I can't tell ya'll just how happy I am to show ya this.
These are snippets from a datalog I did today, at various MPH, and Loads.

180dF Coolant temp.
180dF Oil Temp.
75dF ambient air temp.

This is also on 87 Octane, and obviously in a lean cruise mode, well other
then the 150 K/Pa area. <G>

<Must have a High Speed, Speedo error>

.EngRun. Mph.Rpm.KPa.Tps.CtsF.MatF.Spkf.PW.WB
00:14:51 30 1425 71 22 182 91 20.8 3.48 17.6
00:14:51 30 1400 71 22 182 91 20.4 3.48 17.3
00:14:51 30 1425 70 22 182 91 20.4 3.48 17.6
00:14:51 30 1375 71 22 182 91 20.4 3.48 17.6
00:14:51 30 1400 71 22 182 91 20.4 3.48 17.3
00:14:51 30 1400 71 22 182 91 20.4 3.48 17.6
00:14:51 30 1400 71 22 182 91 20.8 3.48 17.7
00:14:51 30 1400 70 22 182 91 20.8 3.48 17.3
00:14:51 30 1425 70 22 182 91 20.4 3.48 17.6
00:14:51 30 1400 71 22 182 91 20.8 3.48 17.5
00:14:51 30 1425 71 22 182 91 20.8 3.48 17.5
00:14:51 30 1450 70 22 182 91 21.8 3.51 17.4
00:14:51 30 1425 70 22 182 91 21.8 3.51 17.4
00:14:51 30 1425 70 22 182 91 20.8 3.51 17.6
00:14:51 30 1450 70 22 182 91 22.5 3.42 17.2

.EngRun. Mph.Rpm.KPa.Tps.CtsF.MatF.Spkf.PW.WB
00:17:37 58 1825 61 22 184 89 31.3 2.87 17.4
00:17:37 58 1825 61 22 184 89 31.3 2.87 17.6
00:17:37 58 1825 61 22 184 89 31.3 2.87 17.6
00:17:37 58 1800 63 22 184 89 31.3 2.87 17.8
00:17:37 58 1825 63 22 184 89 31.3 3.05 17.9
00:17:37 58 1825 63 22 184 89 31.3 3.05 18.3
00:17:37 58 1825 63 22 184 89 31.3 3.05 18.1
00:17:37 58 1825 63 22 184 89 31.3 2.87 18.1
00:17:37 58 1825 61 22 184 89 31.3 2.87 18.2
00:17:37 58 1825 61 22 184 89 31.3 2.87 17.8
00:17:37 58 1800 64 22 184 89 31.3 3.05 17.9
00:17:37 58 1850 63 22 184 89 31.3 2.87 17.7
00:17:37 58 1800 63 22 184 89 31.3 2.87 18.1
00:17:37 58 1825 63 22 184 89 31.3 2.87 18.1
00:17:37 58 1825 63 22 184 89 31.3 2.87 17.9

.EngRun. Mph.Rpm.KPa.Tps.CtsF.MatF.Spkf.PW.WB
00:22:22 77 2375 78 32 186 89 29.2 3.97 16.7
00:22:22 76 2375 79 32 186 89 28.9 3.97 16.4
00:22:22 76 2375 80 32 186 89 28.9 4.06 16.4
00:22:22 76 2375 78 32 186 89 29.2 4.06 16.7
00:22:22 76 2375 79 32 186 89 29.2 4.06 15.9
00:22:22 76 2375 79 32 186 89 29.2 3.97 16.4
00:22:22 76 2375 78 32 186 89 29.2 3.97 16.6
00:22:22 76 2375 78 32 186 89 29.2 4.06 16.7
00:22:22 76 2375 79 32 186 89 29.2 3.97 16.6
00:22:22 76 2400 79 32 186 89 29.2 3.97 16.5
00:22:22 76 2375 78 32 186 89 28.9 3.97 16.7
00:22:22 76 2375 79 32 186 89 29.2 3.97 16.7
00:22:22 76 2375 80 32 186 89 28.9 4.06 16.7
00:22:22 76 2375 78 32 186 89 29.2 3.97 16.7
00:22:22 76 2375 79 32 186 89 29.2 3.94 16.6

