Group buy / order: 0.65 / 0.643 5th for TDI

I plan to do this in the next few months cash flow is a bit of an issue at the moment...

Based on Adrian's PM comments to me (he has a TDi 75 remapped), he recommends the 0.659 ratio with the A2 remapped.

So today I rang my insurer Churchill. The verbal quote for the following was:

- 5th gear ratio change - zero
- remap from 75 to 95 - £49

Current comprehensive is £200 - so a 25% increase.

I didn't ask but I presume these are full year extra (not on the remaining 6 months)

Seems reasonable to me compared with some remapped cars i have had in the past. Come renewal time you can shop around and possibly find a more favourable quote from one of the specialist brokers such as adrian flux. They always do a good deal for me.

hotdog1, in case you haven't made a deal of your 90 cogs let me know.

One aspect of the higher ratio is I noticed this morning it takes longer ( miles driven) for the engine temp gauge to get to normal operating temperature.

Adrian888 said:

One aspect of the higher ratio is I noticed this morning it takes longer ( miles driven) for the engine temp gauge to get to normal operating temperature.

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Interesting point. So under some conditions it may even increase fuel consumption. Yet another factor in the ever increasing complex equation

But I'm still up for changing mine. Still waiting for a 90PS gear ratio.

Potentially, yes. It brings it home why manufacturers invest a lot of time and money in developing what appear to be relatively simple upgrades such as the Bluemotion equiped VW's.

Adrian would you say you've noticed an improvement in MPG yet?

Yes, the improvement in economy is more than accounted for by other factors than the warmer weather and new narrower tyres. My guess is about 7-8% for my usage. In practice it has gone from 50 ish to 57 ish about half of which is probably down to the gearset change, the rest a mixture of increased ambient temperature and tyres. Even without the economy gains the other benefits which are not easily quantified are for me, very worthwhile. I hope Mike is being kept busy......

Should be able to provide some more data next week as Mike is fitting .659 to my mapped 75. As I have a long drive, I should be able to gather some useful economy data. The plan is that I will break the journey up into sections and recored the DIS data going up and the same coming back. I am breaking it up into chunks so that I can try and maintain the same average speed over each section there and back. If I did it over the whole journey, I only need to hit one traffic problem and all the data will be useless. This way hopefully I can get some meaningful data that will be a good 'steer' for those contemplating this upgrade.

Can you also please record the outside temperature during these sections?

And if possible start both legs of the journey with a full tank from the same brand petrol station.

Thanks.

Will said:

Can you also please record the outside temperature during these sections?

And if possible start both legs of the journey with a full tank from the same brand petrol station.

Thanks.

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I will Will try and make the journeys as comparable as possible but of course I will have no control over the temperature - mind you I am having the upgrade as I have a lot of European driving to do and it makes me wonder what the optimum outside temperature is for fuel economy - where we live in Italy it tipped 48C last year! Don't know about diesel but a cold beer slipped down a treat!

Do you have an iPhone - perhaps you could also record the db noise levels in the car at a couple of motorway speeds before and after? I'd be interested in what the actual reduction in cabin noise is.

Dan, you can monitor the noise levels yourself - basically note the noise levels at 70mph with your current gearing in 5th, then, drop the revs down (using cruise) to the projected numbers for the new gearset and re-measure the noise.

As dBs use a logarithmic scale, it might not seem a lot of a reduction (maybe around 4-6dB), but it does make a difference.

Cheers,

Mike

I could, but I don't have an iPhone

A 4-6dB reduction would be very pleasing.

Skipton01 said:

Dan, you can monitor the noise levels yourself - basically note the noise levels at 70mph with your current gearing in 5th, then, drop the revs down (using cruise) to the projected numbers for the new gearset and re-measure the noise.

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Hi Mike. I'm not sure that would give what dab_b is looking for.

what he has now:
old gear set at 60mph = engine noise at 2200rpm + aero/tyre noise at 60mph

what I think you suggested:
old gear set at ~50mph = engine noise at ~2000rpm + aero/tyre noise at ~50mph

what he needs to test:
new gear set at 60mph = engine noise at 2000rpm + aero/tyre noise at 60mph

I suppose what I'm saying is that engine noise is only part of the contribution. Very interstig thread this Alomst 300 posts long!

No I don't have an i phone, I have been a Blackberry boy for years, so unless you know of a Db measuring ap for that.

As for road noise, the type of tyre will make a big difference as well, so the fact that I am running on noisy fat tyres will not be a good comparison for you lot on 15" skinny ones. You can go on and on trying to identify the little differences but the point is you will only be trying as there are far too many variables.

What will count IMHO is the engine noise reduction of 300/350rpm when cruising at 70. When going down hill at 70 on the motorway I have taken it out of gear and the wind/road tyre noise is not a problem, sure it is not as quiet as some 'luxury' cars I have had but it is still fairly quiet. The real noise offender is the engine and reducing the revs will quieten things down, so I reckon Mikes idea is by far the best measure without having the job done.

Returning to economy, for me the goal is to achieve 70mpg at 70mph, fully loaded, when running on motorway/autobahn/autostrada i.e. once on the motorway reset the DIS and measure. For that I reckon I am going to have to change my tyres as well as the 5th gear. Maybe impossible but I am looking forward to starting the quest next week

Dan, why not cut out all the measuring, you are not a million miles from me, so once I have had the upgrade take a run out 'to the coast' and come and try it for yourself as we have similar cars - although you may wish to bring your sunglasses for mine

Whilst i haven't measured it scientifically there is a definate reduction in noise measured in my case by the radio volume setting required!. When I changed the wheel/tyres the following day the noise reduction was even greater to such an extent windnoise is now much more noticable. I think 70 at 70 is within reach especially if you are prepared to invest in narrower low friction tyres, aero mods and so on. I am looking for 60 at 80..... "cough".... which come the warmer weather and fitment of the aero bits I expect to achieve.