Horsepower vs. torque and engine size

[Runner27]

I'm a little bit confuse about how engine size and number of piston relate to horsepower and torque.

For example, a 2006 SR5 4Runner with a 4.0L 1GR-FE engine produces about 240 horsepower @ 5200 rpm and 266 lb·ft of torque @ 4000 rpm.

A 2009 Subaru legacy 2.5GT with a 2.5L engine (with turbo charger) has 265 horsepower @ 6000 rpm and 241 ft-lbs. @ 3600 rpm.

It seems that the legacy is more powerful than the 4Runner even though it has a smaller engine. I know to get the 265 hp, the rpm for the legacy is a bit high (6000 rpm) but that is not much higher than the 5200 rpm from the 4Runner.

So does the legacy has a much more efficient and powerful engine ?

However I have a feeling that if the legacy plays tug of war with the 4runner, there is no way the legacy can win.

 

[gaterose]

(with turbo charger)

There is your answer.

In most cases it has to do with tuning and other variables, but a turbo or supercharger is always gonna up the ante.

 

[450exc115]

HP is torque at RPM. Torque is the measure of force that the engine produces, HP is the power it produces which is torque times speed (with a conversion factor). Is a Legacy 2.5L turbo charged engine more powerful than a 4runner 4.0L V6.. Yes. But if you look at the hp and torque curve the V6 has more power for most of the RPM range. Or at least till the turbo hits full boost.....

I'd much rather tow and haul with the 4runner... And I owned a 350hp WRX....

 

[JeepWinch]

Run the same boost, same turbo as that legacy on your 1gr and you would be over 300HP with supporting mods. Its an apples to uh, steak comparison.

Essentially any form of forced induction will make a smaller engine act like a larger engine for over all HP numbers. So that turbocharged boxster 2.5L engine's overall "air movement" would be something like a semi tuned 1gr's would be with some airflow improvements to create similar HP #s.

The old saying goes "there is no replacement for displacement" and that holds true even with forced induction. You will always make more power on a larger displacement engine with everything being the same between two engines except displacement.


Hope this makes sense.

 

[rebelbowtie]

Run the same boost, same turbo as that legacy on your 1gr and you would be over 300HP with supporting mods. Its an apples to uh, steak comparison.

Essentially any form of forced induction will make a smaller engine act like a larger engine for over all HP numbers. So that turbocharged boxster 2.5L engine's overall "air movement" would be something like a semi tuned 1gr's would be with some airflow improvements to create similar HP #s.

The old saying goes "there is no replacement for displacement" and that holds true even with forced induction. You will always make more power on a larger displacement engine with everything being the same between two engines except displacement.


Hope this makes sense.

also not exactly true, internal combustion engine has come a LONG way with designs and materials used. with better understanding of fluid dynamics and variable valve timing, multiple cam shafts, more valves per cylinder etc. how else is it that a 4.7 liter N/A small block makes more power than 90% of the big block engines back in the 70s?

 

[JeepWinch]

also not exactly true, internal combustion engine has come a LONG way with designs and materials used. with better understanding of fluid dynamics and variable valve timing, multiple cam shafts, more valves per cylinder etc. how else is it that a 4.7 liter N/A small block makes more power than 90% of the big block engines back in the 70s?

I completely agree. Notice how I said "You will always make more power on a larger displacement engine with everything being the same between two engines except displacement."

I am an advocate of small turbocharged engines making big power. Trust me =)

 

[rebelbowtie]

I completely agree. Notice how I said "You will always make more power on a larger displacement engine with everything being the same between two engines except displacement."

I am an advocate of small turbocharged engines making big power. Trust me =)

as am i friendo

 

[Casper421]

To get your 4000lb+ suv moving, you need torque, low end power. Good luck moving your t4r with a 2.5T. The subi engine has the high end power(hp) while your t4r has low end. When was the last time you were at 4000+ rpm's in your 4runner?

 

[Runner27]

To get your 4000lb+ suv moving, you need torque, low end power. Good luck moving your t4r with a 2.5T. The subi engine has the high end power(hp) while your t4r has low end. When was the last time you were at 4000+ rpm's in your 4runner?

my 4Runner never goes past 2500 RPM, even when I was doing 80 on the highway.

what do you mean by high end/ low end power?

The subaru has roughly the same amount of torque at roughly the same rpm though.

 

[Runner27]

I have also heard from someone that bigger engine does not necessarily mean higher torque. High torque has something to do with gear ratio and transmission system. Is that true?

 

[Synister]

Interesting discussion. Its usually true that max HP is near redline and max torque is much lower in the usable RPM. This is why you sometimes hear the phrase 'HP sells cars but torque wins races'. The amount of time that any vehicle is likeky to spend generating max HP can probably be measured in minutes over the entire life of the car, however max torque is a daily experience for most. In the original comparison you looked at a 4.0l normally aspirated motor and a 2.5l forced induction system; great comparison actually. This illustrates how smaller, modern motors can be made to produce impressive numbers. I believe the 2.5l turbo would do fine in our trucks, maybe a slight ecm change for even lower torque but thats the beauty of turbo engines, totally software managed. Ford really stepped up big with their V6 EcoBoost motor as the premium engine choice in the best selling pickup in 'Merica, out performing even the 6.2 liter monster. The only hinderance is cost; its still a helluva lot cheaper to make and maintain a normal motor, turbos are very expensive as is developing engine mangement software. I hope more manufacturers follow Fords lead because who wants a V8 when you can get a boosted 6!?

 

[Atlanta_man]

I'm convinced that it is the high torque at stall that makes the hybrid/electric systems useful. No transmission needed to turn rpm into torque is helpful too. Locomotives like them for this reason also.

