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Quote:
long-runner intakes are often better for maintaining more power "under the curve" in class events like Auto-x/SCCA. That's simply not true.
Prolly should have said HP limited class events. Back in 2010-2011, I flip-flopped about the use of a hogged out SLP, long-runner intake and an HSR. I sold my HSR to mrc24x who was consistently winning his class in auto-x because the torque (area under the curve) for his TPIS, 350, hot-cammed entry was always faster. He installed the HSR and won a couple of events too. One season later, I bought the HSR back because I thought he wanted to go back to the TPIS intake. If was one reason I ended up STARTING with my modified SLP setup versus starting with the HSR. He was faster until 80mph using the TPIS config. (You know, street car range).
Believe it or not, I still have that HSR 12 years later. Because it was only run in a few events, it still looks close to new.
FWIW, I see multiple websites showing LT1's running 0-60 @ 5.7 seconds....the same as the 1985 TPI (when you "google" it). I also see various other figures including sub 5 sec times with the ZF6 LT1. Probably due to trans gearing. Maybe even diff gearing too? Hell, one website showed a 94 at 5.7 for 0-30, and 13.1 seconds for 0-60 but....wait for it....0-100 at 14 flat. That means the 94 is really, really fast from 60-100mph! You know...less than 1 second! LOL
Quote:
long-runner intakes are often better for maintaining more power "under the curve" in class events like Auto-x/SCCA. That's simply not true.
Prolly should have said HP limited class events.
Still not true. Short-runner intakes like the LT1 make power at higher RPM than the resonantly-choked TPI, but they also have broader and flatter torque curve than the TPI. This is what builds "power under the curve."
I sold my HSR to mrc24x who was consistently winning his class in auto-x because the torque (area under the curve) for his TPIS, 350, hot-cammed entry was always faster.
"Torque" and "area under the curve" are not the same thing. At all. And if you meant "area of torque under the curve," that's not relevant because torque isn't what determines how fast a car accelerates. Power under the curve is what matter.
He was faster until 80mph using the TPIS config. (You know, street car range).
Vehicle speed isn't relevant to any of this unless you car is geared so tall that it's in 1st gear considerably past 80mph (which it's not). By the time you have run through the gears once, the car making the most average power (power under the curve) during the run will be ahead if all else is equal. I'd suggest that there were significant flaws in your test, most probably related to tuning and the fact that there were other differences between your cars than just the intakes. The acceleration numbers for an LT1 C4 are better in every speed interval than those for the L98. That's all you need to know. The idea that torque matters more than power at low vehicle speeds is wrong: it's a conflation of some other principles.
FWIW, I see multiple websites showing LT1's running 0-60 @ 5.7 seconds....the same as the 1985 TPI (when you "google" it). I also see various other figures including sub 5 sec times with the ZF6 LT1. Probably due to trans gearing. Maybe even diff gearing too? Hell, one website showed a 94 at 5.7 for 0-30, and 13.1 seconds for 0-60 but....wait for it....0-100 at 14 flat. That means the 94 is really, really fast from 60-100mph! You know...less than 1 second! LOL
The 0-60 times are largely determined by traction and gearing. To accurately compare intakes, you'd need to have two cars with the same kind of transmission and equal gearing.
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To me, the point of this thread is: How can a 250hp car be "fast". I don't think you (MM) addressed that. You continue to talk in terms of maximum HP as if you were explaining race theory. Fine. Most members (over the years), could talk about and quantify "power under the curve" and we'd all know that that meant -- and be on the same page. Reading your replies would make it impossible to explain how a 4-cylinder making 250hp probably isn't going to be anywhere near as fast as a TPI making 250hp....especially if the 4-cylinder has to rev 1000rpms higher to get to that power level. I'm not going to belabor the point. You want to derail discussion over semantics.
