Why does the stock 2017/2018 Si seem to underperform on the 0-60 & quarter mile relative to specs?

[jhokie]

According to this post: http://blog.vittuned.com/introducing-the-2017-civic-si/ and other dynos I've seen it seems that Honda slightly undersold the torque and horsepower specs on the 10th Gen SI. We're talking ~220 ft-lb of torque observed at the wheels and 205 HP at the wheels, which is better or equal than what Honda is advertising at the crankshaft.

Based on those numbers and the weight of the car I would expect to see a little bit better than the reported 0-60 times of 6.5 - 7.0 seconds and the ~ 15 second quarter mile stock.

I'm still breaking my new Si in so I haven't wanted to push it hard and time anything yet. I've cut it under 4-5k RPM at most during the break-in but I can say it has pushed me back in the seat with that torque. However, has anyone had a better run or have any insight as to why the car appears to underperform a bit vs the power it's putting out?

Sponsored

 

[Xtelotatichl]

Fwd, crap tires, wheel hop, delay with quick shifts, take your pick

 

[repeet]

Gearing is most of the problem. With a slightly higher final drive ratio, we would be able to hit 60mph in second gear. I believe that we have enough power to handle a higher final drive ratio and still be able to achieve 0-60 in under 6 seconds. But with the stump pulling first gear, and having to shift a second time, we're losing almost a full second.

 

[charleswrivers]

As with all turbo motors, the car is going to be somewhat more environmentally sensitive with regard to temperture... though boost pressure is a boon when altitude affects air density

You'll see a decent variation for the instrumented tests for the Sis. Some will do a 0-60 in low 6s with a 1/4 mile in the high 14s.

I will say, compared to previous generations... the car seems to make more power if you consider the area under the HP curve... throughout the whole rev range, but if you consider the last couple thousand RPM, compared to gen 8 or 9 K-series engines... they tending to build more power with higher revs, whereas we're peaking short of the rev limit thanks largely to Honda's turbo choice. It was very common on K20A2s to up the rev limit when reflashing to 8600 RPM as the car still made good power up there, and it was known to be safe because we shared the same valve train as the then type R that had that rev limit by default. So, considering you've peaked by 6000 RPM and little is to be gained by taking the car to 6700 RPM, you incur a small amount of lag, both natural and software induced upon shifting, everytime... and a lot of shifting is needed to finish 1/4 mile... plus you need 2 shifts just to get to 60 (admittedly, gen 9 was the same) it's not terribly surprising. Any car with 2 gear shifts to make 60, with some lag to boot isn't going to set the world on fire. When you look at a dyno chart, you're only looking at power through one gear... you kind of miss what is happening to power upon a gear change. NAs can be deceptively quick for their low numbers... but with linear power, you have to get to the very top of the RPM range and stay there.

Drive your car and enjoy it. The chassis is excellent and it being relatively light makes it nimble... for it's size. There's much room for improvement. Reflashes have a major effect far beyond boost pressure, with regard to making throttle response sharper, turbo lag substantially less, both at full and partial throttle and rev hang vastly improved... if not altogether gone due to the dual mass flywheel.

Where the current Si shines is, with so much torque, you can drive it sort of aggressive but not flat out and it's much faster than the Civics of old. Until the VTEC crossover, my RSX type S was pretty tame. Down low, it made about as much torque as my girls dwarf hampster makes on it's running wheel.

Driven flat out? Yeah... they're all about the same in a straight line if you're looking at sheer numbers... though the current gen puts down better handling numbers with summer rubber than last gen did with theirs... by a lot.

 

[jhokie]

Thanks for the thoughtful replies. Based on the 250 miles I've driven I've definitely felt like it performs better than the numbers indicate.

 

[jayee]

Gearing is most of the problem. With a slightly higher final drive ratio, we would be able to hit 60mph in second gear. I believe that we have enough power to handle a higher final drive ratio and still be able to achieve 0-60 in under 6 seconds. But with the stump pulling first gear, and having to shift a second time, we're losing almost a full second.

IIRC 2nd gear caps at 58mph, forcing the shift to 3rd to reach 60mph... so close!

Also the rev hang on the stock tune affects shifting as well.

 

[SI_honda_2k17]

After 3 months of driving my SI 2017, i’m still wondering what are the optimal shift point to change gear. Since the power drop so quickly after 5500Rpm, i’m thinking that maybe the 1/4 time could be better by not driving it to the redline?

 

[JO3L]

MotorTrend article suggests shifting right at peak HP for best 0-60 performance. That is roughly at 6000 rpms or just 500 rpm short of redline.

http://www.motortrend.com/cars/honda/civic/2017/2017-honda-civic-si-first-drive-review/

 

[Deleted member]

As stated above- rev hang, needing to shift into 3rd to hit 60, and sub optimal tires all play a role. The car could probably do sub 6 second 0-60 with nothing but a rev hang delete and gearing that takes 2nd to 60. Otherwise a basemap can do it.

That said- I think chasing quarter mile times and 0-60 times in a front wheel drive car is missing the point of what makes the Si great. Front wheel drive is inherently not ideal for launches. The advantage of front wheel drive is that it is lightweight. Take it on twisty curvy back roads or a track or autocross.

 

[Design]

The two biggest inhibitors seem to be the boost lag between shifts and the CDV. Both are optimized to minimize drivetrain shock.

 

[Cscott_xGen]

Optimal shifting point... When driving mine I cruise at 3-3200K no mater what gear I am in.

As far as shifting goes.

NO LIFT SHIFT! bang those gear

 

[dmitri]

the car appears to underperform a bit vs the power it's putting out

I've definitely felt like it performs better than the numbers indicate.

So... Which is it?

 

[jhokie]

To clarify I meant it appears to underperform when looking at 0 to 60 and quarter mile runs. Driving it on the road I don't feel that way.

 

[NoelPR]

The two biggest inhibitors seem to be the boost lag between shifts and the CDV. Both are optimized to minimize drivetrain shock.

First thing that came into mind.
Previously the SI was N/A the power was always there even after each shift.
With the new turbo engine, if you release the gas pedal for shifting the car losses boost pressure and momentum. It has to build boost again on the next shift. I know isn't a lot of time but it hurts anyway.

With all the fuss of the whp numbers I was expecting people making mid 14's in average stock but that isn't the case. The car is performing (acceleration wise) like the old ones.

 

[kritz]

Car really shines in the twisties. CD lap times at VIR. The car also is very competitive in GS.

Civic SI 3:14.6
MK7 GTI 3:14.6
Focus ST 3:17.6
BRZ (PP) 3:19.7
Fiesta ST 3:20.4

Other notable cars

Ford Mustang Ecoboost 3:15.6
Honda S2000 CR 3:15.0
2015 Subaru WRX 3:15.5
2012 Civic SI 3:24.1
2006 Civic SI 3:26.5

Sponsored