Go Back   EcoModder Forum > EcoModding > EcoModding Central
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 04-16-2021, 09:10 AM   #21 (permalink)
Master EcoModder
 
Join Date: Jan 2012
Location: United States
Posts: 1,560

spyder2 - '00 Toyota MR2 Spyder
Thanks: 95
Thanked 312 Times in 241 Posts
Quote:
Originally Posted by Ecky View Post
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.

  Reply With Quote
The Following User Says Thank You to serialk11r For This Useful Post:
Ecky (04-16-2021)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 04-17-2021, 09:34 PM   #22 (permalink)
EcoModding Lurker
 
Join Date: Jun 2015
Location: Syracuse, NY
Posts: 11

Subi - '15 Subaru Impreza Premium
Thanks: 0
Thanked 0 Times in 0 Posts
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.
  Reply With Quote
Old 04-18-2021, 01:49 AM   #23 (permalink)
Master EcoModder
 
Join Date: Jan 2012
Location: United States
Posts: 1,560

spyder2 - '00 Toyota MR2 Spyder
Thanks: 95
Thanked 312 Times in 241 Posts
Quote:
Originally Posted by quagss View Post
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.

Last edited by serialk11r; 04-18-2021 at 02:11 AM..
  Reply With Quote
Old 04-18-2021, 07:28 PM   #24 (permalink)
Master EcoModder
 
Ecky's Avatar
 
Join Date: Dec 2011
Location: Vermont
Posts: 4,304

Gaptooth (retired) - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 54.26 mpg (US)

Such Fit - '07 Honda Fit Sport
90 day: 41.27 mpg (US)

Connect - '15 Ford Transit Connect XL
90 day: 20.83 mpg (US)

K-sight - '00 Honda K-sight
Team Honda
90 day: 41.4 mpg (US)
Thanks: 2,100
Thanked 1,884 Times in 1,201 Posts
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.
  Reply With Quote
Old 04-18-2021, 08:19 PM   #25 (permalink)
It's all about Diesel
 
cRiPpLe_rOoStEr's Avatar
 
Join Date: Oct 2012
Location: Porto Alegre, Rio Grande do Sul, Brazil
Posts: 9,158
Thanks: 0
Thanked 1,064 Times in 934 Posts
Quote:
Originally Posted by quagss View Post
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.
  Reply With Quote
Old 04-19-2021, 02:18 AM   #26 (permalink)
Master EcoModder
 
Join Date: Jan 2012
Location: United States
Posts: 1,560

spyder2 - '00 Toyota MR2 Spyder
Thanks: 95
Thanked 312 Times in 241 Posts
Quote:
Originally Posted by Ecky View Post
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.

Last edited by serialk11r; 04-19-2021 at 02:32 AM..
  Reply With Quote
Old 04-24-2021, 07:11 AM   #27 (permalink)
Master EcoModder
 
Join Date: Jan 2012
Location: United States
Posts: 1,560

spyder2 - '00 Toyota MR2 Spyder
Thanks: 95
Thanked 312 Times in 241 Posts
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 :/

Last edited by serialk11r; 04-24-2021 at 07:20 AM..
  Reply With Quote
Old 04-26-2021, 03:24 AM   #28 (permalink)
Master EcoModder
 
Join Date: Jan 2012
Location: United States
Posts: 1,560

spyder2 - '00 Toyota MR2 Spyder
Thanks: 95
Thanked 312 Times in 241 Posts
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).

  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com