Chrysler 300C & SRT8 Forums banner

1 - 17 of 17 Posts

·
Registered
Joined
·
23 Posts
Discussion Starter #1
I'm on a crusade to save our race gas retail outlets and find new locations that have gone under utilized. Why? Because the operators are threatening to remove the pumps because consumers aren't buying the higher octane fuel. Sales of "premium" fuels including the 94, 98, 100 and 104 grades that enthusiasts hold dear to their hearts have dropped off significantly as gas prices have surpassed $2 a gallon.

Sunoco GT104 is the highest octane UNLEADED gasoline that you can purchase at a retail outlet. It supports almost all high compression and boosted vehicles including the SRT8, SRT4 (including Stage 1, 2 and 3R), SRT10 and our other "Z", "V" and "M" -brand competitors.

Current price for a gallon of GT104 is $4.99 at my favorite Sunoco station (29372 Grand River Rd, Livonia, MI).

You can always mix a custom blend of 94 and 104 to make a nice 98. Or just buy GT100. An ideal range for the stock SRT8 is 94-98, but these higher air temps and increased humidity creates the need for a little more.

Other GT100 locations or CAM2 race fuel as it is branded can be found at www.racegas.com

But beyond the Sunoco offerings there are hidden venues around the country that need our support. Running a tank of 94+octane fuel will increase performance and reliability of your 6.1L HEMI or other high performance engine. Lower coolant temps, better combustion, cleaner emissions are all positive side effects. If your buddy the "Enviro-terrorist" was a true eco-friendly consumer he would only run Sunoco 94.

Canadian consumers have it the easiest- all Sunoco stations carry premium 94 octane fuel (in most major markets). This has the added benefit of using 10% ethanol which contributes to a cooler, denser fuel/air charge and reduce emissions. Price is between 80-cents and $1.10 a liter Canadian. Some Mohawk station have 94 octane fuel as well.

Can we all post our favorite location to buy "Race Gas at the Pump" so the board members can support them?

I know there is a little station somewhere in Royal Oak/Clawson, MI that has not only 100 octane unleaded but 116 LEADED for musclecars. I don't know the address though but I think its a Marathon or Citgo station. It a fave during the Woodward Dream Cruise. Find it and post it.

BTW, my condolences to the California folk who only have 91 octane (ya, right) water to run. Since the CARB has had its budget slashed, as well as the State Inspectors, octanes have been floating around the mid to high 80's for the premium grade. Best to buy a 54 gallon drum of Rockett, VP or Sunoco or at least a jug of Cool Blue.
 

·
Premium Member
Joined
·
1,151 Posts
From all I have heard and read, higher octane, especially at the levels you refer to, is a waste and has no real benefit in modern production engines.

True 'race' engines might be another matter.
 

·
Premium Member
Joined
·
4,071 Posts
This gas is only for engines that want to take advantage of N/A compressions approaching 11:1 and higher. The SRT8 does not qualify.

I'm surprised all these boosted i4 civics and rice rockets aren't keeping these pumps in business though.

It doesn't really matter to me anyway. You can mix your own high octane fuels for cheaper than Sunoco sells them.
 

·
Registered
Joined
·
563 Posts
Generally, the recommended fuel is best. For hard run motors, sometimes a jump to 93 may allow the car to optimize a hair better than 91. The SRT-4 owners in CA have seen this repeadtedly.

That said, usually going above 93-94 is indeed a waste, unless the car has special tuning to advance timing. Such as the SRT-4 kits mentioned above (ONLY Stage 2 and 3 equipped Turbo Toys, NOT the others) simce they have a switch to allow the usage of +100 octane.
 

·
Premium Member
Joined
·
4,071 Posts
glhs837 said:
Generally, the recommended fuel is best. For hard run motors, sometimes a jump to 93 may allow the car to optimize a hair better than 91. The SRT-4 owners in CA have seen this repeadtedly.

That said, usually going above 93-94 is indeed a waste, unless the car has special tuning to advance timing. Such as the SRT-4 kits mentioned above (ONLY Stage 2 and 3 equipped Turbo Toys, NOT the others) simce they have a switch to allow the usage of +100 octane.

glhs837, you have the stage III kit right? If I'm not mistaken it requires 100 octane.

You might want to try what my friend uses in his high comp motor. I'll find out what it's called and give you the info.

Basically, it's about $12 a quart and is good for 12 gallons at 100 octane treated with premium 93.

If at $2.50 a gallon with octane booster it's only $3.50....Quite a bit cheaper than Sunoco.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #6
That's an urban myth that has grown into an even bigger lie that is hurting not only your performance but the environment.

