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Discussion Starter · #1 ·
well i know obviously certain shift points give the most hp out
of the engine but im not quite sure why people shift at the points
that give maximum torque since its less than max horsepower. dont
feel like getting flamed but its just an honest question.
 
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You gotta understand what the term horsepower is. It is the most understood performance rating a car can have...
The term power, defined in physics class, is just a measure of how much force an engine can produce over a certain length of time, (BTW force/time is Work) in this case 1 sec.
1 horsepower is equal to the force required to lift 22000 lbs (I think, don't have my phyics book on me) through a distance of 1 foot in the time period of 1 second. Yes it can be confusing, but it is not a measure of force directly, like torque is. Torque is the actual twisting force the engine makes, this is what you "feel" when you drive.
HP is really just a function of torque and rpms, the more torque or the more rpms, the more horsepower.
As with Honda/Acura's the high horsepower number obtained is because the engine is able to "breathe" effectively at high engine speeds, while the torque rating is alot lower. HP is because of breathing ability of engine, Torque is determined only by the displacement and cam profiles.
An engine with good top end characteristics, (torque peak is moved closer to redline) compared to a pushrod motor (can't breathe well at high engine speeds) is able to do the same amount of "work" as an engine with more torque because it has more "time" to get the job done, get it? Therefore they have similiar HP numbers.

Because of the function HP=(Torque*RPM)/5252 (obtained through testing procedures and some Calculus) the HP peak will occur slightly higher than the torque peak.
Best situation is shift at the point that will put you at the peak of the torque curve in the next gear. This way, you can use the torque that is available, rather than shift at higher rpms, and place the next gear higher than the torque peak.

Basically it has to do with the powerband of the engine, search these forums I'm sure there are some more writeups.
:D
 

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Discussion Starter · #3 ·
thanks for the imput on that. so your saying overall its better to shift
into where theirs the best torque than to rev it up high like crazy to
extract the most power and "go" ?
 

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You don't shift at max torque OR max horsepower. For the most speed, you would shift so that the AVERAGE horsepower across the rev range through ALL gears is maximized. It can (and probably will) be a different RPM for each gear. And WILL be higher than peak torque or horsepower.
 

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Discussion Starter · #5 ·
how would i go about finding where the best shift points are,
any ideas on it? id appreciate it
 

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detroit-delsol said:
how would i go about finding where the best shift points are,
any ideas on it? id appreciate it
No prob. First, you need to get the car on a dyno. If you can't or don't want to pay for it, look around the internet for a dyno chart on the same type of car (same engine/trans at least) with similar mods to yours. Next, find out all your transmission ratios. Then, using this website, enter the gear ratios and dyno numbers and hit "compute" at the bottom. When the next page pops up, look under "Maximizing the Area Under the Horsepower Curve" for your shift points in each gear. If you have been shifting far off from these numbers, you might notice a decent improvement when you try the new ones.

Hope that helps.
 

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Discussion Starter · #7 ·
thanks alot, mines still stock as could be without mods.
ill try to search online for the specs for the engine and
trans.
 

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As have been said already, you shift so that you land in the most powerfull or range where you have the most power to have the car keep pulling.

Most Honda people will say that you will want to keep the car in VTEC for each upshift to get the most power out of it when shifting. This is correct to a point.

Many cars depending on modification have different powerbands. And most people especially with high profile cams don't engage VTEC until the 7000 rpm range, but thats also because they re to 9200-9500 rpm.

Anyhow gettin back on track, you'll want to get a dyno plot and look at the torque curve. Where its flatest is where you want to be landing. Well, especially at the start of the flat curve and continue wo the end of the curve and pass that if you have to. just make sure the upshift lands you back in that range, which is also called the powerband.

If you want to know what landing points you have, there are calculations for that. It takes in tranny gears and what rpm you plan on upshifting. It will give the result rpm landing point. Search for it as I've posted it several times in the teg forum.

The question at hand seems very newbie, but is also quite informative when you understand it. You may still not understand it after its been expalined. Sometimes youhave to actually have someone explain it firsthand or do the dyno and race firsthand to understand the idea and logic behind it.
 

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mberndt said:
... An engine with good top end characteristics, (torque peak is moved closer to redline) compared to a pushrod motor (can't breathe well at high engine speeds) is able to do the same amount of "work" as an engine with more torque because it has more "time" to get the job done, get it? Therefore they have similiar HP numbers....
Its not because its a pushrod engine that it can't breath at high rpms. Its because of its r/s ratio and head setup. I have seen/read some custom 572 engine with 1.75 r/s ratio revving up to 9000 rpm and pushing out monstrous power with a good head job.

