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Sounds awesome. My wife is from Edmonton so I am familiar with those wide open spaces. I would think investing in an egt sensor you could log with the ms3 would aid in tuning for cruise economy.
I have been tossing around the idea of an EGT so that I can monitor the exhaust on those long highway pulls. I never thought about logging it into the MS3 that sounds like a terrific idea. Thanks for the suggestion. My wife and I are really thinking about getting out of this Liberal Snowflake Swamp Playground we call BC and moving to Alberta. Don't get me wrong I love BC, but just hate the way the province is turning things. I have a friend that lives in Coaldale Alberta says its great their. Roads are flat and ripe for some street racing. Especially some improvised 1 mile drags.
Originally Posted by jasonsnova
i got little over 19mpg with my nova last year with a not so mpg friendly tune. combo was
71 nova, 6.0 s475 , t56 trans and 3.50 rear gear.
I'm sure i could get it into the low 20's playing with the tune and being a little easier on the right foot
If you can get 20mpg with a Nova I am pretty sure I should be good to go with my little Fiero.
Originally Posted by JoeNova
14 city, 24 highway, and I couldn't keep my foot out of it. Something like 18/28 if I drove a little more modestly.
LOL, I'll be the same way for the first month or 2, the excitement of it, I'll be in boost constantly. I'll need to invest in a tire company before I get the car on the ground.
Originally Posted by Forcefed86
Don't believe there is much/any advantage to running leaner than stoich? If you go leaner than 14.7 it will be down on power and likely require more throttle/DC/RPM to maintain the same power level at your desired RPM.
You're looking for the most complete burn possible. Too lean and you're lacking power too rich and you're wasting fuel. I've seen many argue this as well. But IMO if there were big advantages to learning out the mixture beyond 14.7... you'd see it in the big car companies. Hunting for the best MPG is always at the top of their engineer's lists. Yet every OEM ECU vehicle I'm aware of targets stoich at cruise.
As far as timing goes you want to run the "correct" level of advance that nets max torque at your cruisie RPM. MBT timing will differ for every setup.
High base compression and a short duration cam with a wide LSA helps as well. My 10:1 5.3 was netting 18mpg highway on E85 with my setup at about 55mph. 3.10 gear 29" tire with a glide abound 2900lbs. Pump fuel should have net me around 23. Thats through an unlocked converter and 9". I'm sure a manual setup like yours should be able to hit 30ish+ if done correctly with enough gear.
With the MS3 I auto tune the whole unloaded AFR map to 13.8 or so. When done I smooth the map and setup the closed loop fuel control to shoot for 14.7. The ECU will automatically hunt for 14.7 this way. Regardless of ambient temps loads etc...
If the autotune on the MS3 actually works well, I might be golden. Do you know if the MS3 can log the OEM knock sensors? I am going to have to get creative learning just how much I can tweak it safly. You said with enough gear, The Fiero is a bitch to get "gear" into. Being a transaxle we only have a few options, and of those options only 1 that will sorta hold up and one that is the best, but will set you back $3000-$4000 for the trans + conversion to install it. The 5spd Getrag I am going to use is really only reliable to 450hp / 450lbs of torque but is the best option unless you want to drop the big bucks. I may eventually bite the bullet and go auto, (I hate auto's) for now though, I'm going with the 5spd, then save up for the expensive 6spd swap. The 6spd swap will have me spinning 1500rpms at 70mph. The 5spd is more like 2500rpms at 70mph.
Originally Posted by truckdoug
you do see it in car companies. just not in the US. leaner than stoich tends to create higher levels of oxides of nitrogen...something we are loathe to do here as it creates smog.
in rural australia...not so much. I have an '04 GTO p59 computer/OS/tune that has the lean cruise tables. it'll go out to 16:1 under low load high manifold depression operation. but give it 2% more throttle and it checks back to 14.68:1
anyways it's really not gonna gain you much mileage. it's all about how you drive. is every stop sign a chance to get into boost? or do you mostly "walk softly and carry a big stick" ?
