AEM boost comp?

[PSI NRG]

When I got my car back from getting tuned the guy who tuned my car said there's a feature on the AEM EMS called boost comp. This feature allows you to just turn up the boost on the manuel boost controler and the ecu compinsates the fuel curve and timing. Also if I want to run race gas I just have to pour it in and run more boost and not have to touch anything else. Does this make sence? Anyone have any first hand experience with this feature? I'm nervus to turn up the boost on race gas until I know for sure this thats all that needs to be done.

 

[GVR4592]

Basically the tuner sets up the fuel tuning, so it's based on volumetric efficiency. There's a table called "Boost Fuel Correct". When using boost comp it's setup to add or remove 100% of fuel for every 100kpa, with 100 kpa being a 0 point. The idea is that for every 100 kpa, the engine will require 100% more fuel.

So at 0 KPA the table would remove 100% of fuel, at 100 KPA it wouldn't affect fueling, at 200 KPA it would add 100% fuel, at 300 KPA it would add 200% fuel, etc, etc.

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Then fuel tuning the boost portion of the map is taken car of by using the main fuel map.

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Fuel tuning of cruising and idle is taken care of by a table called "Throttle Inj Correct". This table corrects the amount of fuel in the main fuel table based on throttle position. Without modifying this table the A/F ratio would be extremely rich during these conditions.

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If it was setup properly in your map it will maintain the same A/F ratio, at a given rpm, for any boost level. Unless the fuel pump or injectors can't handle it. Boost comp has absolutely no effect on ignition timing. You wouldn't want to turn up the boost and race without more tuning of the ignition timing, if your tuner didn't tune those boost levels. Race fuel usually requires a leaner A/F ratio to make optimum power, you may need to lean out the fuel map to achieve maximum power.

 

[PSI NRG]

So basically I can turn the boost up a few psi and be ok but any large adjustments it would require some tuning and of course race gas would need a whole other tune

 

[GVR4592]

Yes you can.

 

[PSI NRG]

Thanks for clearing that up for me. It makes sence now. Just so I understand this concept competely, You can adjust the boost at any level that has been tuned ( Ex. If the car was tuned up to 20 psi you an change the level up to but not more then 1 or 2 more psi maybe 3 but you can lower it at any level and it will be fine). If this is how it works I'll probably have to get another tuning session in to run high boost and race gas.

 

[GVR4592]

In theory you could turn the boost up as much as you wanted and the boost comp tuning method would maintain the same A/F ratio. As long as the fuel system is up to supplying the amount of fuel required and the engine didn't experience detonation it would be ok. The ignition timing is the part I would be worried about. If it wasn't tuned for high boost then it's probably not safe, but an increase of 2-3 psi probably wouldn't hurt anything. Tuning for race gas and higher boost should be very easy, and only take an hour or two. Once the rest of the map is setup it's just a matter of playing with the A/F unitl it's right.

Just make sure you datalog, so you can see what's going on.

 

[PSI NRG]

Great! Thanks for all the help!