Rover p5b

truckdoctor · Post by **truckdoctor** » Mon Dec 06, 2010 12:03 am

This is my rover that is a bit under powered with 160 bhp and weighing in at 1.5 tonn

Hopefully I can replace this v8 with a tuned 4.6 or maybe a Lexus. At present it's undergoing a lot of body repairs and progress is slow in this cold weather.

I'd be interested in your comments on the best way to get more power. Thanks in advance

kiwicar · Post by **kiwicar** » Mon Dec 06, 2010 6:22 am

Hi
if you are going to restore and cruise rather than custom and race I think the lexus and auto combination would sute it very well. Maybe air springs to really smothe out the ride and a really understated exhaust note, subtle style rather than in your face. . . . .
Bes regards
Mike

ChrisJC · Post by **ChrisJC** » Mon Dec 06, 2010 8:47 am

I'd go for a mildly tuned 4.6 and a ZF 4HP22 4-speed transmission. You can keep it all simple (i.e. carbs, distributor and non-electronic gearbox), but it will still work well.

Chris.

DaveEFI · Post by **DaveEFI** » Mon Dec 06, 2010 10:43 am

ChrisJC wrote:I'd go for a mildly tuned 4.6 and a ZF 4HP22 4-speed transmission. You can keep it all simple (i.e. carbs, distributor and non-electronic gearbox), but it will still work well.

Chris.

I'd definitely go for EFI. Probably a hot wire bog standard 3.9 and ZF . In an attempt to keep the MPG reasonable. That's if the EFI and ZF will fit.

I'm not sure now much torque that Rover axle will handle?

BTW, I followed a beautiful white P5B up Cedars Road towards Clapham Common yesterday at about 18.30 Anyone here? It wasn't hanging about.

ChrisJC · Post by **ChrisJC** » Mon Dec 06, 2010 12:19 pm

Personally I would go for Fuel Injection too. In fact, I would try to go with Thor, as standard on a Range Rover P38 (assuming I could get the ECU to work standalone). But I work in electronics so it doesn't scare me.

But some folk are very scared of 'lectrics, and the attraction of old-school carbs ticks their boxes......

Chris.

DaveEFI · Post by **DaveEFI** » Mon Dec 06, 2010 12:51 pm

ChrisJC wrote:Personally I would go for Fuel Injection too. In fact, I would try to go with Thor, as standard on a Range Rover P38 (assuming I could get the ECU to work standalone). But I work in electronics so it doesn't scare me.

But some folk are very scared of 'lectrics, and the attraction of old-school carbs ticks their boxes......

Chris.

My reasoning is all the larger engines only ever came with injection, and assuming it's working properly and you get all the bits should be a deal easier to fit than trying to tune a carb or carbs never fitted by the makers.
Other plus is it should less effected by vapour lock.
The idea of say a complete Lexus powertrain is good - but the amount of worked needed to do that is rather greater than a little wiring.

Which of course it would also need.

ChrisJC · Post by **ChrisJC** » Mon Dec 06, 2010 1:54 pm

I run a couple of 2" SU's on my 4.6 (in my Landie), rolling roaded to get the right needles.
I do have MegaJolt for the ignition, and I find the combination of the two gives really quite startling performance for a Series Landie (about 250BHP in 1.7 tonnes of vehicle).

On a 4HP22 transmission.

Chris.

CastleMGBV8 · Post by **CastleMGBV8** » Mon Dec 06, 2010 2:00 pm

Some this has been suggested but here's a bit more detail.

The 3.5 3.9 and 4.0 engines all share the same relatively short stroke of 71mm. and for a large heavy car you really need an engine with a decent amount of torque ie. power from idle upwards especially with an auto box which means you won't be revving very high.

The 4.6 Rover has an 82mm stroke with peak power at approx 5200RPM so would provide the basics you require and can be further improved with mildly flowed heads and a high torque cam if required.

Don't be confused by BHP rating as these only apply to peak power at hi revs, torque is what provides that lovely surge of acceleration when you push the throttle.

