Extremely thirsty supermodel - eco attempt!

[serialk11r]

Originally Posted by Ecky

If you're feeling adventurous, you can always go even thinner, and send a sample off to Blackstone for analysis (metal content).

I would only dare to do that with a Redline 30 weight (since they're A3/B3/B4), and if the oil cooler thermostat could be switched out to slightly lower temp. The thermostat is mechanical and opens at 102C.

If I knew for sure I wasn't going to exceed 4000rpm for the whole oil change, then a common 5w-30 might work. You do get diminishing returns, since the thinner oil could make it run under boundary lubrication conditions, and this engine has wide clearances which is why 10w-60 was speced.

[quagss]

Look on the website bobistheoilguy.com. There is a member AEHaas, who has several exotic cars. Ferraris mostly. He runs 0w-20 in them. I would recommend you try Redline 10w-30. Yes it's expensive but you'll only need to change it once every 2 years maybe.

If you can write a custom tune, you should lean it way out. Forget 14:1, try 18. I would imagine the robust V8 can handle lean burn as the large metal volume and overbuilt cooling system can handle the heat.

[serialk11r]

Originally Posted by quagss

Look on the website bobistheoilguy.com. There is a member AEHaas, who has several exotic cars. Ferraris mostly. He runs 0w-20 in them. I would recommend you try Redline 10w-30. Yes it's expensive but you'll only need to change it once every 2 years maybe.

If you can write a custom tune, you should lean it way out. Forget 14:1, try 18. I would imagine the robust V8 can handle lean burn as the large metal volume and overbuilt cooling system can handle the heat.

Thanks for the comment, I am aware of all this.

The issue with running a light oil is that unlike the BMW S65 and S85 engines which had tight bearing clearances and failures on 10W-60 oil, Vantage owners all run 10W-60 with basically no engine failures, suggesting the oil is pretty well matched to the engine.

Certainly it is unlikely that 10w-30 oil at 100-105C would be an issue for street driving, but dropping 3 grades feels too aggressive on an engine that would cost 20k to rebuild, and it's possible that the thinner oil film will have diminishing returns for efficiency.

I would be shocked if I made it to 2000 miles in any year on the car, so it really doesn't make sense to buy Redline oil for 70 dollars more when my OCI is going to be like 2000 miles. The shelf life of oil is shorter than the time it would take to accumulate 7500 miles. M1 is very very cheap at 4 bucks a quart and the base stocks have fairly good VI.

As far as tuning goes, the issue is this platform isn't common and well supported the way Subarus or BMWs are. Even on a popular platform, lean burn can be very difficult to implement due to the ECU restricting open loop AFR to rich only.

There is a guy who did figure out pretty much all the workings of the ECU and ran lean burn (in open loop), but he spent many years and tens of thousands on his car. The easier way to do lean burn is to replace the O2 sensors with wideband sensors and bias the closed loop AFR, but it requires considerable custom ignition timing adjustments if you want the most out of it, and you need to spoof the post-cat sensors as well, so it'll take 2 wideband emulators + sensors + 2 sensor simulators and quite a lot of money and/or time on a custom tune.

My limited modifications are vastly easier since the OEM already built in all the timing compensation and it's just a matter of accessing a few tables. I will never break even on this mod, but for a little bit more effort over an off the shelf tune I can get my car a few % more efficient than 99% of the others.

[Ecky]

I imagine you could get a fair bit of mileage with running as little lean as 1.04-1.07 lambda, even without adjustments to ignition timing.

Heat isn't an issue at low load (which it would be during cruise), and temperature actually starts to drop off past ~1.04-1.05.

[cRiPpLe_rOoStEr]

Originally Posted by quagss

I would imagine the robust V8 can handle lean burn as the large metal volume and overbuilt cooling system can handle the heat.

It's a sophisticated British design, not even supposed to be as dumbproof as a small-block Chevy.

[serialk11r]

Originally Posted by Ecky

I imagine you could get a fair bit of mileage with running as little lean as 1.04-1.07 lambda, even without adjustments to ignition timing.

Heat isn't an issue at low load (which it would be during cruise), and temperature actually starts to drop off past ~1.04-1.05.

Yes, but the gains are bigger if you can go leaner. Lean burn is like high volume cooled EGR but with faster flame velocity. To get the best effect, you can bias everything lean and run open loop idle richer, or run open loop lean while cruising. Running open loop in commonly used operating conditions has its own drawbacks, and not forcing open loop limits the gains. Biasing the sensors means a few hundred bucks in narrowband emulators, a bunch of custom wiring, and a lot of custom tuning to reset the ignition timing.

For a car that doesn't have emissions restrictions and for which you have complete control over the ECU's programming, you definitely want to run very lean, maybe with warmed intake air or a hint of EGR to help with ignition.

