Manual shifting

[Zenmervolt]

I've heard it described this way: torque will get you there quicker. HP will get you to a higher top speed. So if you have 100 HP and 200 Torque vs 200 HP and 100 torque example one will have a lower top speed, but 0-60, 0-100 and 0-top speed will be quicker than example two. However if you're running a high speed track like Daytona or Le Sarthe you will probably do better with the high HP as opposed to short tight tracks where acceleration is king.

Not accurate. Not even close.

100 hp with 200 ft-lbs will mean that torque falls off massively at higher RPM. In fact, to have only 100 hp with 200 ft-lbs of torque would mean that torque peaked at 2,626 RPM (100 = 200*2626/5252), with torque falling off massively after that point to only 100 ft-lbs at 5252 RPM. The engine would be a peaky pain in the ass with almost zero usable RPM range. Basically, it would be an old-school diesel. And we all know how well those old diesels would accelerate...

Now, the engine with 100 ft-lbs and 200 hp would have to rev to 10,504 RPM where it would be making 100 ft-lbs of torque and 200 hp. Torque would climb steadily from idle to HP peak.

Additionally, the second engine can take massive advantage of gearing, while the first cannot. Let's say that we need an output shaft spinning at 2,626 RPM. For the first engine, that's a 1:1 gear ratio. No torque multiplication, so the result is that the output shaft sees 200 ft-lbs of torque and 100 hp. For the second engine, however, that's a 4:1 gear ratio. 4x torque multiplication, so the output shaft gets 400 ft-lbs of torque and 200 hp.

The second engine will accelerate much faster than the first and it will have a higher top speed. It's all in the link I posted earlier. HP at high RPM is what you want so you can take advantage of gearing. Low-rpm torque can make a car feel "effortless", but high RPM horsepower will accelerate faster unless someone terribly buggers the gearing.

 

[KOUKI507]

Hi,

100 hp with 200 ft-lbs of torque or 200 hp with 100 ft-lbs of torque... Are those combinations of numbers achievable anyway?

 

[Gedi69]

Not accurate. Not even close.

100 hp with 200 ft-lbs will mean that torque falls off massively at higher RPM. In fact, to have only 100 hp with 200 ft-lbs of torque would mean that torque peaked at 2,626 RPM (100 = 200*2626/5252), with torque falling off massively after that point to only 100 ft-lbs at 5252 RPM. The engine would be a peaky pain in the ass with almost zero usable RPM range. Basically, it would be an old-school diesel. And we all know how well those old diesels would accelerate...

Now, the engine with 100 ft-lbs and 200 hp would have to rev to 10,504 RPM where it would be making 100 ft-lbs of torque and 200 hp. Torque would climb steadily from idle to HP peak.

Additionally, the second engine can take massive advantage of gearing, while the first cannot. Let's say that we need an output shaft spinning at 2,626 RPM. For the first engine, that's a 1:1 gear ratio. No torque multiplication, so the result is that the output shaft sees 200 ft-lbs of torque and 100 hp. For the second engine, however, that's a 4:1 gear ratio. 4x torque multiplication, so the output shaft gets 400 ft-lbs of torque and 200 hp.

The second engine will accelerate much faster than the first and it will have a higher top speed. It's all in the link I posted earlier. HP at high RPM is what you want so you can take advantage of gearing. Low-rpm torque can make a car feel "effortless", but high RPM horsepower will accelerate faster unless someone terribly buggers the gearing.

Wow everyones getting technical!!

 

[Zenmervolt]

Hi,

100 hp with 200 ft-lbs of torque or 200 hp with 100 ft-lbs of torque... Are those combinations of numbers achievable anyway?

Yup, though rare given the necessary compromises in modern cars.

The 100 hp / 200 ft-lb type of engine shows up a lot in diesels and truck engines. The old Ford 351 Windsor V8 was putting out 136 hp and 262 ft-lbs of torque at the beginning of the 1980s. In the 90's, the IDI TurboDiesel in Ford's pickups was pushing 190 hp with 390 ft-lbs of torque. The current 6.7 litre PowerStroke puts out 400 hp with 800(!) ft-lbs of torque.

Basically the high torque/low hp combination shows up when you need to be able to apply a LOT of force (towing a heavy load) but don't need to move very fast. With limitations on gearing for consumer trucks, this means you're generally pretty slow. Semis have similar issues (magnified), but may have as many as 21 gears in their transmissions to mitigate. Watch a heavily-loaded semi take off from a stoplight sometime, it will go through 3 or 4 shifts before it even reaches the other side of the intersection because the engine, while producing massive torque, only has about 1,000 RPM between idle and redline.

The 200 hp / 100 ft-lb type of engine often shows up in small sporty cars, though generally not quite to that extreme. For example, there was the mid-'90s Honda Integra Type R which had 195 hp and only 130 ft-lbs of torque. Racing cars also employ this type of engine; Formula 1 cars make ~740 hp at 19,000 RPM, which means only a tiny bit more than 200 ft-lbs at 19,000 RPM. For reasons such as internal friction, valve float, reciprocating mass, and driver preferences, street engines almost never go this route; people don't want to be cruising down the highway at 60 mph and 9,000 RPM just to take advantage of gearing.

So, yes, those types of engines are achievable, but they rarely show up in passenger cars.

 

[chuyler1]

Not to break into a tangent, but I was messing around with mid-rpm turbo vs high-rpm turbo for performance point racing. The mid-rpm turbo provides boat loads of torque while the high-rpm turbo gives you better peak hp in the high rpms. Running laps at Deep Forest Reverse I can't quite decide which is a better approach since I gain and lose time in different parts of the track depending on which one I use. The high rpm turbo appears to pull a little better at the end of the straight, but the mid rpm turbo usually gets a jump at the start. Lap times don't show a significant difference. Keep in mind, the high rpm turbo is rated for more pp than the mid rpm turbo so i had to remove a few other parts when switching between them.

 

[BlademanX]

Thats interesting mid range and low range in real life are like the VAGS and BMW's.....Cars with Torque equals thrills. Thats why TDI is fun!

 

[KOUKI507]

Yup, though rare given the necessary compromises in modern cars.

The 100 hp / 200 ft-lb type of engine shows up a lot in diesels and truck engines. The old Ford 351 Windsor V8 was putting out 136 hp and 262 ft-lbs of torque at the beginning of the 1980s. In the 90's, the IDI TurboDiesel in Ford's pickups was pushing 190 hp with 390 ft-lbs of torque. The current 6.7 litre PowerStroke puts out 400 hp with 800(!) ft-lbs of torque.

Basically the high torque/low hp combination shows up when you need to be able to apply a LOT of force (towing a heavy load) but don't need to move very fast. With limitations on gearing for consumer trucks, this means you're generally pretty slow. Semis have similar issues (magnified), but may have as many as 21 gears in their transmissions to mitigate. Watch a heavily-loaded semi take off from a stoplight sometime, it will go through 3 or 4 shifts before it even reaches the other side of the intersection because the engine, while producing massive torque, only has about 1,000 RPM between idle and redline.

The 200 hp / 100 ft-lb type of engine often shows up in small sporty cars, though generally not quite to that extreme. For example, there was the mid-'90s Honda Integra Type R which had 195 hp and only 130 ft-lbs of torque. Racing cars also employ this type of engine; Formula 1 cars make ~740 hp at 19,000 RPM, which means only a tiny bit more than 200 ft-lbs at 19,000 RPM. For reasons such as internal friction, valve float, reciprocating mass, and driver preferences, street engines almost never go this route; people don't want to be cruising down the highway at 60 mph and 9,000 RPM just to take advantage of gearing.

So, yes, those types of engines are achievable, but they rarely show up in passenger cars.

Really interesting stuff 👍 Thanks