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So, I am going to be dyno tuning a friend’s car running a speed density setup on MS2 in a couple days. I have done quite a few street tunes over the years on MS, HP Tuners, AEM EMS, and some OBD1 stuff and am very comfortable with tuning in general and all of the theory behind it. But, I have some questions on dyno tuning specifically. I have done a fair share of reading and still have these unanswered questions:
1. I will be on a load-bearing Mustang dyno and I know that I can lock in the rollers at a constant speed so I can go through the VE table RPM breakpoints and sweep up and down the MAP cells. Do I do this from idle (say around 1000 RPM or so) all the way to redline in 500 RPM increments? Or is running the engine loaded up above X RPM unnecessarily hard on it? For example, do I really want to lock in the rollers at 6500 RPM and start at 15 kPa and sweep up to 350 kPa? Or should I only tune up to 3500 or (locking in RPM and sweeping all MAP cells), and then do WOT pulls from idle to redline after and just fill in the uncharted cells by interpolation?
2. For spark timing – do I do the same as the above and go cell by cell trying to find MBT, being sure to watch for knock? Again, is it really okay to run big boost at high RPM and just leisurely go from cell to cell, taking your sweet time?
3. How long do you let the car cool down for between sweeps? Or do you just watch for high ECT’s and keep going as long as they are under control?
4. Presumably under these high load scenarios the exhaust and under-hood temps get HOT. What should I be watching out for?
5. Any other general tips/ tricks to keep in mind?
6. Bonus question – how do guys with extreme setups making 2000+ HP tune their cars? I would imagine most engines would blow chunks if you held them at 50 PSI and 9000 RPM (or whatever crazy numbers they are making)? Do they just do WOT sweeps only?
By the way, in case anyone is wondering, the vehicle in question is a 92 Dodge Dakota with a 2.5L turbo Dodge motor with forged internals, ported head, BW HE351 turbo, custom fabbed intake, big front mount, and a manual trans. Goal is 400+ WHP on around 25 PSI or so.
1. You don't need to hit every single cell. Hit the important ones. Ones you'll see during normal driving (run through all gears at light,part,medium throttle. Do some full throttle pulls as well. You can interpolate/smooth everything between. Maybe do a few pulls to verify.
2. Spark tables are easy. Start with a base table from someone with a conservative tune. 90% of the time I only adjust these tables for values below 100 kPa for driveability.
3. I'm abusive. I usually only let the tires cool off when dyno tuning lol. As long as the ECTs aren't going above your normal street temps, there is no reason to let it cool off.
4. Smoke/Fire.
5. Use street tires for dyno tuning. You'll trash radials/slicks by the time its dialed in, and they don't hook as well on a dyno.
6. Non street cars? 10% throttle and wide open pulls only. As long as you can get through the lane, do a burnout, and a pass, that's all that matters. Any other areas tuned is for preference.
1.I like my dyno time to take only 30~minutes and a max of 4-5 full WOT pulls. This will minimize wear and tear on the engine. That said, the vehicle should be mostly tuned by the time you hit the dyno, because you already logged and adjusted the wideband values for every cell you hit while normally driving- and tuned them, right? If not, you need to do this first. Once the vehicle is tuned safely for the street (leave it slight rich and slightly reduced timing) you can "clean it up" on the dyno, which is basically removing a tiny bit of fuel off the crisp edge of the boost regions and adding a slight amount of timing to check for a significant drop in EGT and a significant improvement to torque.
Always Use 0 Smoothing if the graph has a smoothing feature.
2. No because you will cook the engine. You want the WOT run to be the same way the engine will experience WOT when it is actually driving. If this is a boat engine, sure hold it to 5.5k and run up the EGT as high as it will go and watch for knock, stop check the plugs, etc... If this is a drag racing engine you run it to whatever bleeding edge the $$$ from the sponsors are giving you (have spare engines? then make it extra crispy and use race fuels etc...). If this is a street car, and somebody wants to protect their investment, you do NOT keep advancing timing until the engine is on the threshold of knock and you do NOT hold the engine at a constant RPM with high boost in an application for which it is unintended. To hold a high boost engine at high RPM you will need sufficient cooling for all aspects especially OIL temp, for example.
