turbo lag

[theballboy]

Any inofrmation out there on which cars suffer worst from turbo lag?
And as a matter of interet, does a remap have any effect on the lag - ie reduce it
cheers

[HDi fun]

Turbo lag is not to be confused with turbo spool up delay.

The question is a bit open, if not truly ambiguous.

All turbocharged cars will suffer from a degree of lag. Whether this is noticeable or significant is another matter. It's also very subjective, depending upon the driver's expectations.

Car makers have got turbocharging down to a very fine art (fine science, perhaps) nowadays.

Remapping will never alter turbo lag or spool up time directly, both are by-products of the way that turbo-supercharged engines work, but tuning can provide work arounds of sorts to make it less intrusive.

Some people drive turbocharged cars almost expecting to find lag and latency. When it [turbo lag] is not there in obviously discernible measures it can give the impression to the driver that the car is not a lively as it actually is.

A crudely turbocharged car such as a mid-1980s Montego Turbo leaves you in no doubt that it is turbocharged. Is this a good thing?

Well, yes, subjectively speaking, if you really need reminding that your car is turbocharged.

Personally, I prefer the imperceptible build in torque delivery from idle speed which is the trademark of modern turbo-supercharging.

NB - turbochargers are a subset of superchargers - the turbo bit of the word simply tells us that the compressor is exhaust driven rather than being directly mechanically driven.

[waynne]

The EVO FQ400 has a lot of lag, but also makes a lot of power! A lot depends where you want the power to be.

Remaps can make engines seem less laggy by changing the wastegate and boost control to encourage early spooling. In reality this is more of an impression than a real lag removal.

I don't really know of a modern car which suffers from noticable lag. Diesels in particular have loads of low down torque and as this is posted in the diesel forum I guess you are talking from a diesel point of view.

So where do you like your power to be, what are your typical journeys and loads, and we'll come up with a shortlist of cars for you

[HDi fun]

Wastegates are often now only employed as secondary devices. Variable vane geometry is the key to the lagless driveability of modern turbo engines.

Of course, more is generally better, many makers now use assymetric turbos, small to get it going and a big one for an almighty shove nce underway. The engine management ensures a seamless changeover.

Engines such as these deliver enormous power and torque outputs.

[theballboy]

Well, I am essentially looking to change my car in the spring / easter and have been researching for quite a while. I am interested in the 170 tdi passat but read in a number of owners reviews about the turbo lag as a particular issue. This led me to start to question if there exists a difference between manufacturers and whether or not I would even have to consider it since a remap will def be on the cards for the car and therefore might eradicate the issue.

If the lag that applies to the 170tdi passat applies to all the 170 pd tdi vag models then that then applies to my other contenders, a4 / octavia vrs /

As a driver I enjoy the low down torque but torque in genereal which is why i love the diesels - especially for the economy trade off.

[HDi fun]

A remap can offset some of the symptoms of lag. It will not cure the causes.

[theballboy]

Well offset is something then.
appreciated

[pgarner]

certian the vag crdi uses a VNT turbo so lag should be next to nothing.
the vanes may be sticking on those that are used as motorway cruisers, prob over half the passats sold are fleet, its a relativity simple job apparently take off intake pipe and use some penetrating oil before working the actuator

[pgarner]

certian the vag crdi uses a VNT turbo so lag should be next to nothing.
the vanes may be sticking on those that are used as motorway cruisers, prob over half the passats sold are fleet, its a relativity simple job apparently take off intake pipe and use some penetrating oil before working the actuator

[waynne]

I can only really say drive one. Often these reviewers are petrol heads, they jump in a diesel and don't really get it!

I don't think you will be dissapointed in the least. Have a chat with your local VW garage and take one out for a spin.

[HDi fun]

I think a lot of the petrol heads don't want to get it.

[Aerial Andy944]

I drive a 56 plate Golf 170 TDI DPF and can't say there is any 'lag' in the turbo, it spools up very quickly low down at around 1300 revs I would say. Maybe the Passat is a little heavier so could have an effect but I can't see why it's the exhaust gas that drive the turbo isn't it? Alternatively my 20 year old 944 turbo had a real time delay between mashing the loud pedal and the turbo actually spooling up. Replace wastegate, boost enhancer and controller, 3"turbo downpipe and full exhaust system and a remap worked wonders. Spools up sooner holds for longer at 18psi boost instead of factory 12psi so way better to drive all round.

