Anyone got experience with fuel additives

[TdracerTd]

Anyone used caltex E flex fuel? Heard its not as good but it might be a option.

I hear the ethanol content varies too much to tune on without an ethanol sensor and flexible tune. From what I hear it can vary from below 50% to up to 70%. The united that I have bought has never been lower than 80% and as high as 90%.

[Holden202T]

yeah I've heard similar with Caltex, not 50% but heard it goes down to 70% in winter .... but the united fuel doesn't!

E85 is certainly the future but at the moment theres just not enough pumps with it available yet so I can understand the pain! I am in the same boat with methanol, can only buy it in 44's and that's a good 1 hr trip to get it, but as its a race car and only used a few times a year its easily justifiable! but for a streeter I would be certainly looking at E85 as I am lucky enough to have one 5 minutes from home!

[VL400]

Tried an octane booster with U98 at a test and tune late last year, at ANDRA events you must run an approved fuel so additives are out. Figured a TnT day was a good opportunity.

Normally run a 10.14-10.18 during the day (DA of 1000+ feet), added the octane booster and ran exactly the same time. Added a couple of degrees extra timing and no change to the times.

[Gareth]

Agree with the above, all testing we did with additives over a number of years showed no power gains, only reliability in reguard to knock prevention, as I mentioned earlier we ran a highly strung 202 in speedway, race during the day and through summer, we would see knock on the plugs (I even melted pistons once ) running up to 25 laps at a time flat out. On a hot day we would use additives including benzine so as to run the same timing with no knock. We used to play around with fuel temperature as well with mixed results (fuel ice box).

E85 is the go

[Holden202T]

the question I have though, yeah sure you ran the same timing with no knock with the additive, but if you back the timing off so it doesn't knock or kill the motor how much do you really loose ?

that's the big question .... sure its great to get the most out of a motor but if you gain very little but risk long term reliability its really not the right answer ....... if the drop in HP is like 20-30 then obviously theres a benefit to having the higher octane additives .... but one might also argue your running too much compression in the first place for the allowed fuel.

a lot of it also depends on the motor, for example the motor VL400 is referring to might not have enough compression to need the extra octane, and the fact it didn't go any quicker to me seems to indicate its about at the optimum timing already ....

[Gareth]

too much compression in the first place for the allowed fuel.

You guessed it, 12ish to one from memory... Street stock is a class where everyone is looking for the last drop of everything, so timing stayed.

Makes me remember some of the cunning cheating that was going on, flywheels must measure a certain thickness so they would remove the ring gear and drill them out hollow, refit ring gear and no one could tell (unless they weighed it ). There was the one from the HQ racing at the thunderdome I remember where some one was running a 'qualifiying engine' that had the water heated inlet manifold fitted where the water jacket was drilled to fit a small jet (aimed at the middle of the base of the carb) and the cooling system was filled with water/methanol mix, high comp and big timing where employed to make more HP. Sorry to thread hijack

[delcowizzid]

could just use avgas to cut the 98 think about 5-10L in 100L will give you all the lead that leaded fuel used to have.we run 95 on the street and pure avgas for skids and drags just so we dont cause oil downs on the strip LOL. its hard to make the stuff detonate even at 13.3:1 at 21psi on the dyno LOL it burns so clean no carbon what so ever with avgas and its 100 octane when run lean and 130 octane when running rich turbo fuel ratios.the 100 octane rating is rated the same way as MON rating so its 100 MON and a lot more in RON numbers

[Charlescrown]

United Petroleum is out of the equation because they dropped their 100 octane and went to 98. This cars ECU was set for 100 Octane and I was running 98 without logging and guess what. I picked the pieces and 2 grand for parts only later it's back together. I am now going to log via Delco and OBD2. I will be at the track on Sunday the 12th but taking it easy (unless I can't help myself) to run the engine in and get a few logs for future tuning. I have looked at the Jap and Aust timing maps and there is some difference so I backed off the low Octane fuel map and looking seriously for knock now. I know the advantages (and disadvantages) of E85. I don't want to have my car sitting there for a month or 2 with E85 sucking up all that moisture. I would love to be running it but as mentioned the variance if ratio especially with seasons and other problems I cant go that way. All the cars that can use E85 are flex fuel so the ratio doesn't matter whats in the tank. I will be picking up a drum a Toluene tomorrow and mixing 2L with 18L of Optimax which will give me 100 Octane.
I don't believe in the magic bottle of additive which will do damage and loose power with the only advantage of making the snake oil salesman richer. THEY ARE CRAP.

[delcowizzid]

what sort of car

[Jayme]

I dont have a lot of experience with 100 octane fuel .... but if someone went from 98 to 95 then their engine fell apart... I would question that the tune was too close to the bleeding edge to begin with.......