Guys:

I know they changed the way they rate HP, and I know they de-tuned some C3's for emissions...........


But help me understand. If a Vette weighing about 3400 has
a Torque of 270 ft. lbs. To me that sounds pretty powerful, and should be pretty tough in the low end, right?

0 to 70 is all i care about anyway.

 

You typically judge performance by weight to gross horsepower ratio, not torque. Anything 10:1 or lower used to be considered fast. So 3400/300 is 11:1 while 3400/370 is 9:1 which is fast. So a guess at net numbers would be 3400/250 is 14:1 and 3400/330 is 10:1.

 

yeah but if you have a meaty BB and 4:11 gears, all is for naught -
waste of torque because of gear ratio.
All these things work in sync. Sometimes.

 

I like the hp to weight ratios too. I have a jeep that is 12.7 to 1, pretty fast. I have a truck that is 15.3 to 1, pretty fast.

10 to 1 and 9 to 1 is too much for me.

But I think some of the C3's are nearly 20 to 1......... ( not good)

BUT with plenty of torque, I think they might be OK 0 to 60.

I think torque is more important ..........

But I could be wrong..........

 

Torque is important on really heavy cars and trucks it is what pulls them off the line and keeps them moving Think of a high torque engine as strong but slow. Horsepower on the other hand requires torque to get it moving up into the higher RPMs then once you reach the high RPMs is keeps on accelerating until redline.

High HP low torque and low weight cars are sprinters than very quick but the more weight you add to them the slower they are until they are up in their "Power Band" Peak Horsepower.

Horsepower Likes RPMs where as Torque just plants you into the seat until it peaks then when it peaks on a heavy car is when you want to switch gears to continue to be planted into the seat.

For heavy cars like the Corvette like the 4000 Pound 1977 I own it moves off the line just fine with 180 HP at around 4500 RPMs and around 200 Ft pounds of Torque at around 3500 RPMs. It performs best when I allow the Turbo 350 Tranny to switch gears at around 4000 RPMs anything after 4000 RPMs it flatens out on power and I might be able to get a little more out of at 4500 RPMs but not much.

It moves up to 70 Miles per fairly quick but not as quick as my little 3200 Pound Mazda 3 with a 170 HP engine and 5 Speed manual tranny because I have more control over the RPMs and when it switches gears it can smoke my Corvette if I keep the RPMs up between switching gears at around 5000 RPMs and turn off the Traction Controls. My Vette will take the Mazda 3 off the line but the 3 will pass it because it is lighter and almost the same HP it redlines at 7000 RPMS and the RPMs result in faster speeds between gears as long as I am in peak Horsepower.

I cannot get the Vette to smoke the tires but my little Mazda 3 I can smoke them into Second gear and even with traction control on I can get a chirp into 2nd Gear when I drop the clutch than the traction control senses the tires spinning and kicks in.

Moral of the story there is no replacement for displacement the bigger the engine the more low end power it will have.

 

I saw the best explanation on an different forum:

Horsepower is how fast you hit the wall.
Torque is how far you take the wall with you.

 

An open differential twisting the front wheels explains why it's easy to spin the tires on your Mazda 3. My wife's Mazda 3 chirps the tire much easier than my somewhere over 300hp 78 does.

 

This is very true I do not have a Posi Trac on my little 2008 Mazda 3 but it does have a traction control system to keep me from spinning the tires. Helps a lot in the snow I can smoke 4 wheel drive trucks driving in the snow with this car off the line and driving on ice filled roads with studded snow tires.

Do you just not love the off the line power of your V8 much better then the little rice burner?

I know I do it my 4000 Pound Vette plants me into the seat nothing like my other 2 cars which are rice burning 4 Cylinders from Japan. I do not feel the power but my little Mazda 3 will walk away from my Vette when I keep the RPMs in the power band.

But at top end my little rice burner takes the Vette once I get above 40 MPH because I wind up that little rice burning engine and get into the power band and keep the RPMs running. RPMs equal speed where as Torque equals power Where Raw power will just plant you in the seat then keep you there.

 

Torque and horsepower are very missunderstood even by some of the magazine writers. I've seen so much misinformation out there it drives me crazy. Being performance has been my career for almost all of my 60 years here on earth, I want to set this straight.

Torque and horsepower go hand in hand. You can't have horsepower without torque. Torque is a static rotational force. Test this by clamping the socket end of a torque wrench in a vise and pull it up to 100 lb/ft of torque. How fast is the vise going? It's not moving is it? Now if you could get it to rotate to 5252 RPM and maintain the 100 lb/ft of torque, you would have 100 horsepower. The formula for horsepower is torque X RPM/5252. This is why torque and horsepower are always equal at 5252 and the lines cross there on graphs.

