Underrated Stock Si Numbers?

[SDAlexander8]

Agreed, although I think Exedy could have built an OEM clutch that is pretty much just as driveable as the one we got. We'll leave the DMF vs SMF piece out of this since that's a different discussion and assume that for the average driver, a DMF is better. From the conversations I've seen with them, their stage 1 clutch is what we should have received from the factory. And here's what Exedy's acct executive said in regards to Honda under spec'ing (taken from one of the original posts about Exedy's staged clutches):

I also agree that the stock clutch is probably perfectly fine on the OEM tune, but it always makes me wonder if Honda de-tuned things once they realized the stock clutch couldn't hold the torque the engine is capable of. The reason I say that is due to the artificial boost ramp. If you get rid of that w/ a tune and still run near-stock boost, there's still a decent chance of getting slip. Maybe it was done to protect the rods too, but I haven't seen any evidence yet of people bending rods w/ ~20 PSI and the boost ramp removed.

would a pressure plate with a little
more spring force on the stock clutch not suffice? maybe would even give the clutch pedal a little more feel. But I guess then it would be even easier to glaze the clutch with bad driving habits.

 

[PdxJose]

Don’t think it’s overrated. Feels like a 15 second car which falls inline with advertised numbers from factory. Dynos are calibrated differently and can often skew numbers. For example, I went to a dyno day somewhere local in SoFlo, my stock mini made 210 whp when it’s 170 from factory. Stock 8th gen Si made 220 whp. That performance shop most likely misled so many people thinking they are making more power from their “tuner” compared to others.

Dynos are best used as a measurement to see changes. I wish more people would understand that instead of seeing one dyno number and think it’s true.

Gotcha, I know very little when it comes to Dynos but I have heard many times that they are best used when measuring changes as you mentioned. I was just curious to see what everyone else thought because many people on other forums and videos on youtube claim that the 10th gen Si delivers more power than it's manufactured to be. I think it's a great car either way, underrated or overrated on paper.

 

[amirza786]

Gotcha, I know very little when it comes to Dynos but I have heard many times that they are best used when measuring changes as you mentioned. I was just curious to see what everyone else thought because many people on other forums and videos on youtube claim that the 10th gen Si delivers more power than it's manufactured to be. I think it's a great car either way, underrated or overrated on paper.

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

 

[xbbnx]

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

The Si traps anywhere between 95-98 MPH stock

 

[Rich19Si]

The Si traps anywhere between 95-98 MPH stock

Where are you seeing a stock Si trapping 98? Best I’ve seen was 14.6 @ 95.1 stock..

 

[xbbnx]

Where are you seeing a stock Si trapping 98? Best I’ve seen was 14.6 @ 95.1 stock..

 

[xbbnx]

Where are you seeing a stock Si trapping 98? Best I’ve seen was 14.6 @ 95.1 stock..

 

[Drake]

Oof, "1" for cargo space? That's what I'd think a miata would get

 

[arpypat]

Oof, "1" for cargo space? That's what I'd think a miata would get

That's what I was thinking! Definitely a little biased.

 

[amirza786]

The Si traps anywhere between 95-98 MPH stock

That wasn't meant to be a hard number, I pulled it off either car and driver or a similar website just as an example. I'll plug in both numbers tomorrow, it will give a general idea of actual WHP. Keep in mind if you lighten the load or increase the weight, the numbers change due to parasitic losses

 

[arpypat]

Curb weight also takes into account only a 165lb driver, so take that into consideration when using these online calculators. The average american male heffer is around 198 lbs ?

 

[amirza786]

Curb weight also takes into account only a 165lb driver, so take that into consideration when using these online calculators. The average american male heffer is around 198 lbs ?

Yep, that would be parasitic loss. I would assume lots of cars suffer from that in America. I think the scientific term is McDonald's syndrome

 

[jakdotdot]

Curb weight also takes into account only a 165lb driver, so take that into consideration when using these online calculators. The average american male heffer is around 198 lbs ?

That more of an EU thing. The curb weight listed for the SI doesn't include a driver.

 

[amirza786]

The Si traps anywhere between 95-98 MPH stock

So let's go with a 96 MPH trap speed and a 2889 LBS curb weight (not compensating for the driver):

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

 

[arpypat]

Yep, that would be parasitic loss. I would assume lots of cars suffer from that in America. I think the scientific term is McDonald's syndrome

That more of an EU thing. The curb weight listed for the SI doesn't include a driver.

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

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