The pushrod design is not the factor in holding its power back. Its the r/s ratio and head job thats keeping it from breathing at high rpms like honda's do. just keep in mind that a regular Honda engine breathes and redlines just as poorly as a pushrod does.
 

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female four said:
Its not because its a pushrod engine that it can't breath at high rpms. Its because of its r/s ratio and head setup. I have seen/read some custom 572 engine with 1.75 r/s ratio revving up to 9000 rpm and pushing out monstrous power with a good head job.

The pushrod design is not the factor in holding its power back. Its the r/s ratio and head job thats keeping it from breathing at high rpms like honda's do. just keep in mind that a regular Honda engine breathes and redlines just as poorly as a pushrod does.
Actually the pushrod design is the problem, as it's architecture dates back to the 1960's...
Tell me of one pushrod engine that revs higher than 6500 rpms, other than the Nascars??
Also, why is it that just about every car manufacturer, except for crappy chevy, uses an OHC design and not a pushrod design? this is becuase as HP numbers are increasing, it is more difficult to make HP (ie doesn't rev high) in a pushrod motor...

Your statement about someone doing all that work and pushing tons of power, is moot because as with any motor, it can be modded to put out whatever HP you desire or you can afford $$$...

I was simply stating that the pushrod design is outdated, and it is not nearly as efficient as an OHC design...
And your statement about the honda engine breathing and redlining like a pushrod motor, I don't agree.
Why then wouldn't honda just use the pushrod design? It's cheaper to produce for sure...
:number1
 

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mberndt said:
Tell me of one pushrod engine that revs higher than 6500 rpms, other than the Nascars??
Umm... mine. Redline is at 6700 right now, entirely stock internals. Many people with large cams and larger valvesprings go to 7000-7200.
The 7.0L LS7's stock redline is 7000. Same mods will easily yeild 7600+.
You do realize that your "pushrod" theory is TOTALLY off base now, right? The REAL reason why these engines don't spin any higher is, first off, cause they don't need to. If you don't have a baby size economy engine, the amount of airflow you get at 5000 RPM is FAR greater than a normal 1.8L Honda engine at 9000 RPM. Airflow + fuel flow = power, essentially. Another reason is that you have WAY more metal flying around, and over larger distances, in a 5.7L V8. The magnitude of forces inside these engines makes a B18C5 look like a weak kid's toy at redline. The load on the rods would be COMPLETELY rediculous if these engines reved to the same points as little engines HAVE TO (if they want to make power). A little interesting tidbit for you... in 1994, a pushrod V8 powered car (with a redline of over 10k) WON the Indy 500 With Al Unser, Jr. driving. Not saying pushrods make more power, but that pretty much fucks up any "pushrods can't rev" theory.

That point is made... now let's fix your history problem. DOHC engines have been around since the 1910's. Both OHV and OHC are ANCIENT. Remember that.
 

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Nathan123 said:
Umm... mine. Redline is at 6700 right now, entirely stock internals. Many people with large cams and larger valvesprings go to 7000-7200.
The 7.0L LS7's stock redline is 7000. Same mods will easily yeild 7600+.
You do realize that your "pushrod" theory is TOTALLY off base now, right? The REAL reason why these engines don't spin any higher is, first off, cause they don't need to. If you don't have a baby size economy engine, the amount of airflow you get at 5000 RPM is FAR greater than a normal 1.8L Honda engine at 9000 RPM. Airflow + fuel flow = power, essentially. Another reason is that you have WAY more metal flying around, and over larger distances, in a 5.7L V8. The magnitude of forces inside these engines makes a B18C5 look like a weak kid's toy at redline. The load on the rods would be COMPLETELY rediculous if these engines reved to the same points as little engines HAVE TO (if they want to make power). A little interesting tidbit for you... in 1994, a pushrod V8 powered car (with a redline of over 10k) WON the Indy 500 With Al Unser, Jr. driving. Not saying pushrods make more power, but that pretty much fucks up any "pushrods can't rev" theory.

