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Jay Bamrah

Can you increase HP without increasing torque

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I was reading a post about how torque kills our engines and have been researching torque and horsepower and it made me think.

when someone remaps a car and gains 50HP I understand how they can inject more fuel and air to make more torque but how can you make your motor work faster to make more horsepower.

 

surely you’re only making more torque but with the same RPM range and piston length(rotation speed) the horsepower doesn’t change, the only reason horsepower increases is  torque x time=HP and torque got larger ?

 

I guess what I’m trying to say is that when people tune cars are they just increasing torque and horsepower is a byproduct

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Power is torque x speed (with a multiplier if you're not using Nm and radians/sec), not torque x time.

So, at a given engine rpm, if you increase the torque, you will also increase power at that rpm. When you see dyno graphs, they use rpm as the x-axis (along the bottom), and both torque and power on the y-axis. If you pick a certain rpm - say 4000rpm - the engine will make a certain torque, and as a result of that, a particular power. If you increase the torque at 4000rpm (by tuning), you'll have more power at 4000rpm.

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42 minutes ago, spikyone said:

Power is torque x speed (with a multiplier if you're not using Nm and radians/sec), not torque x time.

So, at a given engine rpm, if you increase the torque, you will also increase power at that rpm. When you see dyno graphs, they use rpm as the x-axis (along the bottom), and both torque and power on the y-axis. If you pick a certain rpm - say 4000rpm - the engine will make a certain torque, and as a result of that, a particular power. If you increase the torque at 4000rpm (by tuning), you'll have more power at 4000rpm.

What does torque x speed mean? Does speed = rpm in that case?

 

from what you and Martin said it sounds like what I said was right in the sense that when you tune a car all you do is increase torque and since you have more torque per engine cycle you get more HP?

 

The reason I ask this is because I know torque kills our engines due to the diagonal rods prone to bending, so I was Googling if we can get more horsepower but without getting loads of torque

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It sort of means rpm; rpm is a non-standard unit, so to do torque x speed = power, you have to use:

Torque in Nm

Speed* in radians per second

Power in Watts

You can do a calculation using other units (e.g. rpm for speed) but you have to use a conversion factor to correct it.

 

To get more power, you would generally want more torque, yes. However you can also achieve it by changing where the peak torque occurs, depending on the engine characteristics. So if you had peak power at, say, 4000rpm, it might be that your torque drops off at higher rpms. You might be able to increase the torque at 6000rpm so that it's the same torque you previously made at 4000rpm: in that case your peak torque figure hasn't changed, but because it occurs at a higher rpm you'll make a higher power. It will mean that instead of making peak power at 4000rpm, you'd make peak power at 6000rpm. Hopefully that makes sense...

If your car is tuned properly with forced induction, you won't be in a situation where you can add more power by changing the shape of the torque curve though. Peak power for these engines is very high in the rev range and the torque curve should be fairly flat in that region.

Just my opinion here, but a GT86 with nearly 300bhp (as you'd get with forced induction) is pretty quick. To get that power, with appropriate suspension/brake upgrades, is going to cost £8-10k. If you really want more than 300bhp you'd be better off selling the GT86 and buying something else.

 

(*As a note, "speed" is actually angular velocity, but I thought that was even more confusing!)

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3 minutes ago, spikyone said:

It sort of means rpm; rpm is a non-standard unit, so to do torque x speed = power, you have to use:

Torque in Nm

Speed* in radians per second

Power in Watts

You can do a calculation using other units (e.g. rpm for speed) but you have to use a conversion factor to correct it.

 

To get more power, you would generally want more torque, yes. However you can also achieve it by changing where the peak torque occurs, depending on the engine characteristics. So if you had peak power at, say, 4000rpm, it might be that your torque drops off at higher rpms. You might be able to increase the torque at 6000rpm so that it's the same torque you previously made at 4000rpm: in that case your peak torque figure hasn't changed, but because it occurs at a higher rpm you'll make a higher power. It will mean that instead of making peak power at 4000rpm, you'd make peak power at 6000rpm. Hopefully that makes sense...

If your car is tuned properly with forced induction, you won't be in a situation where you can add more power by changing the shape of the torque curve though. Peak power for these engines is very high in the rev range.

Just my opinion here, but a GT86 with nearly 300bhp (as you'd get with forced induction) is pretty quick. To get that power, with appropriate suspension/brake upgrades, is going to cost £8-10k. If you really want more than 300bhp you'd be better off selling the GT86 and buying something else.

 

(*As a note, "speed" is actually angular velocity, but I thought that was even more confusing!)

