One week with the N75J valve on the MTM Stage 3. Impressions....
10-19-2004, 03:42 PM
#1
AudiWorld Super User
Thread Starter
One week with the N75J valve on the MTM Stage 3. Impressions....
While living in Florida I decided to run the N75K valve with the MTM Stage 3. After seeing Jet's dynos of a 40+ wtq gain in performance (It generated an awesome 278 at the wheels on a quattro) when running the valve, I had decided to give it a try. Since my car was putting down 260lb/ft of torque at the wheels, the idea of having a 300lb/ft of quattro wheel torque was desirable.
I got lucky with mine likely because I was losing 1 psi of boost running the stock TIP and also because Florida is a very flat state. I never went into limp mode and Jet went into limp mode due to overboost multiple times. So everything was perfect in the land of BHVRDR and MTM Stage 3 land until I moved to Kentucky.
For those of you who have never been, Kentucky is not a flat state at all. While driving over a very specific incline and only when under full torque load (stable at 3000rpm then stomp it) I went into limp mode. This was easily remedied by restarting the car, but I knew i'd have to try something different.
Enter the N75J. This represents a valve that uses a faster reacting selenoid than the stock N75, but a bit slower than the N75K.
The results:
Cautionary Statement: Please keep in mind that when I am discussing peak boost numbers, this represents driving the car in third or fourth gear steady at 2500rpms and holding it there. From that point you put the gas to the floor generating the greatest amount of torque load possible for this motor. You will not see boost spikes like this simply flooring it through the gears from 1st on up. I was testing this under the highest torque load conditions so that I could be absolutely certain there would be no overboost.
The N75K would peak under full load at 28-29psi and hold it for a brief 200rpms at approximately 3000rpms. It would then taper to 23psi until approximately 4200rpm where it would slowly drop to 14psi by the 6800rpm redline. Overboost only occurs during specific inclines under full torque load.
The N75J would peak under full load at 26-27psi and hold it for a brief 200rpms at approximately 3000rpms. It would then taper to 22psi until approximately 4200rpm where it would slowly drop to 14psi by the 6800rpm redline. Overboost was never an issue.
The stock N75 would peak under full load at 23psi and hold it for a brief 200rpms at approximately 3000rpms. It would then taper to 21psi until approximately 4200rpm where it would slowly drop to 14psi by the 6800rpm redline. Overboost was never an issue.
Interpretation:
I will be keeping the N75J in the car for daily driving. The added boost peak makes the car a delight to drive in traffic as the boost comes up quick and hard making pulling away and passing very easy. Absolutely no driveabilty issues occured. The N75K is the torque monster but not reliable for everyday driving over inclines or hilly locations. This will be swapped (10 minutes) in for track duty.
cheers! Mike
<img src="http://pictureposter.audiworld.com/57072/n75-stock.jpg">
I got lucky with mine likely because I was losing 1 psi of boost running the stock TIP and also because Florida is a very flat state. I never went into limp mode and Jet went into limp mode due to overboost multiple times. So everything was perfect in the land of BHVRDR and MTM Stage 3 land until I moved to Kentucky.
For those of you who have never been, Kentucky is not a flat state at all. While driving over a very specific incline and only when under full torque load (stable at 3000rpm then stomp it) I went into limp mode. This was easily remedied by restarting the car, but I knew i'd have to try something different.
Enter the N75J. This represents a valve that uses a faster reacting selenoid than the stock N75, but a bit slower than the N75K.
The results:
Cautionary Statement: Please keep in mind that when I am discussing peak boost numbers, this represents driving the car in third or fourth gear steady at 2500rpms and holding it there. From that point you put the gas to the floor generating the greatest amount of torque load possible for this motor. You will not see boost spikes like this simply flooring it through the gears from 1st on up. I was testing this under the highest torque load conditions so that I could be absolutely certain there would be no overboost.
The N75K would peak under full load at 28-29psi and hold it for a brief 200rpms at approximately 3000rpms. It would then taper to 23psi until approximately 4200rpm where it would slowly drop to 14psi by the 6800rpm redline. Overboost only occurs during specific inclines under full torque load.
The N75J would peak under full load at 26-27psi and hold it for a brief 200rpms at approximately 3000rpms. It would then taper to 22psi until approximately 4200rpm where it would slowly drop to 14psi by the 6800rpm redline. Overboost was never an issue.
The stock N75 would peak under full load at 23psi and hold it for a brief 200rpms at approximately 3000rpms. It would then taper to 21psi until approximately 4200rpm where it would slowly drop to 14psi by the 6800rpm redline. Overboost was never an issue.
Interpretation:
I will be keeping the N75J in the car for daily driving. The added boost peak makes the car a delight to drive in traffic as the boost comes up quick and hard making pulling away and passing very easy. Absolutely no driveabilty issues occured. The N75K is the torque monster but not reliable for everyday driving over inclines or hilly locations. This will be swapped (10 minutes) in for track duty.
cheers! Mike
<img src="http://pictureposter.audiworld.com/57072/n75-stock.jpg">
10-19-2004, 04:21 PM
#5
AudiWorld Super User
nO SHIIIITE. My best friend works for Budd, lives in Louisville.
real american car motorhead. has a 350 Chevelle garaged. called my whip an "Awdi". I almost killed him.
10-19-2004, 04:23 PM
#6
AudiWorld Super User
Thread Starter
Easy as a hippie chic at a dylan concert...
Use mechanix gloves or wait to for the car to fully cool and you can access it from up top by just taking out the intake tube. Three screw clamps and your out. 10 minutes. cheers! Mike