.EngRun. Mph.Rpm.KPa.Tps.CtsF.MatF.Spkf.PW.WB
00:25:05 81 2550 153 56 188 92 21.8 9.09 13.4
00:25:05 82 2575 153 55 188 92 21.5 9.09 13.6
00:25:05 82 2550 153 54 188 92 22.9 9.09 13.3
00:25:05 82 2575 153 53 188 92 22.5 9.00 13.5
00:25:05 82 2575 153 53 188 92 22.5 9.00 13.1
00:25:05 82 2650 152 52 188 92 22.5 8.97 13.1
00:25:05 82 2775 150 52 188 92 22.2 8.82 12.7
00:25:05 83 2800 149 51 188 92 22.2 8.97 12.9
00:25:05 83 2800 152 51 188 92 22.2 8.97 12.8
00:25:05 83 2825 151 52 188 92 22.2 8.97 13.0
00:25:05 83 2825 151 51 188 92 22.2 8.97 12.7
00:25:05 83 2825 151 51 188 92 22.2 8.97 13.1
00:25:05 83 2850 151 51 188 92 22.2 9.13 13.3
00:25:05 83 2875 155 51 188 92 22.2 9.40 13.3
00:25:05 83 2875 153 51 188 92 21.8 9.40 13.6

Test vehicle, 87 GN, 3.8L.
Custom coded GM ECM....
10 years in the making, but when you don't settle for any compromises, it takes time. The car also drives flawlessly, it's impossible to get it to burp or act up in any way. Hammering from a cold start, hot start, etc., etc., it just goes as fast as you want to press on the pedal...

The low timing, lean cruise is just sweet.....
So much for the theory about lean mixtures needing alot of timing.

With the latest tuning, and using 87 Octane, I'm saving almost 50 cents a gal in fuel costs, compared to just a few months ago.

 

Well, what economy are you getting like this??

What's it compared to higher timing?

What's it compared to everything?

What method did you use to calibrate the timing and A/F? Dyno? Fuel flow meters? EGT reading?

Otherwise it's just a bunch of numbers that have little meaning.

Edit: Maybe I'm just missing the point - Is it the Lean cruise? The low timing? The 87 octane? What makes you SURE it's "correct"?

 

The higher timing PWs were in the 3.6+ msec range, for the baseline. In the end I'm at 3.2s. That would be about a 10% decrease in fuel consumption.

Timing light, and Wide Band. EGT, was by guage....

You can say all of life is just numbers. What specifically don't you understand?.

Using less fuel, maintaining a reasonable Coolant temp, oil temp., and EGTs show that it is correct. The oil pressure is 10+ PSI higher now, in cruise mode, again showing that heat isn't being wasted in heating the oil, or crankcase air.

The oem timing for cruise conditions was ~44d, and as shown it's in the high 20s.

For figuring fuel flow, it's a matter of summing the PWs for a period of time, and comparing that to the VSS count for that same period. Then the MPG can be calculated. I still have to do an extended freeway trip to double check the injector constant for the calculation.

 

It is hard to guess what is going on without old data. You have worked with that engine for a long time and are familiar with what didn't work and what worked. Guys on a forum have no reference to go by. I only have about 30hrs total tuning a boosted engine so the numbers may mean something to me in about 10 years or so.

The lean burn looks like a regular old cruise lean burn setup. I like the MAT temps at 7PSI. Man, I have to finish welding up my IC. That seems like a fair amount of timing and AFR on the lean side for 87 octane at 150KPA/7PSI. Looks to be SEFI injector BPWs. Is that data snapshot under a load/hill, brakes on, or a snippet of a quick WOT tap?

Some EGT would have been nice to see with that setup. What was the oil temp during extended lean burn?

