Originally Posted by MatthewMiller
(Post 1605968632)
He asked why C4s are so quick from 0-60mph. Part of my reply to him is that they aren't especially quick for their weight or power: they run like we would expect a 240hp RWD car weighing 3200lb and with close to 50/50 weight bias and fat/sticky tires would. A quick perusal of Motor Trend's list of 0-60 times will point out that a ton of cars with similar weight/power are similarly quick, including a legion of FWD four-bangers. I should have led with that, but my point with the C8 is that quick cars these days do the deed in half the time. It's irrelevant whether you think they are exciting/interesting or not.
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Originally Posted by LemonC4
(Post 1605960978)
I understand compared to now they’re pretty slow or maybe average but the thing is these things from 85-89 made like 240hp? I also recently found out the corvettes weighed quite a bit like 3200 pounds it confused me how these pulled mid 5s in the 0-60 range.
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^True.
And in the hands of a GOOD driver, they'll 0-60 faster than the mags have stated. The C4 is a very "driveable" car. Meaning, it's an honest, straight forward driving experience that gives you back exactly what you put into it. So? Well driven, the cars did/do pretty well. On the flip side...remember when 0-60 times mattered and were a hotly debated/compared thing?? :lol: |
Originally Posted by LemonC4
(Post 1605960978)
I understand compared to now they’re pretty slow or maybe average but the thing is these things from 85-89 made like 240hp? I also recently found out the corvettes weighed quite a bit like 3200 pounds it confused me how these pulled mid 5s in the 0-60 range.
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any chance i get to sing the praises of the L98 on the road track, i take.
most guys never take a car to the track (to my surprise!!!!!its a riot!!) but an L98 in the powerband is completely fine on track. Its up to the driver to keep it there specifically on downshifts, learning rev match shifting (i grin every time i nail a rev match downshift that dumps just inside the powerband). keep it in the powerband right around 3500 and use the 330ftlbs thats there for u. If you have an LT1, you will be doing the exact same thing but the powerband is higher. You as the driver control where you are using your stick. If you are on a course with a lonng long straight away you will still be fine on a L98 but u will be in a higher gear at the end of it or u will have fallen on your face at 5000rpm. Learn to shift, learn to be quick with your feet. Think of it like......Tom Cruise in the new TopGun (which is off the charts good)....he was such a good pilot that he knew how to extract the most out of the outdated Jet of his era. Ofcourse im not saying that an L98 will run with a modern car. But ive personally seen an L98 have far faster lap times than an LS its all about extracting the juice out of the fruit. Technique. People say L98’s are awesome street cars because you never get out of second gear and barely into 3rd. A street is like a track with no straight aways longer than the stoplight distance. .... just keep the engine in the powerband....and u can go to a decent straight. Now COTA etc is another thing your L98 will get dusted. Where i live all road course tracks have didly for long straights. L98 FTW, i love them. They give the next gen of Corvette owners a chance to get in cheap, they are rediculously easy to work on with home depot toolsets. Ive never owned an LT1 or and LT4 but i *really* look fwd to picking one up and learning that platform too. I went straight to LT5 and im in lllooooovvveeee. And....4+3 rock. So do ZF’s. :rock: get to the track baby!!!! its an addiction!! |
Originally Posted by VikingTrad3r
(Post 1605972958)
...an L98 in the powerband is completely fine on track. People say L98’s are awesome street cars because you never get out of second gear and barely into 3rd. A street is like a track with no straight aways longer than the stoplight distance. .... just keep the engine in the powerband....and u can go to a decent straight.