Modern engines have the capability to adjust for worse performing fuels. And yes, most of the calibration is carried out at 93-94 octane. However, this is done at ideal engine conditions (cold coolant, cold incoming air, warm oil) that cannot be kept constant on the street.

Modern engines also can adjust for better performing fuels. If you data log your spark and fuel trims, and overlay it to air and coolant temperature, you will see a dramatic difference between 91, 94 and 104 octane.

The ECU dramatically pulls spark timing and dumps fuel to comphensate for rising temperatures and poor fuel to quench any POTENTIAL misfire or knock.

You don't buy a 425HP car to leave 50-60hp on the table. Also, detontation, which the HEMI engine is predisposed to (large quench surface area), and the damage it causes, can be severe. The top ring is very close to the top of the piston to reduce the crevise volume so unburnt hydrocarbons can't hide in there and then escape out the exhaust port, posioning our babies and killing the trees. This makes the top end of the piston fragile as compared to traditional/old school "race engines". Forged pistons help but rock some 91 octane gas on a heat soaked engine and if things don't go your way- poof - off comes a chunk of the ring land.

Anyways, don't use premium fuel if you want, but if you see a station who tries to offer an alternative to the gassy-water in the well, post it here.
 

·
Premium Member
Joined
·
4,071 Posts
SRT800 said:
That's an urban myth that has grown into an even bigger lie that is hurting not only your performance but the environment.

Modern engines have the capability to adjust for worse performing fuels. And yes, most of the calibration is carried out at 93-94 octane. However, this is done at ideal engine conditions (cold coolant, cold incoming air, warm oil) that cannot be kept constant on the street.

Modern engines also can adjust for better performing fuels. If you data log your spark and fuel trims, and overlay it to air and coolant temperature, you will see a dramatic difference between 91, 94 and 104 octane.

The ECU dramatically pulls spark timing and dumps fuel to comphensate for rising temperatures and poor fuel to quench any POTENTIAL misfire or knock.

You don't buy a 425HP car to leave 50-60hp on the table. Also, detontation, which the HEMI engine is predisposed to (large quench surface area), and the damage it causes, can be severe. The top ring is very close to the top of the piston to reduce the crevise volume so unburnt hydrocarbons can't hide in there and then escape out the exhaust port, posioning our babies and killing the trees. This makes the top end of the piston fragile as compared to traditional/old school "race engines". Forged pistons help but rock some 91 octane gas on a heat soaked engine and if things don't go your way- poof - off comes a chunk of the ring land.

Anyways, don't use premium fuel if you want, but if you see a station who tries to offer an alternative to the gassy-water in the well, post it here.

Before I pull out the BS flag, would you mind revalidating something for me?

So you're saying at 425HP there's "50-60 HP on the table" meaning running higher octane fuel than the manual specifies will pick up that 50-60HP??

I'm all ears.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #9
Rule of thumb for best PERFORMANCE

Sorry, I thought you owned a performance car. No really, use whatever you feel comfortable with, but help others find the "good stuff".

Rule of thumb is your compression ratio times ten is the octane you should be running to help ensure the ECU is not decreasing power from the ultimate potential. It's diminishing returns as you exceed 100 octane and once you get into 13+ ratios the gas is custom blended for specific attributes. Same for spec gas for specific race series (like NASCAR and WRC) where the octane number starts to mean less and less.

But for the street:

Economy car (Camry, Kia etc)
8.7 or below: 87 octane

Regular car (300C, CTS, Ram)
9.1: 91 octane

Performance car (SRT, Z06, EVO, STi, M5, Cooper S)
10.0+: 100+ octane

Some exquisitely designed engines can do more with less octane, but its better to err on the side of more octane than less. An example would be a motorcycle engine where 12.5+ ratios can survive on 94 octane.

But large diameter pistons, hemisperical chambers and high compression (like a 6.1L HEMI for example) require more octane. Add in heat, humidity, and stop-and-go driving and you get the picture.

Also, don't use toluene as an octane booster. See article below:

Article
 

·
Registered
Joined
·
23 Posts
Discussion Starter #10
SAE versus real world

No, the engine is rated to SAE standards at 425HP, but under real world conditions, power drops...and drops...and drops, as the engine heats up and conditions worsen.

SAE standards allow for a liberal interpretation. You can have the correct air temp etc to the standard but you use a huge reservoir for the cooling to keep the engines dead cool, and a heated oil supply to keep the bearings alive and slick. You can hold these engine parameters for hours even days. Also the fuel can be cooled, manifolds kept frigid and other trickery to "get the number". Not that DCX does or did this but this has caused a shift to SAE Certified that has a third party inspector monitor the test. But how does this translate into the "50-60 hp" on the table?

