initially I had discounted the v8 due to cost to run but I have been offered a 1990 110 with a 3.5 v8 with twin 40l lpg tanks underneath (not sure on ground clearance yet).
Yes, the v8 will be more thirsty but lpg is half the price so if it was say 14mpg that would mean a cost to run equal to 28mpg.
But I don't know how lpg actually works so must also be using some petrol I assume and if that is the case makes it a lot harder to figure out actual equivalent lpg based on cost to run.
Also, I'm assuming the v8 is a very reliable engine but again, I've never had one.
So any feedback from people who have had a 3.5 v8 with lpg would be great
Ok several questions to answer.
Let's start at the beginning. The 3.5 V8 is a low CR (compression ratio) version of the RV8. 137hp instead of 155 and less torque than the version used in the TR7 V8 and the SD1.
This means that while they performed well for their day, they will not feel spritely today. But it should go ok. Similar to slightly better performance than a stock Tdi, although won't have the turbo sensation. They are smoother and more refined.
They use the LT-85 gearbox. This is quite an agrucultural box, but fairly I durable.
The good thing is, there are loads of RV8 engines about. So it is easy and relatively cost affective to swap in a 3.9, 4.0 or 4.6. And these will really wake the performance up and generally exceed anything any of the diesel Defenders can muster.
In terms of mpg. The Low CR twin carb is probably the least fuel efficient RV8. An EFI larger displacement one will generally do better.
I would expect on petrol that you should average in the region of 15-17mpg for general use. And maybe as low as 12mpg for short journeys or heavy right foot and 19'ish on a run.
I regularly drive a factory 3,5 V8 90 btw.
As for LPG, well best to hit Google if you want to know how it works. But in practice you'll usually get slightly less mpg running it. E.g. If on petrol you were getting 16mpg, then LPG it'd probably be 14mpg.
And pricing in my experience is usually not as good as 50% cheaper. But I think this can be region specific. When I last checked which was a while back I admit. LPG locally was 55-58p/litre and petrol was 105p/litre.
This means that real world running costs will not be halved. But they should be reduced.
You'll usually loose some performance on LPG too.
As far as LPG goes, it can be reliable. But depends on the exact system in use, how it was installed, setup and maintained. Many people have had issues with LPG. But this shouldn't put you off. Just give you some reading up in advance.
How this affects running costs, well that really depends on how many miles you are likely to do in a year.
E.g. Let's say the annual average mpg for a V8 is 16mpg on petrol @ £1.10/litre
And let's say a Tdi averaged 25mpg, which isn't unfair for a 110. Also at £1.10/litre
If you are doing 4000 miles a year.
250 gallons of petrol
160 gallons of diesel
£5/gallon
V8 = £1250
Tdi = £800
Fuel costs for a year.
This means that while the petrol mpg migh look horrific at first. For this distance it'd only cost you £37.50/month more to run.
If you going to be doing say 10,000 miles a year or more, then obviously the cost difference will increase quite a bit!
V8's should be just as reliable as a Tdi and just as easy to repair by and large. They are a 50's design, bit like the Tdi is really. So will need some maintenance. But nothing out of this world. Worn cam and followers is common, but pretty cheap and easy to fix.
And of course, with the V8 you have huge modding potential. An EFI one will really fly and should improve mpg. My 4.6 Range Rover is heavier and is blunted by a 4 speed automatic. Yet it easily managed 17mpg for short journeys and off road. Take it on a longer run at sensible speed and its up to 20-22mpg. And it's massively faster than a Tdi Land Rover.