Now COTA etc is another thing your L98 will get dusted. Where i live all road course tracks have didly for long straights. Otherwise, [back then] I gotta think there were plenty of short-runner cars running 300+ HP even if not made in America. Maybe I'm wrong. OH YEAH....C4's were the first car to hit 1G on the skidpad. They could corner much better than all other cars of their era. And, that's one component of being "fast". |
Originally Posted by MatthewMiller
(Post 1605965507)
Yeah, it's not about "torque," it's about power (which damn sure can be directly measured)
In all these cases power is calculated from the "real" "physical" measured quantities in question. |
Originally Posted by yakmastermax
(Post 1605974059)
Just my two cents, and it could be wrong, but I do not think power can be measured directly in a physical sense as far as I am aware. Whether we are talking about electrical power dissipated through a resistor, optical power incident upon a photodetector, or mechanical power either translational or rotational, what is actually measured is either an acceleration of a body over time, a force applied for a distance over time, a torque applied for a rotational displacement over time, a photocurrent converted to a power using a calibration factor, or the product of a voltage drop (measured) and a current (measured).
In all these cases power is calculated from the "real" "physical" measured quantities in question. I don't really want to hijack this thread any further to go into that. |
Originally Posted by MatthewMiller
(Post 1605975021)
We've been through this before, yak. Something like "acceleration of a body over time" is literally the direct measurement of power, since power is Work/Time. Inertial dynos directly measure power exactly like this, and they don't need an RPM input to give you accurate power numbers. The do need an RPM input to give you accurate torque numbers, however. Therefore, they are calculating torque using the input values of power and RPM rather than calculating power with inputs
Some calculated quantities can be directly measured. I am venturing to say that power is not one of those things. This isn't to say power isn't real. It is a very real physical quantity. Just as far as I am aware there are no direct measurements of it, in the technical physicist sense. |
Originally Posted by yakmastermax
(Post 1605979470)
Measuring the acceleration of an inertial body (roller or translational) over time given a previous measurement of its mass and measurement of the friction losses is a direct measurement of acceleration, not power. Power is then calculated from this direct measurement of acceleration using other directly measured quantities like mass.
Some calculated quantities can be directly measured. I am venturing to say that power is not one of those things. This isn't to say power isn't real. It is a very real physical quantity. Just as far as I am aware there are no direct measurements of it, in the technical physicist sense. |
Originally Posted by MatthewMiller
(Post 1605979884)
It doesn't have to measure acceleration. It just has to know the change in kinetic energy over the time interval: Power=(K1-K2)/(T1-T2).
I think at this point, it's just a semantic discussion. I maintain that power is directly observable and measurable. But the main thing is that we both understand power to be a "very real physical quantity." Too many people talk about power as some abstract quality that has no real meaning, and follow on to say that an engine's torque output is what matters, and that's just not the case at all. Power is a critical thing to consider and to "measure". FWIW in the case of power as calculated from a change in kinetic energy over time, presumably in the case of an inertial dyno, the measured quantity of interest is the angular velocity of the roller. |
Wow...I'm almost to my 20th year in this forum. FINALLY someone has figured out the reason TPI's are so fast!
And, here I always thought it came down to the typical argument of HP v TQ! |
I agree! The forum FINALLY reveals the truth! "TPIs" are fast b/c they look cool! :lol:
(This thread was actually about C4's) |
*sigh* Don't forget, the early L98 C4 was even more impressive when TURNING the steering wheel! For those not aware, back in history, they were banned from the SCCA due to their performance whipping all other cars.
http://showyourcorvette.com/history.php |
Thanks for posting that link, Kael. Somehow, the original post -- asking about 0-60 times morphed into what's shown in your link...at least in my mind. That's because talk of TPIs being good cars inevitably results in bashing them because they don't have "horsepower". When someone asks why early TPI C4's were considered "fast", the facts in the SCCA link are what I usually think of. I also think Lingenfelter's Superram played a huge role in early TPI "greatness" -- which is more similar to the "powerband" of an LS intake.
