the V8 option

interesting thing happened today whilst chatting to the wife about our impending purchase which will be a discovery with a budget of around £5k. she mentioned the word V8. I'm a big fan of diesels myself and as our purchase will be around 10 years old a tough, long lasting diesel seems all right and good. but.

a V8.

it'd have to be an LPG as I have not won the lottery hence couldn't afford to run it on petrol, but I understand the running costs of a V8 on LPG is about the same as a TDi, am I right there?

Also I can't afford to lose any boot-space, and I want to have the option of petrol also, so, is there sufficient room underneath to have a reasonable size LPG tank and a hundred-or-so-miles worth of petrol tank?

Are there any servicing complications with a V8 & LPG system? I do all servicing myself and have never delt with a V8 nor an LPG system.

Waterproofing... approached in an orgsanised fashion, how hard is it to make a V8 comfortable with 2ft to 2.5ft of water?

I'm in two minds, the 300TDi is my engine of choice, but, oooo a V8...

Regards. Mark.(AKA, Mr.Nice.)

Reply to
MVP
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My 3.9 used to give 30-31 mpg equivalent. Since then LPG seems to have become cheaper as a proportion of diesel prices, so might be even better. I don't have first hand experience of 300 diesels, but I'd be surprised to get over 30 mpg out of one.

However, I suspect that if you are heavy footed or drive on hilly terrain the V8 would suffer more than the diesel.

60 litres of useable gas is easily achieved in the sills without touching the petrol tank. You won't drive to John O'Groats on that, but as long as you have a local easy source of LPG you'll be OK. Do be prepared for the fact that LPG seems to take years to deliver though - it's a real PITA in winter as you freeze your nuts off waiting for the fuel to dribble in.

Well, there's a whole other fuel system to go wrong....

Standard wading depth is 500mm, and mine went considerably deeper. On the second lap of the Billing course it became a V7 (and probably a V5 at its worst) but it never stopped and suffered no ill effects long term.

I'm in at least two minds about your predicament. If you get lucky, and get a good LPG conversion you'll almost forget it is there. It will cost about the same to run as a diesel, go considerably faster and sound nicer.

Then again, I suspect that many LPG conversions are for sale because they never ran right. Lots of them are fitted to engines with worn cams, imperfect ignition systems and often to poor standards. When Warren did mine it was crap, because the engine wasn't in great shape. A new cam and ignition overhaul worked wonders.

In the real world I know two TDi's which have way over 200,000 miles on the original engine, without major work, just good servicing.

I know which I would choose, but history shows that I'm really quite stupid....

Reply to
Tim Hobbs

On or around Sat, 19 Mar 2005 16:04:34 +0000, Tim Hobbs enlightened us thusly:

but to balance that, there's a backup fuel system in place for when it does. The petrol pump on mine is currently dead, which is an expensive replacement if you have to do it in a rush.

Reply to
Austin Shackles

On or around Sat, 19 Mar 2005 15:41:36 +0000, MVP enlightened us thusly:

near enough, specially for a 3.9. 3.9s, it seems get slightly better mileage than 3.5s, presumably they don't have to work so hard.

there are 2 under-floor options: replace the petrol tank, or fit sill tanks. The former gets you about 8 gallons of reserve petrol tank in the wing, and (in my case) 64l useable LPG tank in the middle there the petrol tank used to be. This tank option costs a lot, thanks to the cost of the replacement petrol tank.

sill tanks, as Tim said, can be put in. You can get twin 40s, now, which give you the same capacity as my single 80, (about 64l useable, 80% of the total water capacity). 'course, you can add this to the setup I have and get 128l useable, which one day I may be able to afford... This option by itself is slightly cheaper, as the 2 tanks aren't quite as pricey as the single 80 plus the petrol tank.

not really. extra filter (in the LPG line from tank to front of motor), and the vapouriser, depending on how it's installed, may accumulate heavy ends which need to be drained, say about every 24K miles.

waterproofing is a bugbear - good leads and a bit of work can get it OK, but it's till possible to drown it. Mind, 18" with an unmodified one is not unreasonable, with care, so I expect you can achieve what you're looking for. An unmodified diesel won't safely do 2½ foot, anyway - air intake's too low - so you'd be looking at a snorkel anyway...

As regards kits... check out an already-converted one very carefully, ideally get someone who knows about gas conversions to look at it.

Things to avoid like the plague:

  • anything that runs noticeably worse on gas - you shouldn't notice the difference except at maximum welly, in normal driving it shouldn;t be possible to tell which fuel it's on
  • iffy starting or changeover. I proper conversion should change over without dying at least 95%. if it habitually dies on changeover, it is at least badly tuned or setup.
  • insist on starting it on gas. It's a myth that they won't start on gas; I've had a gas-only V8 on a simple open loop system, and my current disco (also open loop) is currently having to start on gas as the petrol pump is dead.