OK, back to figuring out my $58 DFCO RPM bounce problem.

oh yeah, I always wondered where the cross over point was for using less fuel vs. running lean and making more bad emissions.

 

What kind of exhaust pressure do you see with that setup? I wonder if that helps with being able to run more lean burn timing.

 

Typcially lean cruise has A TON of timing. Running right up again the max advance is almost the norm (40+ degrees)

Again, it's about optimising the tune, there's many many hours in figuring out the min amount of timing that keeps the engine happy, in both N/A and boosted mode. It's really not *that* lean, from about 180 K/Pa and above, it richens up, a bunch. And the MATs have allot to do with timing especially when in boost.

Quick WOT *tap*.

EGTs at cruise were 1,100dF, WOT sustained max are typically 1,500dF. The oil temp was 180dF....

No previous oil temps available, I just got the guage installed today, and have been waiting on posting any of this until I knew it was reasonable. The 10+ PSI increase in oil pressure would be an indicator that it's lower then it was.

 

Good post. I always forget that a lot of people run a lot of timing in lean burn. I have been using a max. of 28* w/r/t TDC lately with AFRs around 16.5. I started out with less timing and crept up to 28* and saw to reason to increase it further.

I am in the rough stages of my WOT tuning so 12.8 to 13.1 AFR seems lean to me at 7PSI since I am still down around 11.6 AFR. Yes, MAT have a huge effect on timing and AFR. More than I would have imagined.


The oil PSI being higher is a sure sign of cooler oil temps. You have me thinking.....it is about time I get an EGT for the car. I have been trying to hold out, but with the data you posted I kind of think I need one now.

Any thoughts on the fuel consumption being less vs. the HC and NO2 emitted?

 

Both should be better.
NO2 is from excessive heat. While the EGTs are the same, the flame starts much later in the cycle. With more fuel heating due to having more time for compression to pay it's part, the engine should be overall, more effecient, and my results seem to bear that out, so all the emissions, I would imagine should be less.

At times, it'd be nice to have a 4 gas analyser....... <sigh>

 

So is this all open loop or did you add some lean cruise mode? Ive been trying to up the MPG on my Typhoon ($58, original/stock except for a cat back exhaust). I seem to only see 24-30 degrees timing after adding a few degrees here and there (40-55mph,60-80kpa,14-1800rpm), stock was even less. I dont think I ever see over 32 degrees. Thats a good point you make about the BPW, I will have to try to tune for a lower BPW at a constant speed/rpm/load. Even in closed loop I should see a decrease in BPW if I get the timing where the engine likes it, right?

 

My 80km/h cruise is ~27* at 1400rpm, near 14:7 afr, +/- 45kpa, 87 octane, ~2.5ms pw. So much for ZZ3 heads needing over 40* for cruising timing...

 

You're just fighting with yourself, running closed loop.
Stoich, hasn't a think to do with keeping an engine happy.
Just working with timing, is just going to consume alot of time for min. results.

This is one time, when a Prominator is invaluable. Being able to switch between combos of timing and fuel are key to figuring out what the engine likes. Even with a Prominator, it takes ALLOT of time, to get things dialed in.
----------

Pure Open Loop......
No lean cruise.
Now you have to see what your engine really likes. 2d at time, and move the fuel around.

Ramping down the timing, and ramping up the fuel in concert is time consuming. You want to go from say 16.5:1 to ~13:1 really quick.

 

Here are 2 snippets from some data logs, the first one is 3 months old, the
new one is from today.
While not a perfect match for temps., they're as close as I could find.

The timing Spkf, and PW's tell the story.

