Head-to-Head comparison of tunes for stock FL5 cars. Round 2.

[NoviceFL5owner]

This is the first that I've seen an average HP and tq number on this platform. Good on what ever shop that did this Dyno. It's always good to see when doing mods as the peak numbers are only one data point. You can always look at the curves and see it if it's on the same Dyno sheet. It's harder when on multiple, but the way this was executed was very scientific.

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[Zpeedster M]

I don't know anyone who bought a R and filling it with 87 octane . Probably better get a base model civic if you don't want to get premium octane. Running the tank to empty risks getting the contaminants on the bottom of the tank getting sucked into the engine

 

[jcm]

if you habitually run the fuel tank to near empty your stock fuel pump will eventually need to be replaced. it's best to have it effectively fully submerged to help preserve the life of the pump. you can achieve this by keeping the gas tank higher than 50% habitually

 

[UCF120]

I think what I said is being misread.

I didn’t say I was filling with 87. In my area, all three grades of gas (87,89, and 93) all use the same nozzle. I’ve actually never seen a gas pump with one nozzle per grade of gas. Most people who drive fill with 87. It’s a safe assumption that the car that used the nozzle ahead of me filled with 87 meaning there will still be some 87 in the line before the 93 gets in. So if you habitually fill the tank when it’s at half, over time, wouldn’t the gas tank have a greater percentage of 87 than if you were to run the tank to close to empty before refueling?

For those with tunes that could experience knock with a lesser grade of gas this may be an issue over a completely stock car

 

[ProjectDD]

I think what I said is being misread.

I didn’t say I was filling with 87. In my area, all three grades of gas (87,89, and 93) all use the same nozzle. I’ve actually never seen a gas pump with one nozzle per grade of gas. Most people who drive fill with 87. It’s a safe assumption that the car that used the nozzle ahead of me filled with 87 meaning there will still be some 87 in the line before the 93 gets in. So if you habitually fill the tank when it’s at half, over time, wouldn’t the gas tank have a greater percentage of 87 than if you were to run the tank to close to empty before refueling?

For those with tunes that could experience knock with a lesser grade of gas this may be an issue over a completely stock car

I thought this was an interesting question, so I figured it out.

Assumptions:
The pump hose has 1/3 gallon of 87 octane fuel
FL5 fuel tank is 12.4 gallons

Results:
If you always fill up at 50%, you will have an actual octane rating of 92.68.
If you always fill up near empty, you will have an actual octane rating of 92.84.

Conculsion:
Filling up near empty will increase your actual octane rating by about 0.16.

 

[jtlctr]

I've always wondered the same thing about whatever amount of 87 being leftover in the hose. My solution is to squirt 1/4 gallon of fuel into the garbage can before filling my tank. Kidding of course, but I am actually curious about this question.

As far as running the tank low, I can't imagine this would truly have any detrimental effect as long as the fuel pickup is always submerged. I've always heard running the tank low will allow any sediment in the tank to be picked up by the pump, but I'm not sure about this either. The fuel is always being drawn from the very bottom of the tank anyhow and any floaters in there will presumably sink to the bottom every time the car is parked, regardless of fuel level.

 

[Clark_Kent]

Overthinking is a pastime on this forum. Residual fuel (87, 89, 91) in the line has and never will be an issue with respect to tuning. Just fuel your car up and drive, there's nothing scientific about this.

 

[jcm]

I think what I said is being misread.

I didn’t say I was filling with 87. In my area, all three grades of gas (87,89, and 93) all use the same nozzle. I’ve actually never seen a gas pump with one nozzle per grade of gas. Most people who drive fill with 87. It’s a safe assumption that the car that used the nozzle ahead of me filled with 87 meaning there will still be some 87 in the line before the 93 gets in. So if you habitually fill the tank when it’s at half, over time, wouldn’t the gas tank have a greater percentage of 87 than if you were to run the tank to close to empty before refueling?

For those with tunes that could experience knock with a lesser grade of gas this may be an issue over a completely stock car

yes but you would be damaging the fuel pump

running the tank to empty puts strain and wear on the fuel pump and is therefore not recommended

 

[UCF120]

I thought this was an interesting question, so I figured it out.

Assumptions:
The pump hose has 1/3 gallon of 87 octane fuel
FL5 fuel tank is 12.4 gallons

Results:
If you always fill up at 50%, you will have an actual octane rating of 92.68.
If you always fill up near empty, you will have an actual octane rating of 92.84.

Conculsion:
Filling up near empty will increase your actual octane rating by about 0.16.

nice! Appreciate the math on that…seems like it really doesn’t make a significant difference so that’s good to know!

Overthinking is a pastime on this forum. Residual fuel (87, 89, 91) in the line has and never will be an issue with respect to tuning. Just fuel your car up and drive, there's nothing scientific about this.

Overthinking is my personal pastime …was interesting to see the math on it that ProjectDD did above…no significant difference either way so that’s cool know. Just always wondered if there was enough 87 in the line still to dilute the 93 coming in

 

[Superhatch]

If you get the car tuned for 93 octane, you will not want to fill the car with 91.

As for the use of octane booster, I'm not a fan. You're better off using a splash of E85 to organically raise octane levels and it's significantly cheaper - <$3 per gallon vs. ~$8-$15 for 16 oz. Since you're located in Wisconsin it shouldn't be difficult to find E85. Ethanol pumps are historically concentrated in the Midwest, where corn production is the highest in the nation.

I had an E85 tuned BRZ and unfortunately I live in a bit of a 'good gas; desert. There isn't E85 or 93 in my town although every town around me (15m drive) has both. I think I'm just going to go with a 91 tune and not have to sweat it. The hp/tq difference isn't that great and I'm mainly going for an improvement in drive-ability.

 

[raptor718]

How does a base hondata tune compare to these. Not in terms of gains, but in terms of issues like knock, retard etc?

 

[Nothing]

The residual 87 isn't going to do much, it is within margin for OE and your tuner shouldn't be wringing it out so close to knock that you notice it.

Pumping 87 is a whole different thing. Even 91 on a 93 tune is not good.

It's great to see different tuners reaching similar conclusions for a base map, keeps it simple for those who want to keep it simple but OEM+. Also great to see good reviews and regular board participation from some of them .

 

[dandaman15]

The residual 87 isn't going to do much, it is within margin for OE and your tuner shouldn't be wringing it out so close to knock that you notice it.

Pumping 87 is a whole different thing. Even 91 on a 93 tune is not good.

It's great to see different tuners reaching similar conclusions for a base map, keeps it simple for those who want to keep it simple but OEM+. Also great to see good reviews and regular board participation from some of them .

Why would this be an issue? Curious because I have not heard this before.

 

[Jester04]

How does a base hondata tune compare to these. Not in terms of gains, but in terms of issues like knock, retard etc?

It is not even close, and the knock issue is really not that big of a deal just have to use good quality gas or just get tuned for the gas you will use. But the Hondata OTS is way down on power.

 

[jcfishel]

This was a fun thread to read and very informative. Thanks for sharing the research with the rest of us Phillip!

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