The simple deffinition of horsepower is the work being done. Moving a vehical is the work being done. So to move the vehical from a stop to any speed and any acceleration rate you need horsepower just as you need it to reach top speed.

Now here is how torque should be discussed. Where in the RPM do you want your peak torque and where in the RPM range do you want your torque to come in. More torque at any RPM point means more horsepower to move your vehical. Idealy you want to make good torque at a low RPM and maintain it through a wide rpm range for the street. What people should say instead of "I want torque!" is "I want strong bottom end power", as this is what people really mean.

Now the discussion about which is quicker on the street, an engine with strong bottom end torque or high RPM torque and horsepower. This is just as missunderstood.

 

I agree it is has been disputed for years. They build race cars for horsepower and RPMS than torque comes in second. Raw power comes from Torque which is why Diesel Engines Rule in heavy weight Trucks.

How do us as Vette owners run around well we do it with the Model year Corvettes we chose to purchase. While we can increase HP and Torque with a few simple modifications or just enjoy the cars we drive from the factory. Do we modify them and lose value and make them street rods or just stay in Nostalgia of the model year.

I am a Nostalgia type of guy and if I choose to modify my Corvette it will be a sleeper under the hood and look stock since I purchased a 1977 with only 43,260 miles on when I took ownership. When I get done fixing the suspension age problems it will get a mild cam and rockers to increase the HP and Torque to over 200 HP it already has a 50 state legal dual exhaust system installed which I will improve on by adding MagnaFlow or FlowMaster Mufflers. Just with the Dual exhaust I expect the engine HP to be increased by 10 to 20 percent over the stock 180 HP because it breaths better with a mild cam I can get it a little higher while still keeping the stock look. Am thinking I can get it up to about 220 HP with a slight increase in torque.

 

No! Torque is needed to make horsepower. The higher up in the RPM range you make torque, the more horsepower you make. There is nothing to dispute, it is what it is. You can make torque without making horsepower, nothing moves though. You can not make horsepower without making torque. By the way, they rate truck engines by horsepower because that tells you how much work it can do!

 

I have little 4.6cc R/C engines that produce 3 HP and turn around 12,000 rpms but could I put that on my mini bike with a 3.5 HP 79 CC Gas engine nope can do it. The Little 3 HP 4.6 CC Nitro Methane Engine is no match for the 79 CC 3.5 HP gas engine and can not move the wieght why because it has no diplacement to provide Torque but they produce about the same HP. Just to put it into prosective on HP and engine size. The little R/C engine will propel my 12 pound Buggy to 40 mph in about 6 seconds but I will tell I had I 3.5 HP Mini Bike back in the late 70s that would do 35 MPH it it took a few minutes to get up to that speed.





Interesting Reads and a video

There is a Horsepower to Torque Ratio that the Dynos use to determine HP to Torque Ratios. Not every engine requires lots of torque and it is a ratio 4 cylinder engines can produce 400 to 700 HP and not have an torque to move them until they reach RPMS they have low power on torque but high Horse power.


As I said there is not any replacement for Displament in an Engine. I got smoked in my 1977 Corvette one morning by a Nisson Electic Leaf car buddy of mine who happened to see me and wanted to race LOL. he smoked me he was doing 85 at the point my 1977 Vette could reach speed limit of the line from a traffic light.

An Indy Car engine will turn around 10,000 RPMs with a straight 8 or straight 10 cylinder engine and have over 700 HP but until that engine winds up it sucks the pit crew pushes the car to get it moving there is very little torque in the engine. But they will go over 200 mph

A Stock car has lots of torque small displacement engines and HP they are limited but only turn about 7500 rpms and are judged on what speed they can exit the pit.

A Drag Car has Huge Displacement engine and turns high RPMs spins the tires from the Tree and only lasts about 5 races before they blow it.


http://www.hotrod.com/techarticles/h...e/viewall.html

 

Don't put too much faith in what you read in magazines. I've dealt with magazines for decades. They couldn't get a story right even when I've wrote it for them!

No engine can spin up to RPM to make it's power if it doesn't have any torque as you said some 4 cylinders do, doesn't even make sense. They have to make some torque to spin!

They push off Indy cars because they have 6 inch diameter clutches with tall gearing and close ratio transmissions. They make more than enough power to spin their tires, and once in a while you will see them do it, but it is at the risk of damaging the car. Best to just push it off. Same thing we do out at Bonneville.

