EX-T 1.5 Horsepower Gain 91 Octane vs 87 Octane

So, without paying for an "official" dyno, I used the iPhone app "Dynolicious" to measure peak HP on my 2017 EX-T (1.5t 6mt). Conditions for both tests, though spread about 6 weeks from one another, were in nearly identical conditions (light winds, temperature in upper 40's F). Tire pressures were the same, weight in the car was the same (gas tank nearly full on each), same "test track". App was set with a 15% hp drivetrain loss selected.

87 Octane E0 = 178 Peak Horsepower
91 Octane E0 = 192 Peak Horsepower

That's interesting that it measured almost exactly the rated numbers. First time I've heard of that app. I'm curious about what kind of algorithm it uses.

Can't find the app in the store, do you have a link?

Browncoat3000 said:

That's interesting that it measured almost exactly the rated numbers. First time I've heard of that app. I'm curious about what kind of algorithm it uses.

Can't find the app in the store, do you have a link?

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I was looking earlier today on the app store, looks like it may have been discontinued (i've had it for a couple of years). Here's a gizmodo article on it: http://gizmodo.com/5034542/13-iphone-app-faces-off-against-embarrasses-150-dedicated-dynometer

I don't know exactly how the "magic in the box" works. For my inputs, all I do is label the vehicle and input weight and drivetrain loss (app suggests 15% to 25%), from what I've read on the internets, a front wheel drive manual transmission should be about 15%. For weights -- I have had the car (and myself) on the scales and used those numbers, but factory weight plus driver weight should be close enough.

Edit: Here's a better description of the app: http://news.softpedia.com/news/Dyno...asures-Your-Car-039-s-Performance-91207.shtml
(I do know that it uses the iPhone's accelerometer vs the mass (weight) of the car to do its calculations, but beyond that I don't really know any details of the math involved).

That's the app I have too. I think it's gone I looked too and nothing in App Store . What weight are you using ? How many runs? Here in the north east it's kinda dicey to find a suitable road this time of year without sand on it so I only have a few runs. My best was 0-60 in 7 sec going up a slight grade but I had no weight loaded for a hp calculation.

richd said:

That's the app I have too. I think it's gone I looked too and nothing in App Store . What weight are you using ? How many runs? Here in the north east it's kinda dicey to find a suitable road this time of year without sand on it so I only have a few runs. My best was 0-60 in 7 sec going up a slight grade but I had no weight loaded for a hp calculation.

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I'm using 2900 lbs + driver weight. I did 2 or 3 runs for each octane grade. I mainly wanted to see a peak hp (vs best 0 to 60 time) .. I think you almost have to let the car run up on the rev limiter in 2nd gear to get the peak hp output (which probably won't help your time)


ADD: There's a "full on professional dyno" chart of a stock 6mt showing peak HP of 191.26,.... so maybe the outdated (and out of circulation) Dynolicious is "close enough for gub'ment work".
http://www.civicx.com/threads/mt-civic-dyno.9262/

I'll try more runs this spring when the weather gets better. Do you need to run a full 1/4 mi to get an accurate hp? The car is fast enough for serious tickets for a flat out 1/4 mi run, 93mph +. Right now this thing feels quicker than my old 89 mustang GT automatic, that had a shift kit and slightly higher stall converter installed.

richd said:

I'll try more runs this spring when the weather gets better. Do you need to run a full 1/4 mi to get an accurate hp? The car is fast enough for serious tickets for a flat out 1/4 mi run, 93mph +. Right now this thing feels quicker than my old 89 mustang GT automatic, that had a shift kit and slightly higher stall converter installed.

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My understanding of they physics would be this: IF the iPhone knows your mass (weight), your acceleration, and your speed -- at any given moment, ... then it should be able to calculate your hp at any given moment.
I was only doing "0 to 60" runs for my hp readings. Theoretically, if you're wanting max hp then I would think you could do a "pull" at just about any speed, but you'll need to be near the redline (on the tach) to get max hp.

Having said that, by looking at the graphs, ... all of my peak hp readings came from the end of the 2nd gear pull (not 1st gear). and I didn't go far enough into 3rd gear to know what the results would have been at redline in third (for the "fast enough" reason you mentioned).

So anyway, the short answer, ... I don't think so, but I really don't know.

@Manual is right the math is pretty simple for an iPhone:

Horse Power=( (weight x acceleration) x speed)/375

isnt that too high
honda says our base models make 174hp and 180 (sport)
i use 91 with my lx hatch....so i must be around 180hp then?

hfpdohc said:

isnt that too high
honda says our base models make 174hp and 180 (sport)
i use 91 with my lx hatch....so i must be around 180hp then?

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There's some evidence that the engine is underrated. I read somewhere that Honda used a more conservative number because of the difficulty of accurately dynoing a CVT car.

Browncoat3000 said:

There's some evidence that the engine is underrated. I read somewhere that Honda used a more conservative number because of the difficulty of accurately dynoing a CVT car.

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hmmmmm interesting...they should have dynoed a manual then?

hfpdohc said:

hmmmmm interesting...they should have dynoed a manual then?

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Sure, but there wasn't one back in 2015 when the thing went into production.

Browncoat3000 said:

Sure, but there wasn't one back in 2015 when the thing went into production.

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true........lol

Browncoat3000 said:

Sure, but there wasn't one back in 2015 when the thing went into production.

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Not true... There was plenty... Its only the u.s. that didnt have one... Every other country primarily had m/t litered all over the place.. Unlike the u.s. every other country preffers manuals 10 to 1..

I suspect the under rating is intentional marketing. The SI is coming, maybe it's gonna be say 220 hp or so. Well that would be a flash pro level of software tweak to produce from our sport models actual 200 or so hp. Like the old days now, my 98 firebird formula was rated at 305 hp and the ws6 ram air version trans am, was something like 325... But chassis dynos I recall reading about had them all the same.... Just marketing.
So anyways, this is good for us ....we got more than we paid for with that little 1.5!