Engine Dilemma - 2 Diesel or not 2 Diesel

[Pottsy]

Originally Posted by dragonglance

i have very strong thoughts on deisel and no one has managed to come up with any better answer than "it is more economic on fuel"

They are noisy engines
You have to rapidly change gear all the time to maintain torque
You have to wear gloves when you top up at the petrol station
it will corrode the paintwork if it dribbles

i can keep going.....

I am a petrol head.

I always prefer the most powerful and fun version of a car - that's why I've ended up with cars in the past such as the 911, 968, Boxster, 350Z and M3.

When it came to buying a 5 door family hatch (the Civic), I simply chose the one with the huge power advantage (and as a bonus it has the smoothest, quietest* engine). Have a look at this graph:

power_extra.jpg

You will see that it the normal working range of the engine, the standard diesel car (red) has about 40% more power, and the chipped car (pink) about 75% more power.

I appreciate that there are downsides to the diesel - most importantly the initial cash outlay and (to some) the reminder that the compression ignition sound was until recently often found in taxis and agricultural vehicles. But I just drive and assess.

* under load. I concede that at a constant cruise the petrol is 0.8 dB quieter, but the threshold of human noise level determination is only 1.0 dB, so I ignore it!

[Pottsy]

Originally Posted by TTDegs

sorry - I've assumed you mean diesel vs petrol here - not LPG or nuclear power or something

Hey TT I could compare the diesel to my paraffin powered company vehicle... Even though the company vehicle engines have no reciprocating parts (and are meant to be "turbine smooth"), they produce more vibration at idle, full power and cruise than the diesel!

[TTDegs]

Your company vehicle, to be fair though, does go a bit quicker than the Civic...

do you have power / torque graphs for it?

[Munro]

It would be a fairer comparison between Diesel and Type R price wise.

When I was buying I was choosing between the Diesel and the Type R. I was very tempted by the diesel , it has a superb engine and felt quicker at low revs.

If I have read the graph correctly the red line is the 1.8 petrol. Why is the standard petrol producing 140hp and the standard diesel producing 152hp ? They are both rated @ 138hp

[TTDegs]

becuase Honda employ a Marketing company, and their flagship engines are Petrol

we haven't got a shed load of results to go on, as only about half a dozen people have dyno'd their Civics (and posted results), but consistantly the 2.2s come in way above 140bhp

From memory, only 1 or 2 have dyno'd 1.8s, and they have come in bang on 138 (well, give or take a bhp)

[Munro]

Originally Posted by TTDegs

becuase Honda employ a Marketing company, and their flagship engines are Petrol

we haven't got a shed load of results to go on, as only about half a dozen people have dyno'd their Civics (and posted results), but consistantly the 2.2s come in way above 140bhp

From memory, only 1 or 2 have dyno'd 1.8s, and they have come in bang on 138 (well, give or take a bhp)

I can believe the diesel makes more than the 140hp claimed, the one I drove certainly felt very quick.

It is the first diesel that has tempted me away from petrol. Smooth powerful and the long term reliability of chain rather than cam belt drive . However the economy does not seem to be as good as the VW / Audi engines from what I have read on here.

I have yet to try the 1.8 petrol civic, but have always liked the Honda Petrol engines.

[kenP]

Originally Posted by Munro

It is the first diesel that has tempted me away from petrol. Smooth powerful and the long term reliability of chain rather than cam belt drive . However the economy does not seem to be as good as the VW / Audi engines from what I have read on here.

I have yet to try the 1.8 petrol civic, but have always liked the Honda Petrol engines.

Both engines use a chain rather than cam belt.

What does surpise me about the diesel compared with the petrol is that the graph on the previous page shows quite a narrow torque peak for the diesel.

[TTDegs]

I guess it depends on what you're looking for as 'peak' torque

anything above 250Nm means 2,000 revs until red line
above 300Nm is 2,150 to 4,000
and above 350 is 2,250 to 3,500

realistically, the engine 'picks up and runs!' from about 2K revs and feels like you need to change up at about 3,500 to 4,000 - which thens dumps you back in the 'zone' in the next gear

To a Petrol driver, this sounds like a very small rev range - but when you consider than the red line on the petrol is roughly twice that on the diesel it begins to make more sense.