Yeah this makes much more sense now thankyou for this, I want more power but I do not want to be in the 300s I want reliability so 270hp is okay for me. I am not sure what torque the engine can handle… eveeyone says 300HP but really they should be talking about what torque the rods can stand.

some people I have spoken to said rods bend by accelerating hard at low rpm in a high gear but at low rpm u have no torque so you can argue otherwise here. What’s your take on it

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300bhp is based on mapping for the best possible torque curve. There's no way to get over 300bhp without adding more torque, and most people are interested in power output rather than torque output so it makes sense to say 300bhp as a limit.

I think it's probably more a case of how you drive in low gears vs high gears that leads to the perception of higher gears being the issue. In short, if you're using all the torque, and the torque is too high, you'll bend a rod.

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Yeah this makes much more sense now thankyou for this, I want more power but I do not want to be in the 300s I want reliability so 270hp is okay for me. I am not sure what torque the engine can handle… eveeyone says 300HP but really they should be talking about what torque the rods can stand.
some people I have spoken to said rods bend by accelerating hard at low rpm in a high gear but at low rpm u have no torque so you can argue otherwise here. What’s your take on it
Since you are googling up, Google LSPI ( Low Speed Pre Ignition) and you will get why people say that. It comes back to peak cylinder pressures like the post from Mark yesterday.

Low speed pre-ignition (LSPI) is a premature combustion event, occurring prior to spark ignition in turbocharged, downsized gasoline vehicles. As the name implies, it occurs when engines operate at low speeds and high loads. It can result in extremely high cylinder-pressures and can lead to heavy knock. At a minimum, LSPI can generate an audible knocking noise noticeable to the driver. Repeated exposure to these conditions can cause engine hardware failure, including broken spark plugs and cracked pistons

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And as@spikyone said, it's probably better to buy a faster, more powerful car as there is always an element of risk with going with mods that take the factory numbers up substantially by 30 to 50% ( 260 to 300 bhp).

You need to be ready to take the risk and agree that the overall life of the car / platform will be reduced as it adds an amount of stress on all components from transmission to clutch to Differential to everything in between . Its just luck for how long and whether that meets your personal driving style and needs and you take on the additional wear and tear.

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9 hours ago, spikyone said:

300bhp is based on mapping for the best possible torque curve. There's no way to get over 300bhp without adding more torque, and most people are interested in power output rather than torque output so it makes sense to say 300bhp as a limit.

I think it's probably more a case of how you drive in low gears vs high gears that leads to the perception of higher gears being the issue. In short, if you're using all the torque, and the torque is too high, you'll bend a rod.

Is your car FI?

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most people are interested in power output rather than torque


I have no interest in power. Torque is real-world driveability and the only parameter that matters to me.

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Just now, MartinT said:


 

 


I have no interest in power. Torque is real-world driveability and the only parameter that matters to me.

Sent from my Oppo X3 using Tapatalk
 

 

What’s your HP and what’s your torque? And what mods do u have to achieve them?

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1 hour ago, Jay Bamrah said:

What’s your HP and what’s your torque? And what mods do u have to achieve them?

284nm peak but fairly flat torque curve. Rogue Motorsport EL manifold, Harrop supercharger.

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10 minutes ago, MartinT said:

284nm peak but fairly flat torque curve. Rogue Motorsport EL manifold, Harrop supercharger.

Oh damn 284 that’s a lot and ur rods haven’t bent? How long have u had that setup 

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20 hours ago, MartinT said:

I have no interest in power. Torque is real-world driveability and the only parameter that matters to me.

 

Then you'll be wanting an automatic gearbox and a truck engine. Not especially sporty, but you can spin the tyres right off! I expect you could get a boxer diesel in the engine bay if you really wanted... however I agree that low torque performance engines can be hard work, and not especially good at daily use, having owned a series of high revving engines.

On the original topic @Jay Bamrah it is disproportionately expensive to tune for NA peak power without increasing cylinder capacity. The "famous" NA engines all have ambitious red lines, complex adjusting intakes, fully variable valve timing and really strong engineering around the camshafts. That stuff doesn't come cheap!

If you soak in some of the press around engines like the Porsche block in the 911R, Gordon Murray's Cosworth unit, the Ferrari 458 V8, Honda's F20C, Mazda's Renesis you really get a sense of how hard it is to get more power when you can't make the flame front any faster. Anyone (sort of) can add boost pressure and fuel, but it takes bespoke engineering to raise the redline usefully and not completely ruin the engine for regular use. The FA20 is a pretty good but not exceptional NA engine at just under 100 bhp/L, but it's a much easier normal drive and more efficient than the F20C that just about squeaks 120 bhp/L.

