Twincharger 7DSG - Selects higher gear than it should. Thoughts? [Archive]

logger

16-09-2009, 02:58 PM

When the Twincharger 7DSG is operated in "D", it will readily run at lower revs and a higher gear than most of us are used to. As anyone who has one will know it will climb a hill in 7th gear at around 60kmh and 1300rpm.

There is a notion that with the Twincharger 7DSG operates at low revs in a high gear under load "..you are putting too much strain on it and that its bad for the engine."

At the moment I found the car up gears too early..Upgear too early like car driving 55km/h in D7 around 1200rpm, I can hear the engine clonking, not sure if that the right term. Sound like if you starting a manual in second instead of first.

That is the engine labouring, it's basically the engine crying for help because you're putting too much strain on it. It's bad for the engine in the long term.

Thats what I think too, it reminds me of my early days of driving a manual, where putting into 5th instead of 3rd or 4th instead of 2rd.

Not sure if other 7DSG drivers experiencing the same issue of having a higher gear than what it should be. At the moment I either drive it in S or if i see a hill coming, i would accelerate more, forcing the DSG to downgear(s)

I disagree with this notion for the following reasons:

1) you are applying anochronistic thinking to a a cutting edge piece of technology. We are not talking about a 20 year old holden with a manual transmission.

2) I find it hard so believe that VW would design a car with a highly advanced powerplant and automatic transmission and then forget to configure it, so that in its most automatic idiot proof setting "D", it will allow the driver damage it when driving uphill in a liesurely manner .

3)The ECU on the Twincharger and the 7DSG's Mechatronics unit will have all sorts of sensor imputs. I do not believe the designers would allow them to so readily operate in a regime where it could damage itself.

4) The engine is said to develop maximum boost (not torque or power) at a meagre 1500rpm so surely it is designed to run under load in this regime. see Inside VWs twincharger (http://sammajid.vox.com/library/post/inside-vws-new-twincharger-14cc-tsi-engine.html)

5) My take on it is, the noise you are hearing is a characteristic of the Twincharger + 7DSG. It might be the supercharger or just the engine itself under load, but I reckon it is quite acceptable and I am happy to drive my car in this range until someone can give me a good reason not to.

As always - happy to proven wrong. Can someone with specific engineering knowledge of these engines clarify this for us? Thanks...

sillygogo

16-09-2009, 04:01 PM

Logger:

I am not really sure what is the noise i am hearing. I believe it is because the DSG is in a higher gear than it should be because, the engine vibrates, and "sounds like" in the wrong gear. That was how i found the sunvisor was lose. She is smooth and sweet once it is in to 5 or 6.

I don't think it does any long term damages, however i do believe it is not running as efficent as it should be. :rolleyes:

mickofoz

16-09-2009, 04:43 PM

It's all perception. I currently drive a Polo GTI. I have always "driven" the car the way I thought it should be driven until I saw a video on the VW German website on how to drive a manual VW for max fuel economy. Basically if you follow VW's recommendations, you will end up in 4th gear by the time you hit 40km/h. I tried it and ended up with a 2l/100km saving. Sure, I thought the engine sounds like it is about stall, but after a while, it started to sound normal. Like I said, what we "THINK" it should sound like, is often not the case at all.

Grover

16-09-2009, 05:02 PM

Yes the new VW 7Sp DSG does take "short shifting" to the extreme and while this may result in a fuel saving I do find myself constantly shifting to "Sport" mode for normal traffic light starts and some slow speed corners before shifting to normal "D" mode once it gets over about 30Kph. It just feels better. I think that the right config for me would be to just raise the rev range slightly for the 2 and 3 gear shifts.

That said, "Sports" mode is too much for normal driving cruising.

pologti18t

16-09-2009, 11:48 PM

Best fuel efficiency in a petrol engine is moderate to low revs and throttle opened as much as possible (less pumping losses).

Essentially this means you need to accelerate with lots of throttle but upshift early. This is exactly what the DSG seems to be doing. Keeping the maximum load on the engine.

Dub_Star_V6

17-09-2009, 08:37 AM

Buy a manual. Problem solved.

logger

17-09-2009, 09:23 AM

Very Clever :guitar: ...but seriously:
There is no Problem to solve in the first place. People are trying to make it one and I would like to clear things up, so a myth does not perpetuate.

So far no one has come up with a good reason not to let this powerplant and transmission operate within the manufacturers design envelope.

blutopless2

17-09-2009, 09:28 AM

gee i thought the 6speed dsg in my jetta short shifted way too early...
its in 6th at 60kmh... roughly changes up a gear for each 10kmh increase.
Does the job tho and find that i have learnt when to use the manual mode.

tinto

17-09-2009, 11:11 AM

a twin charged car doesn't seem to suffer for it.
The only thing it chews is fuel if you're not on flat ground (as mentioned in the other tune thread).

My gti (dsg 6) changes down much more readily than my tsi (dsg 6) did, but it doesn't have the supercharger supporting act :)

the dsg mapping for a tsi, tdi and gti are going to match the capabilities of the engine.

tofo17

17-09-2009, 02:02 PM

It's all about fuel efficiency, chasing the poofteenth of a litre per 100km savings that consumers seem to love. Remember VW detuned the TSI from the MkV GT (120 something kw?) back down to 118kw. No doubt they've programmed the shift points as efficiently as possible.

tinto

17-09-2009, 02:09 PM

^ on flat ground that is true.
Take it up a slight hill and the lack of down-shifting isn't fuel efficient.
Try it yourself :)

VeedubTSI

13-09-2010, 01:23 PM

It all comes down to how you are driving. With all automatic transmissions, they go through a weekly cycle or however how often of re-programming themselves. Or possible from the moment you start driving.

The car learns your driving style through a 'fuzzy logic' (I know someone in this field of engineering who can confirm the existence of fuzzy logic) and adapts to your driving style. E.g. if you drive like a grandma the car will not inject as much fuel and will shift earlier, or if you drive harder the car will dump more fuel and downshift more eagerly, I found this evident and could be rectified in my primary car with taking the terminals off the battery to re-program it however do not do this on any VW as I have only verified this fix with Hondas to this date and I will not take any responsibility if you do it. However, it also depends on everything else such as flat ground, tyre pressure.

The 118TSI does sell on the merits of fuel efficiency and power as I've found with the 3 day old 118TSI it does have a 1 gear: 10kph shift point as I found myself cruising at 70kph in D7. Also upon coming off the line the DSG like any manual gearbox does take time to hook up the clutch as i find it dipping into the 900rpm range upon slight depression of the accelerator and the engine gets to the point where it wants to stall evidently in semi-auto and manual transmissions.

As for the rumbling I find it is like popular belief when driving any car, not feeding enough revs into the engine will cause it to stall and under load it will rumble as there is too much load. It may well be a combination of problems such as too high a gear and all, but this is what I think.

Corey_R

13-09-2010, 02:08 PM

Welcome to the forums VeedubTSI.

This thread is a full 1 year old.
The OP, logger, has one of the most extensive DSG knowledges of people on these forums. His name is logger, because he has the abiltiy to log all the stats coming from the DSG. In fact he can prove via logs that the DSG mechatronics does not necessarily adapt to YOUR driving habbits, but rather adapts to the tolerances and wear of the gearbox itself. He can also tell you how to reset the DSG without having to take the battery terminals off.

And really, the purpose of this thread was to state that there, there is actually no problem... logger took a discussion out of another thread to show there was no problem, and when people had nothing more to add, it died a year ago...

idaho

13-09-2010, 04:18 PM

Welcome to the forums VeedubTSI.

This thread is a full 1 year old.
...

I was thinking of replying as this was the first time I had seen the thread, but perhaps not. People are often berated for starting new threads without searching for and adding to existing threads, but it seems that searching and continuing on is also frowned upon. If a new group of posters wish to discuss this subject isn't it reasonable to continue this thread rather than start a new one?

hooba

13-09-2010, 07:57 PM

VeedubTSI

13-09-2010, 08:12 PM

This thread is a full 1 year old.

*Facepalm*

prise

13-09-2010, 08:54 PM

It is true that an engine under load at lower revs will normally feel and sound rougher than one at higher revs and less load but this perceived roughness at lower revs is as much a function of the tuning of the engine mounts as it is the engine itself. I have worked as a vibration engineer in the past, hence my interest in this topic.

