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Model specific boards => Golf mk7 => Topic started by: Hashbrown on 07 August 2020, 12:01

Title: DSG 7 vs 6 speed and GPF?
Post by: Hashbrown on 07 August 2020, 12:01
Hi guys,

So I’ve pulled the trigger on a 67 plate GTI MK7.5 PP.

Would this have the dreaded GPF?

Also would this have the 7 speed DSG box?

I’ve also read that the new GTI’s don’t DSG fart anymore, is that due to the 7 speed gearbox or the GPF or neither?
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: clarky92 on 07 August 2020, 12:39
Hi guys,

So I’ve pulled the trigger on a 67 plate GTI MK7.5 PP.

Would this have the dreaded GPF?

Also would this have the 7 speed DSG box?

I’ve also read that the new GTI’s don’t DSG fart anymore, is that due to the 7 speed gearbox or the GPF or neither?

Yes, any GTI PP 7.5 DSG will be 7 speed and have the PPF/ GPF. As standard it will barely ‘DSG fart’ but an aftermarket exhaust mod can bring back some DSG farting  :grin:
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Watts on 07 August 2020, 12:58
What's so dreaded about the GPF? Genuine question.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: clarky92 on 07 August 2020, 13:20
What's so dreaded about the GPF? Genuine question.

Great for the environment, but the flip side is it completely restricts exhaust noise. Well documented across all makes/ models. It’s way more noticeable on the higher end stuff like v12 Ferrari’s and Audi R8’s for example.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Watts on 07 August 2020, 13:26
What's so dreaded about the GPF? Genuine question.

Great for the environment, but the flip side is it completely restricts exhaust noise. Well documented across all makes/ models. It’s way more noticeable on the higher end stuff like v12 Ferrari’s and Audi R8’s for example.

That's fine then, I was getting a bit worried! Perfectly happy with the exhaust note of mine :smiley: Cheers!
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Will2018 on 07 August 2020, 14:22
What's so dreaded about the GPF? Genuine question.

Great for the environment, but the flip side is it completely restricts exhaust noise. Well documented across all makes/ models. It’s way more noticeable on the higher end stuff like v12 Ferrari’s and Audi R8’s for example.


To be honest VW have pulled off some kind off some kind of witchcraft with the exhaust note. My car is a manual GTI performance and it sounds fantastic on cold start and has a nice burble around town. IMO it has better note than the pre GPF manual GTi. 
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: dubber36 on 07 August 2020, 15:54
What's so dreaded about the GPF? Genuine question.

I'd guess it's the same as DPFs in diesels. It collects all the nasties that some folk don't want releasing into the atmosphere, then every so often when it's stored up enough, it goes through a process that releases all those collected nasties into the atmosphere.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: monkeyhanger on 07 August 2020, 16:41
What's so dreaded about the GPF? Genuine question.

I'd guess it's the same as DPFs in diesels. It collects all the nasties that some folk don't want releasing into the atmosphere, then every so often when it's stored up enough, it goes through a process that releases all those collected nasties into the atmosphere.

It converts those nasties (carbon particulates that can get lodged in your lungs and cause all kinds of health issues) to carbon dioxide. I'd rather have the low level carbon dioxide than the particulates in my lungs.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: P6GTD on 07 August 2020, 21:18
As far as I am aware the GPF was only fitted from around WLTP time late 2018 onwards.
I also believe the GPF fitted cars have a louder exhaust burble and crackle. V nice!
I may be wrong on the above.
However, if you want to see how effective GPF is, go compare exhaust tips on GPF cars vs previous non GPF cars.
The pipes on my car are almost as clean as the day I picked it up new and I never clean them.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Yusee on 08 August 2020, 05:35
What's so dreaded about the GPF? Genuine question.

I'd guess it's the same as DPFs in diesels. It collects all the nasties that some folk don't want releasing into the atmosphere, then every so often when it's stored up enough, it goes through a process that releases all those collected nasties into the atmosphere.

It converts those nasties (carbon particulates that can get lodged in your lungs and cause all kinds of health issues) to carbon dioxide. I'd rather have the low level carbon dioxide than the particulates in my lungs.

