HP:TQ Ratio...
#1
Do I Really Exist?
Thread Starter
iTrader: (2)
Join Date: Nov 2001
Location: London, ON
Posts: 1,034
Likes: 0
Received 0 Likes
on
0 Posts
HP:TQ Ratio...
Hey, I was just wondering if there was any way of figure out how much torque one would get with a rotary at different levels of horsepower. Is there any kind of ratio that would give me a rough answer or some kind of equation?
Thanks guys!
Thanks guys!
#4
Old [Sch|F]ool
No, there isn't a simple ratio.
The torque is defined by displacement and volumetric efficiency (for the most part) and the HP is defined by how much torque you have AND where the torque curve is.
Some rotaries have more torque than HP because they make their power low down in the RPM curve. Others have over twice as much HP as torque.
The torque is defined by displacement and volumetric efficiency (for the most part) and the HP is defined by how much torque you have AND where the torque curve is.
Some rotaries have more torque than HP because they make their power low down in the RPM curve. Others have over twice as much HP as torque.
#5
Do I Really Exist?
Thread Starter
iTrader: (2)
Join Date: Nov 2001
Location: London, ON
Posts: 1,034
Likes: 0
Received 0 Likes
on
0 Posts
How would you build a rotary engine that would have considerably more hp than torque?
Is it something to do with the seals that you use? like 3mm or something?
Im going to be building an engine this winter and would prefer it to have more hp than torque.
Thanks guys!
Is it something to do with the seals that you use? like 3mm or something?
Im going to be building an engine this winter and would prefer it to have more hp than torque.
Thanks guys!
#6
Old [Sch|F]ool
Originally posted by Snufelupogus
How would you build a rotary engine that would have considerably more hp than torque?
How would you build a rotary engine that would have considerably more hp than torque?
Trending Topics
#8
Senior Member
Most porting will decrease torque and increase Hp and the more radical the port the more Hp and less torque. There are other ways to do this (carbon apex seals, lightening rotor assembly, etc) But porting is the most profound of all. The ports are timing just like a cam and you have heard of ricers putting radical cams on that increase high end power same deal with the ports.
they you seem to want it either a extreme extenda street port or a mild bridge port.
they you seem to want it either a extreme extenda street port or a mild bridge port.
#9
Rotary Freak
iTrader: (3)
Originally posted by peejay
No, there isn't a simple ratio.
The torque is defined by displacement and volumetric efficiency (for the most part) and the HP is defined by how much torque you have AND where the torque curve is.
Some rotaries have more torque than HP because they make their power low down in the RPM curve. Others have over twice as much HP as torque.
No, there isn't a simple ratio.
The torque is defined by displacement and volumetric efficiency (for the most part) and the HP is defined by how much torque you have AND where the torque curve is.
Some rotaries have more torque than HP because they make their power low down in the RPM curve. Others have over twice as much HP as torque.
When you take you car to the dyno, what the dyno is actually measuring is the resistance (torque) created by the rolling drum trying to decelerate the vehicle. HP is ONLY CALCULATED from the measured torque figures.
HP is never a ratio of torque but a function of it.
#10
Do I Really Exist?
Thread Starter
iTrader: (2)
Join Date: Nov 2001
Location: London, ON
Posts: 1,034
Likes: 0
Received 0 Likes
on
0 Posts
coolio, I was plannin on doing a pretty wild street port anyways
And thanks HEVNSNT, I was testing out that formula on some of the dyno sheets here on the forum and its pretty darn accruate thanks.
And thanks HEVNSNT, I was testing out that formula on some of the dyno sheets here on the forum and its pretty darn accruate thanks.
#11
Rotorhead
Join Date: Feb 2001
Location: Charlottesville, Virginia, USA
Posts: 9,136
Likes: 0
Received 39 Likes
on
33 Posts
Originally posted by HEVNSNT
Without getting too technical, the formula I gave is theoretical but is the correct formula for calculating HP.
Without getting too technical, the formula I gave is theoretical but is the correct formula for calculating HP.
If your formula isn't correct, then I've been working on my psychic abilities. Try this out - find a dyno chart in which the units are in horsepower and torque lbs-ft. It can be a dyno chart of a rotary, Chevy 350, Honda 4cyl, or whatever, so just go with the first one you see. OK, now for my amazing powers of perception - I predict that the HP and Torque curves meet right at 5252 rpm. How did I do?
#12
Do I Really Exist?
Thread Starter
iTrader: (2)
Join Date: Nov 2001
Location: London, ON
Posts: 1,034
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by Evil Aviator
Your formula is correct. Peejay is just on crack and trying to go off on some type of MEP tangent.
If your formula isn't correct, then I've been working on my psychic abilities. Try this out - find a dyno chart in which the units are in horsepower and torque lbs-ft. It can be a dyno chart of a rotary, Chevy 350, Honda 4cyl, or whatever, so just go with the first one you see. OK, now for my amazing powers of perception - I predict that the HP and Torque curves meet right at 5252 rpm. How did I do?
Your formula is correct. Peejay is just on crack and trying to go off on some type of MEP tangent.
If your formula isn't correct, then I've been working on my psychic abilities. Try this out - find a dyno chart in which the units are in horsepower and torque lbs-ft. It can be a dyno chart of a rotary, Chevy 350, Honda 4cyl, or whatever, so just go with the first one you see. OK, now for my amazing powers of perception - I predict that the HP and Torque curves meet right at 5252 rpm. How did I do?
