Pump gas in stock

[Jim Parsons]

Darrell, regarding your question about pump gas being quicker than race gas this is my assessment based on study and some actual race experience. Race gas is really about “octane rating” to prevent detonation and not about being more powerful.

With the laws and liabilities limiting lead content the race gas companies had to start using lots of “additives” to boost the octane level, that’s also the sweet smell you get. Today there isn’t much “gas” in race gas, another reason it cost more. These additives hurt power in a couple of ways they burn slow during combustion which changes their pressure rise on the piston and spreads it over a longer period which helps with potential detonation but not power. You typically can run a little less ignition timing with lower octane fuel. Actually the biggest reason is lower octane pump gas typically has more BTU’s of energy per pound than our legal race gas! So in your case with relative low compression you don’t need the octane to counter detonation it then makes sense that it will be faster when used. I proved this to myself when living in Denver as I took race gas out of my stocker and replaced with pump gas and picked up a tenth! This was back before specific race gas’ was mandated by NHRA and the old pump gas was still legal.
Why then do we run race gas? A couple of reasons, when pump gas had to comply with clean air regulations and started adding oxygenated additives, i.e. corn alcohol + other things NHRA’s compliance testing at the time for fuel went out the window. By them restricting us to Race gas they could set tight standards for each and compare when testing at the track, that’s why we have to declare our fuel type and brand. The other reason I suspect is they saw an additional money $$ source from the Fuel companies as each has to pay to be on the “accepted” fuel list.

I'm not saying you cant add "stuff" to gas and make it more powerful such as ERC and VP does with some of there highly originated fuels but those are thankfully not on our approved list as they are harmful and more expensive.

Hope this helps and yes there is more to the story but this is my quick take on your question.

Jim Parsons

(Past FIA international Fuel and Lubricant Committee member)


FYI: I tried sending this to you as a private message but it said you box was full.

[Mark Yacavone]

Excellent post by Jim Parsons.
I knew the basics, but that spells it all out.

Now, for the other experts on this subject, what is the low end brand that will pass , or be passed off as something else? I had heard that, a while back, some guys were using AV 100 LL , and calling it something else on the list. Apparently, NHRA figured this out, and put a stop to it, somehow.
PM me, if you don't want to post this info ;-)

[MR DERBY CITY]

Let me address one other thing regarding fuel. Racers are very creative. The fuel in the cell /tank is not ALWAYS the fuel that the racer submits for fuel check. ….

[Billy Nees]

I don't understand............................;-)

[AJ Laferty]

Just for conversation, here is the rule, in part, for gasoline, in the sports car club of america (SCCA) autocross rulebook. FYI "STREET" is more like "Pure Stock" and "Street Touring" is a little like "Stock." The rule used to be "must be pump gas..." would it help or hinder NHRA Stock class if a similar rule was adopted?

"3.6 FUEL A. Street and Street Touring® category vehicles will use fuel which is “Federally approved for use on public highways,” and which does not exceed an octane rating of 93 AKI (Anti-Knock Index = [R+M]/2) with an al lowed variance up to +0.9. Fuel may not exceed 15% ethanol (E15). "

[SDT1DYI]

Originally Posted by LASTNDN

Just for conversation, here is the rule, in part, for gasoline, in the sports car club of america (SCCA) autocross rulebook. FYI "STREET" is more like "Pure Stock" and "Street Touring" is a little like "Stock." The rule used to be "must be pump gas..." would it help or hinder NHRA Stock class if a similar rule was adopted?

"3.6 FUEL A. Street and Street Touring® category vehicles will use fuel which is “Federally approved for use on public highways,” and which does not exceed an octane rating of 93 AKI (Anti-Knock Index = [R+M]/2) with an al lowed variance up to +0.9. Fuel may not exceed 15% ethanol (E15). "

Sounds great but I'm unsure exactly how NHRA would and could test " Pump Gas" at the track.
As stated before in this thread, there are many different additives that can be added to increase performance, so fuel checks are mandatory for a level playing field.
That said, lower class Stock Eliminator cars are normally lower compression engines and budgets can be a concern Pump gas would be a cost saving for these racers and may in some cases help performance.
N and lower class cars, there's no roll bar requirements, simple rule change for N and lower class Stock Eliminator cars would be NO FUEL checks required.
Sure would help the traffic jam after the scales at some tracks!

Steve Teeter STK/SS 620

[Jim Caughlin]

The only comment I can make on this subject is the cost of the fuel that I consume at a race (and I'm running C16 which isn't cheap) is probably the least expensive part of the weekend. If the difference in cost between one of the lesser expensive race fuels and pump gas is going to break you, you're probably in the wrong sport.

