Dyno tuning technic
 

I imagine there are a few ways to do this but I just wanted to get some input. Everyone always mentions tuning by afr but my builder says he's lost a few engines relying on them. His procedure was mainly to richen the mixture to where he got the exhaust gas temps where he wanted them. Generally 1400 or less. Then he fine tuned by reading plugs on the hottest cylinders and adjusting jets to get bsfc numbers where he wanted them. He was shooting for getting bsfc numbers in the .4xx range. So my egts are all around 1400 max after the pulls, bfsc was specifically calibrated to be in the .4s as much as possible and plugs were checked a few times to verify. Afr ratios ended up being in the 10s and 11s a lot using this method. They have a 1 yr warranty so I'm not inclined to screw with them. Just interested in this tuning method from people with more experience.

I used to tune my blown street car using an egt gauge, that was before wideband's were affordable. IMO the problem with tuning by targeting a certain temperature is timing affects exhaust temperature,as well as other variables. Retarded timing will raise egt. I would use the egt gauge as another tool to tune, not the end all.

I'm a nobody but I would tune it on the dyno. The engine will dictate what it wants for a/f and timing. The plug ground strap will tell you where the timing should be.

This will endure being about 28 1/2 pages. Lol. I always use to look at EGT's and AFR's of course with first pull or two primarily focused on EGT's with concern of Pistons turning into the cop on terminator. Problem is when trying to achieve maximum power EGT's can vary several hundred degrees from one engine to another. While on the other hand AFR's will typically make most power with a much smaller window btwn 12 - 13 plus to 1. Both are a great tuning great tuning tools however id lean toward AFR's but that's just me. On the dyno my eyes are dialed in on both with equally importance including BSFC. Ground stap on the plugs are equally important if not one of the most while tuning. That's one thing that don't lie or can ever give off false readings etc. EGT's can easily get thrown off showing extremely high temps from being to rich. Trust your engine builder. He sounds a tad conservative however wants to keep you on the water rather than in the bilge.

It wasn't exclusively egt, but that was one of the first steps. After egts were good, after plugs had been read it was mainly tuned using brake specifics. The O2s just ended up where they were after checking everything else. We did actually lose a few hp while richening it up. He said he was happy with the power / safety margin compromise.

Out of the box was 701 @ 5800 and 670 @ 5200. Ended up losing a bit with jetting and flame arrestor. Hopefully this is the last time this engine goes near a dyno.

https://youtu.be/kjPX-KA4n54

Sounds nice. What cubic inch, intake and heads again? If I remember right 540 plus/cnc 305 or 315's and Edelbrock jr, Bob M cam. Can't remember from old thread you did. I'll bet your glad it's done. Regardless time well spent.

Btw did it like the 1050 the best and did you try 1150 or 1250 by chance.

Tuning on the dyno is nice to get you in the ball park but in the boat is a different story. Unless you drive like a dyno pull.. full throttle from a dead stop everytime :D
I had to pull 4 jet sizes in the boat because cruise was too rich, mid 10`s (great on the dyno).
4 jet sizes= 100* hotter EGTs, which isn`t much (1340* @4000) (Extra fuel extra cooling Id guess)

Too many factors that affect EGT`s readings to use those numbers to tune IMOP but it is one more thing I use ( along with knock sensors and AFR`s) to monitor what the engine likes as far as timing and fuel or if anything is going avry.


http://33outlaw.zenfolio.com/img/s11...09159205-4.jpg

You got the specs right. 305 heads. 454R intake. It liked the 1050 Dom much better than the 986 4150. Went with the QF marine Dom and Daytona ignition. Made within 2 hp of what it made back in Feb with the Crane box and automotive carb with the smooth radius throttle bores. Did not have an 1150/1250 to try. ICD, the boat has O2s so I should know if it changes from the dyno. Most of the fine tuning was done using the bsfc. He wanted it in the .4xx, didn't pay much attention to O2 at all.

I personally, would not use brake specific fuel consumption measurements, to get a tune. It tells you nothing about the actual fuel mixture.