#13
Full Member
Join Date: Mar 2001
Location: Huntington Beach, CA, USA
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
It's not psychic ability dammit! It's the laws of physics All dyno curves, if their power is in HP and torque is in ft-lbs, will have torque = power at 5252 RPM. If it doesn't then the dyno curve is bogus. And Peejay is not on crack...or maybe he is, but if he is on crack, he is still right Depending on what rev range your engine was designed to run, the peak torque will vary, even for the same HP levels.
As an aside, remember not to get so hung up on the peak torque figure. The important thing is not the peak torque figure, but rather the area under the torque curve. An engine that makes 150 lb-ft over a 4000 RPM range has more torque than an engine that makes 200 lb-ft over a 2000 RPM range. That's a fact. If you build a low-peak-torque, high-revving, high-hp engine, but the torque curve of that engine is long and flat, then that engine will be just as fast as a high-peak-torque, lower revving engine with the same HP.
As an aside, remember not to get so hung up on the peak torque figure. The important thing is not the peak torque figure, but rather the area under the torque curve. An engine that makes 150 lb-ft over a 4000 RPM range has more torque than an engine that makes 200 lb-ft over a 2000 RPM range. That's a fact. If you build a low-peak-torque, high-revving, high-hp engine, but the torque curve of that engine is long and flat, then that engine will be just as fast as a high-peak-torque, lower revving engine with the same HP.
#15
Rotorhead
Join Date: Feb 2001
Location: Charlottesville, Virginia, USA
Posts: 9,136
Likes: 0
Received 39 Likes
on
33 Posts
Originally posted by Red Rotary Rocket
It's not psychic ability dammit! It's the laws of physics
It's not psychic ability dammit! It's the laws of physics
Do you need guidance on what to do with your 6-ports? You wonderin' when the RX-7 will be exported to the US again? Does Felix Wankel's ghost approve of your mods? CALL ME NOW!
#16
Rotorhead
Join Date: Feb 2001
Location: Charlottesville, Virginia, USA
Posts: 9,136
Likes: 0
Received 39 Likes
on
33 Posts
Originally posted by Red Rotary Rocket
All dyno curves, if their power is in HP and torque is in ft-lbs, will have torque = power at 5252 RPM.
All dyno curves, if their power is in HP and torque is in ft-lbs, will have torque = power at 5252 RPM.
HP = (torque x rpm)/5252
HP = (torque x 5252)/5252
HP = torque
Drat, the secret to my psychic ability is out! Maybe nobody will believe that formula is correct (even though it has been a standard since before anybody on this forum was born) and then I can make a lot of money by claiming psychic ability!
#17
Old [Sch|F]ool
Originally posted by protlewski
Most porting will decrease torque and increase Hp
Most porting will decrease torque and increase Hp
#18
Old [Sch|F]ool
Originally posted by Evil Aviator
Your formula is correct. Peejay is just on crack and trying to go off on some type of MEP tangent.
Your formula is correct. Peejay is just on crack and trying to go off on some type of MEP tangent.
I mean, some PP engines have 175lb-ft of torque peak and 350hp peak, that's a 1:2 ratio... other engines have 135lb-ft peak and only 110hp for a less than 1:1 ratio... there is no "rule of thumb" as it is entirely dependent on the torque curve's shape and placement relative to RPM.
#19
inteligent extratarestril
Join Date: Mar 2001
Location: The Sunny B.O.P, New Zealand
Posts: 1,313
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by protlewski
Most porting will decrease torque and increase Hp and the more radical the port the more Hp and less torque. .
Most porting will decrease torque and increase Hp and the more radical the port the more Hp and less torque. .
#20
Full Member
Join Date: Mar 2001
Location: Huntington Beach, CA, USA
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
Originally posted by Evil Aviator
No way, you are just jealous mon!
Do you need guidance on what to do with your 6-ports? You wonderin' when the RX-7 will be exported to the US again? Does Felix Wankel's ghost approve of your mods? CALL ME NOW!
No way, you are just jealous mon!
Do you need guidance on what to do with your 6-ports? You wonderin' when the RX-7 will be exported to the US again? Does Felix Wankel's ghost approve of your mods? CALL ME NOW!
#21
Old [Sch|F]ool
Note that the 5252 thing only is when you are measuring power in horsepower (aka lift 550lb one foot in one second = 1 HP) and measuring torque in pound-feet (one pound of force on a 1 foot long lever = 1 ft/lb).
Start measuring things in PS, or kilowatts, or newton-meters or kilogram-meters and you have to calculate differently, and so the "crossover" point is different.
That's why I get irked when people say HP and TQ. HP is a unit of measurement, while "TQ" is just a concept.. That's like saying the car weighs 1500. (What unit of measure?)
Start measuring things in PS, or kilowatts, or newton-meters or kilogram-meters and you have to calculate differently, and so the "crossover" point is different.
That's why I get irked when people say HP and TQ. HP is a unit of measurement, while "TQ" is just a concept.. That's like saying the car weighs 1500. (What unit of measure?)
Thread
Thread Starter
Forum
Replies
Last Post
Howard Coleman
Single Turbo RX-7's
11
01-07-24 11:37 AM
Johnny_Cracker
1st Generation Specific (1979-1985)
39
02-26-20 02:28 PM