Dyno testing race fuel

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tenxal
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Dyno testing race fuel

Post by tenxal » Tue Dec 11, 2018 7:35 am

Interested in dyno results on various race fuels: Sunoco's SR18, Standard and Supreme along with VP C11, C12.

Thanks in advance. :)

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Re: Dyno testing race fuel

Post by grandsport51 » Tue Dec 11, 2018 8:00 am

Interesting Article ( 4 part) in Dragzine!

https://www.dragzine.com/tech-stories/d ... ight-back/

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Re: Dyno testing race fuel

Post by Walter R. Malik » Tue Dec 11, 2018 9:07 am

tenxal wrote:
Tue Dec 11, 2018 7:35 am
Interested in dyno results on various race fuels: Sunoco's SR18, Standard and Supreme along with VP C11, C12.

Thanks in advance. :)
Personally, I like something which will store well and travel well so, VP "Late Model Plus" IS that fuel for an engine which needs consistency, not necessarily the most power.
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Re: Dyno testing race fuel

Post by ClassAct » Tue Dec 11, 2018 2:29 pm

That dragline article was fairly well done for a magazine type test. It was interesting how well the additives did. I use an additive when I'm beating on my car. It changes the tune up a bit so I have to account for it. I suppose I could use the additive all the time, but I'm not running enough compression to justify it. Maybe if I bumped the CR up to 12:1 or so it would be worth it.

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Re: Dyno testing race fuel

Post by GARY C » Tue Dec 11, 2018 5:26 pm

One thing I noticed on the article test back when it was originally done was it gave the appearance of one fuel making more power than another when actually it was just the fact that the car could be tuned properly once they figured out the octane needed for the combination. It would have been interesting if they had ran different brands of fuel with the correct octane and similar chemical make up.
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Re: Dyno testing race fuel

Post by MadBill » Wed Dec 12, 2018 12:11 am

Don't know if they had valvetrain or other concerns, but I would like to have seen them pull to at least 500 RPM past peak power, likely 7200 or so.
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Re: Dyno testing race fuel

Post by David Redszus » Wed Dec 12, 2018 10:29 am

Race fuel performance conversations still miss the important point.

Why does one fuel make more power than another when ALL race fuels have almost identical specific energy values?

Why does one fuel perform well in one engine yet not in another similar engine?

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Re: Dyno testing race fuel

Post by mk e » Wed Dec 12, 2018 11:08 am

David Redszus wrote:
Wed Dec 12, 2018 10:29 am
Race fuel performance conversations still miss the important point.

Why does one fuel make more power than another when ALL race fuels have almost identical specific energy values?

Why does one fuel perform well in one engine yet not in another similar engine?
I don't think they are the same though. I just opened the spec spec for a few VP fuels
https://vpracingfuels.com/wp-content/up ... pdf?inline
https://vpracingfuels.com/wp-content/up ... pdf?inline
https://vpracingfuels.com/wp-content/up ... cSheet.pdf

And the have varying:
stoic numbers at 14.82/14.82/14.25
H:C ratios at 2.06/2.05/2.17
O:C ratio at 0.09/not given/0.035
specific gravity at 0.718/0.735/0.713
RVP 8.1/1.85/6.8
R+M/2 94/120+/100

In tuning the AFR they settled on doesn't appear to follow the H:C ratio as might be expected which I think suggests differences in unburned fuel leaving the engine at different rates although they didn't measure it. The article talks a little about the RVP being linked vaporization rates...and if there is enough octane to allow the timing to be increased to heat the fuel enough to vaporize it, which there was with the C16, it made good power.

Complicated combustion is it seems.....
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Re: Dyno testing race fuel

Post by David Redszus » Wed Dec 12, 2018 12:49 pm

mk e wrote:
Wed Dec 12, 2018 11:08 am
David Redszus wrote:
Wed Dec 12, 2018 10:29 am
Race fuel performance conversations still miss the important point.

Why does one fuel make more power than another when ALL race fuels have almost identical specific energy values?

