jtuck Z28

I am currently waiting on a dyno from FROST and i was thinking about it and i'm sure he will ask me what i wanna run it on. I did a little research to see what is gained and lost from running 93. All i can see as a downside is the money, is this truly the only loss? Also what should i expect to gain from running 93 over 87? I have a M6 2000 z28 longtubes, ls6 intake, and custom grind from martin at tick. Cam is 229/234 .615"/.612" 112+3. Thanks in advance, you guys are great!

luigiandme

iTrader: (2)

If you're worried about spending that little extra on a better grade gasoline, then this is not the right hobby for you.

You want your motor to live and not detonate itself to death? Run 93. The extra amount you pay is good insurance.

therabidweasel

iTrader: (5)

My $0.02 is to run the lowest octane fuel that you can and not get knock. In theory at least, this should give you the most power. If you don't have FI a little knock is not going to kill you. (I just mean to find the appropriate fuel, not running the damn thing knocking all the time).

If you have stock compression you probably will not require 93, but like Luigi says, if the cost of normal fuel is of concern. . .you probably should not be modifying your car.

jtuck Z28

Luigiandme I completely agree on the money part! Out of curiosity what are the power differences ?

joecar

Are you willing to run reduced timing to avoid knocking on 87 octane (i.e. leaving about 30 HP unlocked)...?

therabidweasel

iTrader: (5)

OK, so I was just mowing the lawn and thinking about this questions and how I "knew" the additional HP thing. Basically, all I can remember is that it was told to me by a pretty successful drag racer. . .I don't actually know the physical reason.

So now I am searching the internet to see if there is any evidence.
http://www.hotrod.com/techarticles/e...ng_comparison/

http://www.whitfieldoil.com/www/docs...p-racing-fuel-

For the time being, I think my info above was wrong and I've been operating on myth for a good 20 years. . .

And one last thing. . .the OP was not saying he was worried about the money. He was asking the downsides other than that, if any. . .so OP, sorry for being a dink all around.

ryridesmotox

There are plenty of things people have been told throughout life that are misleading. Happens to th ebest of us.

Honestly I have always run the best stuff I could find. Shell or chevron 91 here, Mobil is high on the list also. They run alot of alcohol (ehtanol) here in fuel which is starting to catch on everywhere, governed by the state (god damn Commifornia) and 91 is cat **** anyways. But the better formual fuels here have always performed well for me. High octane is optimised for higher compression and more efficient combustion chambers. The 2 links above pretty much confirmed to me the value of a higher octane with a fairly efficient motor like an LS that is all aluminum and optimized for the the current fuels. in my opinion I run the highest octane I can reliably find, I tune it with that fuel and I run it religiously and never go lower than that fuel octane. I think it was more vital to run the proper octane rating back in the 60s and 70s. Computers these days can compensate for fuel, elevation, what you had for lunch 3 days ago... everything. You may notice that on a stock motor your engine will pull timing because it can feel knock coming. My dad always ran 87 octane in his C5 vette. I ALWAYS bugged him about it. Then I hooked it up to my HP tuners one day and showed him how the motor was dialing in like 8 degrees of retard and we filled it up with 91 and it ran better. I would have uploaded the logs, but as computers are shitty and always take a dump at the worst time I had to get a new one... lost all my tunes for my last car too. Luckily it was sold before that happened.

OP whatever you want to run, get it tuned on that and then run it religiously. If your area has 'winter blend fuels' then you might have to get a second tune for that as well. It all depends on how close to the edge of the envelope you want to push.

2000ultraZ1911

I think with what ur runnin I'd go for the 93 it says right on the gas lid premium recommend....mines mostly stock I was broke and put 87 in it on a hot day my car hated it it was ping city. But opinions are like A*# holes ....everybody got one lol good luck man.