MPG

[sacharlie]

How's the air over in GB and Europe? In the USA they only let us get half the MPG or less then you guys. They say its due to clean air requirements which don't make sense if we use over twice the gas to get somewhere. I know its got to be a money thing because the USA is run by a plutocracy. But damn wouldn't they make as much money by just doubling the profit per gallon and have us use half as much fuel. So is the air quality that bad for you guys?

[Irving]

The air here is fine and I don't think there's a huge difference in vehicle engine specs/performance for most globally available models. We have similar clean emissions requirements and certainly the last few modern cars I've owned (Saab, Audi, VW, Toyota, Kia) are near identical setups for US and EU.

In fact most of the ODB-II diagnostics you can buy plug-in scanners/cables & software for and are now international standards are as a result of CARB (Californian regulations) of the late 80s/early 90s and that also opened up the route in for third-party engine management tweaking I used to run several different fuelling 'maps' for my Audi depending on whether I wanted road economy or track performance off a dongle programmed from my laptop.

[Burgerman]

What he said. In fact the emission requirements actually improve fuel efficiency in most cases. As for saving the planet I don't give a stuff. Its all bull.

Low Carbon monoxide just means correct mixture. Low unburned hydrocarbon just means efficient combustion chamber shape, etc. Catatonic diverters don't impact MPG or performance unless too small for the engine.

[sacharlie]

From all the car rags the global models have different engines, usually only one or two here in USA but a half dozen or so in Europe. Was reading about the NV200 getting 50-60mpg in Europe but just 23-25mpg in the USA. BM does your minivan ya got from the USA get the same mpg as those sold in GB?

[Burgerman]

Yes, exactly. It IS the same exact 3.8v6.

There is also a diesel. It does more/double mpg, but like all diesels sounds like a truck, is harsh and coarse to drive and compared o the V6 petrol very tiring. Has a small knot of power and a very narrow rpm range. So really needs about 25 gears to row it along. Tested one in 2007.

So having driven both I wouldn't thank you for one! It saves a bit of fuel. But there really is no comparison. One is flexible and smooth. The other isn't... Performance is about the same. But it feels hard work in the diesel.

[Irving]

Think that says more about big Yank diesels than anything else.

My Kia is a 2.9l diesel and a 5-speed auto box. It pulls well and you'd be hard pressed to tell its a diesel. I've driven manual and auto BMW and Audi diesels in the past (pre-accident) and they've been smooth, quiet and responsive...

[Burgerman]

The eu/uk diesel vans have a modern "quiet" Daimler Benz common rail 4 cylinder turbo diesel.

I have driven a few too. Spent the first 37 years of my life tuning and dyno testing cars and bikes, including diesels and one off turbo/injection setups and nitrous systems for road and drag racing. So have a good bit of abused engine experience.

The reason for the limited rpm range of all diesels is that the fuel burns slow. So high RPMS are never great. Not helped by the way the fuel system works. So power drops off fast at high rpm, and always before a petrol variant.
And this is made worse by the need for a small sized turbo. Why small sized? Because a naturally aspirated diesel cant get out of its own way. To give them any sensible power at low RPMs a small turbo that boosts early and high boost at low rpms is required. That is then in its own way as RPMs rise. So you get that lump of power in the low to mid rpm.

This has been fixed in a fashion by using 3 turbos (of different sizes) and some complex valves and computer programming on some engines such as the one in my brothers Mercedes. But again, he had the petrol version before that, and much preferred it for smoothness and much wider usable rpm range. Its like this...

Traffic light goes green. Plants foot. Nothing, whoosh, nothing nothing... Next gear nothing, whoosh, nothing, next gear... Rinse and repeat. With enough gears (and some diesels have seven!) you can get over this.

Many turbos, careful design, much sound deadening etc and much of this is disguised. But its limited rpm range is still there. They are better than they were but given the choice the petrol version is usually nicer to drive and if turbocharged faster too.

[Irving]

Agree on the turbocharged petrol engine... I'd take one over a diesel any day, given the choice... and so much more you can do with engine mapping too. Even before the free-flow exhaust with hi-flow cats, uprated turbo, bigger intercoolers and uprated oil cooler took my stock Audi 1.8l 225bhp to 380bhp. I decided that was enough and didn't go the Nitrous route; some of my mates did and were seeing 500bhp+ (or even more tho there was a tendency to end up with very expensive melted lumps of metal - mainly through lack of understanding coupled with more money than sense!).

[Burgerman]

DIY

www.nitrous.info

Previous life, 20 year old stuff...