confused about power & torque on a couple of cars

[jamieduff1981]

danlightbulb said:

Martin_Hx said:

With 188hp the Honda wont be slow, i wouldn't get hung up about torque! You will not have to "rev the tits off it" to go 30mph to the shops

I can remap the saab though for a measily £80 and it will have 220bhp and 360nm of torque.

If the honda needs revving high to get the most out of it, wont that kill the fuel economy as well? Wheras more power out of the turbo engine at lower revs will help the economy?

Ive been looking for power curves for both cars but cannot find.

If you're generating torque, you're burning fuel. You don't save fuel with torquier engines in the real world, you just find you accelerate quicker everywhere you go. If you want to save fuel, don't accelerate so hard.

[danlightbulb]

TA14 said:

That's my vote as well. (IMHO for the SAAB, or any car, thinking that you can get a 50% increase in both power and torque and better mpg is living in dreamland.)

According to the remapper you do, and he has a very good reputation.

[TA14]

danlightbulb said:

TA14 said:

That's my vote as well. (IMHO for the SAAB, or any car, thinking that you can get a 50% increase in both power and torque and better mpg is living in dreamland.)

According to the remapper you do, and he has a very good reputation.

Well go for it then but don't come back on here crying.

jamieduff1981 said:

If you're generating torque, you're burning fuel. You don't save fuel with torquier engines in the real world, you just find you accelerate quicker everywhere you go. If you want to save fuel, don't accelerate so hard.

[Pablo16v]

danlightbulb said:

TA14 said:

That's my vote as well. (IMHO for the SAAB, or any car, thinking that you can get a 50% increase in both power and torque and better mpg is living in dreamland.)

According to the remapper you do, and he has a very good reputation.

But he would say that but my experience mapping a couple of diesels is improved economy is marginal at best. I also had a petrol SAAB 9-5 2.0t re-mapped from 150bhp to around 210-220bhp and I didn't see any improvement in economy.

[TA14]

Pablo16v said:

But he would say that but my experience mapping a couple of diesels is improved economy is marginal at best. I also had a petrol SAAB 9-5 2.0t re-mapped from 150bhp to around 210-220bhp and I didn't see any improvement in economy.

Absolutely - a 40% increase in power means more fuel will be used. (For small increases in power it is possible to have a balance of more power and better mpg by ignoring some of the OEM considerations like emissions and component life.)

[danlightbulb]

Pablo16v said:

But he would say that but my experience mapping a couple of diesels is improved economy is marginal at best. I also had a petrol SAAB 9-5 2.0t re-mapped from 150bhp to around 210-220bhp and I didn't see any improvement in economy.

But you didnt get a decrease though either? Thats the point. I am a bit concerned about the honda's low 29 mpg official figure which means the actual will be lower still, but dont want to turn this into an mpg thread.

[Super Slo Mo]

danlightbulb said:

Pablo16v said:

But he would say that but my experience mapping a couple of diesels is improved economy is marginal at best. I also had a petrol SAAB 9-5 2.0t re-mapped from 150bhp to around 210-220bhp and I didn't see any improvement in economy.

But you didnt get a decrease though either? Thats the point. I am a bit concerned about the honda's low 29 mpg official figure which means the actual will be lower still, but dont want to turn this into an mpg thread.

It will depend how you drive it. If you don't use the additional power, or take advantage of the improved mid range by shorter shifting, it probably won't make a lot of difference either way. If you do use the extra power you'll use more fuel.

I have some vague recollection that the car's on board computer might not be able to account for the remap in some cases too, so it might think it's better on fuel than it really is. I might have imagined that one though, you'd have to carry out back to back manual calculations to be sure.

[TA14]

Super Slo Mo said:

danlightbulb said:

Pablo16v said:

But he would say that but my experience mapping a couple of diesels is improved economy is marginal at best. I also had a petrol SAAB 9-5 2.0t re-mapped from 150bhp to around 210-220bhp and I didn't see any improvement in economy.

But you didnt get a decrease though either? Thats the point. I am a bit concerned about the honda's low 29 mpg official figure which means the actual will be lower still, but dont want to turn this into an mpg thread.

It will depend how you drive it. If you don't use the additional power, or take advantage of the improved mid range by shorter shifting, it probably won't make a lot of difference either way. If you do use the extra power you'll use more fuel.

