Good evening,

I have had my plenum on for just shy of a week and it is now cracked. I am not sure how or when it happened, but I noticed it today at lunch.

Needless to say, I was careful with the install after all the other "crack" reports. I do have a version 2, but the crack is at the center-front bolt that supports the plenum. I would just throw some epoxy on it, but I cannot do that. The crack is closed when the engine is off. However, when you start the engine, it opens up. So, epoxy won't hold in that situation. The the next startup, it would just open again. Thankfully, I do not have an air leak, or it is really small. For visual confirmation of this, please see the images below.

I have been waiting to post my review of this product because I also wanted to post a video. However, at this point I really don't think it matters. My plenum is now cracked. The water block did not fit right. The bolt just forward of the plenum neck will not take due to poor alignment. There is plastic "burrs" on the inside of the plenum neck. I think the plenum is rubbing my strut bar. To top it all off, the cats I ordered with my plenum also have their issues. Normally, I do not make big issues of small fitment problems, but this is too much. I think the forum needs to know some of the issues that have cropped up. I know of at least a few people having fitment and delivery issues. I myself had both.

So, what do you think I should do? I can't fix it myself because the crack opens and closes. I can't leave it on because I have a race this weekend. If I send it back to be replaced, how do I know this won't happen again?

Picture of cracked area with engine off:

 

Image of plenum with the engine running (now you see the crack):

 

Okay, now it gets worse. I just went down to my car to take a closer look.

I used a 4mm allen wrench to try and loosen the bolt to see what would happen. Well, the bolt was turning, but it was not loosening. For those that don't know, the bolt pictured above screws into a support that comes with the plenum. The bottom of the support screws into the lower plenum. The new upper plenum then goes on and the bolt pictured above then screws through the plenum and into the support. However, when I try to loosen the bolt, it turns but it is not un-threading. This means the support it is connected to is un-threading from the lower plenum. The net result is that the support is pushing up on the plenum as I unscrew it. The thread lock is holding on to tight.

If I really wanted to remove the bolt pictured above, I would have to destroy the plenum in the process. Becuase the support is coming up it would make a huge crack in the plenum. Lovely.

 

my take on plastic plenums:
nissan is cheap.. if they could have made the stock plenum plastic, they would have.... i mean the rest of the intake is all plastic (minus TB). even the radiator support is plastic!

i hope you get a full refund or replacement. good luck, dude!
m

 

Bummer dude..looked like a great product but I suppose thats the down side of plastic (type) unless its specifically treated or fabricated with high temps in mind.
It does look better than a crawford ...but im sure that doesnt matter to you at this point from the sound of it. Not to start a this manufacture or vendor is better than that one I just happen to have a crawford though.. very satisfied here.

I wouldnt worry about it ..they -->Kinetix are a very good vendor im sure you will get the replacment you so desire.

 

Skidazzle,

You are right. I had the g/f work the throttle for a moment while I watched the plenum. When you just blip the gas so that the rpms momentarily rise to 3000, the plenum flexs like craxy. Funny thing is, it goes from flat, to pushing up and then sucking down. Not sure why that is. It pushes up as soon as the throttle boddy opens and then sucks down once the pistons get up to speed.

350z4Steve,

I know kinetix is a good vendor and I know they will do the right thing. I too do not want to start a vendor vs. vendor discussion. Hopefully I can get this worked out soon. Needless to say, I will be back on the stock plenum for this weekend at Mid-Ohio

 

I had the same thing happen, same place. You can feel the loss of power when it cracks and you get an intake leak. Tadashi noticed mine at TS. I emailed Kinetix, they said the mold had slipped and they had some variances on a few Plenums where it was only 1/16" thick in that area. I also noticed the major flexing when you "blip" to throttle. I was very hesitant about putting another plastic Plenum on. But, they sent me a new one in about one day and a half. I put it on and all is well. The second install went very smooth. I love the mod. the sound, the power. As long as they stand behind it you're alright.

 

Normally, I would agree with you RCKTDAWG, but not in this case. They may stand behind, but what happens when I am on a track flying down the back straight at 6600rpm. If the plenum cracks, it could cause some other damage. Not something I am excited about.

 

I felt the same way, I was bummed! But, I put the replacement on and it's been fine. Also, they said that the major flexing was because it was thin in that area. So far mine has been fine, however I am keeping an eye on it. At this point I believe it will be OK.

 

Sounds like a problem for sure but let me make a few points.

take ALL the bolts off, like you are removing the plenum completely and then go to the problem bolt. As you unscrew it the inside piece will lift up (like you stated) and then will dislodge from the lower hole. Remove the whole plenum and then you can get at the inside support to remove that one. Looks like you added to much locktite!

another thing.. If the strut bar is rubbing you have it misaligned. IE - opened to much or closed to much. It happened to me so I made an adjustment and it went away.

finally - and I am not pointing fingers. The part that cracked is not one with the version two hole modifications. there is no metal inside that hole and possibly, just possibly, you overtightened that one a little to much and the crack showed up a couple of days later.

