steveyrich

iTrader: (21)

First off, I've spent a lot of hours researching and learning about tuning. I have a question that I've never really found discussed or answered well. I understand tuning for MBT on e85 and using VD to ensure gains with each increase in timing.

When people talk about timing at peak torque, where exactly does this occur? I've also heard people reference it by peak load, which to me is a different thing. My stock turbo car hits full boost at 3500 which is the maximum load my car sees. My car doesn't make peak torque until around 4500, this is what I see on similar cars on e85.

When tuning timing, where should the timing be the lowest at? Is it at 3500 when my car is seeming the most load, and then increase from there? Or should the timing stay at the same number until I hit my peak torque around 4500 and then climb from there?

My tune is set to hit 2 degrees at 3500 and climbs to 3-4 at 4500 and then to 6 at 5k and then 18 by 7k.

Could I start raising the timing at 4500 or earlier? I know I can verify if it is making good gains with VD, I'm just looking for the guideline and principle from people who know what they are doing. Should it stay low until that peak torque is hit or can I raise it more safely once peak load is reached at 3500.

Thanks for the help. Examples, logs would be a plus!

Steve

wizzo 8

iTrader: (35)

I have my low timing when you see the highest load. Smaller turbo is lower in the rpm and bigger turbos in the higher rpm. With my black I hit full load about 5200rpm.

jdm-vr4

Hmmm was hoping for more responses.. also interested to know.

steveyrich

iTrader: (21)

Thanks Wizzo, yes I too have lowest timing at peak load, just wondering about when peak torque is made if the timing can be higher or if it needs to be close to that peak load number and then raise after that.

Hopefully some others can share their experience.

Steve

tt460

There is no magic number for what timing should be at MBT, peak load, etc. The only way to optimize it is by dynoing the car or reading the strap on the spark plug.

Every engine combination will be different. Selection of parts, heat rejection, inlet temps, intercooler efficiency, fuel, etc etc etc all play into how much timing can be run and when.

tt460

The point I was trying to make if it wasn't clear was to learn how to read the spark plug. This is the ONLY way to determine what is going on inside the combustion chamber. It tells you both if the fuel mixture is correct as well as timing.

10isace

iTrader: (12)

I'm interested in this too. I don't want a specific timing map, but a guideline to timing. Do tuners log a WOT and put the lowest timing at peak load or at peak torque? Also, like the OP asked, do we ramp up timing after either one of these?

wizzo 8

iTrader: (35)

Yes to this question

mt057

iTrader: (6)

Search for MBT everywhere. It is not limited to the peak load/torque range. Generally from what I see and what I have done is aim to have lowest timing right around peak load and then raise it toward redline. I also have a lower timing during spool up. Constantly watch for knock or power drop. Fuels like E85 will go past MBT with out knocking. (as I am sure you know)

Once you start to not see significant gains then stop adding timing. Maybe even back off a degree for safety.