Old Tune:
(Thou, with 6 coil DIS)

EngRun Mph Rpm KPa Tps CtsF MatF Spkf PW WB
00:02:32 56 1750 60 22 174 74 35.6 3.17 15.8
00:02:32 56 1750 60 22 174 74 35.6 3.17 15.8
00:02:32 56 1750 59 22 174 74 35.6 3.17 15.7
00:02:32 56 1750 60 22 174 74 35.6 3.17 15.6
00:02:32 56 1750 60 22 174 74 35.6 3.17 15.6
00:02:32 56 1750 59 22 174 74 35.6 3.17 15.6
00:02:32 56 1750 59 22 174 74 35.2 3.27 15.6
00:02:32 56 1750 59 22 174 74 35.6 3.17 15.5
00:02:32 56 1725 61 22 174 74 35.2 3.14 15.5
00:02:32 56 1750 60 22 174 74 35.6 3.24 16.2
00:02:32 56 1750 61 22 174 74 35.2 3.14 16.3
00:02:32 56 1750 60 22 174 74 35.2 3.27 16.3
00:02:32 56 1750 60 22 174 74 35.2 3.17 16.2
00:02:32 56 1750 60 22 174 74 35.2 3.27 16.2
00:02:32 56 1750 60 22 174 74 35.6 3.14 16.2

New Tune:

EngRun Mph Rpm KPa Tps CtsF MatF Spkf PW WB
00:20:50 56 1775 59 21 190 87 31.3 2.78 17.1
00:20:50 56 1750 60 21 190 87 31.3 2.78 17.2
00:20:50 56 1775 59 21 190 87 31.3 2.78 17.2
00:20:50 56 1800 59 21 190 87 31.3 2.69 17.3
00:20:50 57 1750 59 21 190 87 31.3 2.69 17.4
00:20:50 57 1775 59 21 190 87 31.3 2.75 17.5
00:20:50 57 1775 59 21 190 87 31.3 2.75 17.2
00:20:50 57 1800 58 21 190 87 31.3 2.66 17.2
00:20:50 57 1775 59 21 190 87 31.3 2.69 17.4
00:20:50 57 1800 59 21 190 87 31.3 2.78 17.3
00:20:50 57 1775 60 21 190 87 31.3 2.69 17.4
00:20:50 57 1800 58 21 190 87 31.3 2.69 17.4
00:20:50 57 1775 58 21 190 87 31.3 2.69 17.4
00:20:50 57 1800 59 21 190 87 31.3 2.69 17.4
00:20:50 57 1775 58 20 190 87 31.3 2.69 17.4

 

Yeah I know open loop would get me there, I just haven't wanted to spend that much time on it. Ive got an Autoprom, but I cant scan and emulate at the same time. I make one small change, drive on it to see how it runs, and compare mileage to that last change. Ive been up to 16 from 13 mpg, now this last change seems to put me at 15. My changes have been small. I know stoich osnt the best for mileage, but I have a cat and really want to keep the truck stock. I tried changing the stoich AFR to 14.8, figuring that a change that small may help mileage while having minimal drawbacks. So far its not noticeable while driving, but I dont know about any gains. I need to setup the WB on it again. When I got the truck the commanded AFR was nearly spot-on the WB AFR.

Im sure I could make faster ground if I could datalog and emulate at the same time, but I dont have a driver available when I have the time to tune anyway. Most of my free time is during the day, when other people are working.

 

Going slow is fine, if you keep good notes, IMO. Being able to see the trends is what matters.

 

I wasnt saying I could/would make larger changes if I had a driver and the hardware abilities- I would still make small changes, Its just that I feel I could see the affect and make further changes faster. I think there would also be less error factors, because all logging could happen on the same day, at the same temp and so forth.

Grumpy, even without seeing any previous log to compare to, I am impressed with your numbers.

 

Well, good numbers, good work Grumpy!

With my limited experience in tuning, all I can say is that I am mostly surprised when I figure out how little timing my L03 likes in some areas.

In the 40 - 50 kpa area it is up to 6 deg more than the stock chip with a maximum at 31 deg. From 50 to 70 kpa it just slightly more (2 deg) to slightly less than stock, depending on load an where max torque is. From 80 - 100 kpa it is less than stock with a total of around 22 deg at 100 kpa and 3600 RPM and up.

