ok whats the best diesel engine for a t25/3 ?

Post by **T'Onion** » 23 Dec 2006, 20:43

ok i have a 1.9dg on lpg but i'm thinking about swopping to a diesel and need to know wots the best ? and which is easiest

Post by **HarryMann** » 23 Dec 2006, 20:52

Easiest and cheapest would be the 1.6 or 1.9 VW diesels canted over at 50 odd degrees with the standard VW kit from a scrapper.

Either NA or TD, the TD giving more performance of course. Many look for the 1.9 TDs, often the '91 ~ '95 Passat or Seat TD AAZ engine being choice.

TDi's cost more to buy and install, but fit in much the same way.

Theres a good fitting guide on Brickwerks site I think, and some basic notes in our Wiki. Gearbox and clutch need changing slightly to suit.

Post by **T'Onion** » 23 Dec 2006, 20:54

cheers Clive .. will look into the brickyard thing as i know Si do know his t'onions about diesels

Post by **TechtroT25** » 23 Dec 2006, 21:33

I've got a pre imobiliser Audi 80 TDI 1z motor in mine gotta say its loads better than the DG its replaced get around 40mpg and loads more power torque ect love it cost me around a grand all in have a word with philippacman on here

Post by **HarryMann** » 23 Dec 2006, 22:50

Yup, Phillipacaman has done a few nicely I've heard of and of course Syncro-Nutz have just done three for their expedition, think all with mechanical pumps, these are called mTDi engines.

Brickwerks and Syncrospares must have done a good few conversions as well, and there's a good half dozen on the forum with IDI diesel's starting to pep them up a bit.

The IDI are the indirect injected engines, up to the first TDi which was Direct Injection with turbo and intercooler. The IDI engines can be made to rev much higher than the Tdi's.

A good way to build a nice one, would be to source an early TDi bottom-end or short engine, and build an engine up with IDI AAZ head and turbo setup.

If you're building an engine rather than just dropping one in and hoping, the areas to pay attention to once you've got a short engine that has good compressions, is the head (absence of cracks) and manifolds (unwarped) and a good turbo. The exhaust layout depends which manifold layout is used, AAZ or off the JX 1.6.

Heads come up on eBay for £175 ~ £400, VEGE or VW new. Worth making sure its new or refurb condition and you can then look at more power or at least 100,000 miles trouble free. Turbos can be had for £50~400, take your choice, it needs to be at least reasonable nick. Most stick with the KKK K14 or Garrett T2 from the 1.6 JX but others can be fitted.

100 BHP+ is fairly easy, but a fair bit of kit is required to run this reliably I think (oil cooler, intercooler possibly and plenty of gauges)...

http://wiki.80-90.co.uk/index.php/Turbo_-_Manifolds

We're putting more and more diesel and diesel tuning stuff up on the Wiki all the time.

Post by **futurecut** » 30 Dec 2006, 21:35

Whay are you thinking of moving away from lpg then?

Post by **jed the spread** » 30 Dec 2006, 21:54

i was going to ask the same thing.

jed

Post by **HarryMann** » 30 Dec 2006, 22:44

This is what you want...

A quasiturbine running low octane petrol using an adjusted 4-stroke Otto cycle with photodetonation could halve all the fuel used by IC engines in the world...

Does that sound an interesting engine to stick in the back, would run on LPG nicely too. No cams and valves and so much torque proably only need two gears (fwd/reverse), and weigh about 1/4 of your current lump..

Just food for thought

Post by **andysimpson** » 30 Dec 2006, 23:15

If your thinking of changing to diesel for economy there is no way a diesel can compete with lpg for running costs.

Tdi's are excellent when they have the correct gearing, there is no t25 gearbox thats almost suitable.

1.9 td's ok power, more reliable than any t25 engine, easly/cheaply modded to tdi performance, suits the higher geared t25 gearboxs.

Post by **andysimpson** » 30 Dec 2006, 23:29

HarryMann wrote:This is what you want...

A quasiturbine running low octane petrol using an adjusted 4-stroke Otto cycle with photodetonation could halve all the fuel used by IC engines in the world...

Does that sound an interesting engine to stick in the back, would run on LPG nicely too. No cams and valves and so much torque proably only need two gears (fwd/reverse), and weigh about 1/4 of your current lump..

Just food for thought

Probably like other weird engines won't last, no one will want to touch it. A perfect example is the mazda rotatarys, no low down torque, wear out quick, poor economy, mechanics see them coming and hide.

