Tuning DSMLink v3 for Road Course / Autocross

[WillRaceForBeer]

I've got a few questions that I'm having a hard time finding answers to, I think it comes from the fact that most DSM owners go for HP and straight line performance. For me right now I'm becoming very interested in responsiveness under all possible load/rpm conditions. I think I want to get this nailed down before tuning for max power at WOT. I tried the stock Evo8 maps this morning and I could feel a difference in normal driving, with no obvious downsides. A/F ratrio was fine and no knock. Car felt less sluggish when giving light throttle under cruise or from a stop.

Has anyone tried the Evo8 Ralliart maps as a base tune?

What approach do you guys use to tune for a variety of rpm/load conditions?

 

[TSiAWD666]

I can't imagine you needing to do much in terms of deviating your tune just for a road course at your modification levels. A 16g is pretty damned responsive on the road course even with the old ghetto o2 sensor voltage and s-afc method (yes, that's how I did it back in the day haha). I think the only thing I did when I had basically your same mods was add just a little more fuel than I would when going for absolutely maximum short term power as over time on the road course my EGTs would get over 900 C towards the end of a session which is a bit scary. I imagine perhaps i was heating up and knocking over time resulting in what I can only speculate was a bit of timing pull and excess fuel coming out, but back then I wasn't logging/watching for those things so I can't say for sure. Adding a bit more fuel definitely kept my max EGT at a more reasonable level.

I can't comment yet on higher levels as while my car has the potential for them, I haven't even finished breaking in the engine and it's been down for almost a year now with the extensive body work it's undergoing. Ask me in a few months and I might have some info as I'll be hitting track events to start getting the car dialed in for competition.

Btw I'm in Herndon.

 

[jtmcinder]

This is a cool question.

Most people who "tune" do it on long, WOT pulls. Great for dyno-wars and drag-racing. But maybe not optimal for autocrossing. Most of all, there's that pesky "tip-in knock" stuff.

I found that, if I tuned using 3rd-gear, WOT pulls and then put the car in second and punched it and lifted and punched it and lifted, I had much more knock than during the extended pulls. In the end, however, I didn't do anything about it (partly because I'm a bit smoother than punch and lift, rinse, repeat; but mostly because I'm an incompetent tuner). But I'm sure that there are ways to tune a car specifically for autocrossing. I hope this discussion continues and becomes detailed.

 

[turbosax2]

I'll give a bit of input.

-While tuning, I typically start with third gear long pulls, from 2k rpm or so. Once I'm satisfied with that, I'll also do pulls from 3k, 4k, 5k, etc., and maybe some fourth gear pulls, too. I like to see a full spectrum, since I'm most likely to be pulling from 4k or 5k on the track.
-I always tune to the ragged edge of knock, first setting boost, then afr, then timing. Once I find that ragged edge, I always back it off to a safer level.
- In cases where I've tuned a car going road racing, back it off even more. I lowered the boost a couple psi, richened up the afr a tad, and dropped the timing a bit. Between that and splashing in some race gas (to help the 93 pump gas), I felt it was safe to track with lap after lap. Of course, logging during the race is extremely helpful. When dealing with a car that consistently overheats, I richened the tune even more and dropped the boost more to help.
-For autocross, I don't back off from the full-out tune as much. Maybe just lower the timing a bit.
-Play with the base tip-in factor. I've found this to increase driveability and response.


This is all from my somewhat limited experience. I wish I had more time to race and tune the car!

 

[WillRaceForBeer]

Very cool responses so far.

TSiAWD666 - I had not thought much about the impact of long-term heat (I do fortunately have an upgraded radiator and fans, and a Big FMIC), but I had not thought much about how EGT's will change over the course of running a few laps. I imagine the gradual increase is due to the heat soaking of the engine, and all parts involved. I'll have to keep an eye on that, and perhaps consider Water/Meth to combat that a bit. BTW, my mods list was out of date, but I am still running the evo 3 16g, just with better management supporting mods.

I'd be down to meet you in Herndon some time, are you planning to run at Summit Point? if so what events? I'm hoping to be ready for FATT on the 31st. Need to order a brake kit!

jtmcinder - I have no experience yet with adjusting the "tip-in" trims, but I've seen what you are describing for many years, and now I have to wonder if it's Rich knock... I'm very curious if anyone has solved this through leaning out the "tip-in" curve.

turbosax2 - when you do different rpm starts, do you seen knock from "tip-in" fuel?? What kinds of changes have you made to the tip-in? I imagine you've lowered them a bit, but I'm curious how much and at what points... how bad are the stock tip-in values?

Thanks!

 

[Scott McIntyre]

It think its was "Engine Management and Advanced Tuning" by Greg Banish that provided a proper way to tune your car at different RPM & load levels. It's a time consuming process though, and requires a dyno to do it properly (road has too many variables like traffic, grade, etc.)

You must be logged in to view this image or video.

In any event, it's a very good book to read if you haven't already. Here's a sample: Engine Management: Advanced Tuning - Greg Banish - Google Books

 

[Tyeler18]

This is a very interesting topic which I'd love to learn more about as ill be in the same boat in the next few weeks. I don't have enough multiple load tuning experience to add to this, but am definitely interested in learning more on it.

 

[arrowhead]

Well guys there is a lot of good info coming out and although I consider myself a complete ignorant about tuning a FI,turbo car, I am having a difficult time braking from traditional carb tuning to FI.
But I do find a lot of similarities on response time, tip in, I think it is called by FI tuners, if I am mistaken please correct me, this in a carb is corrected by, 1 going to a bigger squirter on the carb, and road racing requires a larger pump capacity.
Like in Holleys going from a 25cc to a 50 cc, it is the constant of stopping. going again, downshifting 2 or 3 times in a row, that drains that pump. Also I always removed the economizer valve. later to become a power valve by name, as I did not want anything altering my mixtures, is that the same as rich knock?

