290 BHP seemed slower than it should - why?

Merrick Tinkling Coat

Merrick Tinkling Coat wrote: »

There is virtually no turbo lag in vag turbos, don’t know how this misconception keeps getting repeated.

U can't expect close to 300bhp from a boosted 4cyl without lag. Seriously.

Twin turboes still have lag.....and the GTi isn't twin turbo iirc.

unkel

Lag is far smaller than it used to be, but it's still there. The 0-30km/h times of modern turbo hot hatches would be appalling if they were ever measured (their turbos make up for it after though). The only way not to have any delay when accelerating is to have a very large normally breathing petrol engine. Or an EV.

Neilw

Augeo wrote: »

U can't expect close to 300bhp from a boosted 4cyl without lag. Seriously.

Twin turboes still have lag.....and the GTi isn't twin turbo iirc.

Have you driven or owned one? They have very little lag and boost from very low in the rev range, dsg also helps.

LillySV

beauf wrote: »

The cupra is 0-62 of about 5.6 secs
The BMW is 0-62 of about 7.0 - 10.4sec (different models)

No idea which model you are talking about.

But that people think a car with 0-62 sub 6 secs is not fast makes me wonder have people become desensitized to speed, or just never drive them on a decent drivers road.

The figures above are wrong... there is beamers doing similar times ...the 330e for example.... but anyways I would t base buying a car on the 0-60... I’d prefer grunt the whole way through the rev range and good handling

pippip

LillySV wrote: »

The figures above are wrong... there is beamers doing similar times ...the 330e for example.... but anyways I would t base buying a car on the 0-60... I’d prefer grunt the whole way through the rev range and good handling

They're not wrong, we're only comparing times of the x1 in the OPs post. Of course there's faster BMWs than 7sec

DaveyDave

I haven't noticed any lag in my 1.0 TSI. The turbo is on boost at 2,000rpm but you wouldn't even notice. There's no lack of power between 1,000-2,000rpm and anything above that isn't an obvious increase. The only thing that's obvious is the peak power at 5,000-5,500rpm.

I can't comment too much about the 2.0 TSI as I've spent just over an hour in the Cupra. I didn't notice anything immediately obvious about the bigger turbo kicking in.

TheAnalyst_ wrote: »

Lot of these VAG cars have a lazy throttle response which can make a big difference to the feel of acceleration.

It's definitely just the dull accelerator. The delay is the drive mode, not turbo lag. Throw it in Sport/Cupra mode and the throttle is immediately responsive. Sport mode even does wonders for my 110hp Golf.

It's the same with supercars, you need track mode to get the aggressive acceleration out of a 458 or Huracan, otherwise they'll be fairly tame and easy enough to cruise around in despite being 550hp+.

endacl

U_Fig wrote: »

Torque = Acceleration
BHP = Top speed

BHP = How fast you hit the wall.
Torque = How much of the wall you take with you.

Mike9832

endacl wrote: »

BHP = How fast you hit the wall.
Torque = How much of the wall you take with you.

All far too complicated

Everything being equal eg weight, tyres, 4wd drive system, transmission etc a car with more bhp is always faster

Example

An F1 car with 1000bhp/500nm will be way faster than an F1 car with 750bhp/5000nm

Torque don't mean **** with everything else being equal

You ever hear F1 drivers/teams etc talk about being down 200nm of torque compared to other teams, no.They don't care

It's bhp that counts, if they are down even 50bhp, it's game over, can't compete in a straight line

Look at Honda woes by being down only 50bhp few years ago

https://www.autosport.com/f1/news/129486/alonso-honda-still-lacks-more-than-50bhp

Same in the real world

Golf Gti with 350bhp/350nm is way faster than 200bhp Golf Gti with 10 million pound foot of torque

Neilw

Neilw wrote: »

Have you driven or owned one? They have very little lag and boost from very low in the rev range, dsg also helps.

I had a gti for 4 days in Germany....i averaged 26mpg iirc.
So I gave it plenty right foot.
I wouldn't buy one TBH....i couldn't justify the outlay on a car that size (physically not engine wise).