[Stan Weiss]

Originally Posted by Jim Parsons

Darrell, regarding your question about pump gas being quicker than race gas this is my assessment based on study and some actual race experience. Race gas is really about “octane rating” to prevent detonation and not about being more powerful.

With the laws and liabilities limiting lead content the race gas companies had to start using lots of “additives” to boost the octane level, that’s also the sweet smell you get. Today there isn’t much “gas” in race gas, another reason it cost more. These additives hurt power in a couple of ways they burn slow during combustion which changes their pressure rise on the piston and spreads it over a longer period which helps with potential detonation but not power. You typically can run a little less ignition timing with lower octane fuel. Actually the biggest reason is lower octane pump gas typically has more BTU’s of energy per pound than our legal race gas! So in your case with relative low compression you don’t need the octane to counter detonation it then makes sense that it will be faster when used. I proved this to myself when living in Denver as I took race gas out of my stocker and replaced with pump gas and picked up a tenth! This was back before specific race gas’ was mandated by NHRA and the old pump gas was still legal.
Why then do we run race gas? A couple of reasons, when pump gas had to comply with clean air regulations and started adding oxygenated additives, i.e. corn alcohol + other things NHRA’s compliance testing at the time for fuel went out the window. By them restricting us to Race gas they could set tight standards for each and compare when testing at the track, that’s why we have to declare our fuel type and brand. The other reason I suspect is they saw an additional money $$ source from the Fuel companies as each has to pay to be on the “accepted” fuel list.

I'm not saying you cant add "stuff" to gas and make it more powerful such as ERC and VP does with some of there highly originated fuels but those are thankfully not on our approved list as they are harmful and more expensive.

Hope this helps and yes there is more to the story but this is my quick take on your question.

Jim Parsons

(Past FIA international Fuel and Lubricant Committee member)


FYI: I tried sending this to you as a private message but it said you box was full.

The lower the CR the quicker a peak cylinder pressure will decay. If I can have a lower peak cylinder pressure but have it at a point farther ATDC it is possible to have the same if not more turning force on the crank. In many cases peak cylinder pressure is 10 to 14 ATDC where a good amount of that force is trying to push the crank out of the block. Remember how the rod crank angle plays into using cylinder pressure as turning force.

Stan

[Darrel Goheen]

Originally Posted by Jim Parsons

Darrell, regarding your question about pump gas being quicker than race gas this is my assessment based on study and some actual race experience. Race gas is really about “octane rating” to prevent detonation and not about being more powerful.

With the laws and liabilities limiting lead content the race gas companies had to start using lots of “additives” to boost the octane level, that’s also the sweet smell you get. Today there isn’t much “gas” in race gas, another reason it cost more. These additives hurt power in a couple of ways they burn slow during combustion which changes their pressure rise on the piston and spreads it over a longer period which helps with potential detonation but not power. You typically can run a little less ignition timing with lower octane fuel. Actually the biggest reason is lower octane pump gas typically has more BTU’s of energy per pound than our legal race gas! So in your case with relative low compression you don’t need the octane to counter detonation it then makes sense that it will be faster when used. I proved this to myself when living in Denver as I took race gas out of my stocker and replaced with pump gas and picked up a tenth! This was back before specific race gas’ was mandated by NHRA and the old pump gas was still legal.
Why then do we run race gas? A couple of reasons, when pump gas had to comply with clean air regulations and started adding oxygenated additives, i.e. corn alcohol + other things NHRA’s compliance testing at the time for fuel went out the window. By them restricting us to Race gas they could set tight standards for each and compare when testing at the track, that’s why we have to declare our fuel type and brand. The other reason I suspect is they saw an additional money $$ source from the Fuel companies as each has to pay to be on the “accepted” fuel list.

I'm not saying you cant add "stuff" to gas and make it more powerful such as ERC and VP does with some of there highly originated fuels but those are thankfully not on our approved list as they are harmful and more expensive.

Hope this helps and yes there is more to the story but this is my quick take on your question.

Jim Parsons

(Past FIA international Fuel and Lubricant Committee member)


FYI: I tried sending this to you as a private message but it said you box was full.

Thanks Jim. It's always amazed me how many people think the higher the octane rated fuel the more power it makes and normally it's just the opposite. In simple terms...the higher the octane the harder it is to ignite. Even before I switched to pump gas I was pretty certain that 91 octane would be quicker than the 112 I'd been using.Then frequently the argument has came up that pump gas isn't consistent like race fuel. I proved that wrong 20 years ago when all I run was pump gas in my Chevelle. I've run pump gas long enough in my Stocker now that I see no problem with inconsistency over running race fuel.