You say the LT1 accelerates faster at every speed interval than the L98. I disagree. I believe acceleration is fastest when the torque CLIMBS fastest. That's 'what acceration is. It means for that second, microsecond, whatever, it's gaining speed/momentum faster than the second before. Look at the dyno simulation below. One is a TPI-like curve, one is an FFI curve (also a TPI), and the last is an HSR. I used MS Paint to indicate where acceration is fastest. The "upside of the L98 TPI bubble" is also steeper. Yeah, the overall avg HP of an LT1 is better -- assuming you look at the entire useable range (0-redline). In an L98, the redline is lower. Without looking, I'd guess the rpm where it reaches 250hp also occurs at a lower rpm. When you're road-racing or doing auto-x, you might not go all the way through gears. The fact mrx24x was winning in his HP class was torque. You can call it horsepower or power under the curve. When he swapped to an HSR, he had to compete in a class that was 75hp higher....or 100...or something higher. At the end of each gear, sure he was faster running an HSR -- but that doesn't explain the merits of a TPI...or why it "worked" for a street car in it's time.
THE POINT OF THIS THREAD ISN'T TO DISCUSS LT1 VS L98. I THOUGHT IT WAS TO HELP EXPLAIN WHY IT (AS A 250HP CAR) WAS A LOT BETTER THAN MOST (IF NOT ALL) OTHER 250 HP CARS BEFORE IT.
Again...maximum acceleration is indicated by the orange broken line...... And, it doesn't occur with the short-runner intake OR at the highest RPM.
Note: if a reader hasn't seen a dyno before, the top 3 lines are measured torque. The bottom 3 lines are calculated HP using torque and RPM. Each one of the HP lines corresponds to one of the Torque lines.
The C4 was absolutely bad ***, 250 horsepower and 340ft lbs of torque was a BIG DEAL. The car was state of the art for its time even the tires were a big deal.We now have idiots writing articles the 1984 Corvette was the worst Corvette ever comparing it to cars that didn’t exist when it was built. Go back and read the press from 1984 about that same car…… IF numbers were all that mattered NOBODY would drive a 1953-1962 and I wouldn’t have sold my C8 and bought another C4 instead.
The roadholding on this new machine is so advanced that we recorded the highest skidpad lateral acceleration—0.90 g—ever observed with a conventional automobile by this staff. That figure practically trivializes the previous high-water marks, in the 0.82-g range, generated by such exotics as the Porsche 928and assorted Ferraris.
Item: It is hands-down the fastest American automobile, capable of 140-mph top speeds, 0-to-60 times under seven seconds, and 15.2-second quarter-mile forays at 90 mph. In fact, these figures qualify the Corvette as one of the half-dozen fastest production automobiles in the entire world!
Last edited by JD'S WHITE 93; 12-17-2022 at 06:31 AM.
To me, the point of this thread is: How can a 250hp car be "fast". I don't think you (MM) addressed that.
Then you didn't read my posts here. I absolutely addressed it: an L98 C4 is exactly as fast as one would expect a ~3200lb car with with its weight distribution and drive train layout to be.
You continue to talk in terms of maximum HP as if you were explaining race theory.
Nope. Again, you're either not reading my posts carefully or you're misconstruing them. I have been talking about "average power" and/or "power under the curve" (pretty much synonymous).
Most members (over the years), could talk about and quantify "power under the curve" and we'd all know that that meant -- and be on the same page.
Ironically, your own posts show that this is not true at all. Almost nobody seems to understand the concept of power, much less "power under the curve" or "average power" over an interval, and people like you are making this worse! There is a lot of mythology around "torque" and the TPI system wherein many people believe that some horsepower is better or more effective than other horsepower. That's just wrong. The simplest way to put this is: if two cars are otherwise equal (mass, traction, etc.), the car that puts the most average power down over a time or speed interval will accelerate faster. This is by definition of the term "power." Notice there's no mention of torque in there. There's no voodoo. The tractive force that accelerates a vehicle is purely determined by two factors: the vehicle's speed on the road and the power reaching the road. It's just that simple.
Reading your replies would make it impossible to explain how a 4-cylinder making 250hp probably isn't going to be anywhere near as fast as a TPI making 250hp....especially if the 4-cylinder has to rev 1000rpms higher to get to that power level.
