Why have I lost 20hp+?

[Idaho2018GTPremium]

A little research shows Canada switches to winter blend fuel on September 15th. If your last dyno was prior to that you were on summer blend fuel. That alone could account for your 20hp.

Nice find - that's probably the culprit.

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[WildHorse]

What makes it look good? I made 20 less today lol

Cause dynos can vary that much, easily. 2 degrees less timing will do it, overly rich due to colder temps can do it. I myriad of things. If the tune is the same, 3% difference I wouldn't worry about it. But that's just me. Did you log it ?

 

[KT3]

Cause dynos can vary that much, easily. 2 degrees less timing will do it, overly rich due to colder temps can do it. I myriad of things. If the tune is the same, 3% difference I wouldn't worry about it. But that's just me. Did you log it ?

Log as in..? I’m still new to this

 

[Freedom]

455/472 is 3.5% difference. I'd relax about it...

 

[Dfeeds]

These gen 3s are very knock sensitive. As others have pointed out it's a good bet it's the gas. I've been logging my car (fp power pack) and I saw about 3-4 degrees difference just by switching fuel brands, despite both being 93.

 

[BigBeed]

A little research shows Canada switches to winter blend fuel on September 15th. If your last dyno was prior to that you were on summer blend fuel. That alone could account for your 20hp.

US switches on September 15th as well. Not sure if it is the same for Canada but in the US it is mandated that refineries switch back to summer blend by May 1st but some do it sooner.

Winter blend contains more butane then summer blend. They can not add as much butane in the summer do to it's high volatility and pressure so summer blend is more refined. In the winter the RVP limit is increased and they can add more butane to the mixture and this makes gasoline cheaper to produce. It also "cheats" the octane rating being that it is not as refined as summer blend.

 

[KT3]

US switches on September 15th as well. Not sure if it is the same for Canada but in the US it is mandated that refineries switch back to summer blend by May 1st but some do it sooner.

Winter blend contains more butane then summer blend. They can not add as much butane in the summer do to it's high volatility and pressure so summer blend is more refined. In the winter the RVP limit is increased and they can add more butane to the mixture and this makes gasoline cheaper to produce. It also "cheats" the octane rating being that it is not as refined as summer blend.

Apparently we are September 15th as well

 

[CorvZ061]

US switches on September 15th as well. Not sure if it is the same for Canada but in the US it is mandated that refineries switch back to summer blend by May 1st but some do it sooner.

Winter blend contains more butane then summer blend. They can not add as much butane in the summer do to it's high volatility and pressure so summer blend is more refined. In the winter the RVP limit is increased and they can add more butane to the mixture and this makes gasoline cheaper to produce. It also "cheats" the octane rating being that it is not as refined as summer blend.

in my brief research Canada switches to winter blend on September 15th and summer blend on April 15th

 

[BigBeed]

in my brief research Canada switches to winter blend on September 15th and summer blend on April 15th

Seems about right as we see a major drop in blend rates at that time. (I work at a company that ships butane by truck to various refineries and pipeline injection sites.)

 

[Nickel]

Was the first dyno you got SAE corrected?

 

[WildHorse]

RVP ratings are great if you have a carbureted vehicle, pointless with high pressure EFI systems.
https://www.enginebuildermag.com/2013/11/impact-of-todays-fuels-n-carbureted-engines/

 

[S550_Newbie]

RVP ratings are great if you have a carbureted vehicle, pointless with high pressure EFI systems.
https://www.enginebuildermag.com/2013/11/impact-of-todays-fuels-n-carbureted-engines/

Can you throw some octane booster in the tank and do another test? Would that counter the winterizing of the fuel?

 

[cactus_kid]

To many of these will always cause a loss in power .........................

 

[Meatball]

I’ve seen them near or at 500 on E85. Otherwise would require dangerously aggressive timing on pump gas.

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