Personally, I'd tend to buy an unconverted one, and convert it meself or have it done by someone who knows what they're doing. Given the choice and the budget I'd hunt a 3.9, or failing that, a 3.5i - the hotwire is not bad to convert, and gives less problematic answers than carbs if run mostly on gas. Carbs can be a sod if you do a lot of gas-only, they tend to refuse to go again on petrol without faffing around.

Should easily be doable in your budget. Kit to convert mine with replacement tank and wing petrol tank was something around a grand, add about 200-300 for fitting if you're not doing it yourself. I'd guess about

2-300 less for twin sill tanks.
Reply to
Austin Shackles

yea, whatever I get will be having a snorkel and extended breathers.

Do the 3.9's have electronic ignition or can the be easily fitted with same? thinking about damp-proofing again mainly.

Noted

I think I'd prefer to buy a stock one and have someone fix-it-up with LPG I'll add snorkel first incase it affects the tuning.

Range concerns me a little, is there a rough miles per litre (actual or tank-size)?

Regards. Mark.(AKA, Mr.Nice.)

Reply to
MVP

On or around Sat, 19 Mar 2005 18:13:59 +0000, MVP enlightened us thusly:

My 3.5 disco is getting a bit over 13 mpg on gas. 3.9s, as I said, are reckoned to do a bit better.

probably get slightly more if I drove it more sensibly, and also would probably get slightly more with a more advanced conversion - a closed loop one would maybe gain an mpg or two, but at the moment, it costs too much to upgrade it.

and yes, 3.9s are electronic distributors (I think, all of 'em) but in any case, it's a straight swap from points to electronic.

Reply to
Austin Shackles

Unless, of course, it's one of those that really won't start on gas. Mine was programmed to start on petrol than change over once above

1800 rpm (IIRC).

Short of plugging in the laptop I couldn't have started on gas if I'd wanted to...

Reply to
Tim Hobbs

My 110 WILL NOT start on gas. It runs perfectly on petrol and gas, the mixtures are spot-on, but if you try a gas start you'll be picking up all the inlet pipes that it WILL blow off when it goes bang! The reason for this, I think, is the length of the inlet (from the mixer to the valves) as it's a flapper system that's on it. Way, way too much gas builds up in the plenum for safety when the engine is cranking over. It starts on petrol by default, and about 3 seconds later, still at idle, switches seamlessly to gas. OTOH, I've yet to see a carb V8 or a Hot-wire efi that can't gas start. Badger.

Reply to
Badger

You sound like you've already talked yourself into an LPG V8 Mark, methinks. Go on, you know you want one really, don't you? Just think of that beautiful exhaust note....... and no diesel clattering or vibration....... Twin sill tanks (assuming no air suspension bollox to get in the road) should do nicely, methinks.

"This is a totally unbiased opinion on behalf of B.H.Engineering, Rover V8 engine specialists." "Hate somethin', change somethin', hate somethin' change somethin' make somethin' betterrrrrrrr.... fit a V8!" (thank you, Honda, for the best tv adverts of the decade! ;-) ) Badger.

Reply to
Badger

On or around Sat, 19 Mar 2005 20:54:15 +0000, Tim Hobbs enlightened us thusly:

mine has an auto-changeover, too, but you can switch it to start on gas. In the case of mine, you switch it from gas to petrol and back to gas before cranking it.

Reply to
Austin Shackles

On or around Sat, 19 Mar 2005 21:05:50 +0000 (UTC), "Badger" enlightened us thusly:

Mind, why does it backfire? shouldn't, in theory, be able to :-)

Reply to
Austin Shackles

Erm, you've confused me.

It WOULD start on petrol. Only on petrol.... It wasn't especially set up like that - it's just how the kit worked.

I don't know why, but Badger's explanation seems sound. It also means the injectors get some petrol through them regularly I guess. The amount of petrol used on starting is very low, so I don't see any merit in being able to start on gas unless you plan to remove the petrol system entirely.

Reply to
Tim Hobbs

why? what's the point in that? Cause it was tuned to only run on gas and wouldn't start on petrol?

(BTW, I know nothing about V8s, specially gassed ones :-) )

Gromit

Reply to
Gromit

I really am in 2 minds here, oooo decisions decisions. the spec I had in mind was... around 10 years old,

5 door, 7 seats, automatic, 300tdi. (I like my diesels and I can continue using the biofuel I've been using) but an LPG V8 certainly has my attention..... budget for an up and running vehicle will be £5k. in addition I'll be adding a nice full length roof rack, a little armour, snorkle and extended breathers, mebbe some driving lights.

Regards. Mark.(AKA, Mr.Nice.)

Reply to
MVP

On or around Sun, 20 Mar 2005 10:36:21 +0000, MVP enlightened us thusly:

well, FWIW, mine was 1800 to buy and getting on for a grand to convert.

