Nice find, but I'm not drawing any conclusion based on MON/SG. Anyone else? Other than the Maximal SG seems to be a fair amount lower than all the others.

 

I'm going to cast my bet that the experts will say that for two approximately equally
prepared gasolines, (R+M/2 etc), intended for the same general purpose, the specific
gravity difference will be about as important as the color... Wish me luck...
Joe

 

not true the higher the SG the more energy it contains per gallon

 

what heat range plug are u using?

 

agreed the higher the #...will require more air... well if your tune is running on map or maf for your afr readings u may have to adjust but the difference is very little.. im betting on plug heat range

 

exactly, and we are talking a 5% difference in density of fuel. All other factors being equal, the higher SG will have about that much more energy for fuel alone.

so in Jitsus case we not only have lower octane but lower density of fuel, a double wammy.

Using say 0.735 as the original and 0.701, the difference 5-6% drop in SG. If say you were operating at an A/F ratio of 12 (arbitrary as it does not matter), then with the new fule the ratio would change to 12.6 If you are already on the ragged edge, this could be bad and if you add to that the 3 octane points less of this low SG fuel, you got problems.

It would be nice to see a list of all the fuels and their data. it would be nice to find a fuel with the same octane you tuned for, but a higher SG.

maybe there are no experts for this...we have yet to hear.

 

yes you nailed it... i did not take into account the couple of oct points...

 

Sean, if I haven't told you once, I've told you 1,000 times, DO NOT RUN YOUR CAR ON A FUEL DIFFERENT THAN THE FUEL YOUR CAR WAS TUNED ON!!!!! I hope you didn't just learn a VERY expensive lesson b/c you didn't listen... A 5.79 60-130 is NOT worth a motor and if it's b/c of using the wrong gas......then it's REALLYYYY not worth it.
Peter

 

how much of a difference does it make if you run your car on a different octane ? i mena doesnt the ecu adapt and add timign when upgrading to a good gas ?

 

and another thing on the specific gravity subject im looking at the VP racing fuels chart , im comparing the MS 103 and the MS 109 . the 103 has a SG of .743 and the the MS 109 a SG of .722

isnt the higher the octane the higher the specific gravity ?

so how much better is the 109 really if its higher in oct but has a less specific gravity then the 103 ? can anyone clear this up for me lol .

 

One thing is for sure, I will absolutely NOT run the car at 1.5 bars again until I have some C 16. I can get it from Tommy for a decent price.

The remaining 35 gallons of Sunoco that I have will be mixed w/ pump gas which has a SG of nearly .77 or so. If I mix a gallon of Sunoco max w/ 2 gallons of pump I can run up to 1.2 bars but no more (cleared this idea w/ Todd). Anyway, if I run more boost poor paulie will not have a chance against me.

When I get some VP C16, then I will come gunning for Whitey (Peters car).

 

yah, unfortunately the ECU probably reacts by pulling timing to avoid knock just like it would with less octane. I would guess that this would depend on how the ecu programing is done.

there has to be some data on this, but it may not be in our cars. It really doesn't matter where it's from as it would apply here as well. I'd like to know this as well. It may be by actual testing only as there does not appear to be any open source info.

 

yah, at 1.5 bars if you detonate before the ecu can save you, you might end up with an extra wide, wide body

 

here is a chart showing data for many fuels...

http://www.racefuels.com/compchart.htm

 

It seems the bottom line is that SG affects the A/F ratio fairly significantly which makes a big diff at higher boost levels.