Underrated Stock Si Numbers?

[amirza786]

So then that 186.7whp number using the coupe's weight without a driver and trapping at 93.9mph would be a lot heigher if you added a 200lb driver trapping at say 95mph.

3100 x (95/234)^3 = 207 whp est

Yes the formula is correct. But as the weight goes up, the trap speed would have to come down in the real world. The math would be off if you increase the weight but the trap speed stays the same

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[xbbnx]

That would make the whp a bit over 199. I think that is a bit high so my thoughts is that they removed some weight from the car because the curb weight reported by Honda is 2889 LBS. What I posted earlier comes more in line what TSP reported, and if you take into account parasitic loses from the crank HP reported by Honda, 187 thru 189 whp makes sense

That makes no sense, why would you think 200 whp to the wheels is too high? Why would you dismiss the calculation here by claiming "they removed some weight" just to somehow justify your 186 whp claim? TSP got those numbers, but we know dynos are not really a good measure. We have seen other dynos get 200 to to the wheels but for some reason you are stuck to TSP's numbers but you know dynos are too inconclusive. If you put the Si's trap speed and weight on a whp calculator you get 200hp, not sure why that is hard to believe.

 

[amirza786]

That makes no sense, why would you think 200 whp to the wheels is too high? Why would you dismiss the calculation here by claiming "they removed some weight" just to somehow justify your 186 whp claim? TSP got those numbers, but we know dynos are not really a good measure. We have seen other dynos get 200 to to the wheels but for some reason you are stuck to TSP's numbers but you know dynos are too inconclusive. If you pit the Si's trap speed on a who calculator you get 200hp, not sure why that is hard to believe.

I'm not dismissing, it is possible that it has 200 whp to the wheels, but I have to look at other evidence as well from reputable sources, such as TSP, which btw I don't think are 100 percent. If the numbers you provided in your previous post are accurate, no weight was removed from the car, than the numbers in the calculation are correct and it has or is close to 200 whp

EDIT: I was questioning the numbers, not the calculations. You can't change math (1+1 will always equal 2) but the solution to the equation is only as good as the numbers input. I always question numbers because they can be fudged (not saying that is the case here)

 

[fenix-silver]

Regardless, somewhere around 200 WHP goes back to the original point that Honda underrated the actual BHP. If you are generous and say a 10% drivetrain loss, you are looking at ~220 HP at the crank.

 

[amirza786]

Regardless, somewhere around 200 WHP goes back to the original point that Honda underrated the actual BHP. If you are generous and say a 10% drivetrain loss, you are looking at ~220 HP at the crank.

It's funny, we are having a discussion about horse power, and these ads are popping up all over Chrome:

Gotta love Google tracking everything you do LOL

 

[fenix-silver]

See what u are missing!!! Lol

 

[xbbnx]

That's the point I am making. This does NOT feel like a 186whp car. I have seen multiple reviews (Matt Maran motoring etc) that have said the same. Honda has definitely underrated this engine by 10-20 crank horsepower.

 

[amirza786]

That's the point I am making. This does NOT feel like a 186whp car. I have seen multiple reviews (Matt Maran motoring etc) that have said the same. Honda has definitely underrated this engine by 10-20 crank horsepower.

It's possible. I don't know why Honda would do that, maybe for emissions or as another member stated, to save money on adding a better clutch. If you really want to find out, just take it to the track (or get it from a friend who tracks thiers) and capture it's trap speed, input the curb weight plus any added weight like your weight and use the Engine HP calculator. That number would be the whp your car is generating and all doubts are removed. That being said, even if it's 186 whp, that's pretty good for a car with this curb weight. Most 2.0L NA engines are around 170 BHP, which would bring them to maybe 155 whp

 

[Rich19Si]

This feels like a 185whp car. A 205whp/200wtq car with its weight does not do 14.6 on a good day. Honda did not underrate these cars. They would’ve sold more...

 

[RickTheWelder]

If you really want to know the actual whp being produced, there is a mathematical formula that will give you an idea. You would take Horsepower = Weight X Velocity over 234 to the 3rd. Assuming an Si Coupe weighs around 2,889 LBS and its trap speed is 93.9 MPH:

According to this calculation it's whp is 186.7. As weight goes up (adding passengers, luggage etc) the trap speed will go down as well. so there will be some losses in whp as well. The trap speed example is that of a stock Civic Si coupe

That's really weird that you got this final number. When I dyno'd my stock Si sedan before I began my mods, that is EXACTLY what the whp ended up being.

 

[amirza786]

That's really weird that you got this final number. When I dyno'd my stock Si sedan before I began my mods, that is EXACTLY what the whp ended up being.

Math don't lie!

 

[vieux georges]

When I received my SI on june 29, 2017, after more than
2 months of waiting, I started to search for true power.
I found some values that I share with you.
In a workshop in the north of the United States, Pensylvania
or Ohio, I don't remember, the same car gave 3 different
results on the same day:
187 whp and 215 wtq in the early morning
178 203 around 10:00 am
175.5 213 around noon.
I found other results elsewhere in the U.S. :
180 and 198
186 207.......
It can be assumed that the first value reflects reality when
measured under good conditions.

 

[AndrewsCivicSi]

As someone who previously had a stock BRZ (which has 205hp and a 156lb-ft), my Civic Si feels way faster. Just merging on the highway while flooring the accelerator on my BRZ was painfully slow that I felt sorry for the people behind me. The Si doesn’t feel like that and doesn’t feel much slower than my 15 WRX.

 

[gtman]

As someone who previously had a stock BRZ (which has 205hp and a 156lb-ft), my Civic Si feels way faster. Just merging on the highway while flooring the accelerator on my BRZ was painfully slow that I felt sorry for the people behind me. The Si doesn’t feel like that and doesn’t feel much slower than my 15 WRX.

It's the torque.

 

[Rich19Si]

As someone who previously had a stock BRZ (which has 205hp and a 156lb-ft), my Civic Si feels way faster. Just merging on the highway while flooring the accelerator on my BRZ was painfully slow that I felt sorry for the people behind me. The Si doesn’t feel like that and doesn’t feel much slower than my 15 WRX.

It’s the torque and the area under the power curve. They run very similar numbers in the 1/4 mile.
The BRZ feels much slower like the K20/K24 engines because those engines needed to rev in order to produce decent power.
Many reviewers consider the BRZ slow, but it’s power curve and numbers matches that of a K20, which was praised as being “fast”. I wonder why people don’t consider the 8th/9th gen Si slow, only the BRZ?

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