It would be impossible to explain that indeed, because it isn't true! A 4-cylinder making an average of 250hp over a time or speed interval would push a car just as fast as the same car with a V8 making the same average power. If you want a real-world example, a 2020 Civic Type R weighs in at over 3100lbs and is rated at 306hp with "only" 295lb/ft of torque. It runs the quarter mile in 13.4 at 108mph, which compares favorably to an LT1 C4 with the same power rating. The C4 may weigh slightly more (stripped-down base models weighed closer to 3200lb than the common 3300lb often stated) but it also has a big advantage in standing-start traction because it's RWD. Again, power is power and the car doesn't care how many cylinders the engine has or what RPM it's turning. It just cares how much power is reaching the ground at any given moment.
I'm not going to belabor the point. You want to derail discussion over semantics.
This isn't semantics. You're just plain wrong. As I wrote before, power isn't some abstract theory and it sure as hell isn't just semantics. It's a very real unit that predicts how fast an engine can do work.
I believe acceleration is fastest when the torque CLIMBS fastest.
Yikes! You don't have any idea how any of this works! Not only is this wrong, it might be the wrongest thing I've ever seen posted about power and torque...which is quite a feat! You're just inventing **** at this point. Acceleration is fastest when the most power is put to the ground. Period. I mean...holy ****, Gregg!
THE POINT OF THIS THREAD ISN'T TO DISCUSS LT1 VS L98. I THOUGHT IT WAS TO HELP EXPLAIN WHY IT (AS A 250HP CAR) WAS A LOT BETTER THAN MOST (IF NOT ALL) OTHER 250 HP CARS BEFORE IT.
The point was to explain why/if the L98 C4 was "quicker" than other cars, not "better." What other 250hp were there at the time? Not many. In 1985, when the L98 came out, the 928S got a bump in power to 288hp. It weighed 3450lb (considerably more than the C4) and still went significantly faster: 14.9 at 102mph. Not much else out there compared to these two cars. The C4 was unquestionably the faster car around a road course or autocross course, for a lot reason not having to do with power/torque. Again, the L98 C4 was exactly as fast as its mass, traction, and power would predict.
Again...maximum acceleration is indicated by the orange broken line......
Again, no it isn't. You don't know what you're talking about. It's time for you to stop miseducating other people on this and start learning actual physics.
Originally Posted by ME93
so what does a lt1 a4 2.59 run in the qtr ?
It's relatively slow because it doesn't put down as much average power through the 1/4-mile as an LT1 with steeper gears. I don't know why anyone would really care about this, though: if you care about how fast your C4 is in a straight line, then you don't have one with 2.59 gears!
Originally Posted by JD'S WHITE 93
The C4 was absolutely bad ***, 250 horsepower and 340ft lbs of torque was a BIG DEAL. The car was state of the art for its time even the tires were a big deal. We now have idiots writing articles the 1984 Corvette was the worst Corvette ever comparing it to cars that didn’t exist when it was built.
All of this is true, and nobody here (including me) has said otherwise. Please try to separate what I've actually written from the things other people have written that have hurt your feelings.
Last edited by MatthewMiller; 12-17-2022 at 09:55 AM.
Then you didn't read my posts here. I absolutely addressed it: an L98 C4 is exactly as fast as one would expect a ~3200lb car with with its weight distribution and drive train layout to be.
Nope. Again, you're either not reading my posts carefully or you're misconstruing them. I have been talking about "average power" and/or "power under the curve" (pretty much synonymous).
Ironically, your own posts show that this is not true at all. Almost nobody seems to understand the concept of power, much less "power under the curve" or "average power" over an interval, and people like you are making this worse! There is a lot of mythology around "torque" and the TPI system wherein many people believe that some horsepower is better or more effective than other horsepower. That's just wrong. The simplest way to put this is: if two cars are otherwise equal (mass, traction, etc.), the car that puts the most average power down over a time or speed interval will accelerate faster. This is by definition of the term "power." Notice there's no mention of torque in there. There's no voodoo. The tractive force that accelerates a vehicle is purely determined by two factors: the vehicle's speed on the road and the power reaching the road. It's just that simple.