With apologies to Yakmaster, for interuping with my inane scarcasm, the Superram and long-runner intakes are often better for maintaining more power "under the curve" in class events like Auto-x/SCCA. In this forum, mrc24x's racing record is testiment to that. When forum members get to bashing TPIs in favor of the LTx cars, just point them to that SCCA link! If that doesn't work, LSx platform links! LOL All Corvettes are worthy! :thumbs: |
Originally Posted by GREGGPENN
(Post 1605989136)
That's because talk of TPIs being good cars inevitably results in bashing them because they don't have "horsepower".
And your little quotation marks around "horsepower" are exactly what I meant when I replied to yak that too many people believe power is a made-up, abstract concept that doesn't really predict vehicle performance. And that's dead wrong, and he agrees, and he's a physicist. Power is real and, by its very definition, it is predictive of vehicle performance. A torque number is not. When someone asks why early TPI C4's were considered "fast", the facts in the SCCA link are what I usually think of. I also think Lingenfelter's Superram played a huge role in early TPI "greatness" -- which is more similar to the "powerband" of an LS intake. long-runner intakes are often better for maintaining more power "under the curve" in class events like Auto-x/SCCA. All Corvettes are worthy! :thumbs: |
Quoting from linked story:
"The 1988-1989 Corvette Challenge series came about because, in the Sports Car Club of America's (SCCA) Showroom Stock GT category, Corvette had no challengers. From the fourth generation Corvette's introduction in 1984 through the 1987 season Corvette's combination of superior handling, excellent brakes, sticky Goodyear "Gatorback" VR50 tires and the Small Block V8's power and torque ran away and hid from its Showroom Stock competition." Stock, not tweaked. |
Originally Posted by MatthewMiller
(Post 1605989636)
In race trim, they weren't stock and they were making quite a bit more power.
Originally Posted by kael
(Post 1606008889)
Stock, not tweaked.
Now, here is what this guy knows: *They didn't race them with cats and I'd bet that they didn't use muff's either. If you watch YT vids of era races, the cars are loud. So... right off we know...that ain't STOCK. They did not drive them out of a show room, and onto the track. *Conversely, Ain't no stock headed, stock cammed L98 making 350 NET CHP with stock heads/intake/cam. No way, no how, not happening. MY guess is that they used a blueprinted long block (to me, ""blueprinted" could be interpreted to include head porting and cam timing), open exhaust/no cats, ported stock manifolds, custom tune, and some "Free mods" like a real CAI. With that in mind, I could buy a claim of ~280 NET CHP....MAYbe a number approaching 300 if head porting happened. But that's pushing it in my mind and a number above that is either boastful fantasy or GROSS CHP. Documentation showing otherwise, welcome! :yesnod: |
Challenge cars had the original engines swapped out for challenge engines during race preparation, the original engines were tagged and "supposed" to be reinstalled at the end of the season.
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Originally Posted by kael
(Post 1606008889)
Quoting from linked story:
"The 1988-1989 Corvette Challenge series came about because, in the Sports Car Club of America's (SCCA) Showroom Stock GT category, Corvette had no challengers. From the fourth generation Corvette's introduction in 1984 through the 1987 season Corvette's combination of superior handling, excellent brakes, sticky Goodyear "Gatorback" VR50 tires and the Small Block V8's power and torque ran away and hid from its Showroom Stock competition." Stock, not tweaked. ETA: It's important to not let this take away from the excellence of the C4 in its day. It did in fact dominate SS while it was still allowed, beating out sports cars from other countries that cost quite a bit more. None of those cars are quick or fast by today's standards, either. In 1990, the SCCA started the Escort World Challenge. The Corvette mostly squared off against the Lotus Esprit Turbo, which inexplicably was suddenly faster on straights despite not being faster in stock form. But when you have a turbo, you can chea...err...optimize things. And the SCCA kept adding ballast to the C4 to give the Lotus a chance. The Corvette still won most of the races. It was just a great road course in every way, and was fast in its day. We should keep in mind that the Ferrari supercar of that time, the Testarossa, still only had 385hp and ran the quarter in 13.5 at 107mph...or about as fast as a new V6 Camaro today. |
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