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He wouldn't have made much of a living as an expert engine tuner otherwise, really... :)

Hmmm, at 30mpg and a cost of roughly £1500 for the conversion, you'd need to do nearly 27k miles to make your money back.

Only worth buying pre-converted used cars.

At 15mpg it's an easier decision. And some people keep their cars longer than 27k miles

Aye, there is that, but it does kind of put things into perspective.

Fine for someone racking up the miles - I'd want payback within a year, or two at the most (You never know when the dictatorship are going to hike the tax on LPG), however, if you are racking up the miles, you'd be foolish to pick something that only returns 15mpg anyway.

That's the sensible way, but it depends on how much you're spending. I know a guy with a newish Grand Cherokee 5.7 who spent £1500 converting it to LPG and adores it. Converting a V8 to LPG was cheaper than buying a new diesel, is quicker, quieter, comfier, sounds better and is better on fuel.

The choice of buying a diesel or buying a V8 with LPG isn't really a difficult choice. I'd go for the V8 + LPG every time. Discounts on new V8s are more easily available than discounts on diesels and £1500 is the cost of a sat nav system in the average big V8 price range - it's also less than the discount you tend to get by buying the V8 instead of a nasty diesel.

If you include exemption from the congestion charge and that LPG runs so much cleaner than petrol, you're looking at a V8 that will last for a very long time, not cost much to run and for me that's enough to justify an LPG vehicle over anything with Dr Diesels Evil Invention.

That's up to you. If your van doesn't have a high output donk you're not going to find it rapid running on BP Ultimate or LPG.

[snip dodgy stuff that one probably shouldn't put on t'internet]

But, good luck with it. I hope you don't get caught.

Pah, undersized engine there.

3.8 is the ONLY size they do it with in the US. Over here we get a 3.3 petrol or a turbo merc sourced 2.8 deseasel turbo rattlebox.

Since theres bugger all difference in fuel economy twixt 3.8 and 3.3 and a big improvement in all of the powercurve I have to wonder why.

Hmm then you should look at a vehicle with a real engine.

Nice Windstar sir?

Noo . I drove one...

You'll find out soon enough, surely?

The point is why is 3.3 ok for europe and 3.8 the only option for US when fuel economy is the same but it "can" go better?

You'll probably find that the US version has to meet additional emissions rules over there that they can't meet with the smaller engine variety at the same power output.

Plus, everything's bigger over there anyway.

What I'm saying is that you'll find out if the 3.8 is worth it and if you haven't driven one, you will soon.

A lot of larger capacity V6s in American cars have relatively low outputs. Say 190 bhp for the 3.8 (I seem to recall that the 3.8 Camaro from the early

2000s of so was just under 200 bhp) and ~170 bhp for the 3.3. Sure the 3.8 produces more torque but if you start telling us about this, we'll start pointing, laughing and whispering "diesel loved in disguise" behind your back. :-)

Reasons various for this - consumption isn't one of them, emissions is (how perverse, I know). I'd not be surprised if your 3.8 is marginally quicker than the 3.3 and marginally thirstier under optimum conditions. In the city it may be noticeably thirstier.

208

(I seem to recall that the 3.8 Camaro from the early

Mmm I love torque. Diesels have less though unless you turbo them and if you can do that then you can do the same for a petrol engine. Or the playing field isnt level. Now how good is your smelly narrow rpm band rattler?

Well their figures say its pretty similar mpg even allowing for the usa shrunken gallon. Anyway its going to burn propane!

A whole 208 bhp?

Is this front wheel drive?

It's 50+ mpg / 600+ miles between fills good, though. As for a narrow power band it really isn't an issue, I can change gear when the engine speed is outside the 2,000 to 4,500 rpm range. Or 1,700 rpm to 5,000 rpm come to think of it. I'm not sure how different that will be to your 3.8.

As I say, wait and see. There are good reasons why the relatively low output US V6s and V8s are all automatic. It's because of a narrow power band...

Unfortunately it has to be because of the dropped floor.

Lots! I drove the deseasel version thank you very much.

But its not narrow, 700 rpm to redline usable easily. Not so with a deseasel. Thats why they come with about 35 gears nowadays to try and find one where the engine works...

[snip]

Ahha so you have a large shopping trolley?

No no I don't mean the diesel version of what you have, I meant, *my* diesel.

Is the diesel version the 2.5 four pot? Not a wonderful piece of kit.

So no different to anything with ~200 bhp and a diesel engine, then. The Saab's redline is at 4,600 rpm but it'll exceed this engine speed in at least the lower four gears. Peak power is at 4,300 rpm come to think of it.

But if you're trying to tell me that it has relatively strong acceleration at 700 rpm I'm not going to believe you. The TiD's usable power band (i.e. squeeze the pedal harder at 2,000 rpm and you have lots of acceleration relative to at peak power engine speed).

My petrol Honda Accord and diesel Saab 9-3 have similar speed ranges (not identical) for the forward gears. It just so happens that the Honda's gearing was short for the class. The 9-3 is there or thereabouts for the class of car. It doesn't make the Honda nor Saab right or wrong. Can't use fourth at 30, must be 35, but third for both works from around 20 up to at least 70.

Your 3.8 may be different, but every large capacity US V6 I've driven needs over 2,000 rpm on the tacho before it accelerates well and the transmission knows this so changes down if it needs to. Just 'cos it'd lug along at

1,200 rpm doesn't mean it uses that ratio for a gradient.

Doesn't it strike you as strange how some drivers criticise a petrol engine for having a relatively narrow power band when they're used to manual turbodiesels but others dislike a manual turbodiesel's relatively narrow petrol band when they're used to manual petrols? It's a driver training issue for a vehicle with manual transmission.

If the generic turbodiesel engine has a too-narrow power band then the only automatics we'd see would be CVT rather than more conventional four / five / six / seven speeds.

That's why the smelly (DPF) narrow rpm (1500-4500rpm) underpowered (190bhp)

3.0 litre diesel parked outside has seven gears.