It would be impossible to explain that indeed, because it isn't true! A 4-cylinder making an average of 250hp over a time or speed interval would push a car just as fast as the same car with a V8 making the same average power. If you want a real-world example, a 2020 Civic Type R weighs in at over 3100lbs and is rated at 306hp with "only" 295lb/ft of torque. It runs the quarter mile in 13.4 at 108mph, which compares favorably to an LT1 C4 with the same power rating. The C4 may weigh slightly more (stripped-down base models weighed closer to 3200lb than the common 3300lb often stated) but it also has a big advantage in standing-start traction because it's RWD. Again, power is power and the car doesn't care how many cylinders the engine has or what RPM it's turning. It just cares how much power is reaching the ground at any given moment.
This isn't semantics. You're just plain wrong. As I wrote before, power isn't some abstract theory and it sure as hell isn't just semantics. It's a very real unit that predicts how fast an engine can do work.
Yikes! You don't have any idea how any of this works! Not only is this wrong, it might be the wrongest thing I've ever seen posted about power and torque...which is quite a feat! You're just inventing **** at this point. Acceleration is fastest when the most power is put to the ground. Period. I mean...holy ****, Gregg!
The point was to explain why/if the L98 C4 was "quicker" than other cars, not "better." What other 250hp were there at the time? Not many. In 1985, when the L98 came out, the 928S got a bump in power to 288hp. It weighed 3450lb (considerably more than the C4) and still went significantly faster: 14.9 at 102mph. Not much else out there compared to these two cars. The C4 was unquestionably the faster car around a road course or autocross course, for a lot reason not having to do with power/torque. Again, the L98 C4 was exactly as fast as its mass, traction, and power would predict.
Again, no it isn't. You don't know what you're talking about. It's time for you to stop miseducating other people on this and start learning actual physics.
It's relatively slow because it doesn't put down as much average power through the 1/4-mile as an LT1 with steeper gears. I don't know why anyone would really care about this, though: if you care about how fast your C4 is in a straight line, then you don't have one with 2.59 gears!
All of this is true, and nobody here (including me) has said otherwise. Please try to separate what I've actually written from the things other people have written that have hurt your feelings.
YOU just typed a 400 word response, you’re swearing at Gregg, talking down to other members and now you’re talking about MY feelings being hurt lol 😂
YOU just typed a 400 word response, you’re swearing at Gregg, talking down to other members and now you’re taking about my feelings being hurt lol 😂
All I wrote to you was not to confuse what other people write outside of this forum with what I've written on it. I'm not talking down to anybody (again, you're misconstruing what I've actually written), just trying to get correct information out there. It's a fact that Gregg doesn't understand this stuff. That's neither an insult nor my fault.
PS - the "400 words" is a result of trying to explain to people how this stuff actually works and how Gregg's ideas about it are incorrect. You most definitely don't have to read them if you find that amount to be excessive!
Last edited by MatthewMiller; 12-17-2022 at 11:58 AM.
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Originally Posted by MatthewMiller
Acceleration is fastest when the most power is put to the ground. Period. I mean...holy ****, Gregg!
WRONG! This is where your knowledge needs review.. As a car moves faster and faster, it's putting out more and more power. (Think one gear...say 4th). As you get to the top of the engine's power, the curve flattens. Acceleration slows. It'll be putting out lots and lots of power but losing ability to accelerate faster. Acceleration is not the same as velocity or power.
ACCELERATION (def): the rate of change of velocity per unit of time
In calculus, accleration is the first derivative of velocity. One tells you how fast an object is traveling, The other tells you how it's speed is changing in that moment in time.
My statement in the prior post is accurate, acceleration is fastest when the slope of it's acceleration is steepest. Don't confuse velocity with acceleration.
Avg power is a different point -- though valid. Avg power can determine velocity at the end of a point in time. Without respect to all other variables, an engine more avg power will be faster, yes. (You have that part right). Up to around 4500-5k rpms, the L98 TPI has more avg power than the LT1. It takes the 4.5k-6k rpm internal for the LT1 to equal and surpass that. So, the amount of average power of an LT1 (which isn't the point of this thread -- but what you want to talk about), is MUCH greater from 4.5k to 6k rpm. At that point, the total avg power shifts in favor of the LT1.