A 4.6 should be a bolt in with a minimum amount of wiring if you can get a complete unit with all the EFI bits and the loom.

They come up on e-bay but be careful regarding engines with the slipped liner problem unless they can offer proof of pressure testing, or a guarantee if from a commercil source but make sure it is being sold complete as it gets expensive buying parts later.

The later ZFHP22 2 wheel drive gearbox possibly from a jag XJ or similar (but check for bellhousing compatability) would be a sensible upgrade and give enhanced drivability and I think 4th is overdrive so cruise MPG should be improved.

Ashcroft Transmissions specialise in ZF boxes so should be able to advise on size etc., their web site is quite informative but obviously at least most of their boxes will be 4WD but the main internals are the same as the 2WD boxes.

To fit the later box will probably require mods to the gearbox crossmember and possibly the length of the prop shaft and front joint unless you are very lucky.

Hope thats a help.

Kevin.

truckdoctor · Post by **truckdoctor** » Mon Dec 06, 2010 5:02 pm

Thank you all for your replies, I need to do some work on sourcing the correct parts etc. and you have given me some direction to follow. Personally I have zero fears of electronics and injection systems as I worked years ago with Bosch and the L and Motronic systems and know it's the best way of fueling an engine, wether I can get it to fit on this car is another matter but well worth considering.
One question though, the ZF 4HP22 4-speed transmission , how does the physical size compare to the BW 35 Thanks, Steve

kiwicar · Post by **kiwicar** » Mon Dec 06, 2010 5:13 pm

How about the XJ/XK 8 engine and box, 4 or 4.2 litres, optional supercharger, 5 speed auto on the 4 litre engine, 6 speed auto box on the 4.2 engine, if the electrics offer no fear to you then a nice engine and gearbox combination. And while you are at it grab the diff and replace the rover diff with it.
Best regards
Mike

DaveEFI · Post by **DaveEFI** » Mon Dec 06, 2010 5:19 pm

truckdoctor wrote:Thank you all for your replies, I need to do some work on sourcing the correct parts etc. and you have given me some direction to follow. Personally I have zero fears of electronics and injection systems as I worked years ago with Bosch and the L and Motronic systems and know it's the best way of fueling an engine, wether I can get it to fit on this car is another matter but well worth considering.
One question though, the ZF 4HP22 4-speed transmission , how does the physical size compare to the BW 35 Thanks, Steve

It's a lot bigger. Because it has to fit between the same centres as the manual box on the Rangie, the torque convertor is spaced off the flywheel and a longer than necessary bell housing used. Lots of room in a Rangie.
I don't know the P5B well, but things look quite tight under the bonnet.

ChrisJC · Post by **ChrisJC** » Mon Dec 06, 2010 9:39 pm

As Dave says, the ZF4HP22 on the Rover V8 has a massively long bellhousing (well, about 3-4inches longer than necessary).
A different option would be to keep the bellhousing of something else, and make an adaptor. That way you could shave some length of it.

If you PM me your e-mail address I will send you a partially dimensioned drawing of the 4HP22. It covers the 'box body, but says (I think, it's in German) that the bellhousing and tailcone are application specific. Mind you, somebody could measure the bellhousing easily enough, and the tailcone doesn't matter as it's smaller.

Chris.

DaveEFI · Post by **DaveEFI** » Mon Dec 06, 2010 11:36 pm

ChrisJC wrote:As Dave says, the ZF4HP22 on the Rover V8 has a massively long bellhousing (well, about 3-4inches longer than necessary).
A different option would be to keep the bellhousing of something else, and make an adaptor. That way you could shave some length of it.

If you PM me your e-mail address I will send you a partially dimensioned drawing of the 4HP22. It covers the 'box body, but says (I think, it's in German) that the bellhousing and tailcone are application specific. Mind you, somebody could measure the bellhousing easily enough, and the tailcone doesn't matter as it's smaller.

Chris.

The TH180 as used on later SD1s has a removable bellhousing. I've oft wondered if a later GM box - pref 5 speed - would fit that bellhousing. Sadly later GM boxes are pretty rare in the UK - unless anyone knows different.