Increasing gearing?

Hi to all,
I have a 1.4 Piaggio Diesel and would like to increase the gearing.
90% of my driving is a 50 mile daily commute on A roads with very little weight in the back so I dont need the ultra low 1st gear or whizzy revs when cruising at 50mph.
Also the van is to be used for kayak trips which will often involve 250-300 mile round trips, again there wont be much weight in the van.
I can put on 13 inch wheels which I have worked out will give me an approx increase in gearing by 8.3% if I am right.
My main question is what diff?
Does the diesel engine have a lower diff to help it pull away when loaded up, if so what model do I need to look for to buy a diff from to increase the gearing further.
Any information welcome :-)

Wheel size means nothing, calcuate the rolling radius of the tyres. Think you can use A petrol diff, but look on my website for the ratios.

I run 175/70/13's on my van, I noticed a fair difference from the 12" ones. I can cruise quite happily at 55-60(as I spend all day at 56 anyway it's not a problem ) 70 gets a bit buzzy and to be fair to the wee van I don't do it often. My commute is around the 50 mile mark there and back mostly on motorway and as it's quite exposed I find 55 enough when it's breezy

I end up at 70 plus on the motorway most of the time, and the little 1.3 is not economical at all at that speed.

Cheers guys,
A couple of good ideas to put into place, now its the hunt for some 13's to fit :-)
I am looking for an good cruising speed of 50/55mph so Logi's tyre info is most welcome.
I have done 2 x tanks of fuel while driving hard and flat out where ever possible and the MPG return was 48mpg (as close a calculation as you can get filling at pumps).
I am now on the 2 x tanks while driving softly and keeping under 45mph to see what the increase is.
Flat out the 1.4 diesel Piaggio managed 70mph on the flat, intolerable to drive at that speed because of high revs, engine noise and vibrations and thats from some one who drives an LDV Convoy as his other vehicle.
Cruising at 45/50mph is rather nice but if lower revs can be achieved then it would be a bonus   

In all honesty the derv hijets are not the ones to own ideally.

Being curious why are the derv ones not the ones to own ideally?
Is it because of noise, slow acceleration, low top end, struggles on hills, throttle is either on or off or is there more   

think you have answered your own question, all of the above   

All of the above, plus add hard to get parts, not very durable, and an arse to setup the injectors and timing.

Basically, the consensus is they're shite

But you can run them on chipfat biodiesel

Hummgh interesting, you would assume the engine being from a company that makes diesel engines for plant machinery would be robust, I wonder how many of the non durable ones are down to lack of servicing ie ol and filter changes etc.
Parts being hard to find will be just like having a classic car.
Had a look at the injector and timing setup in the manual and yeah like a lot of cars its a pain.
I was lucky and picked up a crash damaged 05 plate 1.4 diesel with 32,000 miles on the clock for £550.
Parts to repair came to £130 delivered to my door.
Half a day with a hydraulic ram and the foot well and front panels are now straight.
My thinking is if I get 2/3 years out of it with general running costs I will be doing well   Fingers crossed.

One very important point that ALMOST everyone misses when talking about putting larger wheels and particularly tyre size to save fuel is ---- your speedo is going to read slower the larger the rolling  circumference so if you dont want points on your licence you need to know the percentage slower your wheel is turning. 

One way of finding out is to to put a chalk mark on the tyre and measure the distance the 12" wheel travels one revolution. If for example the rolling circumference is 40" for the 12" and for a 13" it is 44" then you know your speedo will read 10% slow thus 27 mph shown on the speedo is actually 30mph -- that is assuming your wonderful Daihatsu speedo is accurate in the first place.
. Just worth bearing in mind though if you up your tire size.

Cheers Woody   
When altering vehicles in the past I have used the active speed signs the police put up and keep driving past at various speeds until I know the new speedo readings.
Will use the wheel measurement this time   

Yes I have done that myself although three of the regular ones I go through are slow --one 
of them by 3mph at 30.

ldv.tek wrote:Hummgh interesting, you would assume the engine being from a company that makes diesel engines for plant machinery would be robust, I wonder how many of the non durable ones are down to lack of servicing ie oil and filter changes etc.

Engines in boats and diggers and generators etc all get kept at constant rev's, life is pretty easy for them, they hold a steady load and keep steady temperatures. Many of them are just connected to a Hydraulic drive pump, so the get a steady life.

