"300 rpm less can make a difference?"

[Snoetje]

It`s seems a strange combination, but I always have thougt the vRS engine can run very economical if using torque wise enough.

From the beginning I watched the numbers in a spreadsheet and noticed that on my normal daytrip (morning 20 miles, evening 20 miles)

the MPG varied around 40 when driving normal. (not irritating boy racers/gentleman racers)

To keep it short I managed to get 42 a while ago, keeping the refs under 2500. (abuse some will say)

Some negatives:

- takes a lot longer

- the car loses it respect :P

- quick driving needs more shifting

Some positives:

- better MPG

- less nois of engine

- higher top speed?

Thinking of the diesel Superb I drove for work (2.5tdiV6, 2200rpm@80mph) I searched Briskoda for a diesel box rebuild in the vRS.

It has been done by members, though not with the "standard" amount of torque. (220lbs, remapped as the standard :P)

Also prices are to high to justify the costsaving of such a box.

Since the TT 6-box has the same high gearing as the Octy`s fifth, I asked around at local (Dutch) gearbox companies.

One of them was serious and asked some details (I thought 02J was the boxcode, but EHA seems to be it) and yesterday he mailed me

the price for a conversion: 300rpm lower @ 70 mph for about 480 euro (320quid) as long if it can be done normaly from under the car.

When seeing a lower rpm maybe there is less need to speed, a better MPG, less nois, less tickets etc.

But if worth the money and less noisy then standard, hmm...

Anyone? :P (thougt this would be a nice one)

Greetings, Snoetje

[RichB86]

I agree that 5th is annoyingly short as im used to vauxhall with usually excessively long 5th gears but means high speed cruising doesnt involve running the nuts off the engine.

i think those that are running the diesel gear box have said you need 300bhp+ to make it work properly

[bengie]

but with a diesel box we're not talking 300rpm, we're talking x000's less as the gearing is massively different.

[Snoetje]

That was a downer for me - the gain of -300 is a bit low - but again its also between the head,

70mph @ 2400rpm gives less nois and the speed isn`t much different compared to 80 mph.

For instant: a truck drives slowly (50mph) but on holidays those guys get a pretty good average;

proved by the time you see them again and again after the tankstops...

Yes they have a bigger tank, but not the point. (with a second LPG tank I still see it with longer stops)

The "new" driving - with lower 5th - would make the vRS driver more aware of its economy/speed

and therefore less needy for the need for speed. ("let those cars think they are faster, the vRS has beter MPH and MPG")

So it`s not only "just" 300 rpm that makes the difference than, you have to think wider.

Any thoughts welcome again

A bit like Linux this; together making the product better :P

[KenONeill]

With the engine revs you're quoting, I suspect that, at the lower speed, you're effectively running the car off-boost, so the question becomes whether or not it makes enough power to keep moving at the higher speed and lower revs you're proposing. There I can't help, but I don't think putting an L&K 130PD 6-speed box in a vRS without changing the diff is likely to work out too well. The diesels are typically geared to about 30mph/1000 rpm in top, and the extra cog in the 6-speed provides another intermediate gear, not an over-driven cruising ratio!

[ScoobyChris]

I guess it depends how many mpg you're actually going to gain from the proposed mod and as Ken hinted at, if you're off boost you're going to need more throttle not less to maintain speed up hills (not that that is much of a problem in Holland ). 40mpg is a pretty respectable figure though and it's what I average in my diesel rep mobile. However, the difference is mine tends to have a hard life and is " enjoyed" regularly and I think I'd be frustrated owning a vRS and crawling around not using it for what it was intended?

Maybe some additional sound proofing and possibly an lpg conversion would be money better spent?

Chris

[Steevie Wonder]

With the engine revs you're quoting, I suspect that, at the lower speed, you're effectively running the car off-boost, so the question becomes whether or not it makes enough power to keep moving at the higher speed and lower revs you're proposing. There I can't help, but I don't think putting an L&K 130PD 6-speed box in a vRS without changing the diff is likely to work out too well. The diesels are typically geared to about 30mph/1000 rpm in top, and the extra cog in the 6-speed provides another intermediate gear, not an over-driven cruising ratio!