That point is made... now let's fix your history problem. DOHC engines have been around since the 1910's. Both OHV and OHC are ANCIENT. Remember that.
Well let me first start off by saying, I can see that your opinion is biased, because it seems, according to your sig, that all you owned/own is Chevy's

You are TOTALLY WRONG!!
Pushrod motors do not rev, as their heavy iron and steel parts don't like to be moved around at high speed... Hello Aluminum?
Wow, your redline is 6700 now, it was 6000 on the older ones... Yeah it's obvious, if you put HIGH QAULITY components in the valvetrain you can rev higher, but like I said before, u got $$ u can make a metro rev to 10 grand...
So, that argument is moot...
Second, if you like to spend $$70 on a tank of gas, go ahead...
Yeah V8's don't need to be revved to make power, it's because they have ENORMOUS engines to make up for the fact that they are INEFFICIENT...
How does it feel to know that my economy engine is FAR more efficient than you Pushrod Vette motor? :giggle

That is the bottom line here, Efficiency, which your Chevy lacks... You can't argue that cause you know its true... What u got like 57HP/Liter?
Believe me, I know how you domestic heads feel, I had a Chevy as my first car :lol2 ...

You say "The load on the rods would be COMPLETELY rediculous if these engines reved to the same points as little engines HAVE TO (if they want to make power)."
Is it my fault that Chevy doesn't properly engineer their vehicles, NO... If they had been properly designed with QUALITY COMPONENTS, then you could rev it higher, and the stress on the rods would be able to be handled by the stronger rods... Ever hear of Aluminum alloying? Chevy along with American cars in general, have very low tolerances, and therefore are not built as well as Japanese cars.
I know firsthand because I've owned both, so don't tell me...
Hell, you're engine is not even aluminum, does Chevy evn know aluminum exists? Oh I forgot, Aluminum was too expensive in the 60's when this engine was designed :clap ...

As for the history, I don't really care that DOHC engines were around in 1910. How does it feel to know your engine is from the 1960's? :clap

No matter what you say here, pushrod engines are not only outdated but are extremely inefficient.

Go watch some more Nascar and get off this forum, cause all your gonna get is SHUT DOWN :byye :byye
 

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Oh get off it both of you.

The "my car gets 40mpg" is REALLY getting old, and quite frankly, is irrelevant. The issue at hand is power, not economy. Who gives a shit if you get 40, 50, or 300mpg, when were arguing over the power characteristics of each motor? Even his big V8 still probably gets 22-25mpg. Thats because at 70mph, hes probably sitting at 1500rpm, where we're at 4500.

Lets be honest here. An OHC engine is far better at revving, only because it HAS to. If a B18C had the same redline as an LS1, it wouldnt make ANY power (not to mention we would all be swapping out our B18C's for B18B's). An OHV engine isnt a good revver, simply because it doesnt need to. It has the displacement to make up for that extra 2500rpm. Have you ever seen a V8's dyno chart? The max hp and max tq are almost equal. (ie 400whp, 400ft/lb tq, or close to it). Thats because the V8s have so much displacement that they make much of their power down low, and dont NEED to rev to 9000rpm.

Yes, an OHV engine is outdated. And I agree that the technology on honda motors is better than a chevy V8. HOWEVER, that doesnt mean that a Honda engine is better suited for making power. Simply put, a stock v8 will ALWAYS make more power than a stock I4. (NA for NA). Theres no replacement for displacement... and thats all there is to it. When an engine has 4 times the displacement of another, guess who is going to make more power?

Hondas do make more horsepower per liter, but that doesnt really matter if youre comparing a 1.8 to a 5.7L does it?
 

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Well, shit. If I'd know you were this fucking ignorant, I wouldn't have even responded nicely last time. Here's that negative rep you've earned. You'll be getting a few more (when I can give them) to make sure it's color matches your level of intelligence appropriately.
mberndt said:
Well let me first start off by saying, I can see that your opinion is biased, because it seems, according to your sig, that all you owned/own is Chevy's
Well, except for the Jeep Grand Cherokee, Ford Escort ZX2, and Mazda 6 that I also currently own, yeah... all I own is Chevy. :rolleyes I don't put them in my sig because THEY ARE SLOW. Well, probably about as fast as your car, but that's not the point. Dumbass. Anyway, as if I've only owned 3 cars in my life. Jeez.

