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I'm sure someone has measured it by now (not sure anyone will post it), but I'm wondering what the intake/exhaust lift and duration are on the HR's (factory obviously, in case that was unclear).
If anyone knows (at least the intake duration maybe?) I'd really appreciate it.
Since 1989 Nissan has used 248 durations and ~~ 9.90 -10.5mm max lift in V8 and V6.
Unfortunately the actually precise shape of the duration curve is more important than the duration.
Since 1989 Nissan has used 248 durations and ~~ 9.90 -10.5mm max lift in V8 and V6.
Unfortunately the actually precise shape of the duration curve is more important than the duration.
I was just doing research on plenum design and for that duration seems to be the determining factor.
Unfortunately there are many simplified easy equations that can get you close but for that last 10% towards perfection you need some serious Calculus.
Knowing when the valves are fully closed is important for tuning the length of plenum runners, but has little importance in the actual calculation of grams of air [mass] flow while the valve was open.
Unfortunately there are many simplified easy equations that can get you close but for that last 10% towards perfection you need some serious Calculus.
Knowing when the valves are fully closed is important for tuning the length of plenum runners, but has little importance in the actual calculation of grams of air [mass] flow while the valve was open.
Just out of curiosity what do you do that you know so much technical info?
2 Master degrees [MSEE & MBA] plus 18 years of study in automotive engineering and 60 years of life helps.
Its funny because I had a professor that everyone hated (dynamics) and he hated teaching the class. His field of specialty was valvetrain design and he works with Crane Cams for developing better cam/rocker arm profiles for the LSx motors.
I went to his office one day and saw a rocker arm on his desk and instantly realized that he was one of the few professors here that had a passion for something similar to me. I am getting my degree in Civil Engineering so its a completely different field, but I had quite a few good discussions that taught me the basics of that stuff. I'm trying to learn by brail if you will....how the more complex aspects work.
If you know of any good books dealing with head flow "theory" and how the harmonics of the plenum and pre-plenum intake (and header and post header exhaust) affect the power output of a motor I'd love to read them - I just hate to spend hundreds of dollars on books that are either over my head or don't really teach something I can apply.
* Many Japanese oem contract with Cosworth to do their designs, so what Cosworth is doing is just tweaking their own work.
The problem with oem is that it must work at idle and cruise rpm for the average Joe.
Right, and OEM's have to minimize emissions with the exhaust systems while still trying to make power.
There are a lot of things left on the table as far as shifting the power band and I was more asking so I could look at the plenum stuff on my Tacoma (88 2.4L tacoma fwiw) because after seeing the HR intake I realized the complexity (square ports).
I switched plenums on my BMW (M52-M50 plenum) and lost bottom end gained top end, so I was curious how the Nissan plenum was designed in terms of power band, etc.
As to rpm tuning one need only measure [Accurately within 1/4"] the distance from the plenum box horn thru the runners to the midlift point of the intake valve.
Cam Lift/Duration
Fairlady Z33
