91 octane tune compatable with 110 or 100 octane?

[RockStang]

OP - If you google "race fuel stoich ratings", the first thing that pops up is a thread on YB. That should get you started on stoich and mixing fuels. It's unlikely that you are going to have racing fuel that nicely matches your 91 fuel stoich. You really should retune not just for the sake of A/F ration but for the increase in timing and power you can get when properly tuned for the fuel.

I run, or used to run Octanium with 93 and never had an issue after probably 20-30 tanks. I got tired of buying Octanium so I run 93 most of the time and switch periodically for fun. It allows me to run 1ish psi more boost and 6-7 degrees more timing for 30-40 whp according to the dyno. Obviously you have 91 so your results may vary but it definitely gives you some octane and knock headroom.

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[ahl395]

As long as the race gas is unleaded with 10% ethanol, there will not be a change in stoich. You suggest methanol injection, which WILL change stoich because methanol is now added to the fuel mix. If you inject meth, I would definitely change the tune for it.

If you run race gas that is 14.1 stoich, it should be perfectly safe as long as it is well mixed. There is some concern that if the fuel isn't well mixed, that you may get 100 octane in the lines and your ECU will advance timing, then when 91 gets picked up and in the fuel lines, then the ECU may have to pull all that timing back quickly to avoid knock. In reality, I haven't seen this happen, but some people warn about it. I have personally run down to a 50/50 mix of Sunoco 260GT and 91 octane.

The octane booster should also be safe as long as it's well mixed into the tank. Add the octane booster to a tank right before you fill up and having it in there first should help mix it well.

As for whether you'll gain any power, that is completely dependent on the tune. If the tune allows for a lot of knock correction, then you may gain some timing. If the tune is already on the safe side, and doesn't allow for a lot of additional advance, then you will be just throwing money away and you won't see any gain, but it should still be safe. Octane shouldn't cause any change in fueling... you will not run richer or leaner, it will only allow changes in timing advance. A difference in stoich is what will affect fueling, and 14.1:1 race gas or octane booster should not affect stoich.

If you use a race fuel with the same stoich then there won't be a problem, but I think most will be different. It may work, but I wouldn't take that risk without getting the tune checked out. I think Lund charges $50 to review datalogs, not much money and it's worth the peace of mind.

I agree a retune is best for meth injection too, but it's a better solution IMO than messing around with mixing race fuel and pump gas. I drive alot though, to those that don't it may not be as much of a hassle.

 

[erikkire18]

thanks Ill probably do meth injection, is it just water or there is additional things in it? I was looking and snow and they have water meth kits I think. any brand and you recommend? thanks

 

[F1scamp]

thanks Ill probably do meth injection, is it just water or there is additional things in it? I was looking and snow and they have water meth kits I think. any brand and you recommend? thanks

Nope, just water, thats why they call it “meth” injection.......:shrug:

 

[erikkire18]

any brands or kits recommended?

 

[ahl395]

thanks Ill probably do meth injection, is it just water or there is additional things in it? I was looking and snow and they have water meth kits I think. any brand and you recommend? thanks

any brands or kits recommended?

Although people run plenty of different mixes 50/50 water/methanol is the most common. You can buy it pre-mixed this way or you can buy VP M1 and mix it yourself with distilled water which is much cheaper (and you can vary the ratio if you want).

There's alot of solid kits out there but I would say it depends how serious you want to get with it and how much you want to rely on it. Personally I rely on the meth quite a bit (3psi and 3-5* timing) so I wanted the best system I could get. For that I would recommend Alky Control. Highest quality kit that there is IMO but that also comes at a price of course. If you don't plan on relying on the meth as much a cheaper kit from Snow or AEM would work fine too. As far as nozzles go, DevilsOwn is my personal favorite after trying both Snow and Alky nozzles beforehand.

I recommend mounting the nozzle as far from the throttle body as possible, after the MAF or BOV to allow for the best mixing/distribution. You may want to opt to move your IAT sensor to after your nozzle as well to read most-meth IATs. What power adder are you running?

 

[erikkire18]

I don't wana rely on it nor get a tune for it, cuz if anything goes bad than I can damage the engine, so I was thinking of just having it for cooling and extra support for the 91 cheap fuel we have here in CA. I have a hellion twin 62 kit. I bought 100 octane this morning and they will be adding it and doing some logging today

 

[ahl395]

I don't wana rely on it nor get a tune for it, cuz if anything goes bad than I can damage the engine, so I was thinking of just having it for cooling and extra support for the 91 cheap fuel we have here in CA. I have a hellion twin 62 kit. I bought 100 octane this morning and they will be adding it and doing some logging today

In that case I'd go with a Snow/AEM kit. You can leave the timing alone so it will just max at what's safe on 91 all the time and you won't have to worry about the quality of the 91 your getting. I would still datalog and get your tune looked at however. STFT can pull fuel to make up for the extra fuel added from the meth but only to a certain degree. Best to get it looked over to be safe. I had to get a few changes done to my tune after I added the meth (aside from increased timing).

 

[erikkire18]

yah ill do data logs once i install it to make sure everything is good thanks

 

[erikkire18]

Although people run plenty of different mixes 50/50 water/methanol is the most common. You can buy it pre-mixed this way or you can buy VP M1 and mix it yourself with distilled water which is much cheaper (and you can vary the ratio if you want).

There's alot of solid kits out there but I would say it depends how serious you want to get with it and how much you want to rely on it. Personally I rely on the meth quite a bit (3psi and 3-5* timing) so I wanted the best system I could get. For that I would recommend Alky Control. Highest quality kit that there is IMO but that also comes at a price of course. If you don't plan on relying on the meth as much a cheaper kit from Snow or AEM would work fine too. As far as nozzles go, DevilsOwn is my personal favorite after trying both Snow and Alky nozzles beforehand.

I recommend mounting the nozzle as far from the throttle body as possible, after the MAF or BOV to allow for the best mixing/distribution. You may want to opt to move your IAT sensor to after your nozzle as well to read most-meth IATs. What power adder are you running?

what nozzle size do I pick? thanks

 

[ahl395]

what nozzle size do I pick? thanks

Snow and DevilsOwn both have nozzle calculators. It is just an estimation of course and will vary by setup. Snow uses ml/min, DevilsOwn uses GPH but you can convert between the two.

https://www.snowperformance.net/category-s/191.htm

http://www.alcohol-injection.com/en/ (Scroll down, Left side of page)

 

[DavidHuff]

I don't wana rely on it nor get a tune for it, cuz if anything goes bad than I can damage the engine, so I was thinking of just having it for cooling and extra support for the 91 cheap fuel we have here in CA. I have a hellion twin 62 kit. I bought 100 octane this morning and they will be adding it and doing some logging today

Did you buy unleaded fuel and what brand?
Cost per gallon?

 

[erikkire18]

Did you buy unleaded fuel and what brand?
Cost per gallon?

yes i got 100 sunoco unleaded. it was $65 for 5 gallons. I am going to fill up again with pure 91, do you prefer 76 or chevron? i currently use shell but theres still some knocking at like 7k rpms. My meth kit arrives next week so hopefully that also helps. just wana see what fuel is best and stick to that one

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