Motor vehicle engines are a whole different kettle of fish.. they use the rev range to do the work over and over again gear after gear. They tend to get worked from cold, and turned off after just being worked hard. Let alone cornering forces that effect the lubrication system.

The Hijets body design makes their coolant system implementation unique as the hoses have to swoop down below the footwells - this it one of the biggest factors in the exaggerated symptoms of over heating problems with these vehicles.

Couple that with the typical "low budget" type owners these van tend to live with, it becomes obvious why so many are in poor running order. I think the diesels can often attract "an even more tight walleted owner"! So yes your right, servicing is always neglected. And due to the low numbers sold, and how many have already been crushed, I would estimate there are no more than at a very rich guess best 100 diesel hijets remaining here in the UK, this maybe more like 75 actually. Again at a speculative  guess I would say many have been killed off through lack of parts availability after they have had crank failure or overheating or even just trying to get a replacement vacuum pump!!

But the Hijets unique appeal is what's keeping them in popular use in a market prominently flooded with new to 5 year old cars, and obviously this forum helps a few get saved. Yes a few of us break hijets, but see them more like Donors, giving their hearts and saving the remaining few from the crusher.

While there is no firm data on this website for Daihatsu's.

Keep in mind these statistics are not entirely accurate.

It claims there are 1474 Hijets taxed in the UK, and from dealing with people hunting parts and this forum I would guess that its about 20 Petrol Hijets to 1 Diesel Hijet

This website also claims there are 904 Piaggio Porters Taxed on the road in the UK... they must all be in London or something!! It actually states there are 91 Piaggio Porter Diesels taxed in the UK.

http://www.howmanyleft.co.uk/vehicle/piaggio_porter_diesel

http://www.howmanyleft.co.uk/?utf8=%E2%9C%93&q=Piaggio+Porter

http://www.howmanyleft.co.uk/?utf8=%E2%9C%93&q=Daihatsu+Hijet

The speedo on mine is now spot on and matches my satnav speed with the bigger wheels n tyres

That was a really good informative and creative journalistic article HJ. Thank you for that and ALL your massive contributions to this Forum.

When I got my first Hi-Jet Pick up 11 years ago I was attracted through working with Hi Jets at Romahome with development work on the Caravan Pods and the Comercial Arm of Romahome S.V.S. ( Specialist Vehicle Services ) and the Pods developed for County Council , WRVS and AA 

I loved the thought of a Fuel Injected 16 valve 1300 lump in such a tiny beast and most of the ones SVS sold were Dual Fuel but with a bitter history they always tried to steer customers away from the troublesome thirsty gutless Diesel option. 

Just one question LDV while it is fresh in my mind -- Does LDV stand for Loves Daihatsu Vans or Loves Diesel Vans . Come on LDV time to fess up !!

So 11 years down the line I still have my original " Little Red Pickup" in my posession and it has been the longest I have EVER owned any vehicle for and it has probably been the most reliable vehicle I have ever had too.

It was ages before I needed to spend any money on it and that was for a couple of Radiator Caps so I phoned the Local Daihatsu Dealer for a price : £27 each. Nearly had a Heart Attack.
But the Storeman was a customer of mind and gave me the part number of a Pattern one and I phoned Partco -- £3. Bit different. I then started to enquire from my friend in the Daihatsu 
stores about prices of other bits and was horrified by what I heard. 

So that was it. I put a wanted ad in the paper and on Wightbay and soon owned several Daihatsu's for spares and then repaired some from the ones I was breaking and sold them at a very handsome profit  then started selling spares on the Island only. 

Then a YEAR AGO TODAY I discovered this Fantastic Forum and the rest is history as the saying goes. This is now Post number 1002 ( I thought I would wait for 1002 or there would be all the old jokes from Logi about Carpet Cleaner etc. )

I want to say a GREAT BIG THANK YOU TO ALL OF YOU WHO KEEP THIS FORUM ALIVE but especially to L.P. whose brainchild this was and who puts in a lot of time and effort and to our MAIN MAN MATT ( HJ )for all his devoted time and effort to keeping us all on the road and all the other regulars Logi, Rich, PFM, dinoh, Bushwacker, Oldie, Daisy, Xxemaphor,Eddie, Lab Rat,
Melboy and many others . Thanks Guys and Gals for making this Forum SO GOOD. 

                                                                                 All the best to all of you Woody.

Cheers for all of the posts guys, the speedo tyre chart is awesome :-)