 

[galactic_04]

People say a they want horsepower but what they really feel is torque. I guarantee if you drive 2 cars with the same horsepower and one has 1.5x the torque on the lower rpm range, you'll appreciate the power much more.

I had a Jetta TDI that was pushing 275ft/Lbs at 1800RPM but only 135HP. I drove a Honda Civic SI brand new and told him it wasn't fast enough and the salesman was amazed. he said he thought the TDI was slow... problem was even with 65 more HP the Civic has NO TORQUE and was just plain slow. I was used to being able to shred 225/40 18's with no problem... I'm a big fan of torque...

Just FYI: with a N/A engine (no turbo ot supercharger) I'd go with a 2.5 V6 over a 2.5 4 cylinder any day. Designed properly, the V6 will always have more low end torque inherently.

 

[settytb]

@ galactic not true. Big cylinder inline engines have more torque than small multi cylinder engines...look at like the supercar v10-v12's they have no torque compared to their horsepower. The cummins diesel is an inline 6. hp is just torque x rpm. Notice the hondas make high horsepower but low torque numbers it's because they rev to 8k rpm. Where diesels make very low hp numbers because they don't rev high at all. But turbos make their max torque way lower than na engines so they are better off the line as well. There is some lag but modern variable vein turbos minimize the lag and maximize the torque. smaller turbos spool very quickly but tend to die out at high rpms. Big turbos have way more lag but make bigger boost/power at the higher rpms. If you want daily drivability go with a small turbo. If you want big dyno numbers throw a huge "snail" (turbo) on there But bigger displacement engines can spool bigger turbos sooner as they have more exhaust gases. A huge turbo'd big block will make way more than a turbo'd smaller engine. But turbos work great for fuel economy as well. It's just all in the tune so to speak. With a few mods you can make way more power out of a turbo than an NA engine. You can turbo any engine, you just want to lower the compression or if doing it on a stock engine run very low boost like <8psi and you should be alright.

 

[rebelbowtie]

comparing a turbo charged diesel engine to a N/A gasoline engine is an even worse comparision that the OP

 

[zerowkul98]

Im not going to pretend to act like i understand everything youre talking about, but oli DO get the general gist of it. What i WISH someone would help clear up is the argument (albeit a friendly one) i have with Toyota salesmen when i go in for routine service and they try to convince me to trade in my V8 4th-gens for a 5th gen Trail. My side is always this: Not until they put in the 4.6L V8 that they equip the Lexus has. They they say that the V6 it comes with has more torque blah blah.

What are you guy's take on that argument?

 

[rebelbowtie]

the torque needs to be lower in the powerband for a truck/SUV. you go mosey over to a Ford or GM forum and see complaints about the newest engines and their high HP/TQ ratings on paper. but because 400lbs of torque at 4500rpm doesnt tow a boat as well as 300lbs of torque at 2500rpm does.

 

[JB.]

Im not going to pretend to act like i understand everything youre talking about, but oli DO get the general gist of it.

If you ride a bicycle there's a really easy analogy. Pedal pressure is the torque and pedal speed is the horsepower. Try to get started in the highest gear and you can give max push to the pedals and for a moment the bike goes nowhere. The torque is there but it's wasted until it can go into motion. The faster the torque goes (the pedals) the more horsepower is being produced.

What i WISH someone would help clear up is the argument (albeit a friendly one) i have with Toyota salesmen when i go in for routine service and they try to convince me to trade in my V8 4th-gens for a 5th gen Trail. My side is always this: Not until they put in the 4.6L V8 that they equip the Lexus has. They they say that the V6 it comes with has more torque blah blah.

What are you guy's take on that argument?

The take is that it's a complete fabrication.

Both V8s have more peak torque and it's available much earlier.

It's true the dual-vvti V6 has more horsepower but it's only 10hp more than the vvti-V8 and wouldn't be felt until somewhere after 5000rpms.

All the info you need to call BS is in brochures or the owners manuals.


4.7-liter DOHC 32-valve EFI VVT-i V8 260 hp @ 5400 rpm/ 306
lb.-ft. @ 3400 rpm

4.0-liter DOHC 24-valve EFI dual independent VVT-i V6 270 hp @ 5600 rpm/278 lb.-ft. @ 4400
rpm

 

[kkz]

Im not going to pretend to act like i understand everything youre talking about, but oli DO get the general gist of it. What i WISH someone would help clear up is the argument (albeit a friendly one) i have with Toyota salesmen when i go in for routine service and they try to convince me to trade in my V8 4th-gens for a 5th gen Trail. My side is always this: Not until they put in the 4.6L V8 that they equip the Lexus has. They they say that the V6 it comes with has more torque blah blah.

What are you guy's take on that argument?

I'm going to guess and say Toyota doesn't want their premium stuff on their non-luxury vehicles.

The take is that it's a complete fabrication.

Both V8s have more peak torque and it's available much earlier.

It's true the dual-vvti V6 has more horsepower but it's only 10hp more than the vvti-V8 and wouldn't be felt until somewhere after 5000rpms.

All the info you need to call BS is in brochures or the owners manuals.


4.7-liter DOHC 32-valve EFI VVT-i V8 260 hp @ 5400 rpm/ 306
lb.-ft. @ 3400 rpm

4.0-liter DOHC 24-valve EFI dual independent VVT-i V6 270 hp @ 5600 rpm/278 lb.-ft. @ 4400
rpm

I think he meant this engine:

4.6 Liter
301 hp @ 5,500 RPM
329 lb-ft @ 3,500 RPM

 

[settytb]

It's more about bore and stroke...larger bore and longer stroke produce more torque but less peak rpms. Shorter stroke and smaller bore make more horsepower at higher rpms.