The only time I see 200+ temps is on a hot day 80+F running slow up long steep uphills (over 13%) and low rpm, the engines just work harder. Low range and lower gears help a bit, but it is the slow speed that really hurts, mind once I crest and even a tiny downhill temps drop like a rocket I actually hit 168 at one point.

This leads me to believe our engine are also running too lean, but my 04 has not oil cooler so that might actually help.

 

@Richard Gallant I do think they are too lean. Several tuning companies in the U.K. will reflash your ecu to mitigate the lean spots in the mid range.

My temp behaves the same way. I’m sure I would hit 200 on a long uphill in low rpm. My transmission shifts kind of funny and likes to upshift to the highest gear ASAP. I bought a reman transmission computer that I hope will make the shifting behavior more normal. It hunts for gears and just upshifts way too soon.



Apparently fuel mileage and emission were the decision making factors, so they leaned out the tuning as well. Tornado Systems has a good description on their website. You can send you ecu to them for a remap:

Tornado Systems | Bosch Motronic Ecu upgrade for Land rover Discovery 2 4.0/4.6 and Range rover P38 Thor engine

 

How can it be lean with the narrow band 02's controlling it? It's no so much that is runs lean, it runs close to stoich all the time. Other engines actually go in to PE mode over about 80% throttle where as the Rover never does. PE should be AFR 12.5-13:1 for best power, but the Disco stays right around 14.7 all the time.

 

@Extinct understood a hair of that...

So you’re saying the O2’s ensure the mixture is good so it’s not too rich or too lean, right?

PE = power enrichment?

From you synopsis it sounds like the tuning is just not ideal.

Comtinued good conversation. Thanks for all the contributions.

 

Yes, you got the gist of it. The factory Rover tune never goes lean except when the deceleration defuel kicks in (coasting for long periods) but also does not go rich when is should at close to WOT for max power. GM engines and many others go in to a PE mode any time the throttle goes over about 80% and go to a rich mixture. From the factory the air fuel ratio in PE mode goes to about 11:1, but best power is at 12.5-13 depending on RPM. The go too rich from the factory to prevent engine damage, but they are overly cautious. Most tuners lean it out. PE mode is open loop of course because the oxygen sensors cannot read anything richer than about 14.75. Rover tune stays in closed loop all the time, being controlled by the oxygen sensors. You can see it if you make a long uphill pull at WOT while watching the oxygen sensor output, they just keep cycling. Its too lean for best power, but better for emissions.

 

Great info. So there’s some potential for an ECU reflash to improve performance over the stock tune it sounds like.

I just found a post from a long time ago that posted the link to this article. On page 29 the article discusses a % of block failures on Rover V8’s. “How to power tune Rover v8 engines” Worth a quick read:

https://books.google.com/books?id=gm...20rover&f=true

 

From reading this forum for 7 plus years I have heard story’s of guys doing everything right and the engine blows
there are also guys that have high miles without any issues
it’s a hit and miss

 

Not fully relevant, more just an interesting observation about my 2015 RRS. After being so obsessive about the temps in the discos and doing all I can to keep them below 200, I was so shocked when I got my RRS and saw temps almost always between 225 and 260. It’s just crazy how hot modern engines run compared to the old boyes. Hotter engine temps are almost always in pursuit of better emissions, which is what I’ve heard is the reason for LR spec’ing the higher temp thermostat in the D2.

 

@Brandon318 its also weird to me how hot newer cars run. Most of them have electric water pumps which gives very precise control over the coolant flow and coordination with the thermostat.

Basically higher coolant temps are safer with more precise control. And I believe it’s all in the name of better emissions.

In college I was on the Formula SAE team. It’s a collegiate race at design project. You build a small racecar with a sport bike motor. We used a Yamaha R6 motor. It was happiest running 215-225. We had it to almost 280 degrees F twice without causing catastrophic damage (awe had a poorly designed cooling system. Quote the opposite of the Rover V8’s ability to handle high temps!

 

P38 had an oil cooler, D2 with the 4.6l engine has not. That makes a difference of 20 F in oil temperatures. I know this since I added an oil cooler to my '04. Maximum oil temperature without oil cooler was 260 F, with oil cooler it gets to 240 F (temp sensor on a sandwich plate). All tested under the very same conditions and after cooling system overhaul: 180 thermostat, new fan, new radiator. Coolant temperature differed only a few degrees with or without oil cooler and stays around 190 F, even if oil temperature reaches 260 F. So don't be fooled by coolant temperature, when it comes to actual thermal stress in the block.