I thought the fwd drivetrain wasn't ideal for 150mph plus capability and the associated power etc etc. The awd seat offering would be preferable IMO.

As I said, theres lag....you say very little lag....both statements can co exist but I think folk who own them are very rose tinted in their appraisals.

unkel

Mike9832 wrote: »

You ever hear F1 drivers/teams etc talk about being down 200nm of torque compared to other teams, no.They don't care

It's bhp that counts

It is indeed BHP that counts, but only if you are doing the revs that have the max level of BHP available. That's easy in F1 as the engines idle at about 6,000rpm

A modern turbo petrol hot hatch doesn't have the max BHP available until about 5,500rpm. Doesn't even have max torque until about 1,800rpm. And it idles at about 700rpm

It takes a long time to get from 700rpm to 1,800rpm let alone 5,500rpm. Lag.

DaveyDave

DaveyDave wrote: »

I haven't noticed any lag in my 1.0 TSI. The turbo is on boost at 2,000rpm but you wouldn't even notice. There's no lack of power between 1,000-2,000rpm and anything above that isn't an obvious increase. The only thing that's obvious is the peak power at 5,000-5,500rpm.

I can't comment too much about the 2.0 TSI as I've spent just over an hour in the Cupra. I didn't notice anything immediately obvious about the bigger turbo kicking in.



......110hp Golf.

......

You've a 1 litre with a small turbo. The lag isn't noticeable as the power that comes after it isn't all that noticeable either.

No lack of power before it kicks in (your words) and no obvious increase when it does (your words again).

unkel

unkel wrote: »

....
A modern turbo petrol hot hatch doesn't have the max BHP available until about 5,500rpm. Doesn't even have max torque until about 1,800rpm. And it idles at about 700rpm

It takes a long time to get from 700rpm to 1,800rpm let alone 5,500rpm. Lag.

Indeed....i mentioned the gti comes into it's own when going fast but the fanboys won't have any of that :pac:

DaveyDave

Naturally aspirated cars are the same. Every car has to go up in the revs for peak power.

There's no question turbo lag exists to some extent. The question is it is noticeable? Put the foot down in a VAG and it will go. You aren't waiting around for anything and it isn't going to kick you in the back. The likes of a McLaren MP4-12C has very obvious turbo lag as you put the foot down and not much happens then there's a sudden surge of power at 3,000rpm whereas the NSX is much smoother, both twin turbo.

LillySV

pippip wrote: »

They're not wrong, we're only comparing times of the x1 in the OPs post. Of course there's faster BMWs than 7sec

What u on about? Who mentioned an x1? Is there even such a thing? So we not comparing liters or fuel types? This is the biggest load of nonsense bull****e I’ve ever read... I’ve read loads of bolox talk up to now and I think I’ve reached my max. Time to unfollow... best of luck op, choose what u like

unkel

DaveyDave wrote: »

Naturally aspirated cars are the same. Every car has to go up in the revs for peak power.

They have it a lot less. My Porsche 928 (5l V8) had just under 300Nm torque at idle. A modern hot hatch gets that too, but not until close too 1,800rpm

The difference is lag vs no lag

pippip

LillySV wrote: »

What u on about? Who mentioned an x1? Is there even such a thing? So we not comparing liters or fuel types? This is the biggest load of nonsense bull****e I’ve ever read... I’ve read loads of bolox talk up to now and I think I’ve reached my max. Time to unfollow... best of luck op, choose what u like

Ffs you have some attitude on here.

Sorry 1 series not x1, my point/post is exactly the same.

unkel

unkel wrote: »

They have it a lot less. My Porsche 928 (5l V8) had just under 300Nm torque at idle. A modern hot hatch gets that too, but not until close too 1,800rpm

The difference is lag vs no lag

You aren’t going to be sitting at idle if planning a fast start though you are going to have the revs built up and the turbo spoiling and as the turbos spool at low rev’s in vag turbos this is quite easy to do.

