Lean burn mode rules 70+mpg
 

I had the best day ever running in lean burn mode 18.5 to 19.0 A/F ratio.
Running a 10% ethanol blend premium fuel I got 64.8mpg.

The engine worked great and I still have some more testing with it running a 22:1 A/F ratio.

I reduced my mph down to 58mph due to the fact I know I won't get good results until I finish my aero-mods.

I did some testing at 22:1 A/F and the car did surge a bit. So I might be at my max A/F ratio?

Anyway time to celebrate!!!!!!!!!!!!!!!!!:cool:

What kind of vehicle is this, the 93 Honda Del Sol? What type of A/F ratio meter are you using and where is the wide band 02 sensor placed. Is this after market metering devices? Most gasoline internal combustion engines of any sort including older lean burn engines will loose load pulling power at 18 to 19:1. Without a turbo or a better means of maximizing heat energy losses or the ability to utilize more internal energy of the fuel, I suspect that where or what you readings are may be off a bit. Also slower burning fuel such as a higher octane needs the higher compression to provide a more complete burn unless you have advanced your timing accordingly. Most cars that are not higher performance models run at 8:1 to 8:75 and will not gain any performance or mileage with a higher octane. Just some quick thoughts. Accuracy is where all will benefit from your gains. Keep up the good work.

Congrats on the good numbers :thumbup:

Its a 93 Del Sol thats about 2" lower then stock. Thats the only aero mod at this time.

I'm running two wide band sensors(PLX wide band with gauge and a Innovate LMA-1). Both are around 18" from the turbo. They both read the same all thru the rpm range.

I use the LMA-1 for tuning other cars and recently had it in a Honda B18 that would miss fire at 16:1 A/F at light load. So I was totaly surprized when the Del Sol would run this lean and still make great power. In fact it will pull a hill at 17:1 and not even slow down.

But get this at idle I can't go over a 15:1 A/F with out it starting to do the lean miss thing.?

naturalextraction -

He's controlling the fuel with a Neptune engine management system :

Details: dturbosol - 1993 honda del sol s Fuel Economy - EcoModder.com
I googled and found this on the Neptune :

HRTuning

He's leveraging the tuner culture.

CarloSW2

Here are the mods.

Motor: The motor currently has less then 1800 miles on it since rebuild, I am currently using Castrol 5w30 and a K&N oil filter for break in.
D16z6 head complete rebuild by Cylinder Head Services
Stock port
New Skunk2 intake manifold
New Zex Stage 2 cam (59300)
New Supertech valve springs
New Supertech valves
OEM 60mm LS throttle body
New ARP headstuds
New OEM valve seals
New OEM retainers
New OEM valve keepers
New OEM headgasket
New OEM valve cover gaskets
New OEM cam seal
New OEM timing belt
New OEM timing belt tensioner
New OEM alternator belt

D16z6 block
New 75mm YCP vitara pistons Suzuki
New Eagle rods with big bolts
New ACL main bearings
New ACL rod bearings
New OEM main seal
New OEM oil pan gasket
New OEM water pump
New OEM oil pump
New OEM oil pickup
New OEM main bolts

Drivetrain:
D16z6 tranny with 1st gen OBX LSD
New Action 2md clutch
New OEM axle seals (located on tranny)
OEM resurfaced flywheel
New Energy Suspension shifter stabilizers

Brake and Suspension:
GSR front brakes*
GSR rear sway bar/LCA's*
Strut bar welded into trunk*
Koni Yellows*
H&R Race springs*

Exhaust:
RRP 2.5 inch ECUTOUT for track and then connected to STOCK exhaust for quiet street drive

Turbo Setup:
Greddy 15G turbo
Greddy cast turbo manifold
Greddy cast elbow
Greddy downpipe
Ebay intercooler
Ebay SSQV BOV
Ebay intercooler piping
Hallman Pro MBC

Fuel Management and other MISC:
P28 with Neptune RTP
PLX wideband with gauge
New Motorola 2.5 bar map sensor
New Precision 780cc injectors
OEM resistor box
Walbro 190LPH
Autometer Boost gauge
Autometer Oil pressure gauge

I'm also running a crazy ass NGK spark plug.:eek:

How are you protecting your engine from damage? I would think 17:1 A:F would lead to holed pistons.

At a very light load is what saves the pistons.IMHO

The car is kinda hard to drive. As in, the gas pedal is barely being depressed. I'm going to build a valve the will be centrally located on the intake manifold that I can activate with a switch to become my cruz throttle. The valve will be adjustable for how much air it can let in.

Edit You got me a little worried so I just check all four cylinders with a bore scope. All looks well. I do need to make a better egr system though.

Thanks!!!!

I have to give a big thanks back to ya for having this forum. It has helped a lot.

Its time for me to donate and get some of those cool ecomodder stickers:thumbup:

Thanks for the info links to the Neptune info CarlosSW2. pgfpro-in regard to idle: your turbo is helping at higher rpm related to pressures even at ambient although you may not read any psig. It is still helping to push air. It is also helping the fuel to burn when the natural vacume of the engine otherwise would not sufficient enough to allow for lean mixture to burn. Thus why at idle it suffers.
This bringing me to air temperature and potential damages. (I've been studying and experimenting related to different fuel distribution methods and management for the ICE for over 4 years now. I in list the help of some of my physicist and mathematical friends from Sandia labs when the information or findings exceed my temporary limitations. I have access for testing at the labs Los Alamos or Sandia and use of typical dynometers rear and engine.) Lean burn will not hurt your pistons from the standpoint there is not much to burn. This in keeping the combustion chambers within an "ideal" temperature range. What damages them under a lean burn condition is fuel droplet sizes, particularly when the chamber is hotter and this is where timing is a factor as well as the fuels ability to burn, and flame front travel. I've run two engines at the 18:1 to 21:1 just fine and maintain some levels of usable power in both a motorcycle and car. (car being a 1972 Duster 318). After 36K miles the engine was torn down to find no burnt valves, very clean piston tops all while running the engine mostly on low grade unleaded. (Stretched head bolts were the only culprit)
While droplet size from modern day injectors are quite small, in a hot chamber they still can create pinging or complete detonation damaging pistons or valves. Thus why engineers developed DPI for better fuel distribution with higher fuel pressures. Other factors that create anomalies from injected engines would be pump pressure consistencies due to possible voltage drops at pump, restrictions, fuel density changes due to ambient temperatures, to name a few. Your management system is constantly monitoring and trying to make changes quickly but can not compensate as quickly or as well under leaner conditions. Leaner conditions basically require changes to the fuel itself, delivery, air temperature controls and more accurate consistencies in all areas to the induction and fuel delivery systems. Delivery and firing timing becomes much more critical. Without your turbo you would expect to have the same issues you experience at idle but at higher rpms without other control devices. I personally do not recommend inter coolers in relation to obtaining economy in the ICE. Their good for power but not for economy. That gets into a whole other discussion regarding adiabatic/thermal issues and other control issues. Keep in mind the basic efficiencies of most ICE's to be at ->30% anyway. Most of it is lost to heat energy. This being why I like the volumetric efficiency gains turbos make while using expended heat energy. Thus bringing up the overall efficiency factors of the ICE, although not by a big margin.
Also keep in mind cylinder chamber temperatures are much lower due to the fact you are NOT burning the same volume of fuel. Note your exhaust temperatures under those conditions. But the fuel cannot change its burn rate under those conditions. It's the fuel that creates the problems primarily, keeping in mind the other issues stated above.