When talking about a 250hp 4 cylinder vs a 250hp V8 Corvette, they will not be equally fast. A V8 that can generate 250hp in 4500 rpms will get to that maximum PEAK hp faster. It can accelerate faster than the 250hp 4 cylinder. THAT is what acceleration is.
TI THOUGHT IT WAS TO HELP EXPLAIN WHY IT (AS A 250HP CAR) WAS A LOT BETTER THAN MOST (IF NOT ALL) OTHER 250 HP CARS BEFORE IT.
It's not b/c of TPI, that's for sure.
The biggest meaningful diff between the 240hp C4 and the last 240hp car that came before it, is TIRES. But any 240 horse, ~3200 lb car will go ~mid to lowish 14's in the mid to upper 90's.....just like a TPI C4.
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Continuation of my prior post:
Notice how horsepower keeps rising after torque peak? It's not because the car is accelerating faster. The RATE of acceleration is actually slowing. That's why the horsepower curve FLATTENS as it gets higher and higher. (Eventually, it falls). The amount of power is still increasing beyond peak torque because it is being applied more frequently. (The instances of "BANG" are happening more frequently). The RATE of "BANGS" are happening more often than the "STRENGTH" of the "BANGS". That's power. It's not acceleration.
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Originally Posted by Tom400CFI
It's not b/c of TPI, that's for sure.
The biggest meaningful diff between the 240hp C4 and the last 240hp car that came before it, is TIRES. But any 240 horse, ~3200 lb car will go ~mid to lowish 14's in the mid to upper 90's.....just like a TPI C4.
OK...So put the same tires on a 250hp 4-cyl rice banger and it'll keep up with a C4 TPI. Got it!
As a car moves faster and faster, it's putting out more and more power. (Think one gear...say 4th).
Maybe it is putting out more power as it moves faster, maybe it isn't. I don't know why we would think about keeping a car in a single gear: that's never how we actually use a car, especially in a straight-line attempt to accelerate as fast as possible.
As you get to the top of the engine's power, the curve flattens. Acceleration slows.
Oh, so you actually don't believe that as the moves faster and faster, it necessarily puts out more power (as you stated above)? That's good, because it's not true.
Acceleration is not the same as velocity or power.
I never said it was the same as those things, obviously. I said acceleration is the result of power applied to a mass. You're the one who confused things when you tried to equate acceleration to the slope of the torque curve, which is some really high-level silliness. To wit:
My statement in the prior post is accurate, acceleration is fastest when the slope of it's acceleration is steepest.
That's not what you wrote before. You wrote: "I believe acceleration is fastest when the torque CLIMBS fastest. That's 'what acceration[sic] is." Then you proceeded to show us dotted lines on the slopes of both power and torque curves and claim that they represented the point of highest acceleration in the vehicle. That's just wrong. All of it.
Don't confuse velocity with acceleration.
Why would anybody confuse those things?! I said nothing of the sort. I'm well aware of derivatives and integrations and the difference between acceleration and velocity. The only thing I said regarding velocity is that it's one of the two factors that affects the tractive force that accelerations a wheel-driven vehicle. Power is the other factor.
Avg power can determine velocity at the end of a point in time.
Yes, and neither acceleration nor power can occur without an interval of time...by definition.
Without respect to all other variables, an engine more avg power will be faster, yes. (You have that part right).
Good! If you'll just stop there and quit all the nonsense about torque slopes and other goobledeegock, then we can stop.
Up to around 4500-5k rpms, the L98 TPI has more avg power than the LT1. It takes the 4.5k-6k rpm internal for the LT1 to equal and surpass that.
That's not accurate. We've been over this before. For review, here are GM's own internal documents that Tom400CFI posted in the past:
The L98 has more power than the LT1 for about a 1000rpm band around 3000rpm, where it gets a bump from the resonant "supercharging" effect of the long intake runners. Below that the two engines are equal, but that really doesn't matter because we don't see that RPM in an acceleration run anyway. But from 3500rpm onward, the 92 LT1 has more power and that advantage keeps building in big fashion because the L98 peaks at about 4200rpm.