The kid in the video is a smart kid and was doing well until he threw the part in about weight. He is making the same mistake you are. You are leaving out torque multiplication. See like your little model car motor that make 3 horsepower at 12,000 RPM. 3 horse is 3 horse. With torque multiplication it could pull your minibike.

I'll give you an example. I will use round numbers to make it easy. Lets say you have a 600 HP Big Block and a 600 HP Diesel truck engine. Do you think that the 600 HP Big Block can put the same torque to the ground as the 600 HP Diesel? I bet you think no. Well it can and I will show you how.

BBC 600 HP @ 6000 RPM. 600*5252/6000= 525.2 lb/ft of tq @ 6000

Diesel 600 HP @ 2000 RPM. 600*5252/2000= 1575.6 lb/ft of tq @ 2000

For the diesel to run 60 MPH @ 2000 RPM with 36 inch tall tires it takes 3.57 to 1 gearing.

For the BBC to run 60 MPH @ 6000 RPM with 36 inch tall tires it takes 10.71 to 1 gearing.

The gear ratio is the torque multiplication. Watch what happens next when we multiply the torque of each engine by the gear ratio.

Diesel 1575.6*3.57 = 5624.89 lb/ft of torque to the pavement!

BBC 525.2*10.71 = 5624.89 lb/ft of torque to the pavement!

You see? Horsepower is always what moves things. Of course the BBC would live a short life like this, but it could do it just like your little model car engine could pull your minibike with the right torque multiplication. The bigger engines can produce horsepower at lower RPM's and live longer. That is why they build them big, to live long lives at low RPM's.

Anyway, anybody that states torque gets you moving and horsepower gives you miles per hour is just plain wrong, period. A lot of industry people even get this wrong, magazines especially so.

PS: Just an example of torque and no horsepower. Electric motors make peak torque at full stall. In other words when the load is greater than the torque produced they don't turn so zero horsepower but peak torque!

 

Close, but not entirely accurate. Torque gets you moving, horsepower keeps you moving and momentum (mass x velocity) is what determines how far you take the wall with you.

 

Also,
Horsepower moves the car out of the showroom, and
Torque moves it for the next 150,000 miles.

 

hp=(tq X rpm) /5252

and yes,,, tq is what gets you off the line... hp is what keeps you going


tq is manly compression and CI, hp is cam and heads.....

 

Paul, read my previous posts.

The idea that torque gets you going and horsepower keeps you moving comes from the 19th century and the invention of steam locomotives. Steam engines make maximum torque at full stall (no motion), so in a sense that was true for the trains. Later trains were powered by electric motors powered by diesel generators. Electric motors also make peak torque at full stall, so if we are talking trains, in a sense the torque does get a train moving and horsepower keeps it moving.

Automotive style engines are running already when you give it gas and take off. You are using horsepower from the onset. You stall an automotive engine and it makes no torque, no movement, no horsepower. Everyone who says torque gets a car moving and horsepower keeps it moving is completely wrong. It is a leftover idea from two centuries ago. It is always horsepower in piston powered cars!

It is simple physics!

 

v2racing
i understand your point of view here... but still my point stands...imho,, thes high tq motors with big ci rip the tires... SMOKE EM in fact... but fall on there face past 4k rpm... as a high hp motor blows on by... i see this all the time at the track....

and lets take a look at the RX7 (used to own one) lots of hp that car can make.. 500hp infact... but no tq... it is a gutless wonder off the line... but once going and at 5krpm+ it moves!!!!

 

You are now talking torque placement in the RPM range, and torque curves, which is the proper way to discuss it. I'm in complete agreement with big torque at low RPM's will help get things moving, but it is still the extra horsepower produced at those lower RPM's by that big torque that is doing the work of moving the car.

It is not an opinion of mine or point of view of mine, it is a fact based in physics.

 

we may be seeing this close to eye to eye… but exactly//.….hp is nothing but a formula of torque and rpm. your hp increases as the rpm's move up AND you can keep your tq curve up, keeping the tq curve up is a matter of flow through the heads. . … but the tq on the other hand has very little change compared to the hp. lets look at a new dodge truck.. we just got one… like 800 tq, but only 500hp… this truck jumps off the line, but a 50-80 push on the freeway …. just not the same.

so… ill stand by, tq gets you moving… hp keeps you moving…

but yea… i have been wrong on more than one occasion… and if you could show me somewhere an article on how you believe, i would love to read it… i am very interested…… and this may be just a matter of semantics…. thinking the same thing here, but with a different understanding of the words..