Rover SD1 V8 and Rover P5B V8 engine - Are they the same?

[edwardbear]

There is a p5b engine and box for sale on this very forum and I'm considering it for my taxi v8 conversion. I've seem the converstion with the sd1 engine. But are they the same?

[SmokeEm]

Heads are deffo different IIRC. Not sure about the block.

[Darkspeed]

In basic terms all of the RV8 engines 3.5 to 4.6 - are pretty much the same but differ in many details.

[edwardbear]

Ok sounds like there fairly similar. What kind of details are we talking about anything devastating difficult to work with

[Darkspeed]

Just improvements with age - The 4.6 being the best (but with it's own issues) the P5b being the worst - lower power - rope seals - old.

[edwardbear]

curse word. The search for a old-ish quite powerful engine without an ecu goes on

[colnerov]

Hi, some detail differences to the block are that the P5b/P6b have rope seals at rear and don't stay leak free for long. SD1 have lip seals, better. Compression ratios on the earlier engine are 10.5 to 1 and need the timing adjusted to stop pinking. SD1 is 9.35 to 1 but gives more power due to bigger valves. The oil pump is smaller on the early engine, but its not a problem as the engine runs on low oil pressures anyway. You can fit the SD1 oil pump but need to fit the SD1 timing cover and usually the distributor as well because the pump is driven off the bottom of it and are different. There are kits consisting of a pump face spacer to fit the SD1 pump gears, but do need a bit of fettling for a good fit. Oil filters on the early engines have a 13/16" thread, Sdi has a 3/4" thread which are more common. Oil filter attitude is different P5b is straight down P6b and SD1 are more forward facing. Sump pan profiles are different. Mechanical fuel pump on earlier engine, SD1 doesn't have this area machined because it has an intank pump. Early engine has HS6 carbs, SD1 has HIF44 ones.

Colin

[edwardbear]

Very, very comprehensive. The Rover SD1 sounds like the swiss army knife of engines. Are there any other options. Doesn't necessarily need to be a v8 just powerful and easy to fit preferable an auto.

The nissan maxima engine looks like a safe bet as its the same gear box.

[MkX]

Jun 17, 2016 12:36:13 GMT edwardbear said:

Very, very comprehensive. The Rover SD1 sounds like the swiss army knife of engines. Are there any other options. Doesn't necessarily need to be a v8 just powerful and easy to fit preferable an auto.

The nissan maxima engine looks like a safe bet as its the same gear box.

It depends on your definition of 'powerful', do you have a ball park bhp in mind?
What do you need the power for? Acceleration? Top end? Both? Towing?

I've had the Rover (Buick) 3.5L engine in the P5B Coupe, in the P6 & in the SD1, on the whole it's a very good engine, (you've got to factor in the BL problem years!)

The P5B would sit comfortably and silently at 100mph, I never pushed her past that speed. The SD1 was good for 135mph with a 0-60 speed of around 7 seconds.
With spirited driving your fuel consumption is going to be quite alarming by today's standards.  

Other strong & comparably powerful engines of the period, I'm guessing the Jaguar XK/XJ engine will be too big?
The Triumph 2.5 L probably too long as a straight six?
The Rolls Royce 4L, (Vanden Plas Princess 4L R).

[edwardbear]

Purely acceleration. Once I'm up to 70-80 I'm not worried, just want to get there quickly, preferably with a nice sound.

[dodgerover]

Just fit the turbo version of the diesel you have, anything else is getting into doing a load of potentially very expensive fabrication.

[edwardbear]

It's a naturally aspirated engine. So no go

[optimusprime]

Water pumps differ as well ,i found out the hard way ..............

[Battles]

If you're set on an RV8, grab a rotten Discovery with one?

There seems to be no less desirable Disco than a rotten V8 auto, so they were cheap even when scrap was a decent price, now they're even more appealing as engine donors.
Bought one last year for peanuts (it was advertised here for a while but we got it through the local Landie group) and pulled the engine, 'box, axles etc. for a Defender conversion. There were enough eBayable parts left that we were close to getting the purchase price back when the shell was scrapped. We got eff-all for the shell and chassis.

It's not the most powerful variant but you'll probably get a runner so you at least know what you're starting with.

You need the space to strip/store it though.

[alex]

The conversion (in terms of it bolting up and everything that entails) will pretty much be the same so I wouldn't let that influence which RV8 you go for. If you can bolt a 3.5 RV8 in, you can bolt a 4.6 RV8 in. You can fit the entire front housing from one RV8 to another if you don't like the type of water pump it has..fit the later heads to an earlier block, fit carbs to a block that came out of an EFI and so on.

It depends on your budget and how good the advertised engine is. If the P5B engine is a low mileage unit, well looked after and needs nothing it would be very tempting if the price was good. Someone might be able to correct me, but if it actually came out of a P5B V8 it will be a Borg Warner 3 speed auto? Is this what you want?

In all, unless you are intending to fully rebuild the engine when you get it, I'd be more inclined to get a known good early 3.5 than an unknown later 3.5, for example, as a worn out RV8 will disappoint.