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I am new to this forum and I would like to say Hello to everybody. In the last 12 months we converted a Tiptronic to an NGT clone with manual 5 gear box. The engine has been rebuild with mainly following components: 3.8l p&c's , 288* cams, hot film with bigger throttle, sports exhaust. The problem is, that the car delivers only 300 Hp at 5500rpm passed 5500rpm power falls drastically so that at 6500rpm the engine has only 225Hp. Max torque is 495Nm at 5500rpm.
Any advice on what might be wrong would be highly appreciated.
Kind Regards,
Pol
You have two tubes in the normal throttle body. One on top of the other. When the solenoid trips the vacuum stored on a tank next to the air filter operates a flap that opens the bottom tube. This gives you the kick from 5.500 rpm.
Which injectors are you using? Standard injectors are capable of just -and only just-supporting 300 Hp. Also have you checked your fuel pump to be healthy enough to maintain the correct fuel pressure throughout the rev range?
Ok, so you definitely need bigger injectors to get the most out of this engine spec. 993 injectors flow up to about 340HP, but more modern injectors allow for a better spray pattern / more efficient combustion.
As John has stated also have a look at the operation of the resonance flap.....but with power dropping off as steeply after 5500rpm as in your dyno sheet I'd also have a good look at the knock control system pulling back timing to prevent knock.
Knock events can be monitored with a Bosch hammer diagnostic tool plugged into the Motronic Ecu. If knock is to be found, this is in effect a symptom of other causes like too little fuel, too high cilinder head temps / intake temps etc.
Ok, so you definitely need bigger injectors to get the most out of this engine spec. 993 injectors flow up to about 340HP, but more modern injectors allow for a better spray pattern / more efficient combustion.
As John has stated also have a look at the operation of the resonance flap.....but with power dropping off as steeply after 5500rpm as in your dyno sheet I'd also have a good look at the knock control system pulling back timing to prevent knock
Knock events can be monitored with a Bosch hammer diagnostic tool plugged into the Motronic Ecu. If knock is to be found, this is in effect a symptom of other causes like too little fuel, too high cilinder head temps / intake temps etc.
Good luck!
According to my mechanics the resonance flap is working. I forwarded your advice to my mechanics. Thank you very much
06-07-2016, 05:09 PM
Power delivery not as expected
