Aftermarket Plenum

[Jizzo]

What type of power gains would I be looking at with an aftermarket plenum?

What's the difference between Plazmaman, Process West and the Atomic plenum?

[Panda Eyes]

plenty of power gains- if you have the supporting mods to warrant one.

the factory plenum will go to mid 300's at least. so if your plenum is the weakest link and holding you back from making more power then get one. if not then dont bother...

[Jizzo]

Current mods are

Process West 2.2 kit

Xforce 4" dump into dual 2.5s

Wastegate ported and flapper mod

Bosch 968 injectors

Walbro fuel pump.

[arronm]

It's not so much about maximum power gains as much as mid range power and torque

[discostig]

I've got the 968's as well and I don't think you'd see heaps of gain from a plenum at our power levels. Not worth the $1000 anyway. If you could get one for $500 and pay for retune, maybe it'd be worth it..?

[Ralph Wiggum]

It's not so much about maximum power gains as much as mid range power and torque

^this guy

I've got the 968's as well and I don't think you'd see heaps of gain from a plenum at our power levels. Not worth the $1000 anyway. If you could get one for $500 and pay for retune, maybe it'd be worth it..?

Depends on how you class gains? Peak Hp? probably not.A more robust torque curve and better part throttle power/response?

I'd say so

[discostig]

Would it be worth a grand though at low 300s? I guess it's still 50% more than factory was designed for so taking that in to consideration, maybe it would be!

Also you get to have the same peak power but on lower boost, is that right?

Edited 09/11/15 05:27 AM by -Stever-

[Jizzo]

My plan was to have the car re tuned at around 10psi after getting a plenum.

I would rather have usable power and a smooth torque curve.

I'm just unsure of the differences between the models.

Would a Plazmaman (oooh shiny) line up with my existing pipework to the intercooler?

Edited 09/11/15 06:53 AM by Jizzo

[Jizzo]

Would it be worth a grand though at low 300s?

Try $1500 being in NZ.

Edited 09/11/15 06:56 AM by Jizzo

[HI PSI]

I will answer the second part of your query.

To date, I do not think ) that anyone has done any real back to back testing of all of these plenums. So, Which is better/best is still a mystery. In relation to the difference between them, the majority have a common factor. This being, that they use the standard bottom half of the factory runner and replace the top half. This significantly reduces the length of the piping, and in some cases some sharp turns. The Plazmaman, Nizpro and Process West units all use the standard runners. These units, while providing gains, also have their limits and have an obvious restriction - The standard runners..... Look at the pictures below and you will see the shape and size of the runners. Also note that the air is also turning 90 degrees from the entry point of the, now forward facing throttle body and will create turbulence.





While on the subject of turbulence, also note that the Process West unit, is the only one of the three, that has a supplied baseplate. In the picture below, you can see the shaping of the raised port runners. these raised runner entries significantly reduce the aforementioned problem, as it draws the air from around the edge and turns it. Despite being an improvement over it's competitors, the turns for the ports entries should be wider....



Moving on... The Atomic plenum is just a standard FG log plenum that has been modified to suit a BA/BF, As the throttle body on the fg is different to the earlier model, the threads in the flange have to be filled and redrilled (And tapped) to suit the orientation of the earlier model throttle body.



I believe that Atomic, can or does maybe extrude hone these manifolds, to help increase runner volumes. The FG manifolds, are probably the best value (bang for buck) of these types of plenums and have produced good power. While maintaining good even distribution of air to each cylinder. As earlier, and to the best of my knowledge, the gains from the extrude honing have not be ascertained.
Lastly, we have two plenums that have been specifically designed with performance in mind. The Plazmaman Race Series and Hypertune plenums are for the those that are chasing every last possible gain. Pictured below, are the Hypertune on the left, and Plazmaman unit on the right. These units both have large, straight billet runners with well shaped venturi on the inside of the plenum. Again, no back to back testing that I know of...

Edited 09/11/15 10:12 AM by HI PSI