All the VAG TDI cars I've driven recently have been fine except the new weedy 1.6 tdi Golf because that only has a 5 speed box and long gearing.

[theballboy]

Originally Posted by Aerial Andy944

I drive a 56 plate Golf 170 TDI DPF and can't say there is any 'lag' in the turbo,

Great, how would you rate the engine for power / torque yourself. FOr example Im driving a 130 tdci remapped to around 155 id say. SHould I expect to see much more improvement?

Cheers
THanks also for other responses

[theballboy]

also , what do you guys think about the mondeo st for power?

I mean in comparison to the 170 VAG. Am I right in saying that its not all about BHP but that nm and lb per ft count alot too.

example
VAG - 170bhp
340 nm
256lb-ft

but
st - 155bhp
360nm (more)
265lb-ft (more)

DOes this mean that the st would feel more powerful in terms of that torquey push?

PS. nothing would give me more joy than to spend a whole week testdriving all of these cars. But how do you go about doing that eh?

[HDi fun]

The Mondeo 2.2d ST is a quick car. And it drives and feels like one. Even in factory tune.

Torque is what flings the car foward when you apply some right foot pressure to the accelerator pedal.

As a 4 cylinder sporty car I'd take the Ford over the VW without any further procrastination.

[Aerial Andy944]

Originally Posted by theballboy

also , what do you guys think about the mondeo st for power?

I mean in comparison to the 170 VAG. Am I right in saying that its not all about BHP but that nm and lb per ft count alot too.

example
VAG - 170bhp
340 nm
256lb-ft

but
st - 155bhp
360nm (more)
265lb-ft (more)

DOes this mean that the st would feel more powerful in terms of that torquey push?

PS. nothing would give me more joy than to spend a whole week testdriving all of these cars. But how do you go about doing that eh?

Torque is good. You need power to produce it though. Can't comment on how either car drives as not driven the big exec barges but the ST is regarded as the sporty drive where as the Passat is the more luxurious and will hold value better I should think. My Golf is a GT spec one and with the 170TDI engine hits 60 in 8 secs and goes onto 140mph top end. Certainly is a very easy car to drive on a motorway cruise, just leave in 6 gear and it pulls from near enough any speed. As me and HDI have discussed recently the torque can overwhelm the front wheels to induce torque steer and the traction control cutting in all the time. Maybe the heavier saloons will cope better. Only way to tell is go have a test drive, there's plenty of cars to choose from.
Failing that get a Porsche 944S2 for £5k and have one of the best handling cars on the planet What you save on the cost of the car will pay for the fuel

[pgarner]

other way around mate power is the by produced of torque. torque is the turning fore of the engine.

im biased and would say go for the VW

caroll shelby is quoted as saying
Horsepower sells cars, torque wins races.

high hp is only good if its spread across the whole rev range best example is petrol hondas
ive owned 2 and both were only good once you got up higher in the rev range down low say 2500 rpm they were gutless and youd have to drop cogs to get into the power band. where as in the turbo bora ive a much better spread of torque across the whole rev range and can quite easily just drop the right foot in 5th to overtake from 50 without having to drop to 3rd

[Aerial Andy944]

Sorry I'll stand corrected I was always told Torque is what pushes you down the road and power is what produced it. I probably got it from watching too much Clarkson, he's always going on about Poweeeeeerrr
Learn something everyday I'd prefer the VW aswell, much better build quality I would think.

Andy

[HDi fun]

Power is a by product of torque and revs when discussing rotating machinery.

[theballboy]

never really considered the st as a serious contender beacause primarily I was looking at the 152 bhp only - same as the vectra 150cdti almost. But now i realise and read that torque figures are massivly different with a factory tuned 400nm over boost facility which when remapped Im sure would give more.

So this is a defcinate line of enquiry for me in my new car search. Only issue is that I have a mondeo currently and I always like a change. But if the drive was going to change dramatically then this is a def contender