Variable Inlet Manifold Mod, and Speed Cruise mod

[Chris Skinner]

During the wonderful time we had at 3Provisies over the weekend I learnt much from the fellow Patrolers.
One was that there was a simple mod one can do so that the speed cruise would continue to operate when shifting over from Auto to Manual tiptronic. With this mod you can then also select SpeedCruise dircetly while in Tiptronic. - I have implemented this mod now (it takes about 5 minutes max), and the result is as advertised and I am really happy.
The second Mod (for the 4.8) was to cable tie the butterfly on the variable inlet manifold adjuster to the full open position by isloating it from the vacuum lever. I read about this mod on the aussie forum - many pages where they rave about the benefits of this mod (see link where both mods are discussed http://www.patrol4x4.com/forum/diy-modi ... mod-44263/). The mod is also very simple and easily reversible.
I have briefly tested to see if there is the advertised performance enhancement since incorporating the mod, and I must say that I do notice a small improvement in low rev regime ie uphill start while reversing and quicker/snappier pull away. This could be due to additional torque now available at low revs, when under normal circumstances the variable intake butterfly would have been closed. I have yet to test to seeif there is any difference when towing - especially the pull away or reverse with heavy boat.
What would be really good though is to somehow quantify this percieved change - "Om te meet is om te weet!" is what they taught us at uni.

So a couple of questions to the forum - has anyone else implemented this mod, and if so, what benefits did you notice? Maybe someone has a contact with someone who has easy acess to a dyno where this can be verified/tested?

[Peter Connan]

Chris if I understand this mod correctly, it only alters the normal operation of the Patrol at part-throttle, not at full throttle. If this is the case, the dyno would not help, as dyno testing is always done at full throttle, otherwise you do not know where you are in terms of throttle opening? I could be wrong here though.

[Gerrit Loubser]

The variable inlet manifold mod does not make sense to me. The purpose of the system is to better optimize the intake plumbing tuning to both the low speed and high speed regimes. The result of disabling the system would be to compromise engine torque at lower engine speeds.

At low engine speeds, it is beneficial for intake air to flow along a path of greater length, thus generating more "momentum" in the air column and contributing to better volumetric efficiency. At high engine speeds and wide open throttle settings, the air flow speed is already high and a shorter path with less resistance is preferable.

The bottom line is that Nissan would definitely not have gone to the expense of fitting the gadget if it were better to bypass it .

[Wheels]

I have tried it and reverted back to the factory setup.

[Chris Skinner]

Ja, I will probably change back to standard mode on the intake mod. I will first do a couple of test runs with the mod selected amd then repeat in the standard mode to try get some kind of comparative data - first have to think of what tests to do...