Tuning for efficency

[treekiller]

Great webcast.. they address fuel types and tuning.. and how to address fuel economy.

fuel availability is an issue in Australia.

Advanced Engine Management - Engine Management System

[Empire]

I'm in the beginning of listing to it so far... but are those guys talking about 30+ degrees advanced?! Plus adding another 12 degrees on that. So something like 45 degrees advanced?! Or are they talking about something different.

[Loren]

Yes, 40-50 degrees TOTAL timing advance is not unusual.

What you're probably used to seeing is timing advance at idle speed, where it is normally set. There, 10-12 degrees is typical... sometimes up to 18 or so (not because it's ideal at idle, but because it shifts the whole curve up and may give you more advance where you do need it).

But, if you go back to an old school distributor with either vacuum or centrifugal advance, they will advance 30 degrees or so BEYOND the static advance that you set at idle. So, if you set it to 10 degrees at idle, you might have 40 degrees at 3k RPM (timing advance usually peaks by around 3k). Modern electronics emulate the same behavior, just with greater accuracy and with more inputs factored in.

So, yeah. 45 degrees total advance. You really need to dive into a MegaSquirt project sometime and learn to tune it. You'll learn a TON about this stuff.

[treekiller]

true. But like they said so many tuners focus on the WOT map they forget that 99% of driving is done in the other cells of the map and getting the most of the combustion is the key to smooth and economical operation. I know of some subaru's that have ran almost 30 degrees advance under boost.. (not heavy boost) tuned for Sunnoco "ultra 94" which I think they've done away with. but it was a VERY consistent product. marketed as their "better then super" line.. alas. I guess Sponsoring nascar changed their marketing strategy. they also offered 86 "economy" grade.

anyone else remember the Sunnoco "dial o matic" pumps? My first Job I was a Station attendant and had to ask what grade (we had like 7) and we serviced every car. "Sir, madam, would you like your oil checked, tie pressures" I was a tip making machine at 14... 16 I was allowed to start doing oil changes, tire plugs. of course I got caught with what I thought was the best scam ever.. when we went to the plastic bottles, from metal/cardboard cans.. I had a empty bottle on the "attendant oil rack" and EVERY car would be a quart low. $0.99 please in my pocket.. that lasted about 6 months untill they installed the digital pumps. and actually opened two of them up for "self serve"??

[Loren]

true. But like they said so many tuners focus on the WOT map they forget that 99% of driving is done in the other cells of the map and getting the most of the combustion is the key to smooth and economical operation.

Exactly (I haven't watched the video, this is just from my own research and experience tuning MS), you can tune the cruise or low-load areas of the timing map VERY agressively. As long as you have a means to detect when load increases (usually manifold pressure, but throttle position and/or change in throttle position can also be used), you can decrease the timing advance to a safe level on acceleration.

But, even then, you're still going to have more total advance under most conditions than the 10 degrees base advance that you set at idle.

I need another MS to tune. It's kinda fun.

[Empire]

Yes, 40-50 degrees TOTAL timing advance is not unusual.

What you're probably used to seeing is timing advance at idle speed, where it is normally set. There, 10-12 degrees is typical... sometimes up to 18 or so (not because it's ideal at idle, but because it shifts the whole curve up and may give you more advance where you do need it)..

yeah, I was only half listening to it while at work and I missed the part where they said that was at cruising.
I was picturing that much advanced timing at idle and was like :-O

I'm gonna have to hit you up Loren for some MS advice when I start my MPG build in the next few months. Still torn between a few different platforms. I think a 240sx would be more fun, but a mid-late 90's civic hatchback might yield the nighest results. But then again, a 300zx could be a fun challenge.

[Loren]

If you want ultimate fuel economy, start with a 3-cylinder Swift/Metro. Most (all?) of those cars were carburetted or TBI, so if you did a proper port fuel injection setup with precise control of fuel as well as timing... there's probably MPG to be gained above the 50 mpg that they are already capable of.

An early 90's Civic would be a logical second choice.

I agree, though... the 300zx would be the most fun. Try to tune it to be as good/better than my Z4. I've been hypermiling my current tank and getting close to 30 mpg IN TOWN. (was actually over 30 mpg until yesterday when I let the car idle for 10 minutes from a cold start after I changed the oil... now at 29.4 with 1/4 tank left to go) If you could tune a sports car just right, you could have a true Jeckle & Hyde. Fuel economy when you want it, power when you need it. 40 mpg on the highway and 0-60 in under 6.5 seconds seems like an achievable goal. (for reference, my Yaris would do 40+ mpg all day long, and 0-60 in about 8.2... the Z4 will do 35 on the highway with some effort, and 0-60 in something like 5.