Like anything, the equipment taking the measurments to provide that data, is all based on the fact everything is properly setup and calibrated. Whether it be a fuel turbine, o2 sensor, etc. Timing has an effect on egt, as well as fuel mixture. You can have too little timing, with lots of fuel, and get xxx egt. then you can add timing, pull fuel, and get xxx egt again, except probably making a good amount more power. Most of the time, playing with that stuff, the power readouts from the changes, will tell you what the engine likes.

Well all the above mentioned items were checked several times throughout the runs, remember these engines spent 2 days each on the dyno. Just found it a little different so much weight was placed on bsfc over O2. Where do people tend to like the O2 readings to be?

Maybe this will help explain it

BSFC is how much fuel is used per HP. It does not necessarily tell you if motor is rich or lean.

BSFC is figured by two measurement only: fuel (lbs/hr) and HP.

BSFC was invented to see how efficient a motor is at converting fuel into hp, and thus is only accurate if fuel flow and hp measuring is accurate.

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So yes, BSFC can be influenced by being rich or lean, but it is not a rich or lean indicator.

What effects BSFC ?
Air fuel ratio
Carburetor sizing (restriction)
Intake manifold (all aspects)
Cylinder heads (all aspects - runner sizing,shape, combustion chamber design, etc,etc)
compression
piston design (dome can interfere with flame propagation, can interfere with air movement during overlap, etc,etc)
piston ring placement (lower it is, more are for fuel to hide from combustion)
piston ring thickness (friction)
piston ring tension (friction)
crankshaft design (aerodynamics, fluid dynamics, etc)
oil pan design (windage, crankcase volume, wet sump vs dry, vaccum pump, etc,etc)
camshaft - oh boy !
exhaust - oh boy !
This is just a few things, so the list of what effects bsfc goes on and on

It all effects bsfc because, again, bsfc is just about how much fuel is used per hp is made ! As you can see, many things effect hp even iof the same amt of fuel is used.

How long since the fuel turbine was calibrated? Was the fuels specific gravity checked before the pulls?

I hate to say it, but if you ended up making less power, with afrs in the 10s shooting for brake specific numbers, your tune prob isnt so good.

Its proven a gasoline engine will make its best power around 12.5 air fuel ratio. Most shops dont use an 8 pack wideband, so you are seeing the average for each bank. Its imperative to play a little with fuel to see how the engine responds once you get in that ballpark afr range.

Timing can and does alter egts as well. The engine will stop responding with power increases, well before it goes into detonation from too much timing. In other words, lets say you have an afr reading of 12.4, and you have 34 deg of timing in it. You bump timing to 35. You see a 8hp gain. You then bump to 36, and see another 8hp. Again, you bump it to 37. Bu, You see no gain, or maybe 1-2hp. Thats where you stop. Theres a lot of variables on what timing the engine requires. Chamber design, piston design, stroke, bore size, afr, spark plug style, etc. Not every big block wants 34 degrees, from a 454 to a 632.

I think there is some mental blockage that guys think they are helping the engine by retarding the timing to what THEY think is safe. Well fuk, why even dyno then? Forget the science behind it, just slap the distributor in at 32 and call it good lol.

Throwing extra fuel at it will show lower egts usually, but that doesnt necessarily mean thats a good thing. We all strive for the best , most efficient power making combo, will argue about alum vs iron head chamber heat, etc. Then when dyno time comes, the crutches are pulled out.

What kind of timing did you guys have in the engine bck?

I'd say his afr meter is off by a little.

Engine made the best power @ 34 iirc. Jetting was changed based on a combination of egt, plug readings and bsfc. I noticed O2 did not change much when jetting was changed. I could however see changes in power and bsfc when jetting was changed. I'll take a closer look at the sheets later today.

What fuel were you using on the dyno ?

93. Didn't ask if it was non ethanol

It be intersting to see the dyno sheets , with the various jetting combos , timing, bsfcs, etc .

Sounds like the combo is making good power though

remember these are the same engines I posted all the dyno sheets from a few months ago. This time around it was strictly jetting changes. I just printed the first and last pull this time around. There were 2 extra pulls in the middle that I didn't print.

Brake Specific Fuel Consumption BSFC simply refers to how efficient fuel is turned into horsepower. Although important it will not tell you if the engine is rich or lean, it will however let you know how efficient or less than efficient the fuel consumption is as it relates to targets set for type of fuel and output power of the engine. I've seen BSFC all over the board on more than one engine. (Valvetrain issues). Hydraulic lifter failure, incorrect springs, broken springs, valve lash settings, agressive cam lobes with incorrect lifters/springs and on and on. So with your builder paying close attention to BSFC just know he's looking for any inconsistencies that wil make tuning nearly impossible along with potentially damaging your engine.

all I'm trying to say there bck is I'm glad to see your builder is monitoring the BSFC. Formulas and simple math go a long way.

It`s summer, why so many dyno sessions? Get em in the boat and tune them there.
Why didn`t 02 reading change with jet changes? That makes no sense

670 out of Bobs combo with dyno headers and no accessories, seems like about as much of a home run as mine, he told me my engines sucked and I messed them up, yet he's still playing with his while I am out boating!

First runs were to test some parts. These final runs were to tune the parts I ended up buying. Should have been done months ago but a few things came up and here we are. Not too concerned, other things are happening. Not sure how much of a change should be seen on O2 due to a jet change? Maybe he knows something we don't about the accuracy of the equipment? Maybe O2 isn't working right and he won't say so? I'm thinking he has some old school thinking like that article MT posted.

I get ya. Plus, it was 90 degrees and 40% on the day we ran. Maybe a little rich is a good thing anyway for when it's cooler/ denser.

I think EGT's are often misunderstood. High EGT's, are often an indicator of too late of ignition timing. However, high EGT temperatures, do not always mean that the cylinder temperature is hotter, it simply means that the heat, is simply being sent out the exhaust valve more , which shows on the gauge. Too much timing advance, can show a lower EGT, but also increase temperature INSIDE the cylinder/chamber. This is why with too much timing, detonation can happen, burnt plug electrodes, etc.

The concept of ignition timing, is simply to fire the plug at the right time. The engine, will tell you what that time is. If the power picks up, you're in the right direction. If power falls off, wrong direction. This is where a dyno is invaluable.You really shouldn't be crutching an engine, with a certain amount of timing, to control EGT's. You want the proper amount of timing, as well as fuel mixture.

I personally believe tuning off EGT temperatures alone, is a bad idea, in a gasoline engine.

I agree. furthermore...
Big reason for EGT guages, was to 'keep a tune' on an engine. Meaning, once engine is all good and out in the field, if any of the EGT's changed, then something is up and time to find out what it is.

Exactly SB.

Lets say you are cruising along at 4000rpm, with 30 deg of timing. Your egt is 1400. You bump timing to 32. Egt goes to 1360. You didnt necessarily cool the cylinder down, you just cooled the exhaust valve.

On the flip side, if you retard the timing, egt will raise, but you may have cooled down the peak cylinder temperature.


Too much timing can be negative work, causing a power loss, ans extreme temps inside the cylinder. Too little timing , hot exhaust valves ans wasted power as well.

How do you find optimal timing? The dyno. And you dont find it by looking at the afrs, brake specifics, egts, etc.

Bck, what kind of timing curve setup did you have in the daytona boxes ?

If you look at how mercury marines Thunderbolt V worked, its pretty cool. It uses MBT timing, (mean best torque)

It would increase timing during cruise, until it no longer sees an rpm increase . If it sees an rpm decrease , it then retards timing slightly.

Whats happening here, is the ign module is tuning the engine to its optimal state, by power output of the engine. You can do this on the dyno as well., by monitoring the power changes.

Again, the proper amount of timing , is the one that makes the best power.

your guy has been doing that for a long time I'm sure, but AFR readings are (in my opinion) the way to go, you want to get high tech run 1 per cylinder, I played with the EGT deal years ago...its a crapshoot on some setups

I would NEVER tune to achieve a bsfc number, the motor needs what it wants. I bought a daytona 8 pack 02 sensor for my dyno, the way to go. I have seen waaaay high egts on blower motors too, adding fuel made them go even higher. Afrs, ground strap readings, egts and bsfc in that order to see how efficient a combo is.
Now, back to bsfcs, IF a guy built the same combo over and over again, ci, cam, heads, you will see bsfcs in a certain range but again, would never tune for them.
Afrs in 10s are generally rich to point of washing cylinders and totally unnecessary on NA motors, fwiw, smitty

I have also been on other peoples dynos where they had older 02 tailpipe afr gauges that weren't real accurate/didn't match/varied all over the place in back to back pulls and they sorta got ignored, hence the modern, quality 8 pack 02 system I invested in for my dyno

Well, let's try this. Maybe he achieved the correct results. What numbers do you guys tend to want to see for AFR and EGT? What numbers do you tend to see for bsfc ? Pretty basic motor, 1050 Dom, hyd roller, afr head, 9.5, 700hp @ 5800

MT, you asked a few questions earlier- I don't know if I posted them before but we check different timing settings. Stopped making power at 34 so that's where it's at. I've been using the standard NA curve in both the Crane box and now the Daytona box as well. I'll agree with you guys that he is probably not using the best technique but on the other hand he has been doing this a long time and I'd hope has decent skills and knowledge base

About .480 bsfc is normal for a na engine, at least from what i have seen on my dyno, 12.2 to 12.8 afr makes about same amnt of hp so i final tune on water towards lower 12s, at 13 its marginally lean, when you sart getting into 11.8 to 11.5 or so na they sart getting piggish, at 11.0 and richer they start getting real piggish and losing hp, in the 10s they start chugging and washing rings, turning transoms black, losing real hp, at least from what i have seen, Smitty

Where do you start getting uncomfortable with exhaust temps? Depending on where you look in the powerband it's down sometimes as much as 10hp and ft lbs after richening it up. Further, how much fatter should it be because we ran it on a 90 degree day to keep it safe on a 72 degree day?

Full Force, I figured with no interaction with you for several months I'd check and see if you grew up a bit. Guess not, so I'll take the low road with you for a post. The engines made over 700hp back in Feb and made over 700 again this week.They made more torque than yours made horsepower even with your blog cabin build threads and two failures due to your incompetence before they ran. What will mine make with accessories? Whatever they make, I don't care. If you actually read the many dyno sheets I took the trouble to post instead of just rambling on like a child you'd see where some of your missing hp is. I'm happy with the parts that I approved of and purchased like an adult and the power results I'm seeing. I don't need to have a boat as an extension to look down and see my p*nis so I'm not losing sleep over when or if I get the engines in. I also don't need you to tell me if I'm happy with my engines or the people that helped build them. I'm going to sum up every post you make very nicely " I don't like Bob or Phil, I really can build an engine, it's someone else's fault, my cigarette is better than whatever you have and I run my boat harder than everyone else". Now you can go back to being blocked and maybe I'll see if you have anything intelligent to say in another 6 mos or so. My apologies to everyone else for derailing my own thread, but I have dealt with so many disappointing people in the marine industry that my tolerance level for any form of bs is nil even on a forum.

BSFC's with good modern heads like yours and that compression, usually .440's-.460's.
EGT: haven't seen those in a long time.
A/F ratio with known good wideband 12.0-12.5 for good safe tune (this is for WOT)
GPS: As fast as you can get it. LOL. Back to serious, this I use as a tuning tool too. Along with plugs and transom color.

Except for some .5xx below 3500 and a brief dip to .396 for 200 rpm the bsfc was always in the 4s. The average bsfc for the pull was .462 so not bad. The highest egt was 1480 on one cylinder at the very end of the run. He really had a thing about not wanting egt above 1450 ish. 1 and 8 were always the hottest and those were the plugs he checked a few times.

Hopefully this comes out ok. I folded them up to get all the fuel info back to back then just took a pic.