Maybe it is just dumb to ask, but: How can this be done? Could you post a formula for doing this? I can't figure this out myself.

Thanks,

Andreas

 

Here's metric fuel economy spreadsheet that I made on a recent road trip (really, just whipped it together in a few minutes so don't think it's typical of my spreadsheeting abilities, hehe). We don't use a VSS on this setup, so there's a middle calculation involved that you could just type over. Then, convert liters to gallons, km to miles, g/s to lb/hr, and invert a few numbers, and presto chango, hehe. I could do it for you, but learning unit conversion is a great lesson for any tuner!

 

Thanks alot Red,

I'll try to shape my capabilities.

 

I've got a generalized question for Grumpy and likely the rest of you as well. As a newbie, hopefully it's not the question of an idiot.

From one of yout posts I'm assuming you have the "prominator" in use. Since it has the ability to store multiple alternative tunings, could you offer an explaination in simple terms how a "milage" VS "1/4 mile" tuning is likely to differ. My expectation is that I'd want separate tunings rather than an "all in one" which you seem to have been able to create. From my limited scope of understanding I've come to beleive (suspect?) each of you as tuners have different criteria from the next guy as to what constitutes a good tune.

What change of criteria constitutes (or creates) better milage versus all out acceleration?

MR Bill is currently building my Prominator Pro as we speak.

Thanks in advance from a DIY prom newbie. Dave Buchholz, Rochester NY

 

IMO- the perfect tune would get great mileage and provide max HP. Great power and torque are produced when an engine is operating at maximum efficiency, so you *should* be able to have both at the same time. The difference is that for power we often tune for max efficiency at a higher RPM range than we utilize at cruise. With a carb this would be difficult to do, with EFI its easier to tune for both.

A difference in tunes, if you could have two or more stored would be in the desired A/F ratio and timing. I plan to have one tune for regular gas, used for normal driving and one for higher octane super unleaded that I could use for max power. My truck and my vette both have forced induction (turbo on one, SC on the other) and require different timing parameters with different fuel grades.

I hope this helps.

 

I'm glad you're getting results like I've been with running low timing and high AFR with low octane. Under light cruise the engine isn't moving much air so running those high AFR's shouldn't pose any problems. Once the specific output of the engine goes up, . Having a bad plug wire or weak ignition fooled me a couple times making me think it was a "too lean" problem when infact it was a closed gap plug and then a toasted coil-cap wire.
Congrats again for your results and persistence.
One more detail that might not have been examined is the fuel. You said 87 octane now and premium before. 87 and E85 both have more energy potential than the higher premium fuels which would only help your mpg. I've always been a believer in lowest octane the engine can handle. Fastburn heads seem to really respond well to the lower octane. These aren't things I've just started to notice. Even in the summer with hot IAT I was able to run my best with the lower octane.

 

Yes, I use a Prominator.

While I might talk about one area of the prom, I don't use a different calibration for performance, then I normally do in day to day use. I'd probably use a slightly different calibration, if I was to go racing on a higher octane then I run on the street. With more octane you have to run more advance, and that'll probably take some fuel work, to get the AFRs optimised.
----------
Might investigate Alky Injection, rather then the higher octane. IMO, it's expensive to run 93, when you don't need it, (other then for the ocassional few second runs). A gal of denatured alky will last for several tanks of gas, if you're running an intercooler, even longer.
----------
Thanks for the laughs, I've been playing with this since before you were driving.

 

I've worked and reworked my tune, getting everything dead-on in terms of fueling. My mileage is still incredibly poor. I finally figured out that there's just no way I'm going to get good mileage with my car.

Why not? Just can't keep my foot out of it! Can't cheat good old F=ma...

Good work, Bruce. Seems like it turned out real nice.

 

Big N/A cams on the street operate very inefficiently and waste fuel. I think Grumpy has the right idea with low octane w/ IC and the injection system. With boost you can run a smaller cam, low octane, and out perform a N/A engine. It is apples and oranges. Once you go with boost you'll never look back.