...... Standing start with turbo spooling means wheel spin or traction control kicking in. But sure if the lag is so tiny and the VAG stuff pulls like fook anyway why would you be building revs and all that :pac:

VAG turbos spool at the same revs as any other equivalent car.

grogi

unkel wrote: »

It is indeed BHP that counts, but only if you are doing the revs that have the max level of BHP available. That's easy in F1 as the engines idle at about 6,000rpm

A modern turbo petrol hot hatch doesn't have the max BHP available until about 5,500rpm. Doesn't even have max torque until about 1,800rpm. And it idles at about 700rpm

It takes a long time to get from 700rpm to 1,800rpm let alone 5,500rpm. Lag.

That's not turbo lag...

unkel

Merrick Tinkling Coat wrote: »

You aren’t going to be sitting at idle if planning a fast start though you are going to have the revs built up and the turbo spoiling and as the turbos spool at low rev’s in vag turbos this is quite easy to do.

Yes fair enough. You can overcome turbo lag that way. Bit of a high blood pressure way to live though, isn't it? And revving your car like a dick while waiting sometimes for several minutes at every traffic light would not really be in my comfort zone either.

In a large petrol engined car or in any EV, you just put your foot down at any time and off you go. No need for any preparations like that.

grogi wrote: »

That's not turbo lag...

Yes of course it is. The very small petrol engine has only a tiny amount of torque until the turbo gets into its zone so it can boost the torque to serious levels. Which doesn't happen until about 1,800rpm. The time it takes from the engine idling until the engine revs at that speed is lag. But maybe you can explain it better than I did?

Zak Flaps

LillySV wrote: »

What u on about? Who mentioned an x1? Is there even such a thing? So we not comparing liters or fuel types? This is the biggest load of nonsense bull****e I’ve ever read... I’ve read loads of bolox talk up to now and I think I’ve reached my max. Time to unfollow... best of luck op, choose what u like

https://www.hse.ie/eng/health/az/a/anger-management/

tuxy

djan wrote: »

The thing that pushes you into the seat is torque and not BHP, this is what diesel engines excel at as they have much more of it and a lot earlier in the rev range (which is also way narrower). For a petrol you have to rev it much higher, at around 4k rpm it will be flying. It might not feel faster but it most definitely is.

Is that why tractors have special seats? It must be difficult for farmers to deal with all the torque those machines have.
Something fairly standard like a New Holland T7 has 1476nm!

Zak Flaps

OP here. Thanks all for your input.

What I'm after is a vehicle with low end torque. Something that you can give a little throttle at 1500 rpm and really feel it. I want to have fun, but within the speed limit !! It's mostly city driving I do.
Regarding the Cupra I mentioned at the beginning, I probably didn't rev it high enough to feel that power lots of you referred to here.
But I have no interest in going near 8000 RPM.

So any suggestions would be very welcome and appreciated. Petrol or Hybrid.

tuxy

Electric it is then!

unkel

unkel wrote: »

Yes fair enough. You can overcome turbo lag that way. Bit of a high blood pressure way to live though, isn't it? And revving your car like a dick while waiting sometimes for several minutes at every traffic light would not really be in my comfort zone either.

In a large petrol engined car or in any EV, you just put your foot down at any time and off you go. No need for any preparations like that.



Yes of course it is. The very small petrol engine has only a tiny amount of torque until the turbo gets into its zone so it can boost the torque to serious levels. Which doesn't happen until about 1,800rpm. The time it takes from the engine idling until the engine revs at that speed is lag. But maybe you can explain it better than I did?

You never drive at idle though, every time you pull off from a standing start you have the car rev’d up a certain amount in a vag turbo even the most sedate pulling out of junction slowly you are in the turbo there is no high blood pressure. I’d have any petrol car up from 1500 to 2k revs pretty much every single time I start off and that has a turbo spooling but I’m not reving to spoil the turbo that’s just how you start off in a car you always rev up.

If you are really going for a fast start you would build revs more but it just feels normal to me, no high blood pressure and you would build revs like that in any car if doing a fast start even a big engined na.

Personally I prefer the turbo power delivery to a bigger engined NA.

Midnight_EG

unkel wrote: »

Yes of course it is. The very small petrol engine has only a tiny amount of torque until the turbo gets into its zone so it can boost the torque to serious levels. Which doesn't happen until about 1,800rpm. The time it takes from the engine idling until the engine revs at that speed is lag. But maybe you can explain it better than I did?