No need to worry. I am sure he will give you a replacement one or may even refund your money since it is so new. (if thats what you want)

I do believe letting everyone know the issues you are having are honest and acceptable but give LSD the opportunity to make things right before you call out the hounds! I for one KNOW he will make things right for you, so when he does, give him the respect he will deserve and let us all know how he made you happy.

good luck on whatever you decide.


btw - I am STILL running on my version one with NO PROBLEMS since the initial prototype.

 

so what you are saying is that at a high speed and a crack develops what is going to happen? I would imagine an air leak will develop and when you slow down you will notice it because the idle is all messed up....(or the car stalls)

OR your saying that the thing breaks into pieces and the engine sucks up a piece of the plenum which causes damage on the inside?

i just find that hard to believe, at ANY speed!

 

All_bark,

Thanks for replying. I certainly respect your opinion. I just want to point out a couple of your comments so that everyone knows I am being clear and not unfair.
Probably. However, that is because the two center bolts worked their way loose and I got a CEL at one point. So, I bought some more locktite (ran out of the stuff that came the the plenum) and re-torqued the bolts. Now, one is stuck. After posting my comment about not being able to get it out, I realized how I could do it and save the plenum. Essentially, I had the same idea you posted above.
This is true and I guess it is possible that I over-torqued this bolt. However, I used the supplied allen wrench and was careful. I don't think I over-tightened it, but then again I didn't use a torque wrench (mine wrench is a large foot-pound one).
I completely agree. I trust that LSD will make things right. I also don't plan to call out the hounds (I don't think I have any). My only point in this thread is to inform the community and hope LSD will respond with suggestions/answers. As for returning/exchanging/etc the plenum, I will handle that directly with LSD, as is proper.
What I meant is that a major leak at high RPM could cause detonation (more air in than the ECU is reading). I am not sure how bad the detonation would be, but I don't want to find out. I did not mean that the plenum pieces would be sucked into the engine. I too doubt that this could ever happen under any circumstances.

 

I have no plenum, so consider me impartial. but if a plenum does crack, its rather possible it could fracture of a peice depending how brittle the material is.

and that could potentially destroy an engine, at the right time on a track it could total a car, and possibly kill a person.

from a legal standpoint, there is a chance the family could sue the manufacturer for negligence if they knew the product had issues and failed to resolve them or recall them.

obviously, this is about 1:1000000000000that this could happen, but a friendly word of advice to lsdunique, resolve these issues or you could find yourself in a heap of trouble one day, even if its just a new engine, or a few million in wrongful death.

 

The plenum is not brittle actually. The thing flexes like crazy. However, because it is plastic, it is susceptable to point loads (i.e. over torqued bolts). As I mentioned above, I find it highly unlikely that the plenum would fracture under any circumstances. My main concern is a large crack causing "un-read" air getting in and causing detonation while on the track at high speed. I am certainly not concerned about my own death. Afterall, I already know when and where that is going to happen (Wrigley field on the day the Cubs win the series, in case you are wondering).

 

Wow, each day I try and decide about the whole Plenum thing and I still feel stumped....maybe a Y-pipe is next.

Good Luck Pep

 

I think All_Bark is pretty close on guestimate on most of your problems.. I have the same problem with the rear hex screw. Actually those two hex screws will work itself loose, for some reason. So I went out and bought a tube of the Loktite, and pretty much drowned the screw with it. I let it dry overnight, and next day, when I tried to unscrew it, it is actually pushing the plenum up, because I probably put too much loktite. The only way is to loose the flange bolts, and then loose the two hex screws.

The plenum does flex quite a bit when you push the accelerator pedal, but that's normal since it is plastic, and it's thinner around the middle.

The crack looks like it's from overtighten. I think if you had the tube of loktite in the first place, you can just put more and then hand tighten it down without too much force. It will stay since the loktite will secure it. But make sure let it have ample time to dry first.. I would leave it overnight if possible.

I am sure LSD will warranty the plenum, if you want to give it another try.. Thanks for sharing the info though..

Hope you will stay with it..

 

I wonder how much (if at all) the flex of the plenum affects performance? I'm not talking about in comparison to the crawford, but relative to its own maximum potential.

 

doubt it, but I wonder about long term reliability, continous heating and cooling, vibration, flexing for a years on end. cracking might just become more common as they get older.

 

i'm not sure i would have made a post like this without giving the guy a chance to make things right for what appears to be one of a very few defective plenums. i'm sure you just scared away alot of potentials...

 

No heat soak is nice. But, cracks suck. I'm tending to agree with what Skidazzle said about Nissan. Hope that this is a rare occurance or, I will say, if the plenum is a considered mod, Crawford looks good in this department.