Toyota prius is another weird one, not seen exactly how it works but the con rods have pivots, it has a very narrow rpm range and sounds like a very sick lawnmower. Under the bonet is scary no room at all with petrol engine gearbox and the electrical drive unit. Has the performance of a slug, economy only slghtly better than other petrols (but less performance) but way off vw tdi's which have far superiour performance and only need 1 service to the toyotas 3. Also seems to have engine reliability problems with the con rods breaking. To sum it up a very expensive car (for what it is) with at best average running costs, certainly much higher than a vw tdi.

The future is diesel.

Post by **HarryMann** » 31 Dec 2006, 02:28

Andy, Hehe - I see that hit home at a very +ve moment for changing the world

The future is Diesel?

Mmmm, is it?

HarryMann wrote: The Otto cycle is in fact more efficient than the Diesel?

True or False

== ==
People like Toyota don't mess about, and they won't be resting on their laurels I expect.. they are one of the few companies going for zero emissions and high mpg in a serious way. And they are doing it all in-house, nothing in the Prius is contracted out, or outsourced - unheard of.

Whilst the VW Tdi and many equivalents are getting pretty good fuel consumption with diesels, they certainly aren't getting it without emssions, nor when that power is really used .

The 2004 Prius is breaking new ground in putting a proper hybrid vehicle out there in the marketplace - credit where credit is due?

Its also no slouch, 0~60 in 10.1s is pretty respectable I'd say, for what is now a midi sized car, not a mini. The original 1275 Mini Cooper 'S' was 10 secs. and few complained about that back then.

If the first generation Prius broke con-rods I doubt this latest one will, I just can't see Toyota standing that for long, unlike other mfrs.

The cranked con-rod is to reduce the offset thrust during combustion that creates high piston/wall friction.

They work on an Atkinson cycle that is a slight variation on Otto - something along the lines of delaying the inlet valve opening to reduce cylinder filling. Seems mad?

But by then building in a higher compression ratio to start with (13:1 +) the effective compression is restored. You then end up with a greater expansion ratio, which is what leads to a thermodynamic cycle with greater efficiency.

Running in full hybrid mode, well over 50mpg in town and about 50 mpg motorway, for an average over 50mpg. I've said many times here that I am convinced people kid themselves silly with realistic mpgs they get, and I think they do, even with modern diesels. For one they seriously ignore any bad figures due to heavy town driving, and always just quote their long run 'best' figures, as well as not serioulsy record their total fuel/mileage over a full year. If they did it would almost always disappoint!

50mpg day in day out without driving stupidly carefully is amazing, and almost zero emissions - but no i wouldn't buy one - yet! One day we may have to

=== Ah! the NSU/Mazda Wankel Question ===

Whatever success Mazda has made of it - and to engineer something like that even reasonably succesfully has got to be given a least a silver star, if not a gold on their homework - they're still making them and still selling them and some really like them, no doubt about it.

But apparently it has serious thermodynamic problems, which are more important than any of its dreadful mechanical complexities could ever be. It just can't be made to be clean and efficient, even though it might seem the ideal candidate. It's just simply the first rotary IC engine, but happens to have been a very bad choice of rotor/combustion chamber design.

It compresses fast first and then slowly, and expands slowly and then fast - to some extent identical problem with the piston/crankshaft engine. The piston sits around at TDC when in fact that's the last thing you want it to do. And it has very heavy constraints over combustion chamber shape. And is 'orrible to cool and lubricate as well, and overly complex to make, witness Mazda devoting a lifetime of years getting it 90% there. It took Herr Wankel 30 years to even get a shape worked out.

In fact about its only + point is that it is entirely rotary, but unlike the quasi-turbine, can't really support continuous combustion.

Just a ramble on what might be coming in 5 or 10 years time - anyone got a CNC mill and we can have a go

Simple innit...

The Future is Multi-Fuel

Post by **T'Onion** » 31 Dec 2006, 02:30

futurecut wrote:Whay are you thinking of moving away from lpg then?

yes, just cost of the price of it at the mo

andysimpson
If your thinking of changing to diesel for economy there is no way a diesel can compete with lpg for running costs.

and was thinking about running the diesel on veg oil

Post by **HarryMann** » 31 Dec 2006, 02:43

Veg oil lubes the injection pump well I hear

but I haven't come across any decent stuff that is significantly cheaper than dino-diesel - have 15 litres sitting outside in a jerrycan - 90p/litre.

Sorry about the hijack, new year (nearly), new ideas (nearly)...

