compression ratio poll

Nope, it came up on my subscribed threads list as current.

 

Yeah, somebody probably voted in it, sent it floating to the top... Where I promptly saw just now it and voted too.

 

Ah, that's probably it. I was beginning to think my computer was in a time warp

 

I voted for 10 to 1. Not a fan of NOS....................in my motors, I love hufffin the stuff at the Dentist's office though :bananaman

 

Unless I was building for E-85 I always get as close to 10:1 as I can.
Compression is of prime concern when you are building an engine because it not only adds HP but it also provides a platform for better economy.
I wish we still had 120 octane gas because then I would go with 11.5 - 12:1 compression - even with a short duration cam for the street.

 

I'm running a 289 bored 0.030" over with 54cc heads milled .010 so they are around 53cc now with 1.84" intake and 1.46" exhaust (351w valves) and a comp camps 280H cam and I can barely run it with 91 octane without detonation... I have my timing down to around 6 to 7 degrees to. this is also my daily driver... so I voted for 9:1 compression to keep things managable. higher compression will get you more power but it'll cost more to run.

 

I'd go at least 12 to 1 upwards of 14 to 1 in fact I am for my street motor its 13.5 to 1.... and I am building a 281ci small block cammer Aluminum trickflow heads and aluminum block. Should push 450 plus fwhp to 500fwhp

but again that's just me.....


and e85 is your best friend of you want to run crazy compression or power adders!!!!!!

 

My last engine ran 10.5 to 1 with iron heads 61cc heads and pop up pistons with a mild cam on 93 pump gas.....cams have alot to do with what you can get away with...static and dynamic compression are two different beasts....but one still affects the other....and that is where valve train timing events come into play

 

"Dynamic compression" is only low at extremely low rpm. As the rpm increases the compression goes up until you reach just over your peak torque where it is higher than your "static" compression if your exhaust is working properly.
That overlap that is interpreted as lower "dynamic compression" is designed to pull more air and fuel in at higher rpm (just above the peak torque it peaks) and with the added density of air you get higher compression.
Now, if you kill that added density with a poor exhaust or other combination of poorly selected parts then it won't reach optimum levels - reducing power output and fuel economy.
If you run a fuel (like E-85 or racing fuel) that thrives on 13+:1 compression you can get away with it.