If we double the numbers above, to get a feel for where they would be in the petrol:

anything above 250Nm means 4,000 revs until red line
above 300Nm is 4,250 to 8,000
and above 350 is 4,500 to 7,000


which sounds a lot better

[Munro]

Originally Posted by kenP

Both engines use a chain rather than cam belt.

What does surpise me about the diesel compared with the petrol is that the graph on the previous page shows quite a narrow torque peak for the diesel.

I know Honda uses the cam chain, however not many other manufacturers do (BMW is one I think).

[dragonglance]

Originally Posted by TTDegs

well if that's the best you can do...

They are noisy engines - not anymore, apart from maybe the first 10 seconds when it's cold
You have to rapidly change gear all the time to maintain torque - definately not true. check out the power / torque graphs in the 'more ooomph' thread in the Engine section.
You have to wear gloves when you top up at the petrol station - I have never worn gloves when I fill up, either petrol or diesel.
it will corrode the paintwork if it dribbles - no idea on this one, but are you saying that petrol doesn't?


bring em 'on!

Lol, well i forgot to say the courtesy car i had was a 07 VW Jetta, it was like driving a tank and it would pull pull pull, hit 2500 revs and then there was nothing lol.

[Pottsy]

The 2.0 VAG TDi engine goes well, but is a rattly old dog - millions of miles behind the Honda. And it has a cam belt, not a chain.

[TTDegs]

There is a new 2.0 DIESEL engine about to go into the TT

170bhp

don't think it's been driven yet (small write up in today's Sunday Times), but expectations are high

I probably ought to nip back over to my old online home to catch up about it

[Pottsy]

TT - is that not the same 2.0 170 bhp diesel in the Golf GT? If it is, then it goes well but it will be known as Dennis.

[TTDegs]

after troggsing through the deluge of vitreol over on tt-forum whenever anyone mentions Diesel and TT in the same post (gawd how that place has gone downhill!), the closest actual info I could find was that it's the same engine as the current A4 Avant.

And that was only in 1 post out of 8 pages, so not even sure if that is right!

It's soooo much nicer over here!

0-60 circa 7.5 seconds apparently

[FWH]

Somehow I doubt the VW group would do two different engines with the same spec.

[nortones2]

Latest version of the 2.0 litre VAG engine is common rail rather than PD. It may be in the Passat in its next version, and possibly in the TT. Apparently smoother due to balance shaft as well as fancy piezoelectric control of the injection sequence. Thus quite feasible to have 2 or even three different 2.0 litre engines at the same time.

[JohnH]

I believe it's a derivation of the same engine as the current (outgoing) A4 B7 170PS TDi (which I have), fitted with Common Rail injection instead of Pumpe Duse, so I sincerely hope more refined and economical..... (see VW/Audi fora for lots of discussion on this).

Early reports of the lower powered 140PS variant fitted in the VW Tiguan imply it is more refined, which after driving the Honda 2.2 I'd suggest it needs to be.

[TTDegs]

the blurb from the official Audi press release:
50 mpg-plus Audi diesel sports car cleans up in Geneva


Feb 28, 2008
Acclaimed Audi TT Coupé and Roadster models adopt a diesel engine for the first time in their 10-year history
Latest Audi common rail diesel engine combines torque-rich sports car punch and extraordinary efficiency in latest TT models.

• World public debut at the Geneva Palexpo (March 6th to 16th 200 – scheduled to open for UK order in early March 2008, priced from £26,350 OTR for summer 2008 deliveries
• Powered by the latest 2.0 litre, four-cylinder TDI engine with ultra-efficient common rail fuel injection incorporating piezo injectors
• Already compliant with proposed Euro 5 emissions legislation, and over 20 per cent more CO2-efficient than petrol equivalent
• 170PS at 4,200 rpm, 350 Nm from 1,750 rpm to 2,500 rpm
• TT TDI Coupé 0-62mph in 7.5 seconds, top speed 140mph, 53.3 mpg combined consumption, CO2 140g/km
• TT TDI Roadster 0-62mph in 7.7 seconds, top speed 138mph, 51.3 mpg combined consumption, CO2 145g/km

