V8 questions

So they say - injection better than carbs for general ease of use and reliability, more power compared to standard carb setup, should stay in tune better. Downside is that if it goes wrong you have an ECU to replace or bodge.

Figures for the RRC suggest 16mpg for 3.5 carbs against 17mpg for 3.9 V8i, so not a great deal in it, but perhaps it could be regarded as "useful".

No knowledge of LPG, but if you're running it on unleaded the cats issue depends on the date of manufacture. Key date is around 1992/1993 in the UK. Before this, the emissions limits were higher and a good engine would get away without the cats. After this date, the limits were drastically reduced and you are unlikely to be able to do without. Some workarounds, to do with the purpose of vehicle and GVW - you might be able to persuade a tester that the newer limits don't apply to your vehicle. This has been discussed several times,with no definitive answer emerging. Suggest you Google it.

On balance, 3.9 every time. Lovely engine.

HTH

After much thought, advice and poking around the great interwebnet-thingy I've settled on (and hope to soon buy) a 3.9 injection LPG'd Land Rover. I've always been a big fan of diesels (with the exception of the wifes saab I've not had a petrol vehicle in years) and the faf of carbs make sme nervous. but a 3.9 V8 is my choice, I'm wary of the electronics but willing to have a go with this one.

Research and advice suggests that the 3.9 is indeed, a good-un.

Regards. Mark.

Yes, and also more electrics to worry about if installing a V8i into a previously-not-V8i-landy.

Will do.

It does indeed - thanks Richard.

olly R

The basic engine is the same, just a larger bore, it's the EFI system that makes it so much nicer.

About 1 or 2mpg.

Nope, none at all. Just don't adjust the timing too far advanced, I've replaced 2 sets of pistons recently that have been destroyed by knock. (Ring lands collapsed!)

It's a lot less heartache to get a V8 model with a clapped engine then fit a decent 3.9 and convert the vehicle to EFI (Fuel pump, fuel lines, wiring pickup points)

Doesn't need cats if pre-92 (I think?) and it won't need them for an MOT anyway if it's running on gas. Construction and use regs will probably say you should have them, but I wouldn't worry about that myself. Something else to consider, from the mot manual I believe, "if the engine has been replaced, the emissions test applicable is for the engine's age, not the vehicle's, unless the engine is newer in which case it is by the vehicle age". In other words, if you rebuild and fit a 1991 3.9 to a 2001 defender, no cats required and no cat emissions test - even on petrol! All you need to be able to do is provide some sort of evidence of the true age of the replacement engine, easily done from the engine number.

EFI is a lot smoother, better emissions, and has an easier and smoother changeover from petrol to gas and back to petrol.

Go for it, you know you want that burble!!!

Yes, I'd been reading your threads before. I don't want a disco though, so am interested to hear people's thoughts about putting a V8i into a 110 or Defender 110.

Yes, a colleague of mine has just bought an H-reg RR with this engine on LPG, and it is fabulous.

Thanks Mark.

olly R

In message , MVP writes

If you are buying one already converted check out the LPG side thoroughly. It can be more hassle and almost as expensive to sort out a dodgy installation than to convert from new. Also look for a conversion certificate and check with your insurance company as to whether they will require an LPGA one - some do.

I did consider a V8 in my current 110 but there are some mechanical differences between mine and one built for a V8 so I then considered looking for a V8 110 of similar vintage (there are a few around) with a knackered engine and putting a 3.9V8 into it, problems being the transplant of the electronics, but do-able.

Regards. Mark.

Thanks for your thoughts! Now just supposing I found a suitable vehicle, roughly how much do you suppose someone might charge to put a 3.9 in, all things being equal? (I live in Scotland. Can you see where this might just possibly be leading....?)

olly R

Thanks Hugh, my 109 ran on LPG, with quite a dodgy conversion, unidentifiable components, tank put in the wrong way up, wrong hoses and things, and I did have to pay quite a bit to get it sorted for when I needed a LPGA certificate. And after all that, it still never really ran properly!

olly R

Yikes! My old 3.5 bobtail averaged 25+mpg on hilly twisty roads. There must be some heavy-footed drivers out there!

I used to get about 11 mpg from the 109 - but as I said, the engine was sh*gged. Was your bobtail very light?

olly R

Pulling one V8 and fitting another is the relatively easy bit. To get the benefit from the 3.9 you really want to ditch the std 3.5 exhaust and fit a performance stainless one, the 3.5's single-outlet manifolds will choke a

3.9. The gas install, as others have said, can be a right royal pain if you have to resort to sorting other people's mistakes. Converting to EFI involves dropping the fuel tank to change the pump for an EFI rangie one, amongst other things, in itself a few hours of work - if a towbar is in the way, that can add time getting the no-doubt rusted bolts out!. The wiring isn't as bad as some make it out to be, there's only 4 wires to connect, and find a suitable location for the ECU. As to where this could lead, feel free to email me off-group via my website if you want to discuss anything in any further detail.

Not amazingly light but I do tend to get a higher than average mpg on all of my vehicles.

Splendid. I'll carry on mulling it all over, and when I get a proper plan, I'll get in touch. Thanks again.

olly R

On or around Mon, 02 May 2005 20:57:13 +0100, PDannyD enlightened us thusly:

probably coasts down hills :-)

seriously though...

3.5 hotwire disco got about 18 mpg on average motoring without trying to be economical. still does, probably, and typically gets about 13 mpg on LPG, although I got 193 miles from 2 litres less than a full tank on a long run at the weekend, which is a tad over 14.

the word on 3.5 vs 3.9 is that the 3.9 is better on economy provided you don't habitually use all the extra power... injection vs carbs is probably more efficient ('specially a late hotwire with lambda sensors) due to more reliable fuel metering.

In my case, 110 auto with the saem type of gas system got about 11 mpg, but the engine wasn't as good as the current one.

In message , Olly R writes

Been quicker to say what was right :)