mberndt said:
You are TOTALLY WRONG!!
Pushrod motors do not rev, as their heavy iron and steel parts don't like to be moved around at high speed... Hello Aluminum?
That is almost so fucking ignorant that I don't want to waste my time destroying you for saying it. But I will anyway. In a minute....
mberndt said:
Wow, your redline is 6700 now, it was 6000 on the older ones... Yeah it's obvious, if you put HIGH QAULITY components in the valvetrain you can rev higher, but like I said before, u got $$ u can make a metro rev to 10 grand...
So, that argument is moot...
Actually, what you said before was:
mberndt said:
Tell me of one pushrod engine that revs higher than 6500 rpms, other than the Nascars??
Yeah, remember that? And I did show you a couple. And now you're like... "Ooops. Can't act like I'm a giant retard... gotta dodge... let's say something about components and shit, then maybe nobody will realize I just got owned by my ignorance..."
What a dumb fuck you are.

mberndt said:
Second, if you like to spend $$70 on a tank of gas, go ahead...
Yeah V8's don't need to be revved to make power, it's because they have ENORMOUS engines to make up for the fact that they are INEFFICIENT...
How does it feel to know that my economy engine is FAR more efficient than you Pushrod Vette motor? :giggle
I can promise you that I get almost the same gas mileage on the highway in my 450+ hp Corvette as you do in your slow ass economy car. Pretty neat, eh? Go ahead and blab about efficiency, you retard. You don't even fucking know what efficiency is.
mberndt said:
That is the bottom line here, Efficiency, which your Chevy lacks... You can't argue that cause you know its true... What u got like 57HP/Liter?
Believe me, I know how you domestic heads feel, I had a Chevy as my first car :lol2 ...
Like I said...
mberndt said:
You say "The load on the rods would be COMPLETELY rediculous if these engines reved to the same points as little engines HAVE TO (if they want to make power)."
Is it my fault that Chevy doesn't properly engineer their vehicles, NO... If they had been properly designed with QUALITY COMPONENTS, then you could rev it higher, and the stress on the rods would be able to be handled by the stronger rods... Ever hear of Aluminum alloying? Chevy along with American cars in general, have very low tolerances, and therefore are not built as well as Japanese cars.
That was the biggest pile of stupid shit I have ever heard that didn't come out of the mouth of some 16 year old retard after watching F&F. You obviously don't understand simple physics.
mberndt said:
I know firsthand because I've owned both, so don't tell me...
Hell, you're engine is not even aluminum, does Chevy evn know aluminum exists? Oh I forgot, Aluminum was too expensive in the 60's when this engine was designed :clap ...
Ok. I guess it's about time to explain why you sound like such a "head up your ass" retard. My engine is COMPLETELY aluminum. As much as any engine could be. AND it was designed in 1996, more recently than your economy car's. The Chevy LS7 I previously mentioned has TITANIUM fucking connecting rods AND intake valves, you stupid waste of life. I never will understand why mouth breathers like yourself insist on speaking when they don't know SHIT about the subject at hand. You are so fucking stupid that you probably think I'm lying or something. You know NOTHING.
mberndt said:
As for the history, I don't really care that DOHC engines were around in 1910. How does it feel to know your engine is from the 1960's? :clap
How does it feel to be less intelligent than a bowl full of pubes?
mberndt said:
No matter what you say here, pushrod engines are not only outdated but are extremely inefficient.
I'll remember that next time I'm driving my Z06 and you're stuck in your economy car. Yep. I'll definitely be thinking about how inefficient this car is.
mberndt said:
Go watch some more Nascar and get off this forum, cause all your gonna get is SHUT DOWN :byye :byye
I watch Nascar about as much as you get laid (i.e. I haven't seen it in years). Go find a better hobby. Believe it or not, this one makes you look even more stupid than you probably are. And that's saying a lot.
 
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Sirfallsalot243 said:
Hondas do make more horsepower per liter, but that doesnt really matter if youre comparing a 1.8 to a 5.7L does it?
Pretty much.
But, that's what I get for being nice and trying to explain proper shift points.... ANOTHER no-brain fuckstick on a mission to "get the domestic guy". Makes me sick. Don't these motherfuckers read or something? There is NO excuse for being that ignorant.
 

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road.head said:
your arguing with the same guy who believes custom headers dont make any power. That should let you know of his intelligence.
Damn. Why hasn't he been neg repped by everyone on this board and/or banned? I hate idiots like this.
 

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ATISTANG said:
See that white car with a blue stripe down below? Theres one under that hood :ninja
I'm pretty sure that question was intended to be rhetorical. He's actually stupid enough to not expect an answer....
 
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