The world’s first bona fide diesel-powered sports car – the new 140mph Audi TT 2.0 TDI quattro – brings 50 mpg-plus fuel economy, a 23 percent reduction in CO2 output and EU5 compliance to the 2008 Geneva Auto Show (March 6th to 16th). Far from being just a flight of fancy, the latest TT is production-ready, and opens for UK order in Coupé and Roadster body styles on Thursday March 6th, priced from £26,350 OTR. First deliveries are expected in summer 2008.The ideal TT TDI engine not only had to complement the much-loved character of the TT, but also had to fit transversely into its compact engine bay. It has the space-efficient shape of the latest 2.0 litre, four-cylinder TDI, and includes performance and refinement-boosting common rail fuel injection incorporating advanced piezo injection technology. Launched to critical acclaim in the new A4 Saloon in 143PS form, the TT has been upgraded to 170PS with an impressive 350 Nm maximum torque output – more than even the 3.2 litre V6 petrol model.

The engine features a new turbocharger with adjustable vanes to allow rapid torque build-up, as well as a sophisticated common rail injection system, whose advanced piezo injector nozzles can perform up to five distinct injection sequences per cycle, the performance ability of the new engine dispels any doubts about its sports car compatibility.

The TT 2.0 TDI quattro Coupé easily reaches its 5,000 rpm limit, thanks to high-tech injection technology and to refinement-boosting balancer shafts. With its 6-speed manual transmission, the car takes just 7.5 seconds to reach 62mph from rest. A top speed of 140mph is possible where conditions allow, and the influence of TDI is made clear by a combined consumption figure of 53.3 mpg.

The stride forward in efficiency over the outgoing 2.0 litre TDI engine also shows in a CO2 figure of 140g/km for the Coupé – over 20 per cent less than the 2.0T FSI petrol model – and in a drastic reduction in untreated emissions of nitrogen oxides. Improvements in combustion chamber thermodynamics mean the new engine can run on up to 60 percent recycled exhaust cooled by the radiator, and ensure that the 2.0 TDI complies with proposed Euro 5 emission limits.

[razorblewnose]

Originally Posted by sid taylor

i am in the same dilema as yourself,i have a golf gt 2.0tdi 12 month old offered £13500 p/x against a petrol 1.8 vetech ex £17440 on the road at colliers erdington birmingham inclusive of metalic paint. as my golf is 12month old it has only covered 6000 miles the dealer says that i do not warrant paying the extra for the diesel .also honda have cheap finance on the petrol but not the diesel 6.9%apr and also offer £500 towards the deposit tried to do a deal with colliers on the diesel but finance 13.1%apr so it makes sense for me to go for the petrol,also is the price for the new car a good price does anybody know

Finally decided to add leather and rear parking sensors. Paid £16,700. After ordering the car I was offered the same deal i.e. 2.2 CDTI SE, Leather Interior, 12 months tax, supaguard protection, full tank of diesel for £16,400 by Brindley Honda in Birmingham Centre. If you want a diesel, the SE Spec is not that bad - and you do get the diesel after all. These prices should give you something to go for.

[JohnH]

Originally Posted by TTDegs

Launched to critical acclaim in the new A4 Saloon in 143PS form, the TT has been upgraded to 170PS with an impressive 350 Nm maximum torque output – more than even the 3.2 litre V6 petrol model.

The current TDi PD 170 has the same power and torque outputs and 145g CO2 but struggles to deliver the claimed mpg in mine and many others experience.

All 258lbft of torque arrives at 2100 rpm from virtually nothing, makes my fwd version very tiresome to drive and I notice that the TT will be a quattro.

By comparison the Honda 2.2 is incredibly linear and easy to drive smoothly. Oddly (albeit in a lighter car) it feels just as powerful (in standard tune) except perhaps when approaching the red-line (which isn't really the point of a diesel imho). It also sounds so much nicer (less intrusive).

I'll need to be convinced that the VAG engine has improved considerably before leasing another Audi, my top choice for next car is the new Accord Tourer if it's out in time.... Also, being >2.0l makes a big difference to HMRC mileage rates if you use it for business.