Easy- as soon as you start the engine it starts to heat up. The ambient air you suck into the air filter is usually 80+ F and rises as the manifold etc push heat into the air charge.

You may have 425hp as you leave for work in the morning, but by the time you reach your office, the engine is at 208 F, air temp is 90 F and the 93 octane fuel is just barely keeping up. Sit in traffic for 40 minutes waiting for a bridge to come down or an accident, and then step on it when it opens up and "pop"! Now the knock sensor and ECU will mitigate the possibility of severe detontation, but even they can make mistakes or be too slow to respond.

Successive dyno tests show the effects of heat soak and changing conditions. A 10-20% drop in peak power is expected.

So maybe a range of 42.5-85hp left on the table is more true.
 

·
Premium Member
Joined
·
4,071 Posts
Well using higher octane gas to compensate for high operating temps is certainly the way to decrease power loss in these ranges.

It sounded to me that you were referring to a 50-60HP gain on the dyno (optimal temps 180 degree for example,) which I think we can agree isn't going to happen.

Personally I think it would be cheaper to adjust the operating temperature of your engine rather than spending all the cash on 100 octane gas.

As far as the additive I was referring to, I think it's MMT and not toulene. I'll have to find out.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #12
Good point

I couldn't agree more.

Using the latest available coatings, coupled with proper air management (extracting hot air from the engine compartment and ensuring cold air gets ingested) is the best way to make and maintain power.

I've seen coatings alone that have allowed an engine to run for a long, long time once the coolant was lost.

But could we still help located the premium fueling stations in our neighbourhoods?
 

·
Registered
Joined
·
563 Posts
vvv90 said:
glhs837, you have the stage III kit right? If I'm not mistaken it requires 100 octane.

You might want to try what my friend uses in his high comp motor. I'll find out what it's called and give you the info.

Basically, it's about $12 a quart and is good for 12 gallons at 100 octane treated with premium 93.

If at $2.50 a gallon with octane booster it's only $3.50....Quite a bit cheaper than Sunoco.
Yep, sure do. Now while it CAN use +100 octane, it's NOT required. Which was my point. I have a switch on my dash that lets the computer run ridiculous timing advance, with the assumption I use 100 or better to control the detonation such timing brings.

As far as where to get it by me, only a few choices. Way up by Baltimore, both on the list. I find Maryland International Raceway (MIR) most convenient.

Oh, I know about Torco, which is what he's most likely using. Stage 2 seems to love it, but Stage 3 is more finicky. I still havent tried HOM, yet.
 

·
Registered
Joined
·
563 Posts
I know performance cars DO benefit from a jump to 93-94. I can't recall seeing any numbers for untuned stock performance cars on 100 octane though. For instance, take a bone stock 03 Cobra, 93 octane to 100, no other changes. Any gain?
 

·
Banned
Joined
·
1,300 Posts
glhs837 said:
I know performance cars DO benefit from a jump to 93-94. I can't recall seeing any numbers for untuned stock performance cars on 100 octane though. For instance, take a bone stock 03 Cobra, 93 octane to 100, no other changes. Any gain?
No. The issue is almost 100% spark timing. In theory, you want the cylinder chamber to explode right at top dead center so all of the force goes toward pushing the piston back down. In reality, flame travel isn't instantaneous, so we advance timing to numbers of degrees BEFORE top dead center. The ideal situation is to have the whole air/fuel mixture buring just as the piston hits TDC so the force can push the piston down.

At certain pressures/temperatures, the air/fuel mixture will ignite without a spark. If this happens too early, you get ignition pushing the piston down while the crank is still pushing the piston up. (This is BAD).

The issue is pressure/temperature. Hot engines and high compression cause the problem. (Hence the trickiness of forced induction with high compression pistons).

So how do we fix the problem? Use higher octane, which is really additives that make the fuel LESS explosive - that is, they won't burn until even higher pressures/temperatures.

In ANY application, there is an octane rating at which the spark timing is at its optimal setting, and the spark timing is as advanced as it ever will be. Increasing octane beyond this number will do absolutely nothing.

Acknowledging the physics of pressure and temperature, the higher the cylinder pressure, the higher the octane number for optimal results.

Personally, Shell sells 93 octane in my part of the country as its standard "premium" fuel. Its all I ever use. JKetron may benefit from higher octane. The rest of us probably won't (without modifications that increase cylinder pressure).
 

·
Registered
Joined
·
23 Posts
Discussion Starter #17
Costco

Costco has 93 octane....3-5-cents cheaper than most others. I run Costco 93 in my 8.1L Big Block which runs 9:1.

BTW, Stage 2 was optimized on GT100 and Stage 3R saw mostly 104 in AZ with GT100 in MI.
 
1 - 17 of 17 Posts
Top