So do you need to go on a long run every so often to get the filter hot enough to do this?
I did relatively few long motorway journeys in my bmw 335d and had problems with the dpf blocking. Any such problems with petrol filters?
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Philip on 08 August 2020, 07:41
EU6c/WLTP/RDE became mandatory in September 2018 and to comply VW only certified the GTI Performance Plus 245 bhp engine and the 230 bhp was dropped from the range.  A mid 2017 PP won’t have a GPF.  The better exhaust note on late 2018 GTI’s with GPF came courtesy of a less restrictive rear resonator.  Pops and bangs can be mapped back in for little money if that’s your thing.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Adam T7 on 08 August 2020, 07:53
I have a MY19 GTI DSG and have only done 7K in 18 months, every now and then I give it a decent blast on a local bypass and so far no issues with the GPF.
And by the way, in Sport Mode (or Individual Mode with the exhaust selected to Sport), the exhaust noise is excellent
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Yusee on 08 August 2020, 08:23
I have a MY19 GTI DSG and have only done 7K in 18 months, every now and then I give it a decent blast on a local bypass and so far no issues with the GPF.
And by the way, in Sport Mode (or Individual Mode with the exhaust selected to Sport), the exhaust noise is excellent

I think it would be too early for problems to show? Mine is a December 18 car with 11k.
I have read that ppfs get hotter more quickly than the dpfs so less likely to block?
I don’t think anyone has mentioned any problems with ppf on this forum.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Watts on 08 August 2020, 08:46
And by the way, in Sport Mode (or Individual Mode with the exhaust selected to Sport), the exhaust noise is excellent

Unless I've missed something the exhaust note doesn't change, it's the soundaktor in the cabin that changes.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: clarky92 on 08 August 2020, 09:18
And by the way, in Sport Mode (or Individual Mode with the exhaust selected to Sport), the exhaust noise is excellent

Unless I've missed something the exhaust note doesn't change, it's the soundaktor in the cabin that changes.

Yeah that’s right, although from the outside my MY19 with 10k on the clock actually sounds pretty good. Way louder than I expected
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Adam T7 on 08 August 2020, 11:38
And by the way, in Sport Mode (or Individual Mode with the exhaust selected to Sport), the exhaust noise is excellent

Unless I've missed something the exhaust note doesn't change, it's the soundaktor in the cabin that changes.

Correct, but the effect both internally and externally is the same.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Watts on 08 August 2020, 13:01
And by the way, in Sport Mode (or Individual Mode with the exhaust selected to Sport), the exhaust noise is excellent

Unless I've missed something the exhaust note doesn't change, it's the soundaktor in the cabin that changes.

Correct, but the effect both internally and externally is the same.

Sorry I'm having a Mr Thicky moment. How can the effect both internally and externally be the same when in sport mode if we agree the exhaust note doesn't change, only the interior sound via the soundaktor?
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: monkeyhanger on 08 August 2020, 13:09
What's so dreaded about the GPF? Genuine question.

I'd guess it's the same as DPFs in diesels. It collects all the nasties that some folk don't want releasing into the atmosphere, then every so often when it's stored up enough, it goes through a process that releases all those collected nasties into the atmosphere.

It converts those nasties (carbon particulates that can get lodged in your lungs and cause all kinds of health issues) to carbon dioxide. I'd rather have the low level carbon dioxide than the particulates in my lungs.

So do you need to go on a long run every so often to get the filter hot enough to do this?
I did relatively few long motorway journeys in my bmw 335d and had problems with the dpf blocking. Any such problems with petrol filters?

Petrol is less efficient than diesel because it creates more heat and less kinetic energy in combustion (diesel is only 8% more energy dense yet is 30-50% better in mpg overall).

Diesel combusts at a higher temp but chucks less heat into the exhaust. As a result, GPFs heat up quicker than DPFs.

However, you don't just need heat to convert soot (carbon) to carbon dioxide, you need oxygen from air - and therein lies the problem for GPFs. Diesel engines run a big excess of air, petrols take in just enough air for the oxygen required to combust the fuel (and nothing more). So when you're driving along with your foot on the accelerator, after 4 or 5 miles you've got a hot GPF but no oxygen...

Unless you drive on a certain way.

If you're one of those people that is always on the accelerator pedal and then on the brake, you'll only get forced regens with the car forcing more air tgrough than it should need. When this happens, your  mpg will plummet (way more than a diesel does under forced regen) - you'll get about 60% of your normal mpg when a GPF is doing a forced regen.

If you're one of these people who reads the road ahead well and comes right off the accelerator when approaching a slower car ahead, or a roundabout/junction, you'll regenerate passively. The only time the petrol engine pulls through an excess of air through normal operation is when you're completely off the accelerator while moving and the engine has no fuel going in. This doesn't work when coasting or idling at a stop because there's still fuel going in.

My wife is one of those who is always on thd accelerator or the brake and wonders why her Polo GTI+ is doing 20mpg and not 32mpg on her 6 mile trip to work once every 2k miles.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: barrym381 on 08 August 2020, 13:20
Pretty sure the golfs will suffer the same as the rs3 on a Dyno


https://m.youtube.com/watch?v=pACT2SUBI_c
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Watts on 08 August 2020, 13:27
Petrol is less efficient than diesel because it creates more heat and less kinetic energy in combustion (diesel is only 8% more energy dense yet is 30-50% better in mpg overall).