Engine mounts are carefully tuned by the manufacturer such that the engine on the mounts has a natural frequency of vibration that is below the idle speed of the engine. As the engine speed increases, so does the frquency of the mechanical vibration of the engine. The higher the frequency of the engine vibration (higher RPM) the smaller % is transmitted through the mounts into the car body so higher revs often feel smoother as less vibration is making its way into the car body. This is the vibration we feel, not the vibration of the engine itself.

Another factor making the the engine feel less smooth at lower revs is something called torque ripple. This is the variation in output torque of the engine that results from the cylinder firings. Engine manufacturers fit special harmonic balancers, but at lower RPM and higher engine loads these become less effective in smoothing out the torque ripple which also increases the amount of transmitted vibration.

My theory is that this is often why people perceive lower revs as somehow being worse for the engine. I have a 118TSI with DSG and do agree that it doesn't sound and feel as smooth when its lugging at 1500 RPM compared to 2000 RPM in a lower gear, however provided the engine isn't pinging (which it's not) I have no concern for its longevity. 80% torque at 1500 RPM is not hard on the engine as thermal loads are low and loads from cylinder pressures are modest compared to loads from reciprocating parts it would experience at higher RPM's. I reckon the fact it rarely needs to get above 2000 RPM driving around town should extend engine life.

idaho

13-09-2010, 09:13 PM

To me it's obvious, nobody likes a smartie who can master the #$@%@! search function on this forum. ;)

I only used the New Posts function so I feel safe to continue. :cool:

It's all about fuel efficiency, chasing the poofteenth of a litre per 100km savings that consumers seem to love. Remember VW detuned the TSI from the MkV GT (120 something kw?) back down to 118kw. No doubt they've programmed the shift points as efficiently as possible.

I think the "detune" is more of a market positioning move as both engines have the same torque over the same RPM range. The only difference is that the 125kw Mk V GT Sport has the power specified 100 rpm higher (6000rpm) than the 118kw Mk VI (5900rpm).

Very Clever :guitar: ...but seriously:
There is no Problem to solve in the first place. People are trying to make it one and I would like to clear things up, so a myth does not perpetuate.

So far no one has come up with a good reason not to let this powerplant and transmission operate within the manufacturers design envelope.

As various people say the shifts have obviously been calibrated to maximise economy. But you need to think about how an engine works to decide if you want it to operate that way.

Torque is directly related to cylinder pressure. The higher the cylinder pressure the higher the torque that is produced for that power stroke. The TSI engine uses the supercharger to increase the cylinder pressure at low speeds that a 2.5L naturally aspirated engine would not be able to achieve. But the price of the higher cylinder pressure is more side thrust on the cylinder walls (because the conrod is angled during the power stroke and more pressure is being applied over a smaller bore area) and more blowby of combustion gases into the crankcase.

Also, 4 cylinder 4 stroke engines have big torque peaks and troughs during an engine cycle as there is no overlap of powerstrokes from one cylinder to another. The individual strokes cause more vibration at lower speeds (because the rotating mass has lower moments of inertia at lower speeds) which gets transmitted to the dual mass flywheel (also in the DSG). So, while I generally drive our car a gear higher at low engine speeds than my wife does, I don't accelerate hard (full torque) at those same speeds.

In the end it probably is a moot point as the original owner is probably unlikely to keep the vehicle long enough to experience any change in longevity. So it comes to personal preference.

idaho

13-09-2010, 09:23 PM

... 80% torque at 1500 RPM is not hard on the engine as thermal loads are low and loads from cylinder pressures are modest compared to loads from reciprocating parts it would experience at higher RPM's...

But aren't the high rpm loads hard on bearings while the cylinder pressure loads are hard on pistons / bores and essentially independent of rpm?

prise

13-09-2010, 09:29 PM

Torque is directly related to cylinder pressure. The higher the cylinder pressure the higher the torque that is produced for that power stroke. The TSI engine uses the supercharger to increase the cylinder pressure at low speeds that a 2.5L naturally aspirated engine would not be able to achieve. But the price of the higher cylinder pressure is more side thrust on the cylinder walls (because the conrod is angled during the power stroke and more pressure is being applied over a smaller bore area) and more blowby of combustion gases into the crankcase.

All this is true but you don/t mention that this is happening over fewer piston strokes. Also the mass of the piston and connecting rod being accelerated up and down creates loads that increase with RPM. Golf diesel engines have a good reputation for longevity and they have been lugging at low revs and high cylinder pressures for years. It comes down to what the engines been designed to do.

prise

13-09-2010, 09:38 PM

But aren't the high rpm loads hard on bearings while the cylinder pressure loads are hard on pistons / bores and essentially independent of rpm?

