993 - GT2 Turbos on standard 993TT ECU
Discussion
Quick question - could a 993TT standard ECU control a 993TT that had had 993GT2 spec turbos fitted, along with additional oil cooler, reduced BP exhaust? Or...would the changes dictate an essential ECU remap? I ask as there's a car I'm interested in with setup...I'm guessing the turbos would introduce previously unseen flow/rpm values? So would the OEM map handle this - less to get maximum power from the new turbos - more to offer correct A/F ratios and timing control? In other words, is there that much tolerance in the OEM map? Keen to hear opinions?
The 408 bhp ECU running the K24s- I thought about what would happen alot.
The higher airflow from the K24s at higher rpm/high load would require LESS ignition and possibly more "protection fueling" for the turbines.
On continued high speed high load use on, say an autobahn, you could damage the turbos and possibly the cats also. The over advanced ignition for the airflow could possibly lead to knock- although the 993 engine DOES have knock sensors (mounted on those bank "bridges"
- it would depend on the ability, resolution and strategy at high rpm at how they would cope. If the engine retards igniton by more than 12 degrees and it still knocks (highly unlikely) then it limits boost by the wastegate controllers. Of course, higher octane fueling could be used- but how high?
The pressure actuators for the waste gate control would be wrong. This solenoid is controled by the ECU and set to limit boost. This is the crunch- the ECU would sense the pressure in the inlet manifold and compensate with the pressure-pot controllers. Thinking about the old ECU may just keep the boost levels the same as with the K16s. So may be none of the first paragraph would happen. This is conjecture- but judging by what Alan said- the first paragraph may actually take place.
The biggest problem then is that- at low speed with the wastegate shut the K24s would produce alot less boost and there wouldn't be enough ignition advance to compensate. The car would feel REALLY flat- much more than need be.
At part load with little or no boost both set up would be much the same. SO fuel economy would be uneffected.
The higher airflow from the K24s at higher rpm/high load would require LESS ignition and possibly more "protection fueling" for the turbines.
On continued high speed high load use on, say an autobahn, you could damage the turbos and possibly the cats also. The over advanced ignition for the airflow could possibly lead to knock- although the 993 engine DOES have knock sensors (mounted on those bank "bridges"
- it would depend on the ability, resolution and strategy at high rpm at how they would cope. If the engine retards igniton by more than 12 degrees and it still knocks (highly unlikely) then it limits boost by the wastegate controllers. Of course, higher octane fueling could be used- but how high?The pressure actuators for the waste gate control would be wrong. This solenoid is controled by the ECU and set to limit boost. This is the crunch- the ECU would sense the pressure in the inlet manifold and compensate with the pressure-pot controllers. Thinking about the old ECU may just keep the boost levels the same as with the K16s. So may be none of the first paragraph would happen. This is conjecture- but judging by what Alan said- the first paragraph may actually take place.
The biggest problem then is that- at low speed with the wastegate shut the K24s would produce alot less boost and there wouldn't be enough ignition advance to compensate. The car would feel REALLY flat- much more than need be.
At part load with little or no boost both set up would be much the same. SO fuel economy would be uneffected.
The ECU will protect the engine....
You will have all sorts of things going on as described above but the ECU simply cuts the spark when critical lean/hot/knock situations beat the ignition/boost control functions ability to manage effectively.
The preferred method to breaking one of these engines is to disconnect the ECU's boost control function and stick on a boost controller, this allows the owner to dial in "unsuitable" boost levels which may work well on a chassis dyno -on the road the ECU will retard the ignition to protect and then cut the spark but prolonged running like this can lead to melted heads and the like.
Companies like FVD/Cargraphic can supply suitable ECUs if you tell them your modifications.
You will have all sorts of things going on as described above but the ECU simply cuts the spark when critical lean/hot/knock situations beat the ignition/boost control functions ability to manage effectively.
The preferred method to breaking one of these engines is to disconnect the ECU's boost control function and stick on a boost controller, this allows the owner to dial in "unsuitable" boost levels which may work well on a chassis dyno -on the road the ECU will retard the ignition to protect and then cut the spark but prolonged running like this can lead to melted heads and the like.
Companies like FVD/Cargraphic can supply suitable ECUs if you tell them your modifications.
Gassing Station | Porsche General | Top of Page | What's New | My Stuff