Rover V8

[rovertech]

Rob,

I am not suggesting aftermarket tuners change the mixture to 15:1. I stated a rover v8 can run at that mixture safely (meaning not detonate) because it can. I can tell you that at least two companies that I have worked with lean them out (obviously with other changes - that should go without saying) for increase in cruising speed economy. I know leaner mixture = increase NOx, I believe I stated that already did I not? I had understood NOx goes down with higher temps and CO goes up, but I certainly stand corrected. I have been known to flip flop facts before. I also didn't say power increased as the engine gets hotter I said it goes down (all things being equal). Again, I understand all things are not equal and a rule of thumb doesn't always pan out. In general I completely agree that most tuning companies exaggerate their claims. There are a few who do really good work however and there are some gains to be realized. That being said I generally don't recommend a re-tune on its own because it isn't that cost effective. If you combine a change of tune with other modifications then (to me) it is worth it.

Oh yeah, no kidding nobody runs lean at full throttle. I never suggested it was a good idea to lean out under acceleration. I can see re-reading my post how you could have drawn that conclusion.

 

[R_Lefebvre]

Not arguing, just trying to wrap this one up.

I don't doubt the Rover V8 can run safetly at 15:1. I don't know any engines that can't. Detonation just really isn't much of a threat at low load cruise. I know you didn't mean that power goes up with higher temps, I just poorly wrote that sentence, should have been "210-180".

I'd be curious to talk with the companies that claim to lean them out at cruise. How do they suppose to control it? You can't run closed loop 15:1 with a narrowband. So you would have to cruise open loop, and your AFR would be "out of control". You'd have to approximate it based on the mass airflow input, just the same as you do at full throttle. But the ECU uses the time it spends in closed loop to calibrate itself, so that the fuel mixture is right during open loop full throttle. So if you're cruising lean, open loop, the ECU never has a chance to calibrate itself. It wouldn't be able to compensate for fuel differences, wear and age on the fuel injection system, etc. You can see this if you drive a Disco with a good scanner that can display the Long Term Fuel Trims and Short Terms Fuel Trims. They are constantly changing.

I ran my car open loop all the time, but it doesn't run quite as well as a factory car, and I'm constantly retuning it as required.

 

[rovertech]

Not arguing, just trying to wrap this one up.

I don't doubt the Rover V8 can run safetly at 15:1. I don't know any engines that can't. Detonation just really isn't much of a threat at low load cruise. I know you didn't mean that power goes up with higher temps, I just poorly wrote that sentence, should have been "210-180".

I'd be curious to talk with the companies that claim to lean them out at cruise. How do they suppose to control it? You can't run closed loop 15:1 with a narrowband. So you would have to cruise open loop, and your AFR would be "out of control". You'd have to approximate it based on the mass airflow input, just the same as you do at full throttle. But the ECU uses the time it spends in closed loop to calibrate itself, so that the fuel mixture is right during open loop full throttle. So if you're cruising lean, open loop, the ECU never has a chance to calibrate itself. It wouldn't be able to compensate for fuel differences, wear and age on the fuel injection system, etc. You can see this if you drive a Disco with a good scanner that can display the Long Term Fuel Trims and Short Terms Fuel Trims. They are constantly changing.

I ran my car open loop all the time, but it doesn't run quite as well as a factory car, and I'm constantly retuning it as required.

I couldn't answer the control question for you Rob. TEMS is one company as an example.

 

[Chazz Layne]

2004 here approaching 80,000 miles. I've had it since early 2006. Coolant flush was done around 60k, no problems to report.



Now my trans cooler does leak ATF... it has been doing that for years.

Scratch that - I have a slowly increasing leak of coolant from the bottom of the throttle body that just developed. Guess I have some work to do...:coffeedrink:

 

[JEFFSGTP]

Scratch that - I have a slowly increasing leak of coolant from the bottom of the throttle body that just developed. Guess I have some work to do...:coffeedrink:

Your truck heard you bragging about it, and decided it needed some TLC :elkgrin: