Educate me on Basic Engine Mechanic - RPM
Thread Starter
Banned
Joined: Jun 2004
Posts: 542
Likes: 0
From: CT
Educate me on Basic Engine Mechanic - RPM
Need some basic mechanic education here...
I may be mistaken but I've always had V6 until TSX....
At the same speed...V6 RPM is LOWER than 4-cylinder , correct ?
I have the impression that given the same horsepower, LOWER RPM is a good thing,
good for engine wear, for fuel eco., correct ?
I kept hearing TSX being called "high-revving" --- is it a negative thing ? why ?
Basically my aim is to keep engine in top shape & ensure durability, I am willing to trade that for speed & power....so now I am consicously limiting RPM to 2K which get me up to 60 MPH....silly ?
I may be mistaken but I've always had V6 until TSX....
At the same speed...V6 RPM is LOWER than 4-cylinder , correct ?
I have the impression that given the same horsepower, LOWER RPM is a good thing,
good for engine wear, for fuel eco., correct ?
I kept hearing TSX being called "high-revving" --- is it a negative thing ? why ?
Basically my aim is to keep engine in top shape & ensure durability, I am willing to trade that for speed & power....so now I am consicously limiting RPM to 2K which get me up to 60 MPH....silly ?
Suzuka Master
Joined: Jul 2003
Posts: 5,241
Likes: 0
RPM is not necessarily related to engine size, its more related to gearing. Your gears multiply the engine torque to make the best use of your engine power. Even a car with a 400 hp engine wouldn't accelerate particularly fast without gears.
Since typically a 6 cylinder engine offers more torque and horsepower than a 4 cylinder, less "gear multiplier" (technically "mechanical advantage" is the term) is needed, so yes a 6 cylinder generally operates at a lower RPM (in the same gear and vehicle speed) than a 4, but again this is strictly a function of the gears.
There are pros and cons of designs oriented toward both high and low RPM operation. High RPM is typically associated with more noise, fuel consumption and (in the very long term) valve-train wear. Of course, when you have a 4 cylinder engine, the increase in fuel consumption is offset by having fewer cylinders. A 4 cylinder motor would have to run 50% faster (all other things being equal, which they rarely are) to consume the same gas as a 6 cylinder engine. More typical is for the 4 cylinder to be geared to run, say 25% or so faster, so you come out ahead fuel-wise.
Low RPM operation typically means less pep, since by general implication you are in a "taller" gear (again, less mechanical advantage). Low RPM engines have less valve-train wear but more cylinder and ring wear, since it must supply more power per engine stroke.
Personally, high RPM engines (e.g. typically 4 cylinder cars) are generally much more fun to drive, since you get to experience greater ranges of engine operation while operating at legal speeds (at least pseudo-legal). Also, on the highway a 4 cylinder engine is almost always in the meat of its power-band and generally fairly responsive. Low RPM gearing requires downshifting to get into the power-band.
EDIT: Oh, one more thing. Honda/Acura engineers their cars for high RPM operation. Few engines sound sweeter than an Honda motor running at 4000-6000 RPM, so live a little...
Since typically a 6 cylinder engine offers more torque and horsepower than a 4 cylinder, less "gear multiplier" (technically "mechanical advantage" is the term) is needed, so yes a 6 cylinder generally operates at a lower RPM (in the same gear and vehicle speed) than a 4, but again this is strictly a function of the gears.
There are pros and cons of designs oriented toward both high and low RPM operation. High RPM is typically associated with more noise, fuel consumption and (in the very long term) valve-train wear. Of course, when you have a 4 cylinder engine, the increase in fuel consumption is offset by having fewer cylinders. A 4 cylinder motor would have to run 50% faster (all other things being equal, which they rarely are) to consume the same gas as a 6 cylinder engine. More typical is for the 4 cylinder to be geared to run, say 25% or so faster, so you come out ahead fuel-wise.
Low RPM operation typically means less pep, since by general implication you are in a "taller" gear (again, less mechanical advantage). Low RPM engines have less valve-train wear but more cylinder and ring wear, since it must supply more power per engine stroke.
Personally, high RPM engines (e.g. typically 4 cylinder cars) are generally much more fun to drive, since you get to experience greater ranges of engine operation while operating at legal speeds (at least pseudo-legal). Also, on the highway a 4 cylinder engine is almost always in the meat of its power-band and generally fairly responsive. Low RPM gearing requires downshifting to get into the power-band.
EDIT: Oh, one more thing. Honda/Acura engineers their cars for high RPM operation. Few engines sound sweeter than an Honda motor running at 4000-6000 RPM, so live a little...
Suzuka Master
Joined: Jul 2003
Posts: 5,241
Likes: 0
Originally Posted by iamhomin
Speaking of fuel consumption, correct me if I'm mistaking.
A 2.4 Liter engine reving at 3k is equivalent to a 3.2 Liter engine reving at 2k, right?
A 2.4 Liter engine reving at 3k is equivalent to a 3.2 Liter engine reving at 2k, right?
VP Electricity
Joined: Jun 2004
Posts: 4,617
Likes: 8
From: Portland OR US
No, RPMs are RPMs... driveshafts spinning translates into wheel speed.