Post by **andysimpson** » 31 Dec 2006, 10:52

HarryMann wrote:Veg oil lubes the injection pump well I hear but I haven't come across any decent stuff that is significantly cheaper than dino-diesel - have 15 litres sitting outside in a jerrycan - 90p/litre.

Sorry about the hijack, new year (nearly), new ideas (nearly)...

Also makes the fuel pump leak, been there done that neve again.

Post by **andysimpson** » 31 Dec 2006, 11:15

HarryMann wrote:Andy, Hehe - I see that hit home at a very +ve moment for changing the world

The future is Diesel?

Mmmm, is it?

HarryMann wrote: The Otto cycle is in fact more efficient than the Diesel?
True or False?

== ==
People like Toyota don't mess about, and they won't be resting on their laurels I expect.. they are one of the few companies going for zero emissions and high mpg in a serious way. And they are doing it all in-house, nothing in the Prius is contracted out, or outsourced - unheard of.

Whilst the VW Tdi and many equivalents are getting pretty good fuel consumption with diesels, they certainly aren't getting it without emssions, nor when that power is really used .

The 2004 Prius is breaking new ground in putting a proper hybrid vehicle out there in the marketplace - credit where credit is due?

Its also no slouch, 0~60 in 10.1s is pretty respectable I'd say, for what is now a midi sized car, not a mini. The original 1275 Mini Cooper 'S' was 10 secs. and few complained about that back then.

If the first generation Prius broke con-rods I doubt this latest one will, I just can't see Toyota standing that for long, unlike other mfrs.

The cranked con-rod is to reduce the offset thrust during combustion that creates high piston/wall friction.

They work on an Atkinson cycle that is a slight variation on Otto - something along the lines of delaying the inlet valve opening to reduce cylinder filling. Seems mad?

But by then building in a higher compression ratio to start with (13:1 +) the effective compression is restored. You then end up with a greater expansion ratio, which is what leads to a thermodynamic cycle with greater efficiency.

Running in full hybrid mode, well over 50mpg in town and about 50 mpg motorway, for an average over 50mpg. I've said many times here that I am convinced people kid themselves silly with realistic mpgs they get, and I think they do, even with modern diesels. For one they seriously ignore any bad figures due to heavy town driving, and always just quote their long run 'best' figures, as well as not serioulsy record their total fuel/mileage over a full year. If they did it would almost always disappoint!

50mpg day in day out without driving stupidly carefully is amazing, and almost zero emissions - but no i wouldn't buy one - yet! One day we may have to

=== Ah! the NSU/Mazda Wankel Question ===

Whatever success Mazda has made of it - and to engineer something like that even reasonably succesfully has got to be given a least a silver star, if not a gold on their homework - they're still making them and still selling them and some really like them, no doubt about it.

But apparently it has serious thermodynamic problems, which are more important than any of its dreadful mechanical complexities could ever be. It just can't be made to be clean and efficient, even though it might seem the ideal candidate. It's just simply the first rotary IC engine, but happens to have been a very bad choice of rotor/combustion chamber design.

It compresses fast first and then slowly, and expands slowly and then fast - to some extent identical problem with the piston/crankshaft engine. The piston sits around at TDC when in fact that's the last thing you want it to do. And it has very heavy constraints over combustion chamber shape. And is 'orrible to cool and lubricate as well, and overly complex to make, witness Mazda devoting a lifetime of years getting it 90% there. It took Herr Wankel 30 years to even get a shape worked out.

In fact about its only + point is that it is entirely rotary, but unlike the quasi-turbine, can't really support continuous combustion.

Just a ramble on what might be coming in 5 or 10 years time - anyone got a CNC mill and we can have a go Simple innit...

The Future is Multi-Fuel

I don't care what toyota claim for there performance or economy figures, there painfully slow, economy around town is good but 50 mpg on the motorway is poor by todays diesel standards and it needs a service every 10k. Also remember toyota were one of 3 car makers that last year got in bother for quoting unobtainable mpg and performance figures.

How they can justify a price tag of around £23,000 is beyond me, you can buy alot of diesel tou would save over an mid range golf tdi of £16,000 and have a nice sounding engine, performance, economy, 31k service intervals. You really need to give the tdi a good thrashing to get them below 40mpg.

What are the owners of prius's going to do when the battery fails, it going to cost much more than the cars worth when there 8-10 years old end result is they will be scrapped which is not good for enviroment and the additional problem of disposing of the battery.

Toyota also don't point out if you have the air con switched on the petrol engine runs all the time, not good for enviroment.

As you have probobaly gathered i am not in a rush to buy one of these

I have not seen close up the honda version but thats supposed to be even less effecient.