I have some vague recollection that the car's on board computer might not be able to account for the remap in some cases too, so it might think it's better on fuel than it really is. I might have imagined that one though, you'd have to carry out back to back manual calculations to be sure.

Dan think this through for a minute. Everyone's saying the same thing on this page except you. Do you really think that an OEM couldn't produce a 50% increase in power and torque with no increase in fuel use but an £80 re-map can. I'd also hazard a guess that at the end of the market that you've mentioned on other threads reliability/servicing/parts/tyres etc. are going to be more significant costs than whether you get an extra 2 or 3 mpg.

[Steven_RW]

The diesel remap that makes more power and torque and mpg is not a myth.

Of course at 70mph on a constant throttle the amount of diesel required is constant before and after re-map so no fuel saving there.

What SEEMS to be the case is that having more immediately available power and torque (which uses more fuel for that period..) seems to mean you spend less time on throttle accelerating and overall you see a marginal improvement in fuel economy.

The tuner I have been close to for 20+ years is an utter cynic about ANY BS or any car claiming more bhp and lets a proper loaded rolling road tell the figures and the real world do the final test.

For some reason, even tho re-mapping a diesel car just means adding more fuel basically, he sees the increase in BHP on the rolling road that you would expect (maybe not the full claimed figure but more power) regardless of this, the owners without doubt on several long term examples are higher MPG on the remapped car. We are baffled and the only solution we can see is what I have detailed above.

The difference was 48 to 51mpg so a small amount and in itself not really worth measuring. But it was done over well controlled and very lengthy periods. Before re-map, after re-map then a year later remove re-map and it went back to the lower figure. Baffling huh.

My input on which car to own: TDI Saab - u won't dream of how awesome your engine is. Proper V-tec rev machine is a passionate piece of engineering and is exciting.

RW

[danlightbulb]

The 150bhp saab 9-3 is heavily detuned/restricted in stock form apparantly. The remapper has a good reputation ive no reason to doubt him. If using the power it will use more fuel i understand that. What i dont want is high fuel consumption just wafting around in mormal conditions.

[Mave]

Steven_RW said:

What SEEMS to be the case is that having more immediately available power and torque (which uses more fuel for that period..) seems to mean you spend less time on throttle accelerating and overall you see a marginal improvement in fuel economy.

That can't be the reason for reduced fuel consumption. If you start at speed 1 with "X" kinetic energy and end at speed 2 with "Y" kinetic energy, then the additional energy has to come from the fuel. (and if it means slightly more of your journey is spent at the higher speed then you use slightly more fuel due to the higher drag).
The only way to use less fuel is by converting it to torque more efficiently, so the mapper must changing some limits imposed by the OEM for some reason, that were having a detrimental impact on efficiency.

Edited by Mave on Friday 27th November 13:12

[Rich1973]

so you have spoken to a remapper, hypothesised about all sorts, raised a discussion about torque and driveability but not actually driven the cars yet.
Its all well and good theorising, but I can't help but come to the conclusion that you are seriously over thinking all of this.

[griffin dai]

alistairolsen said:

Ok, first of all, forget torque, power is ALL that matters, anyone who tells you otherwise doesn't understand.

Give me a car with more torque over power any day.

[SlowV6]

I think there are a few different arguments developing in this thread.
Noobs remap of the B205 engine is very effective. Those casting doubt on the claim should do some wider research or maybe just visit UKSaabs to validate owner's experiences.

The joy of the VTEC, and that is a great engine by the way and comes with a 6 speed box, is higher up the rev range. You'll want to enjoy it and you'll use plenty of fuel in the process! With the Saab lets face it the majority of owners are remapping for more poke and then proceed to enjoy that poke, so again you use more fuel.

I can't help thinking that if economy is a concern then neither the 2.0t or the 2.4 VTEC are your best bet. Neither is going to be stunning and over a normal annual mileage you are looking at +/- £200 a year difference in fuel, which is inconsequential. In this case I would get the one you want. They're chalk and cheese in terms of power delivery, though so you should drive both and decide.

Footnote - if you fancy a Saab, get a 9-5 Aero and then give Noob your £80 for a stage 1. Saloons can be had for SOTW money and 9-5's have at least some lineage back to proper Saabs.

