8.0.1 compression

[Phil]

doesnt higher mean bang goes your engine when you have a turbo lad right

making sense would be the first step to getting answers or feedback henry.

EDIT
apologies only just weeded out your other thread about the rods, forget you had been already asking about all this stuff elsewhere.

Phil

 

[hoochhenry]

listen i think il build the thing and let you fellas know when its done hows that c**p talk from some people

 

[Phil]

listen i think il build the thing and let you fellas know when its done hows that?

sounds good, most sensible thing ive heard you say! goodluck with the build mate, should be interesting!

Phil

 

[thefalls]

I think that it would be a great idea if someone would be kind enough to explain a bit about compression ratios,head gasket thickness...and about various combinations of pistons [forged i mean] with HG....it seems that not many people know much about these things....

And we could sticky this,so that we dont get these kind of threads popping up all the time and it would be nice to have info available....

Thanking you in advance.

 

[profane]

i could start. in simple terms.

compression ratio (c.r) is the ratio of a cylinder's volume when the piston is at bottom dead center (BDC) to the volume of the combustion chamber (in the head) + thickness of gasket (which will affect this vol) when the piston is at top dead center (TDC).

once you know these two volumes and divide the larger value (cyl vol) by the smaller one (comb. chamber vol), you get your compression ratio figures like, 7.0:1 or 8.2:1 etc.

now, the lower the cr, the better it is for forced induction engines and the ability to make more and reliable power with lower octane fuel.

the higher the cr, the better it is for atmo engines (non-turbos) but will require a higher octane fuel.

there are some exceptions thought but these are purely for hardcore drag racing applications, where the cr is very high, but its also running a high amount of boost as well. this is usually achieved by methanol or very high octane fuel.

usually for petrol engines, lowest is 7.0:1 and highest is 15:1.

this is one reason why the 20V 4AGE's have a cr of about 11-12.0:1 so that with high octane fuel, they can make greater power in naturally aspirated form.

 

[Sharagath]

there is a option called search on this forum.
there are multiple 5E-FTE's build, not all with fhe engine as base but they are build on some CR.

mine is a result of some years of research and a good engine builder.
the CR is calculateble, if you search wiki and understand math a bit you can calculate it yourself.

i have got a calculati n sheet for it somewere, not acceseble right now

 

[bimboy]

listen guys those compression ratios are very conservative, 8.0:1 is very low, A guy mentioned that only race cars use high compression and boost. It is true that race cars such as wrc use higher compression and boost that is why they have so much torque, but they are also race cars that run very low compression as well, it is just a matter of your philosophy when it comes to making hp. A 9.5:1 compression is not high, I am not telling you that this is what you have to get inorder for your car to be fast, but in terms of drivability and torque and turbo response a 9.5:1 compression 5e on say 20 psi will be better than a 8.0:1 compression 5e on say 25psi all other things being equal. Every single time, all you have to do is get your car tuned. If this is hard for you to believe or accept take a look at project builds of other cars, such as the evil twin on nissan performance mag. and you will see that they run 18psi on a standard ga16de that comes at 9.8:1 compression. What about all the turbo hondas that are floating around. Yes combustion chamber design is different and will affect an engines capacity to deal with detonation, but for sure they are many 5e's around with alot higher compression than 8.0:1, If you search on this forum you will see discussions on turbo charging a stock 5efhe and guys run all sorts of boost pressure on them, for example the US guys backyard productions. In my opinion it is a waste to build a fully forged engine below 8.8:1 waste of strong internals, read maximum boost by corkey bell. It not the 80's any more. Raise your compression.