That's not lag, that's boost threshold

kirving

Deleted User wrote: »

You can't pull without power (since power is rate of work), and torque is force not power. Remember what I said about plain wrong?

Correct, you can't pull at all without power. But you do not necessarily need high power to be able to pull hard, and give a feeling off acceleration. As I said in the last line of my post, most people judge a cars performance on how quickly it can accelerate off the line at low revs. And may be why someone can think a diesel feels faster than it is.

Deleted User wrote: »

Using that analogy just demonstrates that you don't fundamentally understand what the terms torque/hp represent.

I do understand what they mean, and have the piece of paper to prove it.

(It's not incorrect analogy either. Heavy load on the end of a shovel needs more torque to lift it, and more power = more work done in a given time.)

Deleted User wrote: »

Torque is rotational force. Stop using analogies to try get around understanding what that actually means :rolleyes:

Torque and Power can be difficult concepts to understand and explain, as power is dependant on torque, but cars with the same power don't necessarily have the same torque, and vice versa.

Repeating "torque is rotational force" doesn't make it any easier for someone to understand, and so an analogy isn't the worst way of getting the point off paper sheet and into someones head.

grogi

unkel wrote: »

Yes of course it is. The very small petrol engine has only a tiny amount of torque until the turbo gets into its zone so it can boost the torque to serious levels. Which doesn't happen until about 1,800rpm. The time it takes from the engine idling until the engine revs at that speed is lag. But maybe you can explain it better than I did?

No, it isn't. Turbo lag is a caused by inertia of the rotating parts in the turbocharger.

Imagine following situation: you are coasting down the hill breaking with the engine. You get a constant 3000 rpm out of it, right in the middle of the peak power. There is no air getting into the cylinders, there is not no fuel being burned, there is no exhaust gasses being pumped out. Turbo sleeps. If you press the throttle, the engine needs to suck some air alone, burn some fuel, exhaust some to spin the turbo... There is a delay before the turbo gets enough speed from the combustion and starts pumping air. That is turbo lag. The bigger the turbo, the longer it will take for it to get to operation revolution speed.

Modern petrol engines have very small turbos and the turbo lag is eliminated almost completely. Of course, they will never have* the feel of an EV or N/A engine, but it isn't really bothersome. Diesels have bigger turbos and must employ different techniques to minimise the lag - two separate turbo chargers (one small - to spin almost instantly, one big to provide massive amount of air), twin scroll turbos, variable geometry turbos etc.

* There are technological advances that help to make them even more responsive: racing cars would inject fuel even if there was no load on the engine to keep the turbo spinning. Modern cars might try to blend electric power with the turbocharged engine to get instant response (exp. McLaren P1 or Porsche 918). AFAIR it was Valeo who is working on electrical ways for keeping the turbo chargers spinning and electric superchargers.

grogi

Kevin Irving wrote: »

Repeating "torque is rotational force" doesn't make it any easier for someone to understand, and so an analogy isn't the worst way of getting the point off paper sheet and into someones head.

The figure of maximal torque is completely irrelevant when it comes to acceleration.

What matters is power. From definition: velocity ~ kinetic energy. Increase the velocity and you increase kinetic energy. The rate at which the kinetic energy increases is called power...

But don't confuse the maximal power (quoted in the brochures) with instantaneously available power that you can use to accelerate. If you are driving relaxed at certain speed, you are not going to put the engine in the spot where it can output maximum power. It will be much lower - and while costing on the same gear diesel will typically have more power... (red = diesel, green = petrol)



More read here: https://www.boards.ie/vbulletin/showthread.php?p=107472156?

DaveyDave

What kind of driving are people doing where they need near peak power at low revs or enough torque to move a 40ft trailer?

If the low end acceleration isn't enough, put it in Sport mode. If that isn't enough install a pedalbox. If that isn't enough, why are you looking at a small turbo petrol engine in the first place?

This goes beyond GTI fanboys rose tinted glasses, VAG cars or even small petrol engines. I don't know why you would even entertain the idea of a Cupra. Try a Scania R650...