The newer GTO's are one of my most favorite "Family Sedans" out there. I love the idea of a Hot Rod that can haul kids and be rear wheel drive. LOL, walk softly and carry a big stick. For the first bit when I start driving it, it'll be all boost all the time. However once I calm down, I'm sure it will be a walk softly then take a quick WHACK at those pesky Hondas or high dollar domestics.
Thank You, everyone, for all the amazing info. You have all been a great help. It looks like I'll have no problem getting this car into the mid 20's if not low 30's with turning and driving style. I am sure I'll have a lot more questions later on, once it is on the ground and driving.
Don't believe there is much/any advantage to running leaner than stoich? If you go leaner that 14.7 it will be down on power and likely require more throttle/DC/RPM to maintain the same power level at your desired RPM.
You're looking for the most complete burn possible. Too lean and you're lacking power too rich and you're wasting fuel. I've seen many argue this as well. But IMO if there were big advantages to learning out the mixture beyond 14.7... you'd see it in the big car companies. Hunting for the best MPG is always at the top of their engineers lists. Yet every OEM ECU vehicle I'm aware of targets stoich at cruise.
As far as timing goes you want to run the "correct" level of advance that nets max torque at your cruisie RPM. MBT timing will differ for every setup.
High base compression and a short duration cam with a wide LSA helps as well. My 10:1 5.3 was netting 18mpg highway on E85 with my setup at about 55mph. 3.10 gear 29" tire with a glide abound 2900lbs. Pump fuel should have net me around 23. Thats through an unlocked converter and 9". I'm sure a manual setup like yours should be able to hit 30ish+ if done correctly with enough gear.
With the MS3 I auto tune the whole unloaded AFR map to 13.8 or so. When done I smooth the map and setup the closed loop fuel control to shoot for 14.7. The ECU will automatically hunt for 14.7 this way. Regardless of ambient temps loads etc...
Running leaner than stoich has tons of advantages, but realizing them with a gasoline engine is difficult. Think of fuel throttled diesels and turbines that are almost always running lean. The extra heat that our gasoline engine radiators throw away partly goes to expanding the extra air in those engines. The OEMs are constantly looking for ways to combust lean mixtures while passing emission requirements without blowing up motors.
Doesn’t make sense to me by definition. If a “stoich” mixture is the correct mixture to burn 100% (or as close to as possible) of the air/fuel mixture, then you’d think running leaner is going to be down on power at like throttle position/timing/RPM and running richer is pissing fuel out the tail pipes.
So if the goal is the most efficient use of fuel at say 60mph... You figure the peak torque RPM for the engine. Figure MBT timing for that rpm... Then you target the most efficient burn AFR. That should get you the most power with the least amount of fuel used. Which I guess isn’t the same as the best economy overall.
I looked it up. As mentioned above, I’m wrong. 15.4 or 1.05 lambda apparently is the most efficient AFR to target with a gas engine.
That Holley article is good I guess, but they basically say the test worked according to estimated values calculated by the ECU. I can tell you the average MPG reported by my daily driver are WAY off compared to what I actually get. I want to know what the real world results were. Because according to the article I read 15.4 was ideal. (Wikipedia with better references/sources than a random Holley tech dude).
I think the speed desired and load on the engine is going to dictate what AFR you can get away with. If you locked the rpm in to meet say 60 MPH. There has to be a lean point where the RPM will fall and no longer be able to maintain RPM/Speed.
I use this on my idle in order to get a choppy rough sound. I advance the idle rpm to say 1500ish, then pull fuel until RPM drops down in the high 800 range and idles “mean”. The engine can no longer maintain the 1500 RPM idle with the amount of fuel I give it. Bounces between 17-18:1 at idle.
Last edited by Forcefed86; 06-21-2018 at 08:55 AM.
In my messing with lean cruise i found that there is a side benefit to that power drop as well. with the throttle cracked that much more to make up for the lost 8% you get a more turbulent mixture. which tends to boost economy even more.
I’ll play with it and get back. The mileage is crap on my low compression E85 5.3.
The new 4.8’s are 8.8:1 as well and manage pretty darn good MPG. Anyone have timing maps for the newer L20 8.8:1 compression 4.8s handy? Don't believe they have the fancy VVT or DOD stuff either.
Last edited by Forcefed86; 06-21-2018 at 10:46 AM.