38mph per 1000rpm in mine

I can't see what difference the diff makes, other than a ATB diff would offer better traction. The standard diff would not be detrimental though in anyway.

[KenONeill]

38mph per 1000rpm in mine

I can't see what difference the diff makes, other than a ATB diff would offer better traction. The standard diff would not be detrimental though in anyway.

The diff ratio makes a difference to your overall gearing, and it's actually easier to change a complete diff than just the crown wheel and pinion in an existing unit in some cases. I honestly don't know if this applies to VAG units or not. Incidentally, what other than possibly cruising refinement, is the point of a 345bhp car geared up to be capable of about 250mph in top? I know you'd need more like 1_000bhp to actually get it to rev out.

[Snoetje]

The company mailed me another option this morning, 600rpm lower.

But I agree its doubtfull that in case of uphill (or wind) it would run cheaper with a higher gearing. (watched my speedo the whole week, hmm...)

Al little gain would be good enough though, but regarding to the sound proofing,

what sort of actions would be possible besides the gearing? (don`t remember a member done that before)

Big question seems to be: is the engine torqy enough @ low revs?

(and can you can from that with 300/600less)

[Snoetje]

edit: and can you gain from that with 300/600lbs less

(sorry, switching to another language is hard sometimes :P)

[Snoetje]

and it's actually easier to change a complete diff than just the crown wheel and pinion in an existing unit in some cases. I honestly don't know if this applies to VAG units or not.

I wonderd myself and asked "the company", but in the case of most VAG units (like 5/6 box for AUQ engine)

it is a lot cheaper just changing one gear or so.

They would charge 1200euro (800quid) for a div-change. (only 5-th gear seems cheap than)

[KenONeill]

You'd need a manual that covers both boxes to do it, but check the top gear ratio on both your 5-speed and the PD130 6-speed. It might be possible to get pretty much what you're looking for by swapping your existing diff for the PD one in the PD box, if the PD top gear is something like about 0.9input and 1.0 output.

[bengie]

the 5 and 6 speed boxes are completely different Ken, not just the same boxes with different cogs.

diffs aren't interchangable, neither are clutches/flywheels/starter motors/drive shafts etc etc.

[Snoetje]

And costwise not what I had in mind, the 300 drop (or 600) is the main question.

About crawling around, not the case since on motorway speeds shifting back to 4th

is done anyway to get the best out of a sprint. (doesn`t most vRS drivers do?)

Big question still: is for economy the engine torqy enough @ low revs? :confused:

[Snoetje]

Thank`s for the reply`s all of you

The verdict will be that, for the price of a 5-th change, the economy isn`t good enough. (if it is there, don`t earn it back in 5 years)

On the last trip this evening it wasn`t possible to get te speedo lower than 40,2 MPG. ( :zzz: )

A different gearing isn`t gonna change that (much) since it depends

from more things - I learned by know - as windspeed (!), tyres, earodynamics and weight...

(found a beautyfull stripped Furby vRS on Briskoda, but thats a little extreme for me)

Lowering the car would be a cheaper option and more efficient for the economy, I`m gonna investigate this now.

Idea of the low-gearing was good though I think

Maybe its a fase and I will grow over it. (with a IHI treatment from a Jabbadoctor or something)

[KenONeill]

I saw that Michelin are claiming to have come up with a low rolling resistence tyre again (reading a mag at the weekend).

Lowering the car will reduce the CD a bit, but it would take tunnel testing to determine how much.

[Snoetje]

haha, I don`t have a tunnel (why use a tunnel if never driving in one )

I`m trying to find out how to smoothen the downside of the car. (without carbonfiber plates :P)

The Passat Bluemotion is - compared to standard - lowered and also smoothend at the downside.

That combination would be reachable.

The best economy - out of one tank - I wil post. (with average MPH, weather)

(off course not representative for the rest of the year)

Now a laugh, in 2020 serious at meetings :P

0-400m @ 90 MPG, TRACKRECORD!! haha

("big engines are so lame")