As a general rule - yes. However diesel engines have proven that a properly designed bore, piston and ring arrangement can handle high gas pressures and still deliver long engine life so there is no reason to say why one type of wear would be worse than the other for our engines.

Corey_R

13-09-2010, 10:33 PM

I was thinking of replying as this was the first time I had seen the thread, but perhaps not. People are often berated for starting new threads without searching for and adding to existing threads, but it seems that searching and continuing on is also frowned upon. If a new group of posters wish to discuss this subject isn't it reasonable to continue this thread rather than start a new one?

To me it's obvious, nobody likes a smartie who can master the #$@%@! search function on this forum. ;)

Sorry, maybe my post was a bit full on...
My main point was, that VeedubTSI was not coming in to ask a question, but to "answer the thread" when the OP is already very knowledgable on the topic and created it to answer other peoples questions in the first place.

Feel free to continue it though if there is new stuff to add...

VeedubTSI

14-09-2010, 12:11 AM

Sorry, maybe my post was a bit full on...
My main point was, that VeedubTSI was not coming in to ask a question, but to "answer the thread" when the OP is already very knowledgable on the topic and created it to answer other peoples questions in the first place.

Feel free to continue it though if there is new stuff to add...

*sigh* I felt I was getting moderator bashed after your initial statement. At least I resurrected some topic of some significance as I've seen in the last few hours. I don't know where the lines blur between resurrecting a topic or starting a new one and getting it merged or bashed. All I know is I'm watching the posting dates more carefully next time.

Corey_R

14-09-2010, 08:41 AM

If you are asking a question on the same topic as an existing thread, then you should always use the existing thread (no matter how old), otherwise it'll probably be merged (especially if I remember the existing thread).

I was just not sure if you realised the thread was a year old...
Anyway - as I said last night, my first post was a bit full on, so I apologise.

VeedubTSI

14-09-2010, 10:03 AM

All good. :)

kaanage

01-10-2010, 11:15 PM

All this is true but you don/t mention that this is happening over fewer piston strokes. Also the mass of the piston and connecting rod being accelerated up and down creates loads that increase with RPM. Golf diesel engines have a good reputation for longevity and they have been lugging at low revs and high cylinder pressures for years. It comes down to what the engines been designed to do.

Another post to put in the "thread revival" category...

Diesels are fabulous for lugging at low rpm due to the high cylinder pressure peaks, lack of throttling and the low bore/stroke ratio. All are inherent in the diesel cycle and also require the engine components to be far stronger than for a petrol engine of similar power output. This makes diesel engines pretty much immune to damage from side thrust loads on the pistons and bores.

None of this is relevant when discussing the suitability of the TSI engine for lugging at very low rpms with large throttle openings. Idaho's point about side thrust is a very valid one given that the TSI engine is square bored, but without knowing other details of the engine internals (the con rod length, piston skirt length etc), we cannot know if sustained running at 1500 rpm with the throttle wide open will lead to premature failures.

It is true that many small Japanese designed cars do suffer from premature engine wear when driven by young women due to excessive throttle openings at low rpm but the engines in these cases tend to be quite oversquare (and hence don't suffer unduly from high piston speed when driven for sustained periods at high rpm - crankshafts are another matter) as the Japanese like to chase high power outputs for the spec sheets. European cars are less prone to this as they tend to be designed more for real world driving so they are less highly tuned (in the non-performance versions anyway) and designed more for torque at low rpm than power at high rpm.

prise

02-10-2010, 06:59 AM

Happy to continue the revival.

we cannot know if sustained running at 1500 rpm with the throttle wide open will lead to premature failures.

I don't think anyone was talking about sustained running at 1500 RPM and WOT (at least I hope not for the next owners sake). The thread was about whether the DSG7 shifted up too early and I know that my DSG7 will shift down a gear well before then, however it will hold low revs under moderate throttle openings. Your points about the influence of con-rod length, etc are all good ones - it comes down to what the engines been designed to do.

