Advanced Tuning

When tuning a turbo car there are three main elements: boost, fuel (AFR), and timing. The key to being a good tuner is being able to get the most power without damaging up the motor. I have been tuning my car and many others for years and have read all over the Internet on what to do and what not to do. It seems everywhere you go everyone is preaching keep it rich to be safe. I have always tuned with a data logger that gives me knock, timing, and AFR feed back.

Timing

I have found that timing is the most important thing to keep knock down or in check. High timing will blow head gaskets, break ring lands, and bend or break rods. High timing causes detonation that can cause over double the cylinder pressure so you can see why that would hurt things. With AFR I have found that running lean will give you high EGTs that could melt your motor.

I feel that if you are in a car tuning for the 1/4mi it is really hard to melt something unless you have the EGTs with detonation. Most of the time cars that are detonating have high timing which causes low EGTs so you will break not melt. I have found that running richer does not really stop detonation, but people think it does. When you are running a piggyback fuel computer with a stock ECU and you up the duty cycle you move into a higher air flow map which has lower timing, so it was the timing not the richer AFR that causes the knock to go away.

So how do we stop detonation? There are 3 ways in my book- either higher octane gas, lower boost, or less timing.

Fuel

I have found that leaner fuel definitely makes more power. My car seems to make its best power at around a 12.0-12.5 on race or pump gas. If I run any richer than 11.0 AFR I start to lose lots of power.

Boost

I have found that boost and timing are the most dangerous. Too much boost and we have lots of detonation which breaks things like I said before. I have found that more boost is better to a point.

So how do we put all of this together to tune the car? How I would start is to have the boost low which is 15psi in DSM land under, or 5psi in Honda land. I would set the timing to total out at around 10deg on any turbo motor. If you are a high compression turbo motor maybe 8deg.

For gas I would have 92 octane or higher. When tuning I would get an idea of how the car is being driven. When I tune most cars I assume they are not going to be floored for more than 20sec at a time. If I know I am going to be doing 5th gear pulls I will tune a little different. I would get the AFR set around 11.0-11.8 or about .85- .90 on a stock O2 gauge. Remember, as 02 sensors get old they will read lower. This will make you tune richer than needed which is bad for power.

Now here is the tricky part- choosing a boost and timing setting. Now to really push the limit here you need to have a good way to read knock or be good at reading plugs.

On 1g DSM loggers they tell you knock. I have found that anything over 20cts will start to eat at head gaskets. On our cars the logger can read up into the 40s. I have had as much as 40counts that were real and could not hear the detonation by ear. If you can hear it you have some real problems. If your timing is low enough you can runs lots of boost, but you are making less power even though your boost gauge is high. I would find out what boost level your turbo works best at. I would then start turning your boost up and watching knock. If you get to the level you want and you still have no knock I would then start to add timing until you get some knock no more than 10cts.

If you really want to get the most power I would go to a dyno or track. If you go to the track you need to make sure you can launch and drive the same on each pass. I would start with the boost high and timing low then try dropping boost and adding timing until you run the best or make the most power. Remember knock is what breaks your motor.

Make sure whatever you are using to read knock you know it works. You don't want to be like the rest of the people and go though a few motors till you learn how to tune right.

Tuning A 1G

I feel the 1G turbo DSM is one of the easiest cars to tune. The data logger is your best friend. You can see exactly what happens with each adjustment you make. The data logger has taught me more about how fuel, timing, and boost affect a motor than any person or book could ever teach you.

Your tuning is going to vary depending on what stage you are in. Tuning a stock car or with small mods can be frustrating because of the stock side mount. What looks good in 3rd gear will go to crap in 4th because of the stock side-mount intercooler heating up. If you are tuning with a stock side mount I would tune for 03 counts of knock in 3rd and keep it under 15cts in 4th and never do huge 5th gear pulls.

Stock side mount cars I tune for around 15-16 PSI for 1/4 mi tune. If tuning for 5th gear pulls I would not go over 14psi and would tune for 0 knock in 4th gear.

Front mount cars with injectors and supporting mods I find that if you tune for more than 22psi your timing will be so low that you will not go much faster. I have been able to tune cars with a water alcohol set up to around 26psi and still have ok timing.