Grumpy,
The data you posted with the 7PSI at approx. 3000 RPM and 87 octane. The IAT didn't rise much. Is the IC really that efficient or is it just the lag of the IAT response? Was the injection system on at 7PSI? That is all with coil on plug right?
I think you posted the data to show what can be done with an engine. I know you won't stop there. Are you toying with ECM controlled wastegates or is that something to play with next?

 

<G>
And boost is addictive.
What'll hear what the *Stage Engine* runs for boost.....

That's with the alky off...
Yes, but, at this time it's 6 coils, being fired in DIS mode, ie they're firing in pairs.

Oh something like that.
Actually, there are a few new ideas brewing.
Down at BG Thur night there was a seminar held by a few Buick vendors, that was thought provoking. Lance Ward, one of the F.A.S.T. programers was there, Harry from PT+E, Bailey from Bailey Eng., and Julio from Alkycontrol.com were all there taking guestions. Was a shame no one other then Jeremy and I were there from the 3rd Gen group.....
Probably could have generated a couple dozen threads here, from their thoughts.....

 

Congrats. Is there any safe way to implement the lean cruise on my car without an EGT sensor?

 

If you *miss* by a bunch, you'll see the coolant temp., and/or oil temps raise.
If the oil temp climbs too much you'll also see a drop in oil pressure.

Then you need to just experiment to see what PW/timing combo gives the best mileage.

Having a Prominator is almost mandatory, or at least gets to be cost effective in doing this. At $3 a gal things that were just too expensive to do, are now just a way to save lots of money.

BTW, filled the tank in KY, and it was $52, on a G-Body......
I think the pumps were slightly rigged...

 

Experiemtn, experiment, experiement.

The hardest part about making it work right is actually finding out what your car wants. It might be a little leaner than stoich and a couple degrees of timing or it might be 17 AFR and no timing added. It will be different on even two similiar cars. This is what beat me up when I was trying to make it work effectively on my setup. Until I figured out what the car like it either did nothing for me or even hurt my mileage.

Bruce,

The seminar was enlightening in the aspects of different fuels, the alky, E*5 and 98. Also was nice to see the aftermarket ECMs are kinda catching up to the OEMs :-) Waiting for the day a certain ball bearing center section arrives at my door too lol Its not too often you get to sit there and pick a group of peoples minds like that and anything goes in questions.

later
Jeremy

 

Kind of strange and borderline funny, isn't it. GM ECM at the junkyard = $100, Aftermarket ECM = $2500. I would love to crack open an aftermarket ECM and see what the quality of parts are and the design in general. I wonder if they even conformal coat the modules.

In terms of tuning for lean burn, the only way I see to get it right is using coolant temp., oil temp., EGTs, and plug cuts. Just going by expermenting will probably get you a melted engine without any feedback of what is going on. It won't happen instantly, but running it too hard will kill it a lot quicker over time......whether the engine seems to like it or not.

How can anyone know what the engine wants without all of the proper sensors giving feedback to the person tuning?? I think some people use the term "give the engine what it wants" without understanding what that means. That is not targeted at you 3.8TransAM. I know you have been around long enough to understand what it means. I see a lot of newbies using that phrase and have no idea what it really being said.

 

There isn't much air/fuel being burned during cruising so unless you've got a barn door strapped to the front of your car and are trying to keep 75mph I don't see any real need for looking at ALL those sensors before experimenting with lean cruise. My oil temps hardly moved and I had no oil cooler at the time. Most of my heat was being expelled nicely by the fact that my engine has a lot of surface area and a good working cooling system. A lot of my heat wasn't from the pistons (from my low oil temp increase) but istead the fact that I was running the engine at nearly 3000rpm cruising. Lots of friction at 3000rpm with 8 4" slugs, stamped rockers, and flat tap cam.
Once you start to lean into the throttle it's always a good idea to break out of the lean burn because hey... there's a reason you're leaning into the throttle and I don't think it's because you want to get better mpg
Grump, yup, I'm young and stupid for having figured this stuff out early . It's all relative. That isn't ment to take anything away from your accomplishments because they are great.

