Hi,
The above message from Paolo is just a message from someone trying to stir touble.It happens that this message is directed against me.
I unfortunalety know Paolo, and at one point I even considered him close enough to start a company with him. The day I offered him to do that would have been better if I'd broke my leg and got a car crash.
From this unpleasant experience, I'm still short of a couple hundred dollars that he owe me, and a 300Zx TT engine with a blown hedgasket. That's life....
And I wouldn't trut him to change a spark plug, not even a bulb on one of my cars (based on a real, personal experience)
About the BOV.
I have been driving a 300ZX TT since 1994, and I now have three of them.
One of them is stock, one of them has 400hp, the last one has over 500hp, and I have another damaged one as "spare parts car"
During the last 10 years, I had a Supra Turbo (MKIII), 2 Subarus Legacy Turbo, One Mazda 323 GT, one Celica GT4. one Lexus, one Dodge Stealth.
I personnaly tuned all these cars, and I most of the maintenance myself. I drive more than 200miles per day, so I go through quite a few cars every year
Initially, I wanted to install BOV on my first 300ZXTT, and I started to have serious problems as soon as the BOVs were installed.
To solve the problem, I fitted my car with a portable PC, an AD/DA acquisition card (I'm an Engineer in computers), and I started to log almost every possible signal from the car, and I started to drive.
It turns out that I was mostly running too rich, but I was sometimes running abnormally lean. It was typically while doing an upshift, full boost
Just for the fun, I refitted the stock recirc valves, and all the problems were gone, put the BOVs back in there
Here's what happened.
When the BOV would open, air would escape, and the car would run too rich.(that was expected).
At the same time, if I lifted the accelerator, the car would re-enter close loop, detect an abnormal rich condition, and compensate for it. If at this point I would re-accelerate, then the ECU would go to open loop, but STILL compensating for the overrich condition, causing the engine to run lean for a couple seconds.
Because I doubted the results of both the O2 Sensors(I was reading less than 0.2 v while I was expecting to see more than 0.7), I started to monitor the injector signal, and indeed the amount of fuel delivered to each engine bank wouldn't be enough (based on the AFM / RPM / boost).
Then I wanted to see if the problem was based on the narrow band O2 sensors, so I fitted one wideband O2 sensor to my car.
The wide band sensor confirmed the above, while I was expecting to read between 1 to 1.5v, I was reading in excess of 3v (in case you don't know wide and narrow O2 do not deliver the same signal), I was terribly too lean.
I monitored my detonation sensor signal, and I was indeed experiencing moderate to heavy detonation, certainly NOT something I'd like to see in MY engine.
I was logging this condition 5 to 6 times a day (on my 200 miles journey), so it won't destroy the engine in a flash, but it would seriously reduce the life of the pistons/rings
I had a real close look at the Eprom Code stored in the ECU (M205AFM7 & 8, stock Nissan Tunes), and went through all the fuel tables, VQ tables, etc etc etc, but I could see NOTHING that would prevent this condition.
I had several discussion with Jim Wolf himself to discuss about the above.
Basically, JWT position is : The stock recircs are good for a 600/800 HP...no need to replace them, if you go above, it's not really a street car anymore, BOVs may not the the primary reliability factor in such a car.
As soon as I refitted the stock recirc, the too rich/too lean condition vanished.
Because I knew that my subaru ECU was made by the same mfg than the Nissan one (JECS), I hacked the stock recirc on my Legacy, and I started to datalog, and I could see the same behaviour...even if it seems that anti-detonation procedures on the Subaru are much more effective than in the Nissan (no NVCS here)
A couple years later, I had to help a friend on a 3000GT ... it was fitted with a BOV....I started to datalog (this time, I could use a Palm IIIc), and I could see the same behaviour. The nice part about the 3S ecu, it that it gives you the Knock Count, so it was easier to see detonation.
Of course, as soon as we replaced the stock recirc with another one (from a DSM), all the problems were gone.
I'm not saying it's the same on a Pulsar/Sunny engine, I never had the opportunity to drive and log one every day for a week, would be an interesting project, I just happen to know that a BOV can spell trouble on a SR20DET engine, and I had a serious look at the electronics of a Sunny GTI-R that delivers a little bit above 330hp at the wheels. The ECU is made by JECS, and I had a look at the electronics, nothing drastically different from the ECU of a 300ZXTT.
Based on that, you draw your own conclusions. If you want to enjoy a cool sound, just do it. If you happen to have to rebuild the engine, you'll know why
Now if you want to enjoy the car for a LONG time, you do what you think is best for it..after all, it's your car...
On MY cars, if there's no recirc, I may consider adding a BOV (but I'll probably try to add a recirc, as you can buy one dirt cheap on e-bay), and if the car is fitted with a recirc, I will NOT put a BOV on it at any cost, as recircs are easy to upgrade, and do what they're designed for.
