Have a ?, can you gear around lack of torque ?

M

Moretorque

New member
Joined
May 30, 2015
Messages
38
New here, have a couple ?'s getting closer. just want to understand a few things.

Can you gear around a lack of torque as long as it has the same HP rating or are the motors that make the power earlier in the RPM range just more powerful under load and can maintain it better and pull more weight up to speed.

Could you through gearing get a 700 HP Nascar engine to pull a 80000 pound semi like a 700 HP 1800 RPM engine. Very mixed opinions on this, so who is right on this.

Reher Morrison told me the people who think you can gear around a lack of torque to do the job do not understand HP and a 500 HP car motor would not run a Semi correctly.

Thanks for any info so I can put this to rest.
 
Depends on the width of the usable torque curve and the duty cycle. I feel like what you were told is a direct correlation to duty cycle.
 
reher morrison is likely gonna have a better understanding of gas engines and the answer to your question, than any feedback you will get off this site.
 
I think you underestimate the knowledge base this site represents...


Sent from my Rotten Apple
 
no offense to anyone, just i am familiar with reher morrison and their knowledge of GAS engines. prob should have worded it differently. my apologies
 
gas or diesel , i guess really doesent matter as the question focuses more on the usable torque curve of the engine/engines in question.
 
as highway class trucks got bigger and had to carry more weight, they added more HP/TQ to their motors, but more so they added more gears.
 
Look up hp and torque specs of bull dozers and ponder that vs the amount of weight they move


Sent from my iPhone using Tapatalk
 
Yes. HP is what matters. If you had the gearing to keep a NASCAR engine at 6K-8K you could equal or oupull a semi. But, 500 miles vs. 500,000 miles, and I don't like to think about how many speeds you'd need.
 
JQmile said:
Yes. HP is what matters. If you had the gearing to keep a NASCAR engine at 6K-8K you could equal or oupull a semi. But, 500 miles vs. 500,000 miles, and I don't like to think about how many speeds you'd need.
Click to expand...

Thanks now the ? is what kind of gearing would it take, would it take like many gears and a air shifter like a F1 car to keep it peaked so it does not fall off the pipe under a 80 or 90 grand load ?

Because I was reading where the old Mack Maxidynes 237 HP could pull over 70000 pound load with just a 5 speed 5 gears and maxed out at 62 MPH. I cannot see any gas car motor doing that with a 5 speed and 237 HP ?

With a high torque low RPM engine you can feed it more gear without it choking the RPM down ?

Electric motors are the best way to understand linear torque curve and what it does ?
 
Last edited:
More gear isn't a thing. Higher ratio, lower ratio, multiple ratios.

Electric motors don't have torque impulses the way IC engines to. I'm not an EE so there could be a better way to state that.

In your discussion about horsepower and torque, horsepower is simply a way to quantify the time it takes to apply force (torque).

If your horse power is high, you have the ability to do a large amount of work in a shorter amount of time. Changing that with gearing ratios changes both the time and force.

In your analogy, mathematically you can do the same amount of work in either case, the question is, how long can those structures maintain that power level.

Your mack truck takes 25 minutes to hit 62mph, your nascar does in in five minutes.

The difference between the two is duty cycle. The maxydyne might do its work at 237hp for the rest of forever. The nascar might not make it through the day.

A top fuel engine might make 3000hp for seconds, a tug boat engine will make 3000hp every day for the next 3 years.

I think this is also referred to as specific interval, but would have to check.

Either way, the difference is in the duty cycle of the components, you can do the same amount of work, but for how long? You might make 700hp for 20 seconds for your vehicle engine and then it will have to stop and cool, or you can use a large engine structure and make 700hp at 100 percent duty/ or no down time at all


Sent from my Rotten Apple
 
ever try to tow something too heavy with a gasser that doesn't have enough gears? you kick down and rev the piss out of it and it finally goes into the next gear and then falls below the power band. and repeat. until you just hold it at red line for infinity

to get that kind of load rolling up to highway speed with so little torque, you'd probably need a 40 speed transmission
 
To expand on Biggy238's words. Think of an engine as not the hours it can run, but the amount of fuel you can put through it.

An engine rated at 300HP and the same engine ramped up to 600HP will both generally burn the same amount of fuel before integral components are worn out. Its just that the one at 300HP will run twice as long as it burns its fuel at 1/2 the rate.

Why does the 12v 5.9 at stock last so long, but yet you can run that thing to 900HP in a very stock configuration? Because of this principal. its detuned in a stock form to allow it's fuel burn capacity to last a long long time.

A NASCAR engine is the exact opposite. They make enormous power, but don't last as long because the fuel load they are set to burn is short and they are burning it fast.

Just some food for thought.
 
Scooter's Roofing said:
ever try to tow something too heavy with a gasser that doesn't have enough gears? you kick down and rev the piss out of it and it finally goes into the next gear and then falls below the power band. and repeat. until you just hold it at red line for infinity

to get that kind of load rolling up to highway speed with so little torque, you'd probably need a 40 speed transmission
Click to expand...

I don't care how long it will run, that is not part of what I am after.

I am on another site trying to figure out why on paper it says HP is HP and in the real world people are saying when they got rid of their 300 HP gasser PU and bought a 300 HP diesel it just slaughtered the Gasser in pulling no Matter how they geared the gasser.

I know a gasser needs a auto to work good with a High stall converter but how many gears in a manual would it really take to be competitive in pulling heavy even though it turns way more to build power? I have seen the six speed autos.

Thanks.
 
the 300hp diesel slaughtered the gasser because it did it with twice the torque and at half the RPM with the same transmission
 
Example: The tiny airplane I first learned to fly on had a 4-cyl 160 hp engine.... the displacement was 320 ci (5.2L)! And it still had to be rebuilt every 2000 hours.

But the engine was tapped out near full throttle it's entire life vs a 2.4L honda civic engine might be lucky to see 160 hp 5% of it's life. To hold a high horsepower for many hours on end without failure, the plane engine had to be much larger and the operating RPM much lower. Redline on that plane was 2500 rpm.
 
You must log in or register to reply here.
Back
Top