Turbos;injectors;CFM;lbs/min

[kjewer1]

I believe there is a tuning guide of some sort on the DSMlink forums. I've seen a thread for it anyway, but I've never looked at it. Actually tuning a car is not really something I can see being put into a guide, but I'm sure it provides people with a good start. I've been tuning these cars for something like 6 years, every single week, and I still learn something new at least every week. Just last week I made a pretty significant breakthrough on my car with injector timing, something most poeple never even think about. Tuning is such a huge topic. And there is so much misinformation out there it's ridiculous. It's difficult to know who you can listen to, and who is just talking with no real experience behind their ideas.

Wanting to tune your own car is the first step in the right direction. You really do have to learn by doing. It's a risky business though, so make small changes, and as you go on your knowledge and confidence will increase. When I started doing this, I had no previous experience at all. With previous cars I could bolt parts on and do maintenance stuff, but no tuning. The more you tune, the more you learn about how the ECU (and EFI in general) works. The more you know about how the ECU works, the better you can tune.

I'll provide a quick outline though, just to get people going in the right direction, hopefully, I feel like rambling again...

1) First and foremost, airflow determines power potential. No matter how good your tuning is, you can't make more power than the amount of air and fuel you are burning will provide. Burning air/fuel supplies the energy to do the work, the tuning just determines how efficient the motor is with that supplied energy, and how safely the motor will use that energy. In other words, don't over-tune. You can't make power magically appear through tuning, there are limits.

2) Airflow is power potential, boost is heat (knock). Increase airflow by increasing boost, or increasing the motor's ability to move air at a given boost pressure (cams, intake manifold, exhaust, larger turbine side, more displacement, better intercooling, etc). At some point you won't be able to get away with more boost (knock limited fue to pump gas, etc), and moving more air at the same boost will be a worthwhile pursuit. This is absolutely key for pump gas power.

2) Every setup is different, but the AFR you want to run is pretty well established. On pump gas, 11-11.5. On race gas, 11.5-12.5. Play around with it and log the results, but don't expect huge changes if the rest of the tune/setup makes sense. AFR doesn't have a significant effect on knock until you get real lean, or a real significant effect on power until you get real rich.

3) Timing is a whole other story. This is the big voodoo magic variable. Timing has a significant effect on both power and knock. It's also on a bit of a curve. The trick is to recognize when you have reach the point of diminishing return and stop increasing it. On pump gas, you'll typically knock before the power increase with each degree added starts to drop off noticeably. On race gas you can actually start to lose power and break stuff before you pick up any knock. In the meat of the curve, expect 10-12 whp or 1 mph per degree added. If you start adding 2 or 3 degrees and picking up 5 whp, it's no longer worth pursuing. Drop those 2 or 3 degrees back off, give up the 5 whp, and keep the added safety margin.

4) With timing and AFR in the "normal range," more boost will always make more power. In other words, don't sacrifice boost to get extra lean AFRs or more timing than usual. It almost always makes less power. Taking out a degree of timing and increasing boost a few psi will almost always yield more power. At the same time, don't completely bollix the timing, or run excessively rich AFRs, to try to run excessive boost just to impress your friends.

5) Make some changes, log the results, and try to quantify any HP gain or loss (track trap speed, dyno, or datalog a fixed speed range, like 70-90 mph in third, and note the time it takes). And repeat for the rest of your life. This process will never change. It's time consuming, but necessary. Never trust the ass dyno, trust the data.

6) When you've done all the tuning you can, and you're still not making as much power as you think your setup should or as much as others are making, don't overlook the "mechanical tuning." Cam timing. Compression ratio. Combustion chamber characteristics. Parasitic loss. Turbine/exhaust size. Intercooling capacity. Intake restrictions. And so forth. When you get really bored, go to a full standalone and see the tons and tons of bullshit you never knew existed, and start the learning process on the steep end of the curve again.

It's one big learning process that can be rewarding at times, and dissapointing at times. Good luck, and enjoy.

[cantgo2fast]

thanks a lot ill probably just take it really slow and try not to break anything. I have a completely different set of problems... altitude lol being a mile high sucks sometimes

[kjewer1]

Bah, just turn the boost up.

[cantgo2fast]

ya i keep trying but i cant figure it out i have a joe p with the T hanbdle and the hex screw but i cant figure out which one i have to turn which way to turn it up i wanna set it at 17 cuz im getting 2lbs of creep and hit 19. but i had 3.5 degrees of knock 6533 rpm at 16/17psi surge and 2nd gear pull so i decided to add more fuel and be safe but im upset cu if im pulling knock at 15psi i wont be able to advance the timing any especially at higher boost. i feel like this thread got a different topic i dont want to do anything too much because i dont have a WB yet and i dont know exactly what AF im running and i dont wanna blow anything up.