So the power advantage of the LT1 starts at 3500rpm and builds from there. In any kind of acceleration run, you'll never be below 3500rpm anyway. Since the LT1 peaks at 5200rpm on this graph, you'd probably want to shift around 5500rpm. We'd have to look at the gearing, but I bet you'd never get below 4000rpm...which is why the LT1 car walks away from the L98 car.
When talking about a 250hp 4 cylinder vs a 250hp V8 Corvette, they will not be equally fast. A V8 that can generate 250hp in 4500 rpms will get to that maximum PEAK hp faster. It can accelerate faster than the 250hp 4 cylinder. THAT is what acceleration is.
I wasn't talking about peak power. I said a 4-cylinder engine that puts out the same average power over an interval as a V8 will accelerate the car just as fast if all else is equal. I even gave you a real-world example of a similar-weight 4-cylinder car that has very similar power to an LT1 C4 and is actually even faster! I don't know how you think you can know that the 8-cylinder car will reach it's peak-power RPM faster than the 4-cylinder. That doesn't follow at all.
Notice how horsepower keeps rising after torque peak? It's not because the car is accelerating faster. The RATE of acceleration is actually slowing. That's why the horsepower curve FLATTENS as it gets higher and higher. (Eventually, it falls). The amount of power is still increasing beyond peak torque because it is being applied more frequently. (The instances of "BANG" are happening more frequently). The RATE of "BANGS" are happening more often than the "STRENGTH" of the "BANGS". That's power. It's not acceleration.
Wanna bet? You're making the common mistake of assuming the car only has a single-speed transmission. But all modern cars have multi-speed or even continuously variable transmission precisely so they can maximize average power over an interval of acceleration. If you drive a car and shift around the torque peak for a quarter-mile run and then take the same car for another run but shift around the power peak, which run will be faster? The run where you shift around the power peak will be faster because you are maximizing the average power during the run, and power is what determines acceleration.
And BTW, we don't have to guess at this. The C4 gave us the data because although the L98 and Lt1 have the same peak torque, the LT1 has more power and handily out-accelerates the L98 C4.
OK...So put the same tires on a 250hp 4-cyl rice banger and it'll keep up with a C4 TPI. Got it!
I don't know what "rice banger" is, but I already showed you an example of a 300hp rice burner that more than keeps up with a 300hp C4.
Last edited by MatthewMiller; 12-17-2022 at 05:37 PM.
This is brutal. Greg, you're making stuff up in your head, to support your own bias.
Originally Posted by GREGGPENN
WRONG! This is where your knowledge needs review.. As a car moves faster and faster, it's putting out more and more power. .....
Avg power is a different point -- though valid. Avg power can determine velocity at the end of a point in time. Without respect to all other variables, an engine more avg power will be faster, yes. (You have that part right). Up to around 4500-5k rpms, the L98 TPI has more avg power than the LT1. It takes the 4.5k-6k rpm internal for the LT1 to equal and surpass that. So, the amount of average power of an LT1 (which isn't the point of this thread -- but what you want to talk about), is MUCH greater from 4.5k to 6k rpm. At that point, the total avg power shifts in favor of the LT1.
When talking about a 250hp 4 cylinder vs a 250hp V8 Corvette, they will not be equally fast. A V8 that can generate 250hp in 4500 rpms will get to that maximum PEAK hp faster. It can accelerate faster than the 250hp 4 cylinder. THAT is what acceleration is.
1. I thought you were extolling tq?
2. Show us an acceleration metric where the supiriority of the TPI 0-4500 RPM TOWAK, produces faster acceleration? Find a legitimate, apples to apples pair of cars, compare 'em. What is an acceleration metric for 0-4500 RPM? I'd say that's about the 60' mark at the drag track. What do stock TPI 60'? When well driven? About 2.0. What do well driven LT1 cars 60'? ABOUT 2.0. So where's the "more ave power"???
3. No. I mean.....waht are we assuming here? A high revving, small displacement 4cyl? A turbo 4? A 5.7L 4 cylinder? Doesn't matter, really, it depends on gearing, car weight, rotating engine mass..... Optimized for each combo, they'll both get to their power peaks at about the same time.
But from 3500rpm onward, the 92 LT1 has more power and that advantage keeps building in big fashion because the L98 peaks at about 4200rpm.