 

Exactly, everyone's setup is different. I do in fact have a barn door on my rig (chevy pick-up with a 4.5" thick intercooler that is 12" x 32" with endtanks (24" core). The radiator is 2 5/8" thick at the core. The rig weighs 4500lb+ and has two small quick spooling turbines plugging up the exhaust causing heat. I don't have this setup on the road yet, so I can't say anything about the tune or over doing it with sensors.

The Camaro cruises at 3000 RPM just like the example you gave. It also has two turbine plugs causing more heat and water cooled center section. I also think I need the EGT and oil temp. sensor for this to do lean burn.

Your method of tuning is fine for your setup, but would not work on my setup. I try to lean toward the safe side of things. I looked up EGTs and they look to cost under $50 and can be used with my electronic DMM. I put an oil temp. sensor on the oil pan when I put the turbo drain fittings on it. The poster could actual rig up an oil plug with a oil temp. sensor on it. All relatively cheap insurance and you can almost "nail" the lean burn tune.

Maybe your method of lean tuning will work for the poster. I really don't know. I was just trying to show that there are different methods of doing it.

 

I have, there's nothing fancy in them.

Seems like you're ignoring what experimenting means.
ex·per·i·ment
1. A test under controlled conditions that is made to demonstrate a known truth, examine the validity of a hypothesis, or determine the efficacy of something previously untried.
2. The process of conducting such a test; experimentation.
2. An innovative act or procedure

All these definitions are of a scientific nature, that includes taking notes, and using logic in the process.


If someone uses terms they're unfamiliar with, well that's their problem. There's no way to watch dog everyone, all the time.
So far, I've only seen the *know it alls*, that hang themselves. For the thinkers, they know enough to ask questions, and try to reason thru things.

 

Sounds like a great accomplishment for yourself Grumpy. It sounds like you are onto a similar track as Yunick was years ago. Small cam+turbo=great power and good mileage.

Combo's can vary widely or a single tune, would run all engines. I know for a fact that my NA brick of a combo likes running richer, the faster I go. All these are in KPA, but from 35-60 it likes around 17.5:1(gotta love swirl ports and a strong ignition), from 60-70 that quickly decays down to about 15.4:1, then it further decays down to 14.5:1 at 80. At 85 I am under enough load to run mid 13s A/F ratio. At 90 I am into PE @ 12.8:1. The next step will be a weiand 142 supercharger for me.





PS- I know I need more Decel Enleanment

 

Man, do all you guys speed when out logging data? Looks good Fast355. Good heads & ignition will do that for ya.

 

Fast355 was probably just out on the highway running with the flow of traffic.

 

Actually, I was. Everybody either has the skinny pedal to the floor or on the brake here. Out on the open road the trucks move 80+.

 

I'm not gonna answer that for fear of incriminating myself by double or triple the speed limit :-)

If u ever meet me ask me about buying my TTA and picking it up in my friends 87 Limited Turbo :-)


Seriously, the biggest thing is to experiement with different setups to find what your car likes. (like my GTA its near purely stock and im putting a bung(wideband) in it to experiment on a stock type application, which i should have done years ago)

The hardest part here is the control part. A short highway cruise might be misleading I have found versus a longer avg of 30 min vs. a trip that consumes an entire tank of gas.

The worst part is if you find out you screwed something up or you were band aid tuning over an issue that had slipped your attention.

Its all relative and no one here can quote as saying this works 100% of the time on x engine.

We all have different vehicles, needs, objectives.

Although I think we all strive for smooth reliable power with some inkling of mileage.

later
Jeremy

 

Couldn't say it better myself. I have had a stock CPI 4.3 in my 1987 GMC Jimmy for about a month, that I am about to have a bung put in.

I am also a fan of long trips, I have one log that entails 600+ miles, ONE tank.