Went to the dyno today

ratwing

Active Member
My 3.5 was very worn - on stripping down I found a big chunk of ally broken off one of the lifter bores, lots of missing cam lobes, pushrods that'd broken through the hardened cups in the rockers, a jammed oil pressure relief valve, shells well down into the copper, scored journals etc.
So I bought a so-called good 4.6 which turned out to have slipped liners, damaged pistons and bores, a worn crank, cracked oil pump gears and badly recessed seats - it was actually worse than my 3.5 and then the seller conveniently disappeared...
Well I thought, in for a penny, in for a pound and I've ended up with a decent engine by using the junk 4.6 in part exchange for a recon top hat 4.6 block and added a 3.9 cam, twin HIF6 carbs, lighter distributor springs, slightly oversize valves in the standard re-cut seats and a light porting job on the heads. I ground away any sticking out bits to match the manifolds to the heads and carbs because it only cost me my time and I think every little bit helps.
I also put in an all-steel roller chain, Yella Terra roller rockers (cheaper than new originals!), bigger oil pump gears (but kept to the standard spring strength) and a Mocal oil pump base which meant plumbing in an external oil filter.
While it was all in bits I replaced the old 4 speed box with a reconditioned LT77 too.
Following Des Hammill's SU book I had a go at re-profiling the needles (which is when I found my left and right carb pistons were different) and was reasonably successful but just couldn't get it running quite right all through the rev range. It's another £25 every time I buy another pair of needles to polish down so I admitted defeat and decided to hand it over to a pro.
Which brings me - eventually - to today and my appointment on the dyno at Atspeed in Rayleigh (Essex).
They welded a threaded bung for a lambda sensor into the exhaust, went right through the carbs and re-shaped the needles till it was running properly.
I could tell the difference driving back home, definately a lot smoother and feels quicker too.
I think the Range Rover version with efi and better ignition is around 225hp and 300ft/lb, my final run was 201bhp at 4800rpm (up about 30hp from the start) and 291lb/ft at 2575rpm so I'm quite pleased with the results and they reckon the fuel consumption will also improve so all in all a morning well spent :):):)
 
Won't be the EFi and ignition so much as the P6 exhaust and headers that cost you power over the Range Rover. They are a very compromised design compared to other RV8 applications, even more so with a 4.6.

As the 2000TC demonstrates you can get as much peak power as EFi with a well setup carb system, it just won't run as efficiently across the range or be as derivable.
 
The 4.6 litre engine in the Range Rover came in two versions. The first was called Tempest, and delivered some 225 BHP @ 4750 rpm and 277 lbs/ft at 3000rpm. These engines were fitted with a GEMS 8 Lucas engine management system, which from what I have read, was excellent. Following the sale of Land Rover to Ford in 2000, the Thor engine was born. Fitted with a Bosch Motronic M.L.2.1 engine management system, and with a completely redesigned manifold where torque was given precedence over power delivery. These engines delivered 205 BHP and 300lbs/ft of torque, from memory at 2500 rpm. The manifolds had long slender runners that assist with increasing torque.

Break Horse Power is maximum power with everything removed from the engine. No alternator or fan or anything that will diminish the power as measured at the crankshaft. Power measured at the rear wheels is the best option, and when you have pre and post figures, then you can see just how much things have improved. I had my Rover on the same dyno with the original 3.5 and then with the 4.6. The difference then is like night and day.

Ron.
 
I never bothered to get the old engine measured, I wanted to get the needles right in the new one and it just happens that the figures come as part of that tuning and yes I agree, the power difference between a 3.5 and a 4.6 is quite staggering.
I was getting around 23mpg from the old 3.5, my first home made needles in the 4.6 gave 15mpg:eek: and my last attempt was giving 20 so it'll be interesting to see how the fuel consumption changes (hopefully for the better!).
 
Just take figures like that with a grain of salt, especially when they claim to be engine measurements. If a dyno gives real wheel power measurements only, then you're much better off. Again, different dynos, different figures, so the only way anyone can make a reasonable comparison is to use the same dyno each time, and then compare the figures based upon the changes that have been made.

Good luck with the fuel consumption. Hopefully it will be much improved!

Ron.
 
Interesting reading indeed.
Has anyone fitted GAS to the V8 engine here in Australia, I often see the red symbol on the number plates of all types of cars over here , denoting that Gas is fitted to the engine.
Peter
 
Hi peter, many range and land rovers have been converted. problem with the p6B is finding somewhere to put the gas tank. Most systems start on petrol then turn to gas so you need two tanks. To do it properly you need to change the valve seats and valves plus use higher hot strength pistons as LPG makes them run hotter unless you fit the direct injection type which i don't think anyone makes heads to suit.
 
as an ex dynamometer operator I find comment that different dyno's give different figures erroneous. yes there are are more than one type of dyne . correctly calibrated any dyno ought to only give the indicated BHP at flywheel . figures for at 'wheels' are always much less due to transmission losses. it's standard practise to fit normal items when doing power and torque curves e.g. alternator and fan where fitted to engine . in short as engine were to be 'dropped' into car by manufacturer. this data is used by manufacturers and is checked by government DOT dept inspectors when they want , as published data complying with regulations is a legal requirement . alternator is used as a slave for any drive 'belts' ( e.g. water pumps) and NOT used to add any load other than its own driving losses due to friction etc we will also find where an engine has power steering then the pump too will be fitted and run . this WILL add fluid pumping losses. the idea being to get a correct 'as in car' data set and is corrected for humidity and atmospheric pressure etc . any 'dyne' facility not fitting pumps/ fans when original data form manufacturer is used as 'datum point' will get incorrect bhp as no normal losses being taken into account. for most the actual output is irrelevant . as very very few drivers will be able to 'feel' any change in power around 5-or so bhp in a car. high figures do impress people . e.g. 225 bhp . but weight of car will have major influence as its power to weight ratio at end of day that counts . other factors come into play too especially at speed. friction losses due to air resistance. body shape . added friction ( roof racks /mirrors/rear boot ,mounted tyre/ badge bars ) low rolling resistance tyres etc the list goes on. still always nice to see others projects and giving information and results. keep up the good work
 
problem with the p6B is finding somewhere to put the gas tank.

I toyed with the idea of fitting LPG to Sparky as I had an LPG A6 Audi at the time and knew the benefits. I bought a round tank which mounts on its side, stood upright where the spare wheel fits. Looks like this one -
images.jpg

I never did get round to fitting it though, but this was the best idea I found for where to fit it.

Richard
 
Fuel consumption - so far I've done a trip of 68 motorway miles at 70-75mph and 90 miles at 50-55mph (with some friends who were towing, I wasn't), I then re-filled and it worked out at 25mpg. This most likely isn't too accurate a figure because I didn't fill the previous tankful to the brim and I don't usually drive like this but it gives me a rough idea.
 
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