Out of interest - can anyone tell us what the conrod length on the 1.4 engines is?

logger

02-10-2010, 09:22 AM

..we cannot know if sustained running at 1500 rpm with the throttle wide open will lead to premature failures.
Ha.. That was the only line in the post that got my attention too. Sustained running at 1500 rpm with the throttle wide open is not readily achievable with the DSG7. With WOT it will downshift or the rpm will increase in the same gear. Either way the rpm will increase.

kaanage

03-10-2010, 12:03 AM

Please feel free to be disinterested, logger.

Happy to continue the revival.

I don't think anyone was talking about sustained running at 1500 RPM and WOT (at least I hope not for the next owners sake). The thread was about whether the DSG7 shifted up too early and I know that my DSG7 will shift down a gear well before then, however it will hold low revs under moderate throttle openings.

OK, "sustained" was a poor choice of words. "frequent" may have been better to convey what I meant, which is regular high loading of the engine at ~1500rpm.

The whole thread revolves around the noticably greater vibration of the engine when running with large throttle openings and when the DSG decides to shift up early. And while it may not be WOT, the throttle must be fairly open for the engine to load up enough for the engine mounts to be stressed in this manner. It may well be that the engine mounts are the items that are actually the most highly loaded rather than the engine itself.

As others have also posted, I've found manually shifting later in these circumstances not only reduces the vibration but also the fuel consumption and increases acceleration so the DSG programming is not optimal in these situations. This makes the notion that "I do not believe the designers would allow them to so readily operate in a regime where it could damage itself" a bit of a leap of faith, in my book. Designers are people and in this world of mass production and cost benefit analysis, things can get missed - otherwise, there would be no such things as recalls.

I'm not against shifting very early when the situation justifies it. With very light throttle openings (eg when accelerating only enough to keep up with traffic going down slight inclines), I actually find that the DSG won't shift early enough.

MariusGT

03-10-2010, 03:02 PM

am fairly sure (without digging around for the article 'cause it is SUNDAY!) i read about the simulated testing done on the 1.4TSI engine.

VW had engines tested to over 300,000 kms without too much drama. in fact i'm sure you'll find many a 1.4TSI in europe with kms close to this. whatever the case i understand the push for engineering to focus on fuel economy for marketing, and VW have achieved this while still throwing down some decent performance figures. congrats to them for doing the R&D and being the pioneers in bringing this engine technology to the masses. (has been used in trucks i believe, and some old school rally car--> name??).

--- Dean Slavnich, editor of Engine Technology International and co-chairman of the International Engine of the Year Awards, said: “The international judging panel is hugely impressed by this VW engine. It’s a masterstroke of downsizing technology and a real engineering showcase. I have no doubt that this engine will become the template for a whole new generation of high efficiency, small capacity engines in the years to come.” ---

lastly. isn't the 1.4TSI made from a cast iron block? ie: strong little bugger!?

prise

03-10-2010, 03:03 PM

My experience is different to yours. I've plotted logged engine load against RPM for my vehicle and the DSG7 does not stay long in the high load/low RPM area before downshifting. I have also experimented with manually overriding to a lower gear going up hills on cruise control and found the instantaneous fuel consumption to increase slightly so no complaints in the DSG calibration with my vehicle. A colleague had the same comments as you with his manual TSI wrt the shift indicator - complaining that the engine was labouring and using more fuel when he followed its instructions. His engine subsequenty started idleing rough and VW replaced all four fuel injectors. He now finds the shift indicator suggestion to be fairly accurate and the engine no longer labours.

The greater 'perceived' vibration experienced at lower RPM is normal for tuned vibration isolation mounts as the % of vibration transmitted increases as RPM drops towards the natural frequency of the engine mounting system.

MariusGT

03-10-2010, 04:03 PM

i have kept an eye on the instantaneous fuel consumption and noticed that a lower gear + slightly higher RPM (little or no boost from guage) will use less fuel than the tall gear using more boost.

also, when using cruise control the DSG seems to want to stay in the taller gear more than if you are controlling the pressure on accelerator. if that makes sense?

Not cruise control: drops back to 5th or even 4th going up a certain steepish hill at 60kmp/h
using cruise control: on same hill at same approx speed will stay in 6th much longer and eventually drop back to 5th.

logger

03-10-2010, 10:08 PM

...The whole thread revolves around the noticably greater vibration of the engine when running with large throttle openings and when the DSG decides to shift up early.

Funny that. I started the thread, commenting on how the twincharger/DSG7 combo will "...readily run at lower revs and a higher gear than most of us are used to...". Nothing about throttle openings. It is a chracteristic of the way it has been designed and configured to operate.