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3 hours ago, nerdstrike said:

Then you'll be wanting an automatic gearbox and a truck engine. Not especially sporty, but you can spin the tyres right off! I expect you could get a boxer diesel in the engine bay if you really wanted... however I agree that low torque performance engines can be hard work, and not especially good at daily use, having owned a series of high revving engines.

On the original topic @Jay Bamrah it is disproportionately expensive to tune for NA peak power without increasing cylinder capacity. The "famous" NA engines all have ambitious red lines, complex adjusting intakes, fully variable valve timing and really strong engineering around the camshafts. That stuff doesn't come cheap!

If you soak in some of the press around engines like the Porsche block in the 911R, Gordon Murray's Cosworth unit, the Ferrari 458 V8, Honda's F20C, Mazda's Renesis you really get a sense of how hard it is to get more power when you can't make the flame front any faster. Anyone (sort of) can add boost pressure and fuel, but it takes bespoke engineering to raise the redline usefully and not completely ruin the engine for regular use. The FA20 is a pretty good but not exceptional NA engine at just under 100 bhp/L, but it's a much easier normal drive and more efficient than the F20C that just about squeaks 120 bhp/L.

Thanks man thats a lot of info And makes a lot of sense 

 

Just out of curiosity is your fa20 FI? 

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3 hours ago, nerdstrike said:

... The FA20 is a pretty good but not exceptional NA engine at just under 100 bhp/L...

you left out important variable out of equation. Those "exceptional" NA engines with even higher specific power output per volume, were way less strangled by modern eco emission standards. I'm certain that be it now, those wouldn't be that "exceptional". If even Honda, maker of (in my eyes) best inline-4 engines "gave up" and went for turbo in latest type-r generations, should speak a lot about it. Now only supercar makers can still afford to develop/make "exceptional" NA engines comparable to those in past.

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On 8/8/2021 at 3:28 PM, MartinT said:

I have no interest in power. Torque is real-world driveability and the only parameter that matters to me.


Sent from my Oppo X3 using Tapatalk
 

 

What I meant was, nobody goes to their tuner and asks for a certain amount of torque; nor do they say "what a lovely car, how much torque does it make?". People talk in terms of how much power their car makes, so equally it makes sense for tuners to specify a certain power output as being safe.

I'll also say that torque doesn't matter per se; that's what a gearbox is for. The shape of the torque curve is what matters more (see the infamous torque dip). If you're sacrificing a flat torque curve to increase your peak torque, you'll end up with an engine with a drop-off somewhere in the rev range - it will either feel peaky or asthmatic.

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I agree, but when I went to Abbey and spoke to Mark, it was torque that I wanted and discussed with him. Power then became a by-product of the conversation.

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7 minutes ago, MartinT said:

I agree, but when I went to Abbey and spoke to Mark, it was torque that I wanted and discussed with him. Power then became a by-product of the conversation.

Sent from my Oppo X3 using Tapatalk
 

How does your stock internals handle 284 torque so far? - EDIT - oh I already asked my bad lol 

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4 hours ago, Jay Bamrah said:

How does your stock internals handle 284 torque so far? - EDIT - oh I already asked my bad lol 

The only failure has been the clutch, but it did last a year after the supercharger had been installed.

I've had an Exedy stage 1 clutch installed and that has been perfect.

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3 hours ago, MartinT said:

The only failure has been the clutch, but it did last a year after the supercharger had been installed.

I've had an Exedy stage 1 clutch installed and that has been perfect.

So one year later on 284nm torque ur rods are fine. Tuning developments turbo gets 235nm torque so I should be also so long as I’m not stupid 

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1 hour ago, Jay Bamrah said:

So one year later on 284nm torque ur rods are fine. Tuning developments turbo gets 235nm torque so I should be also so long as I’m not stupid 

I think TD Turbo makes c.230lb.ft, so >310nm. Something worth considering..or it was around that when I looked at both options. My spec is similar to Martins, slightly lower as I'm running stock manifold with 2nd cat delete, with Harrop SC.

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29 minutes ago, AndyK said:

I think TD Turbo makes c.230lb.ft, so >310nm. Something worth considering..or it was around that when I looked at both options. My spec is similar to Martins, slightly lower as I'm running stock manifold with 2nd cat delete, with Harrop SC.

Interesting as I'm running 1st cat delete with stock 2nd cat.

The Harrop is a nice bit of kit, isn't it?

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