A/f 540ci n/a
 

OK, so far I have 3.5 hours on new engines gotta look more at tuning, so far my A/F has been around 13:1 at idle, and nboth engines run hight 11's to low 12's across the board.... cruising at 4000 it is pretty solid at 12.2:1.... so far at 5300 was most I pushed it was at 11.8:1 and a tad richer, I do know I need to add vents to hatch as I KNOW it is looking for more air, that's is tomorrows project... just to be sure I have enough....I think as rpm increases its gonna go more rich due to airflow, I would rather rich then lean LOL

what is a good target for N/A engines? no dyno..... on water under loads....

to me the low 12's are real good and safe.... whats the input?

Tim, I think you are going to find lots of opinions on this topic.

Textbook says, gasoline engines make maximum power at a 12.5:1 air fuel ratio. Thats assuming non ethanol gasoline. Throw some ethanol in the mix, and now you have to go richer to make maximum power.

I put a wideband on my GM big block gas dually before. The setup from GM was to pretty much be at 14.7, until you get over 80% throttle if I recall, then goes to 12.6 ish. 14.7 was best for emissions, and gave good economy, but not the best power, nor safe.

I think the word "cruise" is often thought of in the marine world, as "cruise" like in a car/truck. But, imo, it isnt the same. Take my gas dually for example. "cruising" down the freeway at 55mph, I might be at 10% throttle opening, and requiring maybe 60HP to maintain that speed (just a guess). Now, look at your engine, "cruising" across the lake at 55mph. You might be at 50% throttle opening. It may require 375HP to "cruise" at 55mph.

More load, more throttle input = more heat produced.

Back to your setup, I would like to see around 12.7ish at cruise, and around 12.0-12.2 at wot if you run E10 gasoline. I would look for those numbers on a cool day. Hot days it will richen up a bit. But you dont wanna melt stuff on that cool fall night coming back from the island.

Theres more to this tuning thing, as timing advance can play a role, fuel distribution, etc. More timing advance may work better with a richer fuel mixture, less timing advance may work better with a leaner fuel mixture, and so on. A 454 making 650HP, may not need the same settings as a 540 making 650HP. Larger bores may want more timing advance, than a smaller bore, and so on. Piston design, chamber design, quench, all play a part. This is where dyno tuning an engine is worth its weight in gold. The dyno should not be looked at as a tool to tell you how much power your engine makes, but a tool to let you know what the engine likes, or doesnt like.

Cool so I would think I'm close so far, timing is locked at 32, for now anyway... We discussed that and over winter that may change as I can't do anymore changes now just wanna enjoy it...

I was just thinking of getting it safe for the summer, maybe you need a trip up here next weekend lol

A good example of basic dyno tuning, and the results, are what Mike Tkach and I recently witnessed on the dyno. A friend has some blown 522ci engines that Mike built for him. I designed a custom timing map for it, with the daytona ignition box. For years, we ran locked timing on our blower stuff. The idea of going with these boxes that would allow custom timing map, really opened up a tuning window for us. Playing on the dyno with it, proved its value.

We set the engine up and did some preliminary pulls, the old fashioned way. Timing was locked at 34*, and away we went. We had our air fuel ratio where we wanted it, and had our results from that setup. We then installed my custom timing map to the ignition. Traditional thinking, told us we would lose power in the midrange, by backing the timing down. The main goal of this custom map, was for safety, but my research told me, we just may see no loss, or even an increase in midrange power, from the fact the spark timing was simply too far advanced with locked timing.

SO, we upload the map and do a pull. We were shocked. The engine lost NOTHING in torque. It actually gained a small amount of torque, and the EGT temps in the midrange, cooled down a bit. My map, had 25-26 degrees of advance in the peak torque area. What did this tell me? Well, that if I removed 8-9 degrees of spark advance there, and the engine didnt lose anything, is that we were simply firing the plug waaaay to early at that point in the RPM band. We all know what happens with too much spark timing. So, IMO, this ignition box and map, has opened up the safety margin of this engine, by a huge amount.

Now, I took it one step further. At 34* locked, at 6500RPM, the engine made 1018HP. My map, gave the engine 1 more degree at 6500RPM, bringing the timing to 35. The engine responded with 1036HP. An 18hp gain from 1 degree of timing. It liked that extra degree, but only at 6500RPM.

My thoughts are, this custom program feature, not only added a safety margin, but also netted a engine that will simply be more efficient with a 3d map, and is making more power, from 3500-6500RPM, and idle/start better, with some great features like idle stabilization, and start retard.

What I've learned about locked timing, which is what I believe you run Tim, is that it sucks. There is no way around the fact, that with locked timing, there is some point in the engines powerband, where you either have too much, or not enough timing. As charge density increases, the need for advance decreases. As rpm increases, the need for advance increases. At 3000RPM cruise, your engine may want 36* of timing. AT 3000RPM wot acceleration, it may want 22 degrees of timing.

This is not new info to the pro's, but to a do it yourself guy like me, this data is priceless.

Nice to hear your back on the water. Glad to see your project is all coming together! Good luck and enjoy.

Joe if that kind of gains can be had on a N/A engine inwould probably look into that system over winter possibly, I would love to see that dynoed on a setup like mine, hoping indont have to have engines out to do it though as I wanna not pull for a few years lol

I have the bungs to add EGT and plan to over winter I can't do anymore right now I am tapped out big time!!

Full Force
Your idle could be cleaned up more , you and I have very similar engines. Low 12 across the board is very good and extremely safe. I run 14-14.5 at idle runs clean and crisp. Mine is also fuel injected. What power did end up making?

12.2 at wot for your application would be golden.

Don't know power and honestly I don't even care lol I just want it to run every weekend..

Yes I know idle is rich I just last night found out was the starboard o2 wasn't working so before I kept swapping sides now I can monitor both engines this weekend coming...last weekend was not a timing weekend it was for getting some time on the engines now it's time to make sure they live...

He'll never be able to shift without stalling, at a air fuel ratio of 14.5 on a carb'ed engine. EFI, different ball game.