4.0 v8 feels slow

[pinhead]

is it me ?

although i wanted a td5 i ended up with a 99 s2 v8 on gas its in good condition for the miles with quite a few goodies but i wouldhave expected more grunt from a v8

its the misses motor most of the time but since purchase at 117000 miles its now done 126000 thats in 5 months

i have had quite a lot of v8s in the past but never a rover (2 corvettes f150 lightning and 3 v8 powered boats) and i just feel it lacks power all the way through

have i been spoilt with the big cube yanks or is there somthing wrong i have read a lot about cams wearing and going flat (i had this on the 77 vette too and a new cam made it a diferent car)

also fuel economy seems poor 11 - 12 mpg and as you can tell by the miles covered in short time we do long runs and its just no better than when she goes to work in it all stop start

opinions please

thanks andy

[BogMonster]

Something sounds wrong there then, mine does 14/15 mixed driving and probably 18/19 on a decent run but is your mpg on petrol or gas? gas apparently gives less but I don't know anything about it, we don't have LPG here.

[Bull Bar Cowboy]

Gas is about 10 less efficient than Petrol so that wont help……..

Cams on the later engines tend not to wear so badly ………. But the timing chains still stretch to the point of being silly slack ……… this will retard the cam and the engine loses all bottom end / mid range grunt ………

However, unless it has been well looked after, a Rover V8 on 122K will be long past its best and many will be long past their sell by date.

[pinhead]

yeah the fuel economy is on gas but on petrol its not much better my initial thought was lambda sensor but i swaped the plugs when i did the oil and what not and the old plugs were just the right colour nice light brown

i like what you say about timing chain the vette had 14 degrees of retardation on the cam timing due to a worn chain and the dizzy had no more adjustment (couldnt actualy time it up as the light was so up and down on the pointer) but the cam was more like a broom handle i am not sure if 2 of the cylinders actualy got air as inlet cam was round

has anyone got any experience of the piper cam upgrade it would kill 2 birds with one stone improved performance over stock and removal of any losses from wear i am quite confident of doing the work myself i did the cam in the vette over night (started when finished work at 6 and went on till 5 in morning had to run it in later in the day as i thought the neighbours may not be best impressed)

thanks for the responses so far

[pw8757]

I don't think you are that far out on the MPG for gas.

It may be that you are running on the usual conversion setup for the timing, which is halfway between right for petrol and similar for gas.

LPG burns slowly, so the timing needs to be slightly advanced, letting the maximum explosive power occur at TDC. I run mine at 7 degrees BTDC, which will be further advanced by the vacuum and springs as the power is applied. Plenty of acceleration and no dip in the power curve.

Also, I had a bigger spark amplifier fitted by RPI Engineering, which made a further difference.

[vougese39]

well from that mpg figure i would think the engine is well worn i recently built one for one of my customers a 4.6 10:4.1 comp engine and he now gets 24 mpg on petrol and gas and the ecu is stnadard! is it multi point gas or mono have seen a few monos on a d2 which is scarey

[pinhead]

It's a BRC sequential LPG system that has been serviced a couple of thousand miles ago it runs a clip on ecu and I guess it alters the timing to suit being a non distributer engine

if you go by the look in the oil filler and check out the colour I would say it's not over warn for it's miles it's a dark bronze colour

I think a comp test is next to see if I can get away with timeing chain and cam or need to do a bit more

What should I get with a compresion test

[pinhead]

Well an update on this

I have just had cam and timing chain done new litters etc all britpart bits and although the old cam was worn browning on all lobes an lobes 1 and 3 from the front almost missing but it still does not feel a lot more liveley chain was hardley worn and all other internals that we got to see during process rocker shafts etc looked in good order have only done 20 miles in it so far but I am still sure there is somthing wrong I have done recently a lambda sensor and a maf and now have no codes at all made sure nothing else was at fault before doing cam

So ideas please have done a 0-60 test and it's about 15 16 seconds so is well down

my only next thought would be blocked cats but how to check ?

[FridgeFreezer]

all britpart bits

Well that's doomed it then

[pinhead]

I thought all the parts looked good quality let's hope not doomed

[nicks90]

tbh a 4.0 v8 auto wont really give more than 12-15mpg overall... i reckon those peeps who say it does are driving nothing but motorways at 56mph! father outlaws d2 gets driven to france and back (fairly sedately) on a regular basis and on petrol he only gets 16mpg overall on the trip. Thats with a freshly rebuilt engine too. I borrowed it for a couple of months last year and did a good mix of urban and country roads as part of my daily commute and i only got 12mpg

I was horrified........

[FridgeFreezer]

When you say the 0-60 test is well down, do you mean on factory figures, because almost no car ever makes what the factory claim.

[jules]

tbh a 4.0 v8 auto wont really give more than 12-15mpg overall... i reckon those peeps who say it does are driving nothing but motorways at 56mph! father outlaws d2 gets driven to france and back (fairly sedately) on a regular basis and on petrol he only gets 16mpg overall on the trip. Thats with a freshly rebuilt engine too. I borrowed it for a couple of months last year and did a good mix of urban and country roads as part of my daily commute and i only got 12mpg

I was horrified........

I have just gone back to a 4.0lt Range Rover after having a Td5 D2 for 6 years I drove the new to me RR home a 50 mile drive from the top to bottom of the M3 at around 90 all the way following my wife in her car and the trip was showing 18.3 mpg when I left as when I pulled onto my drive it was on 18.4mpg and after my 40mile drive to work this morning its still in 18.4mpg it should be off to have a LPG kit fitted next week.

My wifes last car was a 4.6 hse with 65k on it but that only managed 13mpg she could get 17mpg but I never managed it.

I must admit anything above 20mpg I would struggle to believe still running through a LR drive 4x4 train

[jules]

When you say the 0-60 test is well down, do you mean on factory figures, because almost no car ever makes what the factory claim.

Not only that very few are compitant enough to get close to the test drivers time.

[pinhead]

I have a g tech pro which takes the guess work out of it from memory it was 15.5 seconds book is 11 ish can't remember exactly but I would expect to get within a second of the time

the pickup was 5.4 to sixty according to gtech and ford claimed the same

I drove a few td5 man discos before the v8 and they felt a lot more stout but the book figures are well down on a v8 they were stockand 1 had 190000 on the clock

I hear what you say about range rover doing 18 on computer and expect about the same as they have similar engine similar weight and simlar aero dynamics I must also accept that most trip computers would lie a little but I did 220 miles this weekend on 2 trips 1 50 miles each way and the other was 120 miles and I filled up before returning mainly motorway with cruise set at 70 where trafic would allow I used 71.4 liters that's under 14 by my maths I would be hoping for between 16 and 17 disco was not loaded up

I will be de cat ing when I get a chance so will see what that does but any more ideas please keep them coming

[nicks90]

I have just gone back to a 4.0lt Range Rover after having a Td5 D2 for 6 years I drove the new to me RR home a 50 mile drive from the top to bottom of the M3 at around 90 all the way following my wife in her car and the trip was showing 18.3 mpg when I left as when I pulled onto my drive it was on 18.4mpg and after my 40mile drive to work this morning its still in 18.4mpg

you sure your speedo and trip comp is accurate?

Not unusual to read 10-15% error at that sort of speed - especially when you factor in tyre size variations, built in 'over read' that all speedos have to have etc.

means your mpg could be down to 16, which would possibly be closer to the mark.