But with more cylinders, engines are much more likely to have more power at lower RPMs. When Honda engines are referred to a "high-revving", it means that they "like" to rev high because that's where they develop power. (It's actually their owners which are "high-revving".)
Here is a chart showing HP by RPM of a TSX 4-cylinder motor. Make sure to look at the baseline, not the modded line.
Here is a dyno chart of a 3.2TL motor. Note the different shape of the curve? More percentage of the potential horsepower is available relatively lower in the RPM scale?
That's what it means...
But with more cylinders, engines are much more likely to have more power at lower RPMs. When Honda engines are referred to a "high-revving", it means that they "like" to rev high because that's where they develop power. (It's actually their owners which are "high-revving".)
Here is a chart showing HP by RPM of a TSX 4-cylinder motor. Make sure to look at the baseline, not the modded line.
Here is a dyno chart of a 3.2TL motor. Note the different shape of the curve? More percentage of the potential horsepower is available relatively lower in the RPM scale?
That's what it means...
Trending Topics
Burning Brakes
Joined: Aug 2003
Posts: 751
Likes: 0
From: Calgary
yea. i rev the hell out of my car ( the intake makes it tempting all too often) . much more enjoyable. if you drive casually, rev it up as high as you please, drive smooth and you shouldnt even notice too bad of milage. i shift at 3000-4500 casually. and pass 6000 often as well.
6MT Snob
Joined: Feb 2004
Posts: 2,276
Likes: 0
From: Chicagoland
Originally Posted by TSX Cman
yea. i rev the hell out of my car ( the intake makes it tempting all too often) . much more enjoyable. if you drive casually, rev it up as high as you please, drive smooth and you shouldnt even notice too bad of milage. i shift at 3000-4500 casually. and pass 6000 often as well.
Got Milk???
Joined: Jan 2004
Posts: 1,613
Likes: 0
From: Irvine, CA
Originally Posted by rb1
RPM is not necessarily related to engine size, its more related to gearing. Your gears multiply the engine torque to make the best use of your engine power. Even a car with a 400 hp engine wouldn't accelerate particularly fast without gears.
Since typically a 6 cylinder engine offers more torque and horsepower than a 4 cylinder, less "gear multiplier" (technically "mechanical advantage" is the term) is needed, so yes a 6 cylinder generally operates at a lower RPM (in the same gear and vehicle speed) than a 4, but again this is strictly a function of the gears.
There are pros and cons of designs oriented toward both high and low RPM operation. High RPM is typically associated with more noise, fuel consumption and (in the very long term) valve-train wear. Of course, when you have a 4 cylinder engine, the increase in fuel consumption is offset by having fewer cylinders. A 4 cylinder motor would have to run 50% faster (all other things being equal, which they rarely are) to consume the same gas as a 6 cylinder engine. More typical is for the 4 cylinder to be geared to run, say 25% or so faster, so you come out ahead fuel-wise.
Low RPM operation typically means less pep, since by general implication you are in a "taller" gear (again, less mechanical advantage). Low RPM engines have less valve-train wear but more cylinder and ring wear, since it must supply more power per engine stroke.
Personally, high RPM engines (e.g. typically 4 cylinder cars) are generally much more fun to drive, since you get to experience greater ranges of engine operation while operating at legal speeds (at least pseudo-legal). Also, on the highway a 4 cylinder engine is almost always in the meat of its power-band and generally fairly responsive. Low RPM gearing requires downshifting to get into the power-band.
EDIT: Oh, one more thing. Honda/Acura engineers their cars for high RPM operation. Few engines sound sweeter than an Honda motor running at 4000-6000 RPM, so live a little...
Since typically a 6 cylinder engine offers more torque and horsepower than a 4 cylinder, less "gear multiplier" (technically "mechanical advantage" is the term) is needed, so yes a 6 cylinder generally operates at a lower RPM (in the same gear and vehicle speed) than a 4, but again this is strictly a function of the gears.
There are pros and cons of designs oriented toward both high and low RPM operation. High RPM is typically associated with more noise, fuel consumption and (in the very long term) valve-train wear. Of course, when you have a 4 cylinder engine, the increase in fuel consumption is offset by having fewer cylinders. A 4 cylinder motor would have to run 50% faster (all other things being equal, which they rarely are) to consume the same gas as a 6 cylinder engine. More typical is for the 4 cylinder to be geared to run, say 25% or so faster, so you come out ahead fuel-wise.
Low RPM operation typically means less pep, since by general implication you are in a "taller" gear (again, less mechanical advantage). Low RPM engines have less valve-train wear but more cylinder and ring wear, since it must supply more power per engine stroke.
Personally, high RPM engines (e.g. typically 4 cylinder cars) are generally much more fun to drive, since you get to experience greater ranges of engine operation while operating at legal speeds (at least pseudo-legal). Also, on the highway a 4 cylinder engine is almost always in the meat of its power-band and generally fairly responsive. Low RPM gearing requires downshifting to get into the power-band.
EDIT: Oh, one more thing. Honda/Acura engineers their cars for high RPM operation. Few engines sound sweeter than an Honda motor running at 4000-6000 RPM, so live a little...
:phatyo:
Thread
Thread Starter
Forum
Replies
Last Post
Billu99tl
3G TL Problems & Fixes
1
Sep 13, 2015 11:30 AM
