3.5 V8 MPG

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Burtie2904

Burtie2904

Active Member
Posts
117
Location
Winchester, Hampshire
So I am currently preparing for a 4000 mile road trip in my 1988 110 3.5 V8 which is basically stock and has 95k miles. The service history is basically unknown and I don't know if it's had a new cam yet or not as only got it 3k ago. And with long term use and this trip I need to get the best mpg possible. And I know it's a V8 it's not what its for but the fact is I love driving the V8 and therefore if it's more efficient I can afford to drive it more.
So basically Iooking for tips on improving the mpg, going off for a tune on a rolling road soon to get the SUs running right.
One question is if it's got a worn cam surely that will help mpg as it prevents more air and fuel getting into the engine?!? Or am I being thick.
Other from that please any tips greatly appreciated, both on mods and driving style.
 
Its an old low comp v8 which is producing around 115hp IIRC and it's trying to lug around a heavy 110.

Carbs are probably due a rebuild and re tune.

As for the Cam if it is worn it'll run like **** and be Flatter than a hooker under an 18 wheeler.

Best pull the carbs and intake manifold off and have a visual look at the cam..

Holley carbs are a popular upgrade for the Rv8.

It'll still do 10-15mpg though regardless of that you do..

What i'd do if i had the cash would be a stage 3 4.6, that'll give oodles of power and economy'ish..

But the rest of the drivetrain would probably shyte itself ;)
 
Henry_b said:
Its an old low comp v8 which is producing around 115hp IIRC and it's trying to lug around a heavy 110.

Carbs are probably due a rebuild and re tune.

As for the Cam if it is worn it'll run like **** and be Flatter than a hooker under an 18 wheeler.

Best pull the carbs and intake manifold off and have a visual look at the cam..

Holley carbs are a popular upgrade for the Rv8.

It'll still do 10-15mpg though regardless of that you do..

What i'd do if i had the cash would be a stage 3 4.6, that'll give oodles of power and economy'ish..

But the rest of the drivetrain would probably shyte itself ;)
Click to expand...
Forgot to mention, carbs have had a full rebuild recently, but yes imma take a look at the cam, I don't really know if it is worn by how it drives because its always been like that to me, feels okay ish..... Can't really tell tbh.
Edit: also what am I looking for to know just how worn it is?
 
Burtie2904 said:
Forgot to mention, carbs have had a full rebuild recently, but yes imma take a look at the cam, I don't really know if it is worn by how it drives because its always been like that to me, feels okay ish..... Can't really tell tbh.
Click to expand...

Yes take a look at the cam, and maybe being as old as it is, maybe she's dure a full valvetrain refresh ;)
 
I often wonder why the RV8 has such a appetite for fuel, after all it's a lightweight lump of only 3.5ltrs. capacity. In years gone by I had associates running iron block V8's with dirty great down-draft carbs. & slush boxes. They seemed to me to be reasonably frugal considering the CI's involved (4.7 was consider sissy) but I guess the low gearing, weight & aerodynamics (lack of) of the host vehicle count against the Rover lump.
 
Burtie2904 said:
One question is if it's got a worn cam surely that will help mpg as it prevents more air and fuel getting into the engine?!?
Click to expand...
If the cams are worn them you're getting less valve opening, to me that means potentially less air getting in, less exhaust gases getting out.
That means less power which means a heavier right foot to compensate

In my opinion
 
norseman said:
I often wonder why the RV8 has such a appetite for fuel, after all it's a lightweight lump of only 3.5ltrs. capacity. In years gone by I had associates running iron block V8's with dirty great down-draft carbs. & slush boxes. They seemed to me to be reasonably frugal considering the CI's involved (4.7 was consider sissy) but I guess the low gearing, weight & aerodynamics (lack of) of the host vehicle count against the Rover lump.
Click to expand...

the 3.5 is rather weak by todays standards and it has to try and lug around a constant 4 wheel drive RR that weighs 2 and bit tonnes.

Shove it in a TVR that weighs nothing and you'll see 20mpg ;)
 
Henry_b said:
the 3.5 is rather weak by todays standards and it has to try and lug around a constant 4 wheel drive RR that weighs 2 and bit tonnes.
Click to expand...

Agreed, but when you talk about 'today's standards' I'm not sure we are singing from the same hymn sheet, as I was comparing American V8's from the same time period as the RV8, the 1960's. Sure the Yank lumps guzzled gas but some of them were double the capacity of Rover unit, so perhaps that was the problem … if the Yanks had designed the Range Rover in 1970 the smallest engine option would probably have been a 4.7L 'There ain't no substitute for cubes' ;)
 
norseman said:
Agreed, but when you talk about 'today's standards' I'm not sure we are singing from the same hymn sheet, as I was comparing American V8's from the same time period as the RV8, the 1960's. Sure the Yank lumps guzzled gas but some of them were double the capacity of Rover unit, so perhaps that was the problem … if the Yanks had designed the Range Rover in 1970 the smallest engine option would probably have been a 4.7L 'There ain't no substitute for cubes' ;)
Click to expand...

Thank the lord the yanks didn't get their hand on the RR :D

The 4.6 has plenty of grunt, it is a torquey as a 350 chevy ;)

With some minor upgrades the 3.5 can make good power!
 
You don't say what mpg your 110 is getting currently but if you are planning to go on a 4000 mile trip, I imagine you will be loading it up with tools and spares so it will probably be worse. Slip streaming coaches can save about 20%-30% on fuel

Col
 
I'm about 11-12mpg on a standard 3.5 P6B engine in a SWB Station Wagon. My TVR is about 10-15 depending upon how you drive it but that's a 4.3BV. You could get 20+ if you drove carefully but whats the point - I've got other cars which I can drive normally.
 
FFG said:
You could get 20+ if you drove carefully but whats the point - I've got other cars which I can drive normally.

I can get that from my RRC auto on a mixture of legal limit motorway/A-road/B-road journeys, but I guess a (standard spec) Classic is not quite so much of a shed.
Click to expand...
 
I meant 20+ from the TVR. The Landy is averaging 11-12 in the 2.5 years I've had it. I don't mind as I wanted a V8 and I'm not doing big mileage so as with the TVR I just fill it up and use it.
 
I've had V8 3.5 110, two V8 3.9 classics and a V8 Disco 1 , I've never had more than sixteen out of any of them and usually 12 to fifteen on petrol and no more than 14 on gas

Present 4litre disco two is the same, 14 on gas
 
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