Thread: 4.6 engine rebuild

I had a top hatted 4.6 built for a customer recently by Triumph Rover Spares (Lonsdale SA), it came with a billet cam and high comp pistons, and it goes like stink compared with the original RRC 3.9 it replaced. A highly recommended combination. Decking the block isn't the way to raise compression as the pistons would also need machining as well as the inlet manifold etc.

Originally Posted by bee utey

I had a top hatted 4.6 built for a customer recently by Triumph Rover Spares (Lonsdale SA), it came with a billet cam and high comp pistons, and it goes like stink compared with the original RRC 3.9 it replaced. A highly recommended combination. Decking the block isn't the way to raise compression as the pistons would also need machining as well as the inlet manifold etc.

Hi how much did it cost?
Cheers peter

I had the heads port matched, a different cam, high compression pistons, tophat liners, and a full balance done to mine. Oh, and the manifold drilled and tapped (blanking screws fitted) ready for when I could have the LPG injection done

Originally Posted by kimandy

I have a situation now where I have to rebuild the 4.6 in my P38.

I am aware of top hat sleeves and I will be doing that but I would like to build it with a bit more get up & go and was thinking of decking the block a bit for a little extra compression, fitting a tow cam, new pistons of course & probably getting the heads worked a bit.

Would love some advice on the best way to do this & which cam / pistons to use & where to get the parts from. Also where to get the sleeves fitted in Melbourne.

It is my understanding that most Aussie P38s came with low compr pistons, so just changing the pistons will give you a better compr ratio. Brian Davis in Sydney and TRS in Adelaide can do the engineering work. If you are replacing the sleeves and pistons anyway, think about increasing the capacity too. Both of them can tell you about that.

Because our engines are used in so many other cars, there are specialists in the UK who can go further still. Google is your friend.

I suggest that you also look at improved injectors because the originals are pretty ordinary - Bosch make an improved version that fits, and you will make great gains by remapping the ECU. Look up Tornado systems - Mark Adams, in the UK.

These ECU remappings are only possible for the GEMS ECU though right? I havent seen any revised mappings or chip systems for the Bosch suite.

Originally Posted by glenhendry

These ECU remappings are only possible for the GEMS ECU though right? I havent seen any revised mappings or chip systems for the Bosch suite.

here's why...

Motronic 5.2 Reprogramming

OK.. I've got the sleeves / pistons / cam sorted and I'm thinking about getting the heads ported.

Can someone tell me more about the upgraded injectors and mapping..
It is a Gems motor.

Originally Posted by kimandy

OK.. I've got the sleeves / pistons / cam sorted

Can you give us details - suppliers and costs?

I am likely to be going through the same process before too long.

Garry