cobraKLR

JimBell'sSUPERCHARGED /TURBOCHARGEDPERFORMANCEGUIDE
1 psi boost = .5 point CR (effective CR)
1 point CR = 2 psi boost (CYLINDER PRESSURE)
1 point CR = 2% HP
1 psi boost requires 1-1.5 octane (minimum)
1 psi boost = 6.8% HP max (1 ÷ 14.7 = 6.8%)
1 point CR = 3 - 5 octane
1 AF ratio = 2 octane
1° advance = 1/2 - 3/4 octane point
10° engine coolant (160° -180° range) = 1 octane
20° ambient = 1 octane
1000' altitude = -1 octane point
1000' altitude = .5 psi (2" Hg)
6°F temp change = 1% air density
30% humidity = 1 octane
10° air charge temperature = 1% HP
20° charge temp reduction through intercooling = .5 psi additional boost with same octane
3/4 PSI DROP = 5% pressure (5% x 14.7 = .75 psi)
ENGINE CFM = CID x RPM x VE*
2 x 1728
*70% for the average engine 90% racing engines
10% HP increase = 7% AF ratio (based on 70% VE) or 10% AF ratio with 100% VE
10 psi fuel pressure = 8% AF ratio: 5 psi = 4%AF ratio
HP = CFM (int @ 28") x .257 x no. cylinders
10HP = .1 sec / 1 mph 1/4 mile
100 lbs = .1 sec / 1 mph 1/4 mile

Problem: If at all possible, avoid fuels
that use alcohol as an additive to
increase fuel octane. We understand
that Mobil doesn't use alcohol in most
states. Alcohol, being more volatile
than gasoline, tends to evaporate and
lower fuel octane. Large in tank or in
line pumps "re-circulate" excess fuel at
idle, part throttle and cruise. This
results in hotter fuel and increased
alcohol evaporation (octane reduction)
from not only the "re-circulation" but
the continuous pressurizing and de-pressurizing
of the fuel. Why do you
think Ford has gone to returnless (no
return) fuel systems? One reason was
to reduce fuel octane losses.

cobraKLR

I just posed this off of a PDF a friend of mine sent me. I looked into the NOS racing booster after I read this and it claims 7 points on something like 16 gallons - close to the 1.5 octane, but not sure where the 3.6 came from. I agree the Toluene or Xylene would be a better choice and much cheaper. I found the rest of the information to be very useful though - which is more what I wanted to share with everyone.

bingo

7 points means from 92.0 octance to 92.7 octane. It is the point get it?

Not sure if this is what you were referring to.
BB

cobraKLR

Sorry, my mind was in two places at once. That data came out of a chart and was based on using a bottle on 8 gallons. So if it raises 16 gallons 7 pts it will raise 8 gallons 1.4 pts. Bottom line I still think octane boosters are a waste of money. I will edit my origional post to remove this information as it isn't even what I was trying to pass along. I just got lazy with the cut and pasting the whole document.

amcfightfan

1 gallon of toluene with 9 gallons of 92 octane gas will get you 94 octane.

amcfightfan

Oh that's right California only has 91. WA only has 92 so it's not much better. I sometimes wish I was back in CT. They had 97 and there was one station by my house that had 100. Not to mention two Suby tuners with in driving distance.

Travis

Blk03WRX

93 here in FL, some places have 104 at their pumps.

cobraKLR

Man did this thread get off track fast. My mistake for posting that octane booster bit. It's the rest of the stuff that should be useful to us.