Why does one fuel perform well in one engine yet not in another similar engine?
I don't think they are the same though. I just opened the spec spec for a few VP fuels
https://vpracingfuels.com/wp-content/up ... pdf?inline
https://vpracingfuels.com/wp-content/up ... pdf?inline
https://vpracingfuels.com/wp-content/up ... cSheet.pdf

And the have varying:
stoic numbers at 14.82/14.82/14.25
H:C ratios at 2.06/2.05/2.17
O:C ratio at 0.09/not given/0.035
specific gravity at 0.718/0.735/0.713
RVP 8.1/1.85/6.8
R+M/2 94/120+/100

In tuning the AFR they settled on doesn't appear to follow the H:C ratio as might be expected which I think suggests differences in unburned fuel leaving the engine at different rates although they didn't measure it. The article talks a little about the RVP being linked vaporization rates...and if there is enough octane to allow the timing to be increased to heat the fuel enough to vaporize it, which there was with the C16, it made good power.

Complicated combustion is it seems.....
There are a few problems with the data.
In spite of two fuels having no oxygen, and one fuel having 3.6%, they show the same stoich value. If correct, it means the oxygen simply has no contribution other than to raise octane and lower the stoich.

The stoich values for a given fuel only refer to the chemically correct fuel ratio, not a/f ratio for best power.

The H:C ratios seem correct and indicate substantial similarity between the non-oxygenated fuels.

The SpG seems wrong, considering that an oxygenate increases specific gravity, unless other components were used to lower SpG.

The octane numbers posted are misleading; only MON values should be considered for race fuel.

What is missing and very useful are the distillation curves for each fuel.
Also to be considered are the heat of combustion and the latent heat of evaporation as well as auto-ignition temps.

In my opinion, formed after blending race fuels for twenty five years, the articles add more confusion than clarity.

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Re: Dyno testing race fuel

Post by mk e » Wed Dec 12, 2018 1:14 pm

If the H:C ratio and stoic matches but SpG does not as with C9 and C16, I guess that means there are differences in the additives. For sure C16 has lead and C9 doesn't for example...no idea what else is different but the RVP numbers *1 point on the distillation curve?) are way different and something is causing that.
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Re: Dyno testing race fuel

Post by David Redszus » Wed Dec 12, 2018 3:20 pm

mk e wrote:
Wed Dec 12, 2018 1:14 pm
If the H:C ratio and stoic matches but SpG does not as with C9 and C16, I guess that means there are differences in the additives. For sure C16 has lead and C9 doesn't for example...no idea what else is different but the RVP numbers *1 point on the distillation curve?) are way different and something is causing that.
A given race fuel blend may consist of several dozen different components, each with different properties and present in various amounts. It is the aggregate blend that determines final fuel properties. Think of them as components and not as mere additives.

The difference in rvp and distillation curves between C9 and C16 is primarily due to the presence of phenylmethane and 1,1,2, trimethylethane, among other components.

Blending a race fuel is much like baking a cake. Using only flour, sugar, cream, eggs, and yeast, a baker can produce dozens of different types of pastry, each with its own characteristic appearance and taste. So it is with race fuels.

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Re: Dyno testing race fuel

Post by steveslowboy » Wed Dec 12, 2018 4:28 pm

When we dyno'd my freshly-built hillclimb engine (inline 4 Suzuki GSXR1100 water cooled), most of the mapping/running-in was completed using regular pump "super-unleaded" Shell V-power /Optima(or whatever they call it these days, but a 97 octane fuel). When final mapping was done using the ELF Moto4T (An FIA-spec 102 fuel) we picked up around 3hp across the board (and similar torque increase) - doesn't sound much,but when the peak is around 175hp, that's a measurable increase.

To be honest, I run race fuel primarily for it's decent shelf-life and consistency - but at around 4x the price of pump fuel it's quite a cost.

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Re: Dyno testing race fuel

Post by David Redszus » Wed Dec 12, 2018 4:57 pm

A pump gas with an ontane index of 93 would actually be a fuel with an MON octane value of only 88.
Compare that to the lowest octane race fuels.

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