Diesel combusts at a higher temp but chucks less heat into the exhaust. As a result, GPFs heat up quicker than DPFs.

However, you don't just need heat to convert soot (carbon) to carbon dioxide, you need oxygen from air - and therein lies the problem for GPFs. Diesel engines run a big excess of air, petrols take in just enough air for the oxygen required to combust the fuel (and nothing more). So when you're driving along with your foot on the accelerator, after 4 or 5 miles you've got a hot GPF but no oxygen...

Unless you drive on a certain way.

If you're one of those people that is always on the accelerator pedal and then on the brake, you'll only get forced regens with the car forcing more air tgrough than it should need. When this happens, your  mpg will plummet (way more than a diesel does under forced regen) - you'll get about 60% of your normal mpg when a GPF is doing a forced regen.

If you're one of these people who reads the road ahead well and comes right off the accelerator when approaching a slower car ahead, or a roundabout/junction, you'll regenerate passively. The only time the petrol engine pulls through an excess of air through normal operation is when you're completely off the accelerator and the engine has no fuel going in.

My wife is one of those who is always on thd accelerator or the brake and wonders why her Polo GTI+ is doing 20mpg and not 32mpg on her 6 mile trip to work once every 2k miles.

Well explained thanks :smiley: I'm of your second type of driver and I've not noticed any big drops in mpg, always amazed at how good it is.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: dubber36 on 08 August 2020, 14:47
Now here's the thing that I don't understand about the DSG coasting function. My understanding is that under normal circumstances, when you are off the throttle, momentum keeps the vehicle moving, which in turn spins the gear box, which keeps the engine turning. No fuel is needed to keep the engine running. With the coasting function, when you are off the throttle, the clutch pack disengages the gearbox from the engine, so in order to keep the engine at tickover speed, fuel is required. Just like when you are idling and stationary. Where does the so called fuel saving come from?
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Watts on 08 August 2020, 14:57
Now here's the thing that I don't understand about the DSG coasting function. My understanding is that under normal circumstances, when you are off the throttle, momentum keeps the vehicle moving, which in turn spins the gear box, which keeps the engine turning. No fuel is needed to keep the engine running. With the coasting function, when you are off the throttle, the clutch pack disengages the gearbox from the engine, so in order to keep the engine at tickover speed, fuel is required. Just like when you are idling and stationary. Where does the so called fuel saving come from?

Now I asked exactly this as I thought the same as you but someone gave an excellent well explained response that convinced me that the coasting function was better. Thing is, I just can't remember what it was! And I do not use the hateful eco mode.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Watts on 08 August 2020, 15:05
Here you go, reply no.23.

http://www.golfgtiforum.co.uk/index.php?topic=284736.msg2602741#msg2602741
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: fredgroves on 08 August 2020, 15:14
It's all energy and energy is created by burning petrol and lost by all sorts of ways other than driving the wheels. The easiest way of trying to stop fuel turning into Co2 is to stop pointless energy loss. Things like led lights make a big difference but the elephant in the room that nobody seems to care about is weight and drag coefficient....
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: monkeyhanger on 08 August 2020, 16:00
It's all energy and energy is created by burning petrol and lost by all sorts of ways other than driving the wheels. The easiest way of trying to stop fuel turning into Co2 is to stop pointless energy loss. Things like led lights make a big difference but the elephant in the room that nobody seems to care about is weight and drag coefficient....

The new ugly front end of the MK8 - is that pedestrian safety or drag coefficient, or something else? VW care about weight saving when it goes hand in hand with money saving - make doors out of Aluminium? Accountants say no. Make them from much thinner steel? Accountants say yes.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Adam T7 on 08 August 2020, 16:16
Aluminium is more expensive than steel but is a nightmare for dents and a swine to repair.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: monkeyhanger on 08 August 2020, 16:22
Now here's the thing that I don't understand about the DSG coasting function. My understanding is that under normal circumstances, when you are off the throttle, momentum keeps the vehicle moving, which in turn spins the gear box, which keeps the engine turning. No fuel is needed to keep the engine running. With the coasting function, when you are off the throttle, the clutch pack disengages the gearbox from the engine, so in order to keep the engine at tickover speed, fuel is required. Just like when you are idling and stationary. Where does the so called fuel saving come from?

Coasting allows the whole car can freewheel, much lower frictional losses running the engine on idle with drivetrain disconnected via disengage clutch than pushing the engine and whole drivetrain to run without fuel.

If you want to remain at the same speed on a slight downhill gradient,  pick coasting. If you want to slow down and grab back some of that kinetic energy rather than heating the brake pads up, battery regeneration charging kicks in to a degree, the motor slowing the car down (like a dyno on a bike for keeping the lights on takes more effort to pedal).

In my A4, there's a variant of the instant mpg display - it's a bar with a scale. Increments of scale are 0, 10, 20, 30, 40, max (mpg) and at the end of the scale is a battery charging symbo.

