Tuning Engine

[boxsterb1]

How do you go about tuning of air to fuel ratio and other important engine settings to get the best preformance. I have seen many pictures of engine and chassis dynos sre these purchased or build from scratch or at a tuning shop that has given you time on their machine.

[boxsterb1]

How do you go about tuning of air to fuel ratio and other important engine settings to get the best preformance. I have seen many pictures of engine and chassis dynos sre these purchased or build from scratch or at a tuning shop that has given you time on their machine.

[Bowtie Man]

Our school has an engine dyno for me to use, and I bought a wideband O2 sensor and controller off of ebay to meter the AFR. I'm sure a lot of other teams have better equipment but what i've got here works

[Charlie]

This is a really basic answer but it sounds like that is what you are looking for.

Use a steady state dyno, put the engine at the conditions of each mapping point (throttle and RPM or MAP and RPM) and tune ign and fuel for best torque. Repeat for all mapping points. Do less and interpolate if you feel comfortable doing so.

[Mustang Mac]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> This is a really basic answer but it sounds like that is what you are looking for.

Use a steady state dyno, put the engine at the conditions of each mapping point (throttle and RPM or MAP and RPM) and tune ign and fuel for best torque. Repeat for all mapping points. Do less and interpolate if you feel comfortable doing so.

-Charlie Ping
</div></BLOCKQUOTE>
Sounds like the way we do things up here to. A good wide band O2 and thermocouples in the exhaust help to tell whats going on with combustion and keep you from leaning out to much.

[Sam Zimmerman]

The exhaust thermocouples are invaluable. No thermocouples can lead to holes in pistons. Holes in pistons lead to pressurized crankcases, which leads to an oily mess and an engine rebuild.

Don't ask me how I know. http://fsae.com/groupee_common/emoticons/icon_wink.gif

The thermocouples have also been very nice for troubleshooting. I wouldn't tune a test engine without them again.

[osubeaver]

I agree. EGTs on each cyl is a must.

[threehondas]

Personally, I've only tuned single cylinders for the past two years.

I was curious if there is a big difference in how each cylinder breathes in multicylinders.

With EGTs for each cyl, what do you see? Does one really tend to run hot? What do CBRs like for EGTs? I've only had EGT with my turbo...

[John Bucknell]

Unfortunately, EGT is not a fine control to tell you what is happening (fuel-air differences for example). There is usually 100 deg F difference max to min just due to difference in installation of thermocouples. What you are looking for is trends across the speed range - ie is the coldest hole always the coldest? Even on engines where we verify the fuel-air ratio is consistent across a cylinder head, and the coolant distribution is good - we still get EGT differences. Change an exhaust manifold - temperature isn't necessarily the same at the port as prior. Most consistent is further downstream (collector) because all the chemistry that is still happening usually has a chance to wind down by the time it gets that far away.

For diagnostic purposes, individual holes is most useful - if one is running some nominal temp steady state, and then suddenly ramps up or down relative to the others - shut it down! Same as you would do in a single.

[ZeroValence]

I know this is a newbie question, but I'm a newbie on a newbie team. With the 20mm restrictor there is less Air and fuel throughout the entire rpm range. Therefore a shorter pre-ignition of the fuel needs to take place. Yes? So the engine management system, what ever setup it is, must be able to tune fuel and ignition. Am I on the right track here? Thanks.

[Chris Boyden]

You really don't get less air and fuel until
the restrictor begans to choke off the air, but until that point, a well designed system could have better breathing characteristics, i.e higher VE, at certain rpm ranges than stock.

When you set ignition timing, you are trying to time the combustion explosion so that the peak pressure happens @ ~14 degrees after top dead center relative to the speed of the engine. So you have less advance at low speeds in order to meet that goal, and more advance at high speeds. If you have too much advance at any speed, the combustion event may peak before top dead center. This force will try and rotate the engine in reverse, which its inertia will resist, the energy has to go somewhere, and usually ends up burning your pistons, stressing rod bearings, rods, etc.

Restricted engines usually run more timing advance than unrestricted, which means more time to burn the mix relative to engine speed. If there was a better mix,then combustion occurs faster, which means you want to delay the ignition event by retarding the timing. This is a somewhat simplistic approach. Others can explain this better than I. Yes, you definitely want a controller that can tune fuel and ignition, that's the name of the game. http://fsae.com/groupee_common/emoticons/icon_wink.gif