Running leaner than stoich has tons of advantages, but realizing them with a gasoline engine is difficult. Think of fuel throttled diesel and turbines that are almost always running lean. The extra heat that our gasoline engine radiators throw away partly goes to expanding the extra air in those engines. The OEMs are constantly looking for ways to combust lean mixtures while passing emission requirements without blowing up motors.
In My Personal Opinion, the reason we don't have 100mpg motors is that they will never pass the emissions testing the government has mandated. Smokey Unlike (sp) did an awesome build that got tons of power and miles per gallon, but it could never meet emissions standards. He did a 2.0 Turbo "Hot Vapor" engine in a Fiero, Hot Rod did a great article on it. It used heated fuel vapor through a carb to run.
Doesn’t make sense to me by definition. If a “stoich” mixture is the correct mixture to burn 100% (or as close to as possible) of the air/fuel mixture, then you’d think running leaner is going to be down on power at like throttle position/timing/RPM and running richer is pissing fuel out the tail pipes.
So if the goal is the most efficient use of fuel at say 60mph... You figure the peak torque RPM for the engine. Figure MBT timing for that rpm... Then you target the most efficient burn AFR. That should get you the most power with the least amount of fuel used. Which I guess isn’t the same as the best economy overall.
I looked it up. As mentioned above, I’m wrong. 15.4 or 1.05 lambda apparently is the most efficient AFR to target with a gas engine.
That Holley article is good I guess, but they basically say the test worked according to estimated values calculated by the ECU. I can tell you the average MPG reported by my daily driver are WAY off compared to what I actually get. I want to know what the real world results were. Because according to the article I read 15.4 was ideal. (Wikipedia with better references/sources than a random Holley tech dude).
I think the speed desired and load on the engine is going to dictate what AFR you can get away with. If you locked the rpm in to meet say 60 MPH. There has to be a lean point where the RPM will fall and no longer be able to maintain RPM/Speed.
I use this on my idle in order to get a choppy rough sound. I advance the idle rpm to say 1500ish, then pull fuel until RPM drops down in the high 800 range and idles “mean”. The engine can no longer maintain the 1500 RPM idle with the amount of fuel I give it. Bounces between 17-18:1 at idle.
I can't wait to start playing with that.
Originally Posted by ddnspider
This image tells it all. You only lose 8% of power from 14.7 to 16.5 but use less fuel so the leaner AFR mpg gain is greater than the 8% power loss.
Originally Posted by truckdoug
In my messing with lean cruise i found that there is a side benefit to that power drop as well. with the throttle cracked that much more to make up for the lost 8% you get a more turbulent mixture. which tends to boost economy even more.
Hmm that's an interesting point. I wonder has anyone tried with a MAF sensor hooked up, it would be interesting to see what the air flow data is vs what it is at 14.7
Originally Posted by Forcefed86
I’ll play with it and get back. The mileage is crap on my low compression E85 5.3.
The new 4.8’s are 8.8:1 as well and manage pretty darn good MPG. Anyone have timing maps for the newer L20 8.8:1 compression 4.8s handy? Don't believe they have the fancy VVT or DOD stuff either.
I hate low compression motors, LOL, is there any way to pump it up? Head Swap, thinner head gaskets, My old 2.8 was 8.9 - 1, I decked the heads to improve compression so I got better fuel economy.
I’ll play with it and get back. The mileage is crap on my low compression E85 5.3.
The new 4.8’s are 8.8:1 as well and manage pretty darn good MPG. Anyone have timing maps for the newer L20 8.8:1 compression 4.8s handy? Don't believe they have the fancy VVT or DOD stuff either.
The L20 is VVT. The compression is so low because of the combination of 243/799 heads and valve reliefs in the pistons.
U work with the newer ECM’s at all? Do they run higher advance than the older stuff to compensate at all? My low compression stuff tended to want 3-5* more timing at like boost. But I was never sure how far to go at light load. The factory timing table they supply for the LS1 looks super conservative. Like 32* max and that’s in super light load areas. Usually like 28* or so with any throttle input.