As you drive along, the bar varies to show your real instant mpg. When the car switches to coasting, the scale moves to a high value (roughly corresponding with around 55mpg on the flat).

However, when you come off the accelerator, the instant mpg goes off the end of the scale and well into battery charging mode.

If you're looking to slow down, the process of engine braking with battery charging/energy recuperation is more efficient than coasting.

I do think that if the "dyno effect" recuperation cane on a little stronger, you'd get more energy back (through battery charging) and be putting less wear on the brake pads. There must be a reason they don't make it any stronger - maybe too strenuous on the drivetrain, like doing 50 in 6th/7th and jamming it into 2nd for some severe engine braking?

At the big VW place in Berlin, they had a demo crank of the recuperation unit. You could crank it to the point it was outputting to the same extent as the car to light a bulb - it took some serious cranking!
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: monkeyhanger on 08 August 2020, 16:35
Aluminium is more expensive than steel but is a nightmare for dents and a swine to repair.

Not sure about the A3 in general, but I'm sure the pre-facelift S3 has aluminium doors, bonnet and boot lid, as dud the old Lupo GTI.

There's an old Triumph Roadster at the end of my street from 1947, built pretty much completely from Aluminium due to the post WW2 shortage of steel. It looks like new!

If renewable electricity projects expand to bring us ever cheaper electricity, Aluminium could be the material of choice in future. It's the most abundant metal in the Earth's crust, easy to get in Bauxite form and easy (but expensive at current electricity prices) to extract and purify the Aluminum from it's oxide. With breakthrough low electricity prices, aluminium could become cheaper than steel.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: fredgroves on 08 August 2020, 17:50
The new ugly front end of the MK8 - is that pedestrian safety or drag coefficient, or something else?

I found this:

There’s real substance in the Golf 8th gen’s sleeker body. Each body section was reshaped and refined in the wind tunnel. And by lowering the end face of the new model, the Golf 8 is the most aerodynamic Golf in history with a drag coefficient of Cd 0.275.

Having the ability to slice the wind in the most efficient way possible yields a ton of dividends. For starters, reducing drag means lesser mechanical force is required to move the vehicle, resulting in higher fuel savings. Also, having a slippery shape significantly reduces wind noise for better refinement.


From here: https://dlmag.com/2020-volkswagen-golf-8th-gen-top-5-reasons-why-its-the-best-golf-ever/
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: monkeyhanger on 08 August 2020, 18:01
The new ugly front end of the MK8 - is that pedestrian safety or drag coefficient, or something else?

I found this:

There’s real substance in the Golf 8th gen’s sleeker body. Each body section was reshaped and refined in the wind tunnel. And by lowering the end face of the new model, the Golf 8 is the most aerodynamic Golf in history with a drag coefficient of Cd 0.275.

Having the ability to slice the wind in the most efficient way possible yields a ton of dividends. For starters, reducing drag means lesser mechanical force is required to move the vehicle, resulting in higher fuel savings. Also, having a slippery shape significantly reduces wind noise for better refinement.


From here: https://dlmag.com/2020-volkswagen-golf-8th-gen-top-5-reasons-why-its-the-best-golf-ever/

Ugly cars will save the world! Not only because they will save a small amount of fuel per trip, but you'll make fewer trips because you won't like to be seen out in it.  :grin:

I wonder what the real mpg savings are in % terms?

Any news on energy saving tech, like EA888 3b with budack cycle tech (like Arteon/Tiguan/Polo GTI) or cylinder deactivation.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: fredgroves on 08 August 2020, 18:38
Mind you, I've just found an article that says the Mk7 is 0.27 lol...

The biggest problem the Golf will always have is the vertical squared off rear that is the hatch. You need a different shape before that goes away and the number gets much lower.

And reducing it by 0.01 is roughly speaking 0.2mpg.

As I've said before on here though, the efficiencies aren't about you personally saving fuel... VW make 900,000 golfs per year. So just for those cars, a 0.5 mpg improvement decreases their contribution to global warming by quite a fair old amount.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: kmpowell on 09 August 2020, 13:47
As far as I am aware the GPF was only fitted from around WLTP time late 2018 onwards.
GPF's were being fitted to 245's long before WLTP. As early back as late 2017.
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: P6GTD on 09 August 2020, 17:12
Sorry....my mistake.
So do the GPF fitted 245s have a different exhaust note to the previous non-GPF cars?
I thought they did but now Im confused!
Title: Re: DSG 7 vs 6 speed and GPF?
Post by: Aparat on 09 August 2020, 17:40
Sorry....my mistake.
So do the GPF fitted 245s have a different exhaust note to the previous non-GPF cars?
I thought they did but now Im confused!
Yes different note but no farts  :whistle: