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How to Dyno Tune your car

 
Old 01-23-2008, 12:48 PM
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Default How to Dyno Tune your car

Mods, I didn't see a place this fit. It really isn't SC specific but I like the new section so I will start it here. Place it where you will.

I don't claim to be an expert and would really like this to evolve into a tips and tricks for dyno tuning thread. But given some discussion in other threads about "is this or that dyno good for tuning" I thought I would start this one.

Disclaimer: You probably know more than I do, and should be ultimately responsible for your actions and the health and well being of your motor. SO... take what you read here as my experience and not a guarantee of more hp and good tuning.

I am currently working through tuning a new setup on my car. Here are the steps I use.

Start with the basics. Make sure everything is connected properly. USE A Wide Band O2 sensor. I am using an EManage Ultimate. The same process probably applies to other EMS but it may be easier or more difficult depending on the tool. Not sure how other systems and or bandaids are tuned but here is my "process".

Start the car. Get it to idle. You may have to fix any vacuum leaks, adjust fueling as required.

Once you are up to operating temperature, set timing and idle as you would on any car per the service manual etc. Depending on your engine management system you may want to alter the base timing.

I try to start with a map from a similar setup that is known to be good to get things going. I will then set the timing a bit more conservative and richen the A/F ratios. Better to error on the rich side than lean.

Once you have timing and idle set, adjust your Air/Fuel ratio in the non boosted portion of your tuning map. Slowly increasing rpm up through the range. Make sure you have a good solid A/F ratio in all the unboosted areas before moving on. So far the car hasn't moved.

Now, turn on whatever logging you have, or autotune if your system supports it. The go for a short drive without getting into boost. Once you are safely back home and parked, review the logs and see if you need any corrections to the unboosted cells based on driving under load.

Once those corrections are made, go for another drive. This time we get to boost a little. Always listen to the engine for signs of detonation or something else wrong, but drive it a little going in and out of boost at different rpm etc. Once you are back home. Look at the logs again, or any changes your autotune has made. Smooth any changes out as best you can manually. Try to interpolate those changes into the next set of higher boosted areas.

Go for another drive, more boost this time, more variation.

Rinse and repeat, until all your A/F ratios look good in the logs and are steady at whatever target you have selected.

Now you are ready to go to the dyno. There are two basic types of dyno, inertial and load cell. An inertia dyno cannot apply load unless the vehicle is accelerating. This makes it impossible to test a car on a level road at steady speed on flat roads or up hill, or slowing down due to hills etc. In addition, an inertia dyno makes it impossible to properly tune a vehicle at anything other than maximum acceleration. A load cell or eddy current dyno allows you to introduce a specific load and hold the engine there.

If money were no object, you could tune each cell in your map for maximum power. I have a 16x16 map or 256 individual points I could tune, but I don't have that much time or money. It is important to have a plan before you hit the dyno. You are paying by the hour in most cases, unless you are just doing a baseline 3 pulls. (those are fun but not what you need for tuning). I generally have the car warmed up before I pull it onto the dyno. I do one baseline pull to redline just to verify that my A/F ratios look good and that my logging correlates to the dyno readings. A/F ratios may be a little different from your wide band to the dyno tailpipe sniffer but the should go up and down together.

Then depending on what you are tuning for, Max HP, Drag racing, autocross whatever. Pick the first cell in your plan and have the dyno operator hold the car there. Then you can adjust the timing in SMALL increments while watching the Torque reading on the dyno. The goal is to get the most torque under that load and rpm. After you get that cell dialed in, move to the next one on your plan and do the same thing. I try to pick 4 to 6 cells and that usually (on a new tune) takes up my hour of dyno time and then some.

Be sure to watch your water and intake temps on the dyno as heat soak can become a problem.

My autocross car spends lots of time going from 4 to 6k with some trips to redline. So a typical cell plan for me on a new tune is

4000 rpm 2 PSI
4000 rpm 8 PSI
6000 rpm 4 PSI
6000 rpm 8 PSI
7200 rpm whatever its making under the most load I can sustain.

After I get the timing maximized in those cells, it's time to interpolate the timing between them.

Kind of long I know, but thats where I start. Any suggestions or corrections?
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Old 01-25-2008, 08:59 AM
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get said load bearing dyno
tune fuel in each cell up to 4600rpm
tune spark to 4600rpm
repeat for 4601rpm+
tune enrichments
get tired of supercharger
buy turbo
????
profit
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Old 01-25-2008, 09:16 AM
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Originally Posted by hustler View Post
get said load bearing dyno
tune fuel in each cell up to 4600rpm
tune spark to 4600rpm
repeat for 4601rpm+
tune enrichments
get tired of supercharger
buy turbo
????
profit
so that 4600 rpm is that where turbos spool up and start producing power?

Just kidding...... sort of
Do you really spend dyno time tuning each cell?

BTW: SCCA National Tour at Texas Motor Speedway on May 3-4 if you want to show me how fast that turbo is for autocross.
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Old 01-25-2008, 10:38 AM
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Originally Posted by Chris Swearingen View Post
Hustler,
Seriously, why the 4600 distinction?
half way between the full range where I typically drive the car...and diy autotune's recommendation.
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Old 01-25-2008, 11:55 AM
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1. Obtain base map
2. Drive car carefully while logging.
3. Run log through Logviewers VE Analyzer, tweak table, accept changes, burn to MS.
4. Run car with autotune enabled and a proper AFR table to further fine tune.
5. Done.

No idea about spark, but i guess its like fuel and you need a dyno for it.
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Old 01-25-2008, 02:25 PM
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Originally Posted by Saml01 View Post
1. Obtain base map
2. Drive car carefully while logging.
3. Run log through Logviewers VE Analyzer, tweak table, accept changes, burn to MS.
4. Run car with autotune enabled and a proper AFR table to further fine tune.
5. Done.

No idea about spark, but i guess its like fuel and you need a dyno for it.

that my friend is good 'ol street tuning, and why people strap on load bearing dyno to tune.
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Old 01-25-2008, 02:40 PM
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With my old MS project, I kept planning on a dyno tune. But I used something called "VexME" which took your desired AFRs, a datalog, your fuel table, crunched the numbers, and spat out a new table.

Worked like a fkng charm, got exactly my desired AFRS 100% of the time. Autotune was just coming out at that time, and was kludgy for me.

Got the spark table from someone with a similar car, and I was good to go.

Is dynoing really going to get you enough more power vs. buttdyno and information sharing to justify the cost?
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Old 01-25-2008, 02:48 PM
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Originally Posted by kyle242gt View Post
With my old MS project, I kept planning on a dyno tune. But I used something called "VexME" which took your desired AFRs, a datalog, your fuel table, crunched the numbers, and spat out a new table.

Worked like a fkng charm, got exactly my desired AFRS 100% of the time. Autotune was just coming out at that time, and was kludgy for me.

Got the spark table from someone with a similar car, and I was good to go.

Is dynoing really going to get you enough more power vs. buttdyno and information sharing to justify the cost?
Well I can't tell you for sure how much the dyno will add to my current setup. I am still getting the A/F where I want it. When I go to the dyno, I will start and end with a pull and we will see what it gets me.

I would love to compare spark maps etc with a similar car. Who is running a '99 motor with a 1.2L lyshom blower. Oh yeah, forgot to add modified pre blower intake, 10 psi, 460cc injectors, water injection and FMIC. Thats the base setup. Once that gets tuned well, we will see how far into the season we are and based on Injector duty cycle and how well it's performed then decide whether or not to switch back to e-85 and what size injectors that might require?
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Old 01-25-2008, 03:57 PM
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I developed my spark maps from a few general tenets:
Higher RPM = less time for the flame front to travel = more required advance.
Richer mix = quicker burn = less required advance.
Torque peak = less allowable advance, generally detonation limited.

I think the induction setup is less important than port design/valve size, displacement, camshaft profile.

But then again, I'm still pussyfooting around with OBD2 and stock everything.
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Old 01-25-2008, 04:42 PM
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Originally Posted by kyle242gt View Post
I developed my spark maps from a few general tenets:
Higher RPM = less time for the flame front to travel = more required advance.
Richer mix = quicker burn = less required advance.
Torque peak = less allowable advance, generally detonation limited.

I think the induction setup is less important than port design/valve size, displacement, camshaft profile.

But then again, I'm still pussyfooting around with OBD2 and stock everything.
Induction method is relevant based on flow characteristics and amount of heat added to the charge.
If my SC keeps building boost to redline and a smaller turbo on a similar engine runs out of breath, the timing at a given rpm and pressue might be different based on the difference in charge temp.

You or I can get close by starting from a similar setup and guessing.
But, spending time on the dyno maximizing the torque by adjusting the timing is the only way to know, engine to engine what "the best" setting is.
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