I used a G-Tech Pro RR performance meter to quantify the differences in horsepower between 91 and 93 octane fuel on the GM Stage 3's 93 octane tune. In short, there is about an 8 to 10 horsepower difference, because timing is pulled after 5,500 rpm on the 91 octane fuel. Here are the horsepower and torque curves:


The reproducibility of this method is shown by the red, blue, and black runs on 91 octane fuel. You can see that 93 octane fuel (green line) has a big advantage above 5,500 rpm, but is identical to 91 octane at the lower rpms.

The displayed horsepower and torque numbers are lower than you would expect on a dyno because of rolling resistance of all 4 tires and air resistance.

 

Nice info man!!

I have some Gtech pro logs of my car while running race gas in High Octane Mode. I'll have to post them when I get a chance.

The GMS3 tune runs a good amount of timing. I log around 23* max at the top of 2nd gear & 21.5* at the top of 3rd gear. 93 octane is really a must to see full power, and GM actually states that the defult GMS3 tune (not in high octane mode) requires (not just recommended) 93 octane fuel.

I have my timing advance logs while in high octane mode that I need to insert into an excel file to show the graphical information. My car while in high octane mode holds around 26-27 degrees of timing throughout the pull.

 

so what this dood is sayyyying is that 93 octane is better then 91 octane?

 

The point is to show that you really do need 93 octane fuel on GM Stage 3's tune, and to show how much horsepower you are loosing by using 91 octane fuel on a car tuned for 93 octane.

 

But what do you do if there is no access to the 93 or 94 octane.

Here in the great white north, Petro Canada was nice enough to close all Sunoco stations, and that did away with anything over 91 octane... boo!! i know.

I'm thinking about running Methanol to bump up the octane, but what mix do I run???

 

You can use Xylene (buy it from Home Depot, Lowes, or a paint supply store) and make your own octane booster. PM me for more details.

Here is the video from today's dyno run of my GM Stage 3 Cobalt SS/SC.

GM Stage 3 Dyno Cobalt SS/SC - YouTube

 

op, do the same test and add lucas octane booster. adds 3.5 full points of octane to 10 gallons of gas, its the best octane in a bottle that you can buy. my tuner said i was probably wasting my money but i convinced him to try it and now he buys it by the case, it allowed him to add 2 full points of timing to his tc. the mmt in it is that same as in nos octane booster theres just more of it. nos has been tested to raise 93 to 95.5, lucas on the other had raises 93 to 96.5.

 

Great info,

I ran 91 once on my GMS3 setup, the car will drive fine but as stated you will see KR at wot.
I saw KR with 91 on the initial punch and at around 5500 rpm when i did this.

The car does feel a hell of alot better when 94 is in.

With proper supporting mods GMS3 is a beast setup that will surprise many.

Head work REALLY helps GMS3, granted it was designed in conjunction with a better flowing head.

I run a GMR head with lots of quality supporting parts.
Car pulls extremely hard, still have not tried 100 mode with the head, this week seems like decent weather, think i will do it then.

 

Will you be able to run your car on the dyno with the 100 octane fuel? I would like to see that.

 

This.

I can only imagine how my car would pull while in h.o.m., a GMR head, and my H62. One day I will complete my setup with one.

 

When I played with the NOS brand octane booster, I didn't notice that it helped very much, if at all. I haven't tried the Lucas brand octane booster, but I was very happy with using Xylene. Xylene (or dimethyl benzene) has an octane rating of 117. Mix xylene with 91 octane pump gasoline in a ratio of 1 to 12 to get 93 octane (although I haven't tried diluting the xylene this much). I would normally add a gallon of xylene to a tank that was about 5/8ths full to make sure I was well over 93 octane for some "high performance" runs. The car pulls hard with at least 93 octane fuel.

 

Have any of you guys trying octane boosters or xylene noticed any issues with your plugs?!? I've seen a few peoples plugs on this site had orange-ish deposits on their plugs from using octane boosters.

I have alwats steered clear from any additives. I run CAM2 during the spring and fall when I make my annual trips for my race gas. I understand you guys with 91 octane only need some sort of boost to help with performance though.

 

I haven't ever removed my sparks plugs to check, but it is nice to know this information now.

 

Has anyone done a comparison of the 93 octane vs. the 100 octane tune other than GM? I would like to see if they got the same results as GM claims.

 

When I dyno'd last year in H.O.M. I made around 10-12 more whp than in 93 octane mode.

I don't run the M62, but I do have a full GMR Stage 3 car (tune, pulley, cooling, etc).

I have graphs and excel files I need to upload (when I get time) so I can make a thread. I have tons of H.O.M. logs.

 

Thanks, that is good to know that you saw at least 10+ horsepower more with the 100 octane mode. Let me know when you post a new thread on the 100 octane mode with the Excel files so I can post a link in this thread.

 

Will do man!

 

By the way, my GM Stage 1 Cobalt made as much (if not more) horsepower (but not torque) on 91 octane fuel than my GM Stage 3 setup. After installing GM Stage 3, I loved the torque, but the car felt like it fell on it's face at high rpms on 91 octane fuel. With at least 93 octane fuel, the car came alive. I can't wait for 100 octane!

 

That's to be expected.....

Have you ever logged some of GMS3's parameters? It commands some decent timing. I have logged a max of 23* in 2nd gear and 22* in 3rd on the 93 octane tune. If you arent running 93 you will def experience KR, and pull timing which shows in your Gtech graph.

You will love HOM with race gas

 

Staged07SS, would you be able to post some of your data logs for timing and KR on the various types of fuel? I would like to see that.
Thanks
Eric

 

I sure will.

I will try and get my logs setup into an excel file by the end of this week.

 

Dont have 93 here in Colorado, best you can find is 91.

I wanna run E85.

 

07staged, what sc are you running? The h62? If so, what is the difference between the two?

 

Yes, I am running the H62.

The main difference between the M62 & H62 are the rotors.

The H62 has 120 degree twist rotors

The M62 has 60 degree twist rotors

The higher twist makes the blower more efficient & helps it to flow more air.

 

How do you know it is raising it that much? It isn't a small bottle is it? Unless you are adding a gallon or more then most only raise the octane tenths of a point not a full point plus. Lucas makes good stuff though.