Edited by SlowV6 on Friday 27th November 13:29

[danlightbulb]

^^ thanks. Don't want to turn this into a re-run of my previous thread so won't go any further on car choices.

I will be testing the VTEC on sunday. The problem is I can't test drive a remapped Saab 9-3 so am going off owners reports.

However I'm fairly sure I won't want to drive everywhere at 6k revs plus, and I am used to the low down torque of a diesel so that's why I'm thinking the mapped Saab will be a good middle ground between the two.

At a 29mpg quoted, I'm concerned I'll end up getting 25ish as opposed to low 30's in the Saab which is £40 per month more in fuel for me (£500 a year). Over two years of ownership that offsets the Saab which is a grand more to buy but also 4 years newer and lower mileage.

But Ive no doubt the Honda is the better quality car overall. Its bigger, better specced, looks nicer, probably drives better.

Edited by danlightbulb on Friday 27th November 13:52

[Super Slo Mo]

griffin dai said:

alistairolsen said:

Ok, first of all, forget torque, power is ALL that matters, anyone who tells you otherwise doesn't understand.

Give me a car with more torque over power any day.

Bit in bold for clarity.

The point being that to get more torque you need more power as the relationship between them is fixed. It really is that simple.

I'm sure it's teaching everyone to suck eggs, to coin a phrase, but torque at the flywheel doesn't directly translate into torque at the wheels, whereas power does, give or take a bit of loss through the drivetrain.

All the torque at the flywheel is telling you is how the engine is producing its power, a 'torquey' engine has more power at low revs, typically.

I'm grossly oversimplifying it, but given the amount of people that bang on about it without having much of a clue, it's probably time for one of the resident experts (i.e. not me ) to explain it in crayon.

[TameRacingDriver]

danlightbulb said:

^^ thanks. Don't want to turn this into a re-run of my previous thread so won't go any further on car choices.

I will be testing the VTEC on sunday. The problem is I can't test drive a remapped Saab 9-3 so am going off owners reports.

However I'm fairly sure I won't want to drive everywhere at 6k revs plus, and I am used to the low down torque of a diesel so that's why I'm thinking the mapped Saab will be a good middle ground between the two.

At a 29mpg quoted, I'm concerned I'll end up getting 25ish as opposed to low 30's in the Saab which is £40 per month more in fuel for me (£500 a year). Over two years of ownership that offsets the Saab which is a grand more to buy but also 4 years newer and lower mileage.

But Ive no doubt the Honda is the better quality car overall. Its bigger, better specced, looks nicer, probably drives better.

Personally I think you've already made up your mind...

Also a couple of other things to think about. You wont have to drive around at 6,000 rpm+ in the Honda. Yes you will need a different driving style, but its nothing that drastic. If you could put the engine sound on mute and change the numbers on the rev counter, it suddenly wont seem like you're really revving the thing any harder relatively speaking than anything else - e.g. if you typically change gear at 3000rpm in a diesel, that might be the equivalent of 5000rpm in a Honda. It just feels like you are thrashing it more because of the noise it makes.

Also Honda reliability is legendary. I'm not saying Saab's are unreliable, far from it, but I would say that unless unlucky, the Honda is likely to be the lower maintenance machine which is something to think about. Even more so if you're going to remap the Saab!

[alock]

griffin dai said:

alistairolsen said:

Ok, first of all, forget torque, power is ALL that matters, anyone who tells you otherwise doesn't understand.

Give me a car with more torque over power any day.

I can apply over 1000 lb-ft of torque to my wheels with a breaker bar when undoing wheel nuts. Torque is irrelevant without knowing the rate it is applied at.

[HustleRussell]

Danlightbulb- this is not a game of top trumps why are you always judging cars by numbers? It seems every time you post on here you're wittering on about statistics.

I guarantee that most of the time when you buy by numbers you'll end up with the wrong car.

If you're interested in a car, go and drive it. If you're interested in comparing two cars, drive both. It really is that simple.

[willmagrath]

Basically, HP = (Torque (ib-ft) X RPM)/5252.

So if you have little torque, you need more RPM's to make the power (Honda VTEC).

If you lots of torque but low RPM (diesel engine), you won't get us much power.