A lot of tuners talking about there are more issues with the OEM plenum. The after market plenum/spacer solves the air flow problem.
Can anyone address the other issues?

 

https://my350z.com/forum/showthread....hreadid=107960

Some details in that thread. Well, not really details. People only said that there are more issues with OEM plenum than just air flow. Plenum like Crawford/Kenitix addressed the air flow and some other issues, and some still need to be worked on.
Anybody know what those other issues are? And what issues have plenum solve other than air flow?

 

nobody cares?

 

Isn't that what everyone else is wondering right now as well?

These supposed "other issues" may not be significant enough to be worth the trouble of fixing. Keep an eye on how these new spacers do in tests against the aftermarket plenums and you will have your answer.

 

the oem plenum works fine, aftermarket plenums don't do much. Everyone seems to really be hard up on trying to get more air into the motor by using a bigger plenum. This is all good, but the factory plenum works great. Where the power to be gained really lies is in the secondary manifold, or runners. There is so much excess material that can be ported, that that's where the power would be made.
Don't worry about your upper plenums, they're fine.

 

Maybe you consider 10rwhp "not much", but for a cheap bolt-on, I think thats pretty damn good (assuming all the dynos supporting the Crawford and spacers are legit)

 

Actually this is not true. We've now logged 64 hours between the flow bench, clay modeling and grinding time on this area of the car alone (so that when my setup is done, not one part is choking another). The single biggest issue is overall plenum volume from the front relative to the bacl. The second is air speed through the plenum, and this is where lots of time and knowledge are needed. There are quite a few totally dead spots in the plenum, and several areas where air actually slows down during it's path. This is exactly counter to what you want. The runners that feed the head are as good as its going to get without dumping the setup completely and going to ITB's. Even the "ledge" that is cast into the runners is an excellent design and helps to speed airflow going into the head.

So where are the other areas? When my setup is done, and before I put it on the car for final tuning, I'll post pictures of what we started with and what we ended up with. The upper plenum is the weak link in the area, and there is quite a bit to be gained. So far the setup that does the best job of addressing the shortfalls in a relatively simple, bolt on fashion, is the Crawford one. However, it does not address all the issues there are (I think they would not be able to sell them if it did, as the time required to make one of these completely "right" is alot. FWIW, I went with a spacer on my setup, because its what our research showed my setup wants. Your mileage may vary of course. Like I said, once I get my setup in my hands again (next phase is finalizing the cam selection), I done mind posting pics. With the airflow side maximized, I'll also see if there is a neat way to insulate things from the heat, though I honestly have not come up with anything worthwhile yet

 

It sounds special, can't wait for your posts.

 

How and to what extent is the Crawford plenum better than the Kinetix, if you've tested both.

 

Z1

Thank you for bringing some semblance of knowledge to this thread. There's so much mis-information and confusion out there, it makes for those of us with a very limited knowledge want to throw our hands in the air. I knew Tony's post was wrong, and that it would contribute to the confusion, but I was not sure how to respond to it, because of my limited knowledge.

I'm glad you have the funding and time to do what needs to be done in order to optimize the NA intake system.

I also want to thank you for legitimizing Crawford's plenum. So many folks here are taking pot shots at Crawford now. We all know Crawford does much testing and research on the products they issue to the public. That is not the case with so many pretenders.

I know we all think about the dollars, I certainly do. But, when I pays my money, I want something that works. Load up your car with the latest junk or fads, that may or may not help, just is not the answer.

Research (and part matching) is necessary to improve the performance of the VQ engine. I'm glad there are at least a couple of companies that do that.

Thanks Again for sharing.

Lou

 

The Crawford one addresses quite a number of the dead areas in the plenum, the Kinetix one did not. However there are areas that neither one addresses; once I post the pics of what we did to mine (and yes it will look stock from the outside!), you'll be able to see the differences. At this point I probably should have/could have made a whole new intake plenum setup for the time invested by our engine builder into this area, but my goal was to have something as stock appearing as possible when it was all said and done

Both the Crawford and Kinetix, as I have said before, address the most serious of the issues, which is the volume front to back, thoguh they do go about it in different ways

 

We have had many cars come in with various plenums on (My car included) and almost everyone has ended up removing them.
The dyno gains "claimed" usually are not the case. In some isntances they do make power like mentined above, and in those cases, good for the plenum hehe. But on an overall assemsent, plenums don't do much. If anything they usually shift the power around, without really gaining any HP. Now don't forget, you can gain HP on a dyno, but it's where that power is made, and how it's distributed that really matters, and most of these plenums don't do a decent job of either. Some do, granted, and better ones are coming out all the time, which is a nice thing. But up till now, the MAJORITY do not really work, especially for the money.
Not bashing any company or anything, but just an honest assesment.

Another thing to consider: no top tuning company has a plenum. Also, no top tuning company bothers with even using one. This is true for almost all track Zs, including our own in SCCA, cup racing, and in japan. There are limits in certain classes that prevent such a modification, granted, but there are many that do not. And you still don't see them being used, or if so, not widely popular.
Just some thought.

I do hope that Newer plenums help, and make a difference, but I've yet to see first hand any plenum BY ITSELF make 10HP, with absolutely no other mods. If there is one, send it to me, i'll dyno it and test it

 

And this is just my opinion, don't flame, i'm not hating or starting anything. Just one man's honest thoughts, nothing more.

 

are you talking the porting and polishing of the stock plenum plus a spacer? can you give us some more details please...thanks

 

it's more than even porting and polishing. As I said, once mine is back in my hands, I'll post pictures

 

thanks z1....we are very interested in your results and appreciated your sharing of knowledge

 

Will you be selling your new set up?

 

yes please post. and i hope its not going to cost 500 bucks with a core exchange.

 

Very legit... and that's what we made at peak dude.

You seemed to miss the near 20 hp at redline... Which is ALSO backed by HUNDREDS of dyno pulls.

 

i've read that too much polishing is not good, that a certain amnt of resistance in the plenum helps the air roll along.