The Official C8 Corvette Thread...

[GoCougs]

Yea, the magical "inertia" issue that only happens when a C8 is on it...

No driveshaft bruh.

[r0tor]

No driveshaft bruh.

And your point is?

[MX793]

Dat inertia, and the flaw of "wheel" horsepower. Engine dyno or no dyno IMO (but a course of PITA if you're testing-n-tuning).

To get those accel numbers it's likely a highly violent launch control (though no mention of such a thing AFAIK).

An inertial dyno cannot read more or even the same power at the wheels than the engine is actually making unless something is broken/faulty.  That violates the 1st and 2nd laws of thermo.  In addition to driveline friction loss, the presence of rotating mass/inertia in the driveline only reduces the amount of power than an inertial dyno reads (hence why I called it a pseudo "loss" as far as inertial dynos are concerned), so "inertia" cannot be to blame for the dyno reading high.

I believe this is a faulty dyno.  Either something was physically broken (e.g. bad sensor) or there were some incorrect parameters entered into the software (perhaps some kind of adjustment factor to account for driveline inertia in the final results file wasn't input correctly, or some other adjustment parameter).

[GoCougs]

And your point is?

Inertial dynos are terrible and should be ignored.

[565]

It's obviously a Dyno error.  Anyone with any shred of automotive knowledge would clearly see that.  MT was just trying to get more clicks after they didn't get to be all alone to publish C8 test times like they were promised (and after they advertised the crap out of their *exclusive* test).  Their sensationalist C8 Dyno backfired on them and that's why they pretty much scrubbed the C8 Dyno article from their front page and there are no links to it from the other C8 articles anymore.

Here is the article in question, which now you can pretty much only get to from a google search:
https://www.motortrend.com/news/2020-chevrolet-corvette-c8-power-dyno/

There are three obvious issues with this result.  First off a 602-615 lb/ft of torque rating for a 6.2 NA pushrod motor not tuned and cammed to be unstreetable is unheard of.  This isn't a turbo motor that they can just turn up the boost for easy power.  To get 600+lb/ft torque means this Chevy SBC would need to be exceeding the NA production car record for torque/liter.  The 458 Italia made 89 lb/ft per liter.  This magical pushrod would be making 99 lb/ft per liter.  It's impossible.  This engine is supposedly super refined, almost too refined and quiet, so there is no way it's running some ridiculous race cam, or running essentially an unrestricted exhaust.  The options to generate this sort of torque would be Chevy fitting  secret turbo or supercharger, which would be detected, or fitting some secret large displacement engine for these tests, which is highly unlikely.

Second is that this supposedly 660hp 3600lb car is only running 123mph traps.  That would be an abysmal trap speed for a car that has a similar or better power to weight ratio than the  C7 Z06 that ran 127-128mph traps.  122-123mph traps is exactly what you'd expect a 3600lb 495HP car to be running with a fast shifting DCT. 

Third, this was a Mustang Dyno (it says so right on the read out).  Having to run closest to 1:1 gearing is really only an issue with inertial dynos like a DynoJet, due to the way it works of measuring how fast you can accelerate the drums of a known mass.  A Mustang Dyno does not need to be run at 1:1 gearing to get close to accurate data due to the way it measures load.  At higher gears you get slightly lower readings on Mustang Dyno because there is more gear train resistance, but this is a small effect.

Look what happened when MT ran the C8 in 6th gear instead of 5th.  HP dropped by 90 HP and torque actually went up.  The graph on those runs looks super messed up too. 



But Motortrend didn't mention this messed up graph at all in their article.

This makes no sense unless changing gears on the C8 massively changed the engine mapping to make more torque at low RPMS and have it drop off at higher RPMs.  This should have been there biggest red flag that they weren't running this test correctly.  Mustang Dynos again have very little variation between gears due to the way they work.

Overall this was just poor automotive reporting.  When they got these nonsensical numbers they should have investigated why running a different gear on a Mustang Dyno resulted in such a vastly different reading, rather than just publishing it.

[CaminoRacer]

They should have had the engine masters guy do the test, they actually know what they're doing and know SBCs.

[12,000 RPM]

This is an embarrasment for Motor Trend, but it's to be expected. Johnny Lieberman's whole MO is fleecing manufacturers out of cars and trips.

[GoCougs]

Most automotive reporting is poor.

'Tis nothing new - most, include auto mags - get snookered by the snake oil of chassis dynos. It's simply not how to even remotely accurately measure engine power.

Dat inertia.

[r0tor]

This is an embarrasment for Motor Trend, but it's to be expected. Johnny Lieberman's whole MO is fleecing manufacturers out of cars and trips.

More like they intentionally faked the results for clicks

[Galaxy]

How reliable are hub dynos?

[12,000 RPM]

More like they intentionally faked the results for clicks

Auto enthusiasts are dumb but they aren't that dumb

The discussion over at TCL is quite robust with similar concerns.

Plus I feel like ANY dyno results from the C8, even if they were spot on, would generate big buzz. Instead, MT's credibility is shot, possibly because the dyno operator didn't know what they were doing? What a shame.

[Eye of the Tiger]

The only dyno that matters is the butt dyno.

[GoCougs]

Nah, M/T is smart enough to know that any sort of fakery would get called out.

[GoCougs]

How reliable are hub dynos?