I reckon if you budget for 1500 for a conversion with multiple tanks and/or replacement petrol tank, which should get you a closed loop system including installation. That leaves you 3500 to hunt a decent V8, unconverted, which should be doable.

on the other hand...

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an example of "how not to do it" in selling on ebay: sparse detail and he's not even washed it for the pictures... The vehicle may well be a good one, and it's young, but I'd be wary.

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and this one's an oddity, no apparent reserve, no bids. I reckon it's some sort of scam; mind, it's pre-approved bidders only. Might just be a cockup.

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another ES:

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a current search on discovery v8i, which pulls up a good variety withtinyour budget, some already converted, some not.

Reply to
Austin Shackles

Be careful putting a snorkel on an engine running LPG, if you let ram-air enter the inlet you'll get backfires, or at the very least, stalling on the over-run due to leaning of the mixture - and we all know what mixture leaning does to a V8; bye bye block, hello overheating. Badger.

Reply to
Badger

Thanks Austin, one of those, already converted, ends in 2 days and no bids, is in Plymouth which is only 30 minutes from me, I've contacted the seller. I don't have the money available yet but the V8 auto Disco is the current favourate.

Any common problems with auto boxes? how do I spot a bad-un?

Regards. Mark.(AKA, Mr.Nice.)

Reply to
MVP

Yes, sorry about that. That's what happen when I post on a Saturday night. :-) Sorry for any confusion!

Gromit

Reply to
Gromit

On or around Sun, 20 Mar 2005 15:58:33 +0000, MVP enlightened us thusly:

It won't go :-)

seriously, though...

put it through it's paces. It should do all of the following:

  • engage promptly at idle.
  • move off with minimal throttle and shift up, almost imperceptibly, so that it's in 4th by the time you're doing 30-35. watch the rev counter, it'll drop 2-300 revs going into 4th.
  • move off briskly if you floor it, and hold first gear till the revs hit at least 4K. Be prepared for upshifts at full chat to be a bit violent...
  • kick down from 4th to 3rd at 50 with not very much boot applied.
  • kick down to 2nd at 50 with lots of boot appplied.
  • go back down the box as you come to a halt. 2-1 is when almost stationary.
  • select any gear (3, 2, 1) when the lever is put into that position, pretty much immediately, certainly within 2 seconds, unless you're above the maximum speed for that gear, and thereafter not change up again.
  • go into 4th-lockup at about 50 mph, under fairly light throttle. revs drop about 2-300 again. Once in lockup, it'll only kick down from that to third, and if you release the pedal, it should go straight back to 4th-lockup, with an attendant revs-drop of 5-600.

BTW, I don't recommend you try for the 3rd gear kickdown threshold, that's at about 85, ISTR.

It shouldn't do any of the following:

  • make undue noises in any gear
  • take a long time to engage gear from rest. normally about 1s in my experience
  • "slur" when changing up - as if on a manual you were slipping the clutch.
  • change up violently/jerkily under light-to-moderate throttle.
  • "hang" in first gear under light-to-moderate throttle - upchanges should be around the 1500-2000 rev mark under gentle acceleration.
  • make a bloody great clang going from first to reverse when stopped - though this is rarely a box fault, it indicates mucho wear somewhere in the rest of the transmission.

You can also do a stall test:

warm up engine and box to normal temp. Engage D, stand hard on the brakes and floor the throttle. IIRC revs should stabilise at about 1800. Don't do this for more than about 5 seconds. Low revs most often mean an underpowered engine, high revs mean a box fault, either converter or one of the clutches, time to walk.

aha: shift speeds for a 3.9:

light throttle: gear-gear @ mph (range)

1-2 @ 9-10 2-3 @ 18-22 3-4 @ 26-30

part throttle:

2-1 @ 10-12 3-2 @ 29-37 4-3 @ 47-54

full throttle: ("feel" for the kickdown position. FT is just before the kickdown cam engages, which you can feel on the accelerator pedal if it's properly adjusted - about the last 1/2"-1" of pedal travel before it hits the floor)

1-2 @ 29-34 2-3 @ 55-60 3-4 @ 74-80 3-2 @ 40-46 4-3 @ 61-67

Kickdown: (pedal mashed...:-))

1-2 @ 34-40 2-3 @ 60-63 2-1 @ 27-34 3-2 @ 57-62 4-3 @ 84-92

Lockup in: 51-54 Lockup out: (decelerating lifted-off, hard to spot) 49-52

Reply to
Austin Shackles

On or around Sun, 20 Mar 2005 15:44:29 +0000 (UTC), "Badger" enlightened us thusly:

Make sure, therefore, that the snorkel has its top facing backwards. And avoid reversing at over 30 mph :-)

Reply to
Austin Shackles

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