What do you mean by load curve?

 

He means that you should draw a trace on your timing map that shows were load goes during a WOT run starting from say 2500 rpm to your highest rpm that you run.

 

Oh I see. I'll have to do that in the morning. But here's a log from tonight. Anything look bad?

 

I want to run lower boost and need to know if I will require a complete retune.

My car was dyno tuned at 30psi and made 450whp. It holds that psi till 5500 rpm before it starts to drop down. It doesn't drop below 25psi until 6500 rpm.

I no longer feel safe spiking that kind of boost and would like to drop it down to 25psi across the board. Below is screen shot of my timing map. Do you think the car will remain safe once the boost is lowered which will normally result in a lower load but higher timing?

 

Your timing looks fine. I would suggest spooling @ 12.2-12.5 and maybe 11.8 afr out the top.


I hope you have a wideband and not counting on logging the afrmap for tuning.

 

Stock turbo or other? What is your load curve?

 

I am running a BBK. Load peak is 330 falling to 260.

 

Can you put a trace (dots) in the cells that correspond to a dyno run or WOT run? Its pretty hard to say anything useful without the trace.

 

Thanks ReaperX.

I do have a wideband. Should stop being lazy and wire it to the ECU to log instead of eyeball.


One question for you guys. Why is the load curve significant? I know it's the cells being hit during a pull but why do you guys ask for it when giving advice? Thanks!

 

The reason we ask is that for us to give advice we need to know what cells the car is hitting. You can have a smooth map that looks pretty, but may have too much timing for a given load/rpm. The more info you can give us, the better we can help you.

 

How's this look for HTA73 Green with S3 cams running 11.8 AFR steady to redline. I seem to be getting random knock now doing pulls. I just did a log and picked up 2 counts of knock just a touch past 5k RPM that became 1 count at at 5600 and went away at 6250. I tried to lower timing earlier and what was 2 counts of knock went to 3. I had never seen 3 counts before that either. Always picked up 1 or 2 maybe. Is it possible that I need to throw more timing at it??? Feels weird to add timing to get rid of knock so I wanted to get a second opinion. I never pick up knock past 7k where I'm running high timing.

I'm 350 load from 4k down.

 

how much boost are you running? Does adding the degree of timing back give you power increase? With E85, the big thing is make sure you're not past MBT. E85 doesn't really knock, it typically goes straight to full on detonation..

 

I definitely lost power when I pulled timing. Logged on the same road back to back. I was a little afraid to add timing after just seeing two counts of knock so thought I would get a second opinion. I've read that E85 doesn't really knock from too much timing so that's what got me researching to see if maybe I don't have enough timing. I got my VE table dialed in really good and my AFR is steadily at 11.8 so that shouldn't be a problem.

When people say they start adding a good bit of timing after peak torque what do they consider peak torque? My torque curve stays flat and I am holding boost so is it just where it first hits near peak?

Right now I'm only running around 25 psi. Hit 24.6 psi at 4k, 26 psi at 4500, and back down to 24.6 psi at 6875. That log had 1 count of knock from around 5600 to 6300. I'm waiting for my double pumper to turn up boost much more. Didn't want to bump it up any until I figure out something about the knock either.

 

You can always add timing as rpm's go up, even if the torque curve is holding flat. You could probably add 1-2 degrees all the way out the top, but with a little less timing around 4k with a little faster ramp from 4500-6, going up one degree every 250rpm instead of every 500, and ending up at 17 or 18 out the top. I can't divulge my timing curve because its not mine, but I'm running 32psi at 4500 tapering to 28 out the top, and my timing is more aggressive then yours. Granted, cams play a role in how much advance the car will take, as well as intake air temps, so take that with a grain of salt.


I would try 1* from 4 - 4500, then ramp it smoothly to 10 at 6k, then ramp it smoothly to 17 or 18 by 8k. See how that does.

 

So would bigger cams typically take more timing or less? Before I blew my head gasket I had S1 cams and was running around 30 psi with only random single counts if knock. Since putting the car back together with S3 cams I keep getting knock.