Much, much better, as they can test power at constant RPM or thereabouts, as a hub dyno relies a constant load like from hydraulics, rather than accelerating a large mass.

[GoCougs]

There I go over to M/T and on their front page they have a blurb about X car making Y (i.e., "lots") of torque.

So painful.

[r0tor]

Auto enthusiasts are dumb but they aren't that dumb

The discussion over at TCL is quite robust with similar concerns.

Plus I feel like ANY dyno results from the C8, even if they were spot on, would generate big buzz. Instead, MT's credibility is shot, possibly because the dyno operator didn't know what they were doing? What a shame.

Their fake news probably got them 1000x more clicks then a real dyno. 

[12,000 RPM]

Their fake news probably got them 1000x more clicks then a real dyno.

Getting clicks for incompetence = frontloading

I imagine a lot of people won't be going back.

[MX793]

There I go over to M/T and on their front page they have a blurb about X car making Y (i.e., "lots") of torque.

So painful.

Yeah, but that's a manufacturer's claim.

[Gotta-Qik-C7]

Like I said earlier. There is no way I'd spend 5 Grand on the Z51 package! Unless I HAD to have Mag Ride! The base car is just as fast and is carrying a couple extra MPHs in the 1/4 Mile!
https://media.chevrolet.com/media/us/en/chevrolet/home.detail.html/content/Pages/news/us/en/2019/nov/1106-corvette.html

[Payman]

Yup. The base car is the one to get.

[Gotta-Qik-C7]

Yup. The base car is the one to get.

Without a second thought......

[MX793]

For drag racing, the cheapest, simplest trim that gets you the most potent engine is usually the best.  That's been the case for a long time (old LX 5.0 notch back Mustangs?).  If you only intend to drive on the street and the local drag strip, base car is your best value.  If you intend to do any roadcoarse driving, or even autox, I suspect the Z51 will be worth the investment.  Besides the MagRide, it also gets the ediff, bigger brakes, and additional cooling for the powertrain.  The first two will be useful for both autocrossers and road racers.  The latter two are geared more toward handling the rigors of sustained hard driving/lapping.

[Soup DeVille]

It would be stupid to buy a C8 for drag racing.

[FoMoJo]

It would be stupid to buy a C8 for drag racing.

Especially since it's slower than a GT500 in the quarter.

[MX793]

It would be stupid to buy a C8 for drag racing.

Yeah, but there are plenty of Vette owners for whom the strip is the only "closed course" or performance driving their car sees.

[giant_mtb]

Yeah, but there are plenty of Vette owners for whom the strip is the only "closed course" or performance driving their car sees.

True. Mashing the gas pedal with launch control for 12 seconds is a far cry below hitting a road course and doing some "real" race driving. Takes balls to make that leap, I imagine.

[MX793]

True. Mashing the gas pedal with launch control for 12 seconds is a far cry below hitting a road course and doing some "real" race driving. Takes balls to make that leap, I imagine.

That's part of it.  Also, drag strips are generally more accessible than road courses.  There are a lot more of them, for starters.  And it's generally much less expensive to go to the local strip and do a couple of runs than to pay for a track day.  Local drag strip has an event every week, $25 to enter the "street" class.  $50 if you just want to do time trials.  Nearest road course, which is a very small course, is a Monticello-esque country club deal (though much less expensive, it's still not cheap), though they do sell individual track days to non-members.  Single track day pass for a non-member is $350.  You can buy a 3-pack for a discounted per diem rate, but it's still over $200 a track day.

[Eye of the Tiger]

That's part of it.  Also, drag strips are generally more accessible than road courses.  There are a lot more of them, for starters.  And it's generally much less expensive to go to the local strip and do a couple of runs than to pay for a track day.  Local drag strip has an event every week, $25 to enter the "street" class.  $50 if you just want to do time trials.  Nearest road course, which is a very small course, is a Monticello-esque country club deal (though much less expensive, it's still not cheap), though they do sell individual track days to non-members.  Single track day pass for a non-member is $350.  You can buy a 3-pack for a discounted per diem rate, but it's still over $200 a track day.

If I could get onto road course for the price of a drag strip, I'd be there every weekend. But I can't even afford one track day ever.

[Gotta-Qik-C7]

For drag racing, the cheapest, simplest trim that gets you the most potent engine is usually the best.  That's been the case for a long time (old LX 5.0 notch back Mustangs?).  If you only intend to drive on the street and the local drag strip, base car is your best value.  If you intend to do any roadcoarse driving, or even autox, I suspect the Z51 will be worth the investment.  Besides the MagRide, it also gets the ediff, bigger brakes, and additional cooling for the powertrain.  The first two will be useful for both autocrossers and road racers.  The latter two are geared more toward handling the rigors of sustained hard driving/lapping.

Actually Mag Ride is NOT included in the Z51 package. It an ADDITIONAL $1895! The performance exhaust IS included in the $5000 Z51 package tho! So you actually have to spend 7 Grand for the set up! And you can only get MagRide with the Z51 upgrade! It's not available as a stand alone option like it has been in the past! 

[GoCougs]

Yowzers. M/T tests a C8 at 0-60 in 2.8 sec and 1/4 mile in 11.1 sec @ 123 mph: https://www.motortrend.com/cars/chevrolet/corvette/2020/2020-chevrolet-corvette-stingray-c8-first-test-review/