3. Your power comes from a low intake air temp, a low intake manifold temp, a low coolant temp, a high OIL temp, a hot cylinder head, a hot exhaust manifold, a hot/wrapped/coated exhaust. All objects which lower underhood and IAT also help keep exhaust system temp INSIDE the exhaust. In other words, when you first start the engine, all temps are equal for an instant. Before the first plug fires the cylinder is the same temp as the water around it. Only once it begins to warm up as it runs does temp begin to leak from the cylinder/exhaust into the engine bay, into the intake manifold, into the compressor of the turbocharger and so forth. Your JOB as an engine builder/ high performance tuner is to recommend issue commands that help the owners CONCEAL That temperature, CONTAIN it within the exhaust system to lower the under hood/compressor temps while the engine sits to go onto the dyno (or race or sitting in traffic etc). Because you have the luxury of turning the engine on and off, you will want to pre-heat the hot objects first (the oil to 180*F~, cylinder, exhaust) and then shut the engine off to quickly cool the compressor (hope you have a water cooled turbocharger) and intake manifold and all associated plumbing. Once these temps are SPLIT (high hot exhaust low cold compressor) you can start the engine and check the oil pressure to make sure the oil is thinned out, then make a dyno pass as quickly as possible with that hot thin oil and a cold compressor. This will be your 'highest number possible' because every subsequent run will further heat the air around the vehicle and make it very difficult to get that same condition again for possibly 30 minutes to an hour you will need to wait to bring the temps back down sometimes. So this is why I said to tune the car on the street first- you walk into the dyno ready to go to make the first pass, as the final pass. This is your goal, Minimal passes means minimal engine wear and tear. It never happens this way (something always needs to be changed a bit or some problems arise) so the goal is < 10 passes total if possible.
4. Temperature rise goes against the octane of the fuel. If you are using 93 octane, there is some temperature at which it doesn't matter what timing you input to the computer- the engine will knock regardless. This is what makes methanol/water injection so powerful, it will cool and remove that excess temperature energy allowing the combustion reaction to proceed without a violent explosive feature. Meth/water or simply water straight is highly recommended for boost applications whether street/strip for safety. Watch for excess temps, the manifold should not glow in a street car, for example. The OIL should sit around 180-212*F~ prefer 200-212. With Oil at 210*F you can run a 165*-180*F coolant temp. It might creep up between dyno passes; this is normal if it only goes up 2-4*F. Excess heating indicates your EGT may also be higher than it should be, as the engine is wasting energy.
5. Start with minimal timing and watch the EGT, using the lowest boost setting possible if you are unsure about anything. Then gradually raise the boost as necessary to tap the compressor or max the limits of the fuel you are using. Usually this is about 18psi on 93 octane fuel, but some applications can tolerate a tiny bit more if only just for a single dyno pass. I would never leave a 93 octane motor to run on 19+psi of boost regularly, it needs to be regulated for just those specific sessions where the IAT is low and the vehicle/engine is easy to cool (cold night times on the highway with time between runs to cool off further). Meth/water helps alot here if the turbo has more in it.
6. Again you can run an engine without boost in a majority of applications first, then gradually turn it up and fine tune every increment. Most of us do this on the street and log the information via computer for review. Then you spend hours driving it around and checking logs for problems. Make every conceivable issue disappear from the logs and from the visual indications of the engine (it has clean plugs, behaves as expected, seems to run clean with no smoke and no leaks, you pressure test the crank case and plumbing, nothing has rattled loose after several/hundred miles of driving while running slightly too rich) And then you take it to the dyno to crispy up the edges by removing a small amount of fuel and a tiny bit of timing can be added just to check what if any improvements are significant.
08-09-2016, 03:30 PM
My first dyno tune - some questions 