So the power advantage of the LT1 starts at 3500rpm and builds from there. In any kind of acceleration run, you'll never be below 3500rpm anyway. .
^This. When going for a basement number, I launch my car at 4000 RPM, slip the clutch and let it hook at the point where the clutch drags the engine down to about 3500 RPM...and I'm off, with a 1.9x 60' time.
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Originally Posted by Tom400CFI
This is brutal. Greg, you're making stuff up in your head, to support your own bias.
1. I thought you were extolling tq?
2. Show us an acceleration metric where the supiriority of the TPI 0-4500 RPM TOWAK, produces faster acceleration? Find a legitimate, apples to apples pair of cars, compare 'em. What is an acceleration metric for 0-4500 RPM? I'd say that's about the 60' mark at the drag track. What do stock TPI 60'? When well driven? About 2.0. What do well driven LT1 cars 60'? ABOUT 2.0. So where's the "more ave power"???
3. No. I mean.....waht are we assuming here? A high revving, small displacement 4cyl? A turbo 4? A 5.7L 4 cylinder? Doesn't matter, really, it depends on gearing, car weight, rotating engine mass..... Optimized for each combo, they'll both get to their power peaks at about the same time.
1) Not even close.
2) Again, the point where torque climbs fastest IS fastest point of acceleration -- regardless of gear, intake, or whatever.
3) You really think a 250hp 4-banger that needs 5500 rpms to reach that peak will keep up with a 250 V8 that does it by 4500? Interesting. LOL
Both you guys. Since you're set on extolling the LT1 vs answer why a L98 was good for it's day, that's fine. Bye. I think it's ironic you brought Physics into the discussion but don't really know to measure acceleration. You think it's what happens when you push the gas pedal. Fine. You'll live great lives with that understanding.
And, yeah, I also understand you're trying to negate any advantage of an L98 by saying "Just rev it above 4k rpms and start from there. Yup...drag racing. Got it. I didn't see ONE SENTENCE explaining why a L98 isn't any faster than any other 250hp car. None.
1) Not even close [that you were extolling torque as the determinant of vehicle performance].
But then:
2) Again, the point where torque climbs fastest IS fastest point of acceleration -- regardless of gear, intake, or whatever.
So you really DO think torque - or specifically the rate of change of torque - determines acceleration? So #1 wasn't just close, but dead on. So you don't even know what you're saying! I have to give you credit, though: in the many, many years I've had discussions with different people about power, torque, and vehicle performance, you are the very first ever to say that acceleration is determined by the slope of the torque curve. You are incredibly wrong, but you are creative an unique!
So let me ask you two questions:
The definition of power is "The rate at which work gets done," with work being defined for vehicle performance as a movement or acceleration over some distance. So more power is exerted if the distance is longer, the time to complete the work is shorter, or the mass is greater. This is Physics 101, so I'm not creating this out of thin air. Since you say that acceleration is determined by the rate of change of torque (force) rather than power and velocity, are you saying that every physics book in the world has it wrong?
William Hay calculated that tractive force (effort) available at the drive wheel's contact patches to accelerate a vehicle is (HP*375)/MPH. All locomotive calculations for performance vs load (especially when having to traverse inclines) are based on this formula. Is this wrong? Is the entire rail industry doing it wrong?
3) You really think a 250hp 4-banger that needs 5500 rpms to reach that peak will keep up with a 250 V8 that does it by 4500? Interesting. LOL
Okay, I already gave you one example that came easily to mind at 300hp. Here's another that's more in the L98 zone: a 2023 VW Golf GTI weights 3154lb and has 241hp with it's four-cylinder engine; and it completes the quarter-mile in 13.6 at 105mph, which is considerably faster than any stock L98 Corvette ever did. Now are you satisfied?
Both you guys. Since you're set on extolling the LT1 vs answer why a L98 was good for it's day
Again, I already answered why the L98 C4 was great in its day and why it is not magically fast but rather is exactly as fast as physics predicts.
Bye.
Bye, Felicia.
I think it's ironic you brought Physics into the discussion but don't really know to measure acceleration. You think it's what happens when you push the gas pedal.
