View Single Post
Old 04-23-2009, 08:26 PM   #10
23109VC
Registered User
 
Join Date: Mar 2008
Location: CA
Posts: 726
i used to own a highly modded Volvo S60R. that car LOVED 100 octane. there was a gas station near me that sold it and I would mix in 5 gallons with a tank of 91 to net around 93-95 octane. i would also fill up two 5 gallon cans and keep it in my garage - i was addicted.

i called it "cracktane".

on that car - dyno proven - it was a 30hp gain to run the better gas.

i did my homework. high octane gas does not "make more power" or "have more engergy" the octane is a measure of how stable the gas is. the higher the octane the more precise and reliable the burn is. so the gas will ignite in a more regular / fashion. imagine that each cylinder - every time it fires - if you had to time *exactly* when it's going to pop. the timing of the ignition is timed wiht the piston being at the top of the power stroke.. to be on the safe side, the car delays firing the spark plug until your piston is already going down. in high temps and high pressure situations the gas can preignite and the gas can start to burn too soon - so the car is timed so that the ignition si always when the piston is on it's way down - and you don't get a power stroke from when the piston is trulyl at hte very very top of the power stroke. for hypothethical concerns - imagine that you only had the spark plug fire when the piston was roughly 1/2 way DOWN already.... you only get 1/2 the downward stroke under power.

now imagine you have high quality gas that burns the EXACT same way EVERY time. now the computer/ignition can advance the timing so that the spark plug fires and it's all times EXACTLY so that the piston is JUST starting to go down,a nd then BAM, it fires. yhou get a power stroke that is the entire length of the stroke.

essentially, the higher octane gas is higher quality, more stable, less prone to preignition, and it will burn ina m ore consistent fashion. which makes it easier for the computer/igntion to advance timing and get the most/longest power stroke. crappy gas causes timing to be retared, meaning the car waits for the piston to go down further before it lights the gas...

high octane gas worked magic in my S60R. after running a tank of that stuff in my S60R, driving on 91 was like driving a different car. the car ran much stronger and OMGF the smoothness was incredible. you could feel it was smoother and much more pwoerful. that, ,however, was in a highly boosted car with above stock boost pressures.... high temps, high pressure - it needed high octane. that car was very sensitive to temps and octane.

i have no idea how the boxster would react. since it's not forced induction - i would assume it would have a far less drastic effect, but it might do something.

if it's 5-6 bucks a gallon, i'd be up for trying some. it's not THAT expensive. put in 5 gallons, then top off with the regular stuff, like 91 here in CA, and then the mixture will be 93ish. there are tables you can find online if you goggle that will tell you waht overall octane you wind up with if you mix 100 and 91 in differen concentrations.

i know the EVO/STi guys have a lot of custom maps and they actually can get computers with switches on them, ,and depending on what octane gas they are running, they flip the switch to go between the 91/93 map, and the 100map. on highly tuned cars, the difference in power thye make on a tuned 100 map is huge.

i kinda think on our cars, that while yhou may feel it, it's not going be so drastic that you become "hooked" on it like you would if you had a turbo car.

that's a good thing! i blew so much money on gas and it was drag to then drive the car on "normal" gas after having access to 100. it's a good thing to have a car that doesn't NEED high octane to run right given how much it costs and what a PITA it is to have to always need it.

let us know how you like it. i'm tempted to go buy some and try it. i moved, so I no longer have easy access to 100, but there is a gas station about 25 miles away that has it.... close enogh to "try" but not close enough to "use".
23109VC is offline   Reply With Quote