...while it may not be WOT, the throttle must be fairly open for the engine to load up enough for the engine mounts to be stressed in this manner. Yeah I suppose 58% is fairly open. It is also fairly closed ;-)

Remember that with Electronic Power Control, the pedal is a power request lever and not a throttle lever. Push flat to the floor to command 100% power and ECU will "specify" an achievable load within its envelope and the engine will respond with an "actual" load. So for example; while foot to floor will give a commanded load of "WOT", throttle angle will most often be a mere fraction of this. At 1500rpm the throttle is just over 1/2 open at 58%. At 2000rpm 66%. You have to get to 5000rpm before you will actually see the throttle wide open!!

.. I've found manually shifting later in these circumstances not only reduces the vibration but also the fuel consumption and increases acceleration so the DSG programming is not optimal in these situations. This makes the notion that "I do not believe the designers would allow them to so readily operate in a regime where it could damage itself" a bit of a leap of faith, in my book.
Fair enough. I'll stick to having faith in the designers and rely on my warranty if they get it wrong. Lets hope they get it right with the brakes :P

My experience is different to yours. I've plotted logged engine load against RPM for my vehicle and the DSG7 does not stay long in the high load/low RPM area before downshifting. I have also experimented with manually overriding to a lower gear going up hills on cruise control and found the instantaneous fuel consumption to increase slightly so no complaints in the DSG calibration with my vehicle. I agree. You have to intervene and place the DSG7 in manual mode to get a sustained high load at low rpm. Even then you will not not see peak loads for more than a couple of seconds before it will override you and downshift.

The greater 'perceived' vibration experienced at lower RPM is normal for tuned vibration isolation mounts as the % of vibration transmitted increases as RPM drops towards the natural frequency of the engine mounting system.
Makes sense. I actually don't mind it all. I find it a pleasant reminder of the cars ability to pull from low revs.

Stoney!

03-10-2010, 11:26 PM

I'd be inclined to say the noises being heard are the injectors rattling away at low RPM, Direct injection is known for it's noisy clatter on idle and under load. Whilst it's probably not the nicest sound, I highly doubt its doing any damage, that said is there anyone that can Flash a DSG, because 7th in local speed limits sounds a bit outrageous to me.

I to have also noticed keeping the revs up on the 118tsi uses less fuel then plonking down through the gears and climbing hills at 1700rpm with the supercharger howling, And I often wondered being a manual driver how the DSG copes in this area, whether the program is intuitive enough to keep the engine in its power and economy sweet spot on hills of around 2200rpm. I got my answer now and clearly it's no.

Stoney!

Ryan_R

06-10-2010, 10:30 AM

If I'm in a hilly area with a low speed limit (i.e. 60) the DSG will often change down as if it wants me to boot it up the hill (I can nearly hear it saying "c'mon slow poke" - actually that's probably me saying it to the person in front). In such cases I switch to manual and change gears between 4-6 to keep things smoother.

RW1

07-10-2010, 05:26 AM

Brian

07-10-2010, 02:26 PM

This may be of interest....

As part of some misfire investigations I've been doing, I re-gapped the factory fitted spark plugs from 0.91mm (36 thou) to 0.79 (31 thou) [VW Maintenance Manual Spec is 0.8mm to 0.9mm]. VW plugs supplied as spares are also gapped at 0.91mm.

The effect has been a smoother engine at lower rpm. As a consequence the 7 speed DSG has been better at handling the gears in the region of 1,700rpm - 2,100rpm. Where in the past I would get gear change down on some hills, the car now pulls up the same hill inclines smoothly without dropping a gear in most instances. The engine is quieter too, both at start-up with that diesel noise period initially and also while driving - almost silent inside the cabin. Gear changes are generally smoother across the gears and engine rpm's and the first gear lurching has gone.

Hows it go at higher revs? eg 5k +.
Years ago I played with spark plug gaps endlessly.
General result was:
Smaller gaps = easier starting and smoother running from idle to around 4k revs but with some misfires towards redline (~ 6k in those days)
Larger gaps = u guessed it - harder starting and poorer low end performance but clean and crisp at the top end.
Mind you Im talking non ECU controlled cars here - just plain old dizzy and carbie. You could end up with thousands of combos by playing with the timing as well..