In My Personal Opinion, the reason we don't have 100mpg motors is that they will never pass the emissions testing the government has mandated. Smokey Unlike (sp) did an awesome build that got tons of power and miles per gallon, but it could never meet emissions standards. He did a 2.0 Turbo "Hot Vapor" engine in a Fiero, Hot Rod did a great article on it. It used heated fuel vapor through a carb to run.
I can't wait to start playing with that.
Hmm that's an interesting point. I wonder has anyone tried with a MAF sensor hooked up, it would be interesting to see what the air flow data is vs what it is at 14.7
I hate low compression motors, LOL, is there any way to pump it up? Head Swap, thinner head gaskets, My old 2.8 was 8.9 - 1, I decked the heads to improve compression so I got better fuel economy.
I really want to perpetrate violent ends to anyone who buys into that 100mpg carburetor nonsense. Most of your fuel energy is lost as heat. whether your tailpipe expels it, or your radiator gets rid of it, it is lost energy. Anything you can do to recover this loss is theoretically beneficial. I am really curious why more development has not happened with the ICE/steam 6 cycle engines. The theory sounds very promising, although the extra hardware may be the dealbreaker. The complexity was the original problem, but we have gone way past that with current computer controls.
I havent had a lot of luck pulling fuel leaner than about 15.2. power goes down far enough it needs a lot more throttle angle and its all downhill from there. I have been playing a lot more with timing lately since i couldnt do any better than about 11.5mpg driving nice. I kept adding timing 2* at a time and ended up getting to about 12.0mpg with cruise timing between 48-52 depending on rpm.
My truck is 4850lb and awd with a 3400 converter but a lot of the numbers i see thrown around for other 5.3 trucks seem way higher than ive ever seen in real life. im not sure if the method people are calculating their economy is different than i am or what. im pretty sure it was seeing about 14 when i bought it 100% stock (4.8 4l60e 4x4 in 2hi on the highway) and i have seen claims in the 18-19 range
I really want to perpetrate violent ends to anyone who buys into that 100mpg carburetor nonsense. Most of your fuel energy is lost as heat. whether your tailpipe expels it, or your radiator gets rid of it, it is lost energy. Anything you can do to recover this loss is theoretically beneficial. I am really curious why more development has not happened with the ICE/steam 6 cycle engines. The theory sounds very promising, although the extra hardware may be the dealbreaker. The complexity was the original problem, but we have gone way past that with current computer controls.
yep cost. but any engine that depends on converting heat (or heat derived pressure) to kinetics can only hit like 73% (carnot's theorem) and that's not even including friction, etc
Now I’m curious what peak efficient cruise timing would be without needing to meet emissions requirements. I’m only at 34*. Again I was looking at the factory spark tables this seems like about the norm for peak cruise timing.
I tried leaning it all the way out to 16:1 this weekend. Defiantly didn’t like that at cruise it would stumble. Dropped it back to 15.4 and it seems fine. I haven’t filled up yet was going to go through at least half a tank before filling up.
what conditions are you calling cruise? and what kinda overlap does your cam have? with overlap in the positive range i think you'll start to see incompletely combusted hydrocarbons from previous ignition events start to dirty up the mix.
i think it would be instructive to find out of you have lean misfire or some sort of pre ignition.
I think I've got 3* of overlap from memory. I'll cruise at 34* with AFR in the mid 15s and it'll idle between 15 and 16.5 based on fuel trims. Doesn't stumble or feel down on power but the cam is healthy.
-.5* of overlap. (@ .050) Cruise for me is highway 55-60ish on the way to work for about 12 miles each way. Doubt there is much reversion going on. Only .525” lift as well.
06-19-2018, 11:14 AM
The Fiero is a bitch to get "gear" into. Being a transaxle we only have a few options, and of those options only 1 that will sorta hold up and one that is the best, but will set you back $3000-$4000 for the trans + conversion to install it. The 5spd Getrag I am going to use is really only reliable to 450hp / 450lbs of torque but is the best option unless you want to drop the big bucks. I may eventually bite the bullet and go auto, (I hate auto's) for now though, I'm going with the 5spd, then save up for the expensive 6spd swap. The 6spd swap will have me spinning 1500rpms at 70mph. The 5spd is more like 2500rpms at 70mph. 