Could the tip in problem be resolved by adding a little more fuel at the lower rpms.

The guys that I am helping out now, sometimes come to me and ask what they should do. I tell them bring me spark plug and I will read it, and then they can refine from there.

Sorry to break in with this but I am sure more people will come up to clarify it.

 

[Tyeler18]

Like stated above, sometimes tip in knock is caused by being to rich. Basically the ecu will squirt an extra amount of fuel when you jab the throttle to try and increase response, however, too much fuel will cause a rich knock. I currently have this problem on my 3g, I increased my throttle tip in as I was having bad knock coming into corners in 2nd. It ended up making it worse, so I needed to remove fuel to prevent it.

 

[WillRaceForBeer]

I was reviewing some logs this weekend and noticed there was a noticeable delay between hitting the throttle and a change in airlow. Also Mafraw was responding much faster then Maf. Turns out there are air flow smoothing parameters that cause a delay, the higher the value the more delay, it's a result of the smoothing algorithm. Anyway, these can be modified in DSMLink v3. Haven't had a chance to get new logs with the values lowered yet.

Scott - that sample was pretty good, I think I'm sold on picking it up, thanks for the link.

Does anyone know if the tip in knock will show up in injector duty values? I looked through my logs but I don't see any obvious bumps in injector duty when quickly opening the throttle body. (I have seen knock tho!)

 

[D_Eclipse9916]

I'd be down to meet you in Herndon some time, are you planning to run at Summit Point? if so what events? I'm hoping to be ready for FATT on the 31st. Need to order a brake kit!

Yeah what events will you guys be running? Im sure a base reclass with your power/weight in TT or PT events in NASA-MA would be easy to jump right into competition

 

[TSiAWD666]

Beats me, I'm still working out little details with my car like some small issues, adding the accusump, and a few gauges, and tuning the engine hehe. I think my first time back on-track will be in June. Really wish I could do that VIR event May 18-20 but I made a commitment on the 19th before I knew about it. In case you guys are interested it's dirt cheap for three days of track time:
MotorsportReg.com : PCA - First Settlers announces Spring 2012 Drivers Ed At VIR (Fri 18 - Sun 20 May, 2012) info at Virginia International Raceway, Alton, VA 24520 (2138)

I probably won't consider competition events until the fall as I have to knock out the license first.

 

[WillRaceForBeer]

Just got the brake kit on, hoping to make the late April FATT on Summit Main. I'd like to do some Time Attack later in the year.

The 3 days at VIR looks awesome, if FATT goes well, I may try to make the VIR event.

 

[snowborder714]

Have you ever road raced before, or is the FATT event your first time?

 

[TSiAWD666]

Which brake kit? man we're getting off-topic

 

[D_Eclipse9916]

NASA-MA is a tad on the expensive side but has a great HPDE to Time Trials to Racing License graduation. Plus you get instructors that are more than just "HPDE" instructors and will be able to help you get faster.

Trackdaze is also a good option.

NASA-MA's time trial also has contingency prizes for Hawk, Hoosier, Toyo, and Goodyear. May want to look into that.

 

[WillRaceForBeer]

Yeah we did! FATT will be my first time. I was a straight line guy in the early days, but got bored with that.

I went with the 3kgt vr4 calipers and 13" cobra rotors.

I should be back to tuning tomorrow, hopefully I can get this thread back on topic

 

[snowborder714]

Just keep in mind that if you want to do TA/TT that you'll need to progress up the HDPE levels (1-4) and then get a license/certified/approval.

 

[eclipsegsx1736]

I agree with everything in this thread related to road course tuning. One thing I'll add - it was briefly mentioned above - is that more than anything, you need to concentrate on keeping water and oil temperatures low after extended lapping. Besides the obvious; FMIC/radiator ducting, A/C removal, insulation of exhaust components, there are a few tuning tricks that do a bit to help reduce engine temperatures:

-turn down boost and increase timing. This will greatly reduce EGTs and therefore reduce ambient engine bay temperatures. The engine will run more efficiently this way. Peak power may be SLIGHLY less, but the extra transient-boost torque will make up for it.
-Run a richer AFR. Obviously, this keeps the cylinders cooler, reducing chance of knock for extended full-throttle.
-run E85 fuel or water/methanol injection. This allows a further increase in timing without risk of detonation, but also due to the fuel's cooling properties helps the engine run cooler. Also, based on actual amount of fuel injected, E85/alcohol has a higher energy potential. This means more power for the same boost level, or better yet for this case, the same power with less boost.

Beau

 

[lowell]

Can link do TPS based boost targeting? It's a nice way to eliminate part throttle surging in corners.

 

[snowborder714]

Here's what link can do boost wise.
boostcontrol [ECMTuning - wiki]

 

[NDgsx]

Fuel is the main component that affects how you tune. Next is oiling, making sure you run a half quart high prevents starvation in corners. What we find with the Evos is pretty simple-

Gasoline- 2* lower timing than a normal drag tune, 10.7-10.9 AFR, 21-22psi. Intercooler efficiency as well as airflow to the radiator are ESSENTIAL and cannot be stressed enough. Dont get enough air to the radiator is obvious, but a heatsoaked cheap intercooler core is just as bad.

E85- Standard E85 timing going to MBT on the high end of the scale, a little leaner is okay 11.2-11.3 and generally no more than 25psi. Cooling as above.