and they go forever.

Answer 2

Higher Compression means in typical cases that the motor will not last as long when compared to lower compression motors....

Higher Compression Motors usually have ring blow by issues somewhere around 50,000 miles up to 100,000 depending upon the drivers abuse or lack there of....

Yes you get higher horsepower from higher compression ....but still there is no rule to follow without having the model and year and make of the vehicle you are thinking of replacing the motor on.

I have had two high compression motors that I installed and I have had no problems with either of them. Each car is different though....Just use someone's knowledge that you respect and that has expertise if you start spending some serious money to beef up your motor....because I have seen more than one person put 3,000 + into a high compression motor, mess something up during the installation and it's toast the first time they fire it up -- rebuilding a motor that you just built will get under your skin and cost you $$$ for the redoing of the machine work so be careful and pay close attention to detail bud.

Sometimes you want a lower compression motor if there are going to be smog issues to get around or if you plan to supercharge a daily driver.....otherwise.....go for it if the $$$ allows you to do the project right.

Good Luck to you.

Godbless & take care man.

Answer 3

Higher compression does make more horsepower but you'll need to have the tolerances of engine parts much tighter to accomodate the increased internal pressures which means beefier engine components and construction, higher torque starters, increased cooling capacity, finer production parameters and increased costs. They are more prone to head gasket failure and pre-ignition or detonation problems which requires finer tuning or engine controls. They also require high octane gas instead of regular which is a financial burden on a daily/weekly basis.

Answer 4

simply put the higher the compression ratio the higher the engine output...but to really throw a monkey wrench into the theory you have to take into consideration cranking psi. depending on camshaft specs a higher compression engine can "bleed off" a little compression psi (in the combustion chamber).
and i would have to challenge the shorter engine life theory....look at the LS1, LS2 and LS7 chevy engines. plenty of these engines running around with 100k+ and no problems. but electronic engine management makes it a lot easier on parts too....
my personal chevy 400 is 10.1-1 and if i get 10,000 miles i would be happy...but i like to shift at 4-6000 every time i crank it up!!!