Are you high right now? Really. You honestly think Tom and I don't know how to measure acceleration? It's rate of change of vehicle velocity over some time or distance interval. That's pretty damn simple. And I won't speak for Tom, but if you car doesn't accelerate when you press the accelerator pedal down (assuming it's in gear), then something's wrong with your car. I mean, it's not called the "accelerator" for nothing. This might explain a lot! LOL
I didn't see ONE SENTENCE explaining why a L98 isn't any faster than any other 250hp car. None.
Well, then you aren't reading what I'm posting.
When people say 250hp car, they mean peak.
See above example of the current VW GTI with 241 peak hp.
1) Not even close.
2) Again, the point where torque climbs fastest IS fastest point of acceleration -- regardless of gear, intake, or whatever.
3) You really think a 250hp 4-banger that needs 5500 rpms to reach that peak will keep up with a 250 V8 that does it by 4500? Interesting. LOL
Both you guys. Since you're set on extolling the LT1 vs answer why a L98 was good for it's day, that's fine. Bye. I think it's ironic you brought Physics into the discussion but don't really know to measure acceleration. You think it's what happens when you push the gas pedal. Fine. You'll live great lives with that understanding.
And, yeah, I also understand you're trying to negate any advantage of an L98 by saying "Just rev it above 4k rpms and start from there. Yup...drag racing. Got it. I didn't see ONE SENTENCE explaining why a L98 isn't any faster than any other 250hp car. None.
When people say 250hp car, they mean peak.
Thats their point. Peak HP doesnt actually mean anything in terms of how fast a vehicle is.
If one car makes 250 hp from 4000-5000 rpm and 150 horsepower from 1000-4000, its going to be slower than a vehicle making 250 hp from 2000-5000 rpm. Peak HP is only a generality of how fast a car is going to be, especially when considering wildly different engine designs.
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Originally Posted by jdjenk
Thats their point. Peak HP doesnt actually mean anything in terms of how fast a vehicle is.
If one car makes 250 hp from 4000-5000 rpm and 150 horsepower from 1000-4000, its going to be slower than a vehicle making 250 hp from 2000-5000 rpm. Peak HP is only a generality of how fast a car is going to be, especially when considering wildly different engine designs.
Ugghhhh...That was MY point. ESPECIALLY the first sentence. I said that a few posts ago. and you obviously understand the point. They interpreted by comparison of 250hp engines to mean avg. I meant peak. EVERYONE assumes peak when you reference how much power an engine makes. Unless you specific avg values, of course. THEY are saying any two 250hp engines will be equally fast. That's what I read.
The problem is no one is explaining how a 250 hp TPI wasn't so bad....especially in the late 1980s. Instead I'm pretty sure I was attacked at chastized for suggesting Torque SHOULDN'T BE EXCLUDED from the explanation. It doesn't allow explanation of torque existing at lower rpms translates to lower advertized HP. Differences in torque are how two 250hp PEAK engines can have difference avg HP and different results. Obviously, differences in where the torque occurs makes a difference too.
Too many think Torque is a four-letter word. Let me try.....TORQ! Yup. You're right.
Peace out...
Ugghhhh...That was MY point. ESPECIALLY the first sentence. I said that a few posts ago. and you obviously understand the point. They interpreted by comparison of 250hp engines to mean avg. I meant peak. EVERYONE assumes peak when you reference how much power an engine makes. Unless you specific avg values, of course. THEY are saying any two 250hp engines will be equally fast. That's what I read.
The problem is no one is explaining how a 250 hp TPI wasn't so bad....especially in the late 1980s. Instead I'm pretty sure I was attacked at chastized for suggesting Torque SHOULDN'T BE EXCLUDED from the explanation. It doesn't allow explanation of torque existing at lower rpms translates to lower advertized HP. Differences in torque are how two 250hp PEAK engines can have difference avg HP and different results. Obviously, differences in where the torque occurs makes a difference too.
Too many think Torque is a four-letter word. Let me try.....TORQ! Yup. You're right.
Peace out...
Thats because torque isnt a measurement of work. You can get whatever torque number you want with steep enough gearing.
12-14-2022, 01:10 AM
Fine. You'll live great lives with that understanding.