This engine isn't short on EGR thanks to the MASSIVE cams, so pumping losses aren't actually that big of a deal. The intake vacuum is pretty modest near minimum load (i.e. pressing on the pedal enough to actually move the car), around 0.6 bar.

@cRiPpLe_rOoStEr I wouldn't call it particularly sophisticated, it's very similar to a Ford V8 in design. This car adds a 2 scavenge pump dry sump system, DLC coated shimless bucket lifters and a forged crank. Everything else is pretty ordinary, and thankfully it seems to all hold together unlike Porsches of the same vintage.

The coolant temperature goes up FAST, though it's a 1.5 bar system so it can run a little hotter than most cars I've seen. I do have some concerns that the radiator is near its limit and my grille tape might not be a good idea. Of course, this isn't relevant to the discussion as lean burn decreases peak combustion temperature and only increases EGT at high load and high speed where the slower combustion speed is a problem.

[serialk11r]

Alright so I don't think I can use lean burn, because that would require always staying in open loop or swapping all the sensors to narrowband emulators, which I'm not comfortable doing. Leaving it at stoich also means I don't need to spend tons of time tweaking ignition tables.

So the final changelist is going to be:
-Retard intake cam position at low load
-Lean out open loop fueling (it's stupidly rich, like a turbo car)
-Reduce closed loop delay
-Reduce DFCO delay
-Enable DFCO in low gears
-Reduce idle speed from 750rpm to 700rpm
-Add more EGR where appropriate

My oil change seems like it's going to be delayed, as the 2 post lift I wanted to borrow isn't available. I wanted to do the first oil change myself to witness the condition of the various bits underneath the engine, and I'll probably pay a shop to do the next one as removing the gazillion bolts is kind of annoying.

I would LOVE to put taller tires on the back, but I have brand new Michelins on here :/

[serialk11r]

So when I got the car paint corrected and ceramic coated, they took off the tape I put over the oil cooler...and I lost almost 2mpg? I didn't do an ABA test, but cruise control 6th gear 60mph with the taped off oil cooler used to be 23.8mpg ish, now it's only 22mpg. Didn't get around to oil change, but I did flush my power steering fluid with Pentosin. Probably a 0.5% gain at best, but this makes me hopeful about thinner oil. I'll need to measure oil temps again, but dropping the oil to a 40 weight will hopefully get me above the taped off cooler and 10w-60.

The nut behind the wheel is of course still easily adjustable: I was pulse and gliding very diligently for 100 miles of freeway and managed to exceed 24mpg during that time, but some slower streets quickly burned through a quarter of the tank while not covering much ground. This definitely has to be an Aston Martin record lol (well, maybe not, the 7 and 8 speed transmission equipped cars probably do better thanks to having a tall cruising gear).

[serialk11r]

Haven't had all that much time to mess with cars lately but I have made some progress on tuning the ECU, and I got my used oil analysis back. On the short trips I've taken the car out, it's been getting around 14mpg :/

Despite the oil having 2000 miles on it and 10W-60 being notorious for shearing very quickly, my Castrol 10w-60 is still at 20.8 cSt at 100C! I'm going to start taping off the bottom portion of the oil cooler to block off more of it until I can get around to an oil change. I haven't been able to borrow a car lift, which I really want because the number of bolts and screws to remove on the bottom of the car is kind of silly. I think with only a small portion of the oil cooler exposed to fresh air, it'll hopefully increase oil temps to around 115C which will drop the viscosity considerably.

The ECU now runs much less rich in open loop, it goes into closed loop sooner, and I managed to get DFCO working, though it cuts out around 1800rpm in lower gears even though I want it to stay until 950rpm. I'm trying to figure that out, and also see if I managed to successfully lower the idle speed for engine on pulse and glide. Then hopefully increasing EGR and reducing some valve overlap will get me another 1 mpg on the freeway.

[serialk11r]

Ugh, this Ford ECU is proving very irritating to work with. Does anyone have a Mustang GT (circa 2005-2010, EEC 6) that they have experience tuning?

The DFCO is pretty stubborn, it seems like no matter what I change, it will go to 1100rpm in 6th gear and about 1700rpm in all other gears. 1700rpm in 2nd gear is about 17mph so I can't actually engine brake to stop signs very effectively as a result.

I've been able to lower the idle to 672rpm (from 750, though it seems to target 736 not 750) which seems to save a little bit of fuel while maintaining 13.6V at the alternator (plenty) and great throttle response off idle, no bogging whatsoever. Air conditioner and fans can be turned on with no bogging either. I retarded the intake cam a little at idle which seems to make it a little bit smoother, but that might just be placebo effect.

With a full battery and warm oil, I think it now idles at about 0.40gph at sea level, hopefully less on a hot day, and hopefully less after I replace the oil with thinner oil.

The car wasn't happy with my VVT changes and the ECU would shut off the engine if I pressed the acc pedal, so I'm trying some different values to see if it helps.