THE LAST Z

iTrader: (5)

I was reading about Torque VS Horsepower and basicly they say Its better to make torque at Higher RPM so you can take advantage of the gearing. I understand that, But how do you make torque at higher RPM's?

transAm-98

iTrader: (1)

kenne bell??

Ben R

That's wrong. Find a new 'they'.

J-Rod

HP = ( Torque * RPM ) / 5250

If torque is higher, HP will be higher. This is a linear relationship, and cannot change.

Steve Bryant

iTrader: (1)

The Last Z,
High RPM torque requires High RPM HP and that means and a relatively large cam (duration and lift) and good volumetric efficiency (heads/induction/exhaust) that will support the cam. This kind of setup is useless for a daily driver/occasional strip car because off-idle and mid range performance is poor.

Define the goals you have for your car and how you use it.

Steve

fotoboy

iTrader: (1)

un less it a blower car then there is alot more to it.

Ben R

Huh? Explain...

SStrokerAce

iTrader: (2)

BINGO... it's not what you want to do on the street.

Ric

Not to hi-jack, but is it possible to build an engine that has equal HP and TQ numbers at any given rpm?

Old SStroker

All engines have the torque = to hp at 5252 rpm if you are using English units (lb-ft and hp).

HP = Torque x rpm /5252

So at 5252, HP = Torque x 5252/5252

or:

HP = Torque x 1

or HP = Torque


Remember, HP is calculated from torque and rpm so it can't be equal at any other rpm than 5252...well, except for maybe 0 with the engine shut off.

Homework question:

If you are stalling your engine against a torque converter and the engine is at 5252 rpm where it made 400 lb-ft on an engine dyno, but the trans output shaft isn't moving, how much HP are you putting to the driveshaft??

Note: Assume 2.0 stall torque ratio and a 3.0 first gear ratio. It makes the calcualtions easier.

tx3

iTrader: (1)

that would be true but the kb wouldnt before the high rpms - the kb would be all low end.. so maybe a kb and then high end nitrous ? haha but there goes your motor :/

P Mack

iTrader: (6)

0 Hp to the driveshaft, the 400 hp is going straight to the tranny fluid temp.

billc5

iTrader: (1)

I'll Try not to display too much ignorance here, but I think that the question may be interpreted to ask how to maintain the most potential torque-Horsepower throughout the entire RPM range at Maximum Manifold pressure. More specific how to maintain the same cylinder force per putt at all RPM at wide open throttle.

For small displacement engines and for street/strip the best solution I've seen is with Forced induction using a positive displacement blower (Roots) feed by a centrifugal blower (turbo charger).

This will provide maximum air flow from idle, high torque, and at RPM above say 5000 the turbo will maintain cylinder force through to red line.

This takes no special heroic engine building, it is a bolt on solution, as long as the drive train can withstand the power and you can supply the fuel, the torque output can be fixed everywhere throughout the RPM range. All the internal components such as valves, timing, cam spec., are irrelevant as you can force the flow independent of all this to create power.

Isnt there a jetta that is doing this?

allngn_c5

iTrader: (3)

I agree with the last, when you use a supercharger you are eliminating the lag from a turbo. When you turbocharge, you eliminate the s/c'r fall off in high rpms. When you use the 2 together it seems like you would have a$$$$$phalt tearing torque, coupled with tons of horsepower all the way to the rev limiter. Don't know of any LS1's out there that are running supercharged and turbo cars at the same time. Sounds good in theory but does it work.

GuitsBoy

iTrader: (4)

Making torque up higher means you to do more work in the same ammount of time. This is exactly what horsepower is. HP is just a measurement that factors torque against engine speed. The more torque you have on the high end the more HP which means the motor is doing more work.

Take LT1 vs. LS1 f bodies.

They both make similar engine torque, but since the LS1 makes its torque up higher, the engine makes more HP and the car is therefore faster. The LT1 motor with its low rpm torque will feel much faster when you punch it from low rpms, but the higher torque of the LS1 will more than make up for it. To feel the same kick in the pants from the LS1 you need to bring it into its torque peak range by unching the throttle at 4000+ rpm.

XxGarbSxX

Twincharging has been around for a while. It's been used on diesels before, and VW is putting out a twincharged 1.4L, which seems kinda pointless because what they're saving in engine materials is being spent on the plumbing and tuning. There's also a twincharged Saturn ION Redline floating out somewhere in PA. Video. The one part where you see the speedometer, it does 40-100 in ~4 seconds.

hammertime

iTrader: (1)

If it's so great, why is it for sale?

V-8 engines make great torque, period. If you tune the engine to make torque N/A, and then add boost, you'll get similar results without the complicated tuning and the expense of a second power adder.

Above all, high RPM power is not the best answer for the street.

GuitsBoy

iTrader: (4)

In terms of drivability, this is correct. In terms of getting to the finish line first, high rpm power is actually the best answer street or track. As stated, its a balancing act to find a happy medium.

Gary Z

Zero - all the power is used to boil oil.

MrDude_1

iTrader: (4)

two people already said it, but im going to agree and disagree... you may or may not have ment to, but its worded as a trick question..


if the trans output shaft isnt moving, then nothings going to the driveshaft... regardless of anything else.


but i agree that when you're stalling a car up and nothings moving, not counting the minimal heat generated by the pressure of pushing things together, all off the energy is turning into heat in the trans...