RangeRovers.net Forum banner

1 - 4 of 4 Posts

·
Registered
1995-2002 Range Rover P38A
Joined
·
359 Posts
Discussion Starter #1
Hi,

I have a P38 from 1996, this engine had a slipped liner, and I've done her up, put top hat liners in her, but also high compression 4.0 liter pistons and a mild (Kent 180) cam in it. Had the crank balanced, made the pistons and the big/small ends of the con-rods the same weight.
Also I took the sharp edges of the ports in the head, and I did an attempt to match the ports in the manifold to the heads a bit better.

She runs absolutely beautifull, but I heard that it's better to have an upgraded ECU after what I've done.
Is this correct? If yes, where to start/look.

Thanks. :)
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
359 Posts
Discussion Starter #3
Thanks!

Anyone experience with chipping a 4.6? Does it make some difference?
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
6 Posts
Hiya,
Yes - I had one setup for my 4.6 with stage 1 heads, RPI PR4 cam and tri-y exhaust for RTV trials where I wanted smooth linear power delivery but full go when asked for. I spent quite some time talking with Mark Adams at Tornado for what I wanted. This was approx 2002. I think the main difference was that it could take advantage of the extra air in and out. Better throttle response to my needs as well.

For you, with higher compression than original, then the spark mapping may need to be altered as the knock sensors would be pretty busy under load with more pinking - depends upon how much extra compression you have. I previously ran a 3.5 P6 high-compression 10.35:1 (std 9.35:1) mostly on LPG but we had to alter the bob weights on the distributor to change the spark timing using the rolling-road when on petrol as a compromise and I fitted a delaying spark amplifier which had different settings for LPG and Petrol.

My understanding is that the BOSCH/Thor system is more picky as it was designed to maintain stoich (air/fuel ratio of 14.7:1) over a much wider range to keep emissions lower so is less happy with changes in air/fuel efficiency i.e. mechanical tuning. GEMS is more flexible and can cope with a reasonable change anyway - say better exhaust and inlet.

I now run top-hat linered ACR 4.6 with a Megasquirt-2 running the P38 coil packs and do the mapping of fuel and spark myself (this is all in a LR90 so no BeCM!). My 'chip' was for the old Lucas 14CUX but he does GEMS as well as BOSCH.

Sorry to mix ancient petrol tuning with more modern 3d mapped spark/fuel systems like GEMS/Megasquirt2 but they all try to do the same job of squirt the right fuel for the amount of air and spark at the right time to get the best bang. :D
Cheers
 
1 - 4 of 4 Posts
Top