So after rechecking the bolts I'm happy to say that they didn't need any re-torquing. I'll probably check it out again in a week after I put more miles on it.

 

Hi Mike (And All),

The bolts aren't coming lose.

It is the axial tension on the bolts that relaxes after the first few thermal cycles. The bolts are not moving.
As long as the plenum gaskets are well set, do not continue tightening them.

The plenum spacer gaskets are thick and compliant. This is to ensure good sealing. It costs a little more to manufacture but the Motordyne select gasket material will also accommodate even slightly rough or irregular sealing surfaces.

After a few thermal cycles the gasket conforms to the sealing surfaces to make a pneumatic seal. This is what relaxes the axial tension but the bolts aren't moving. Unless you notice a idle problem, leave them be.

After approximately 300 miles of driving, the bolt axial tension goes down and the gasket seal improves.

Tony

 

thanks for the explaination, but what is axial tension?

 

Axial tension is the stretching or pulling force as applied to the length of the bolt.

 

so once the spacer is set, wouldnt it be a good idea to snug those bolts up again, after the spacer gasket has conformed to the sealing surface?

 

No. That would just be applying unnecessary force and there is nothing to gain from it.

Don't fix what isn't broken.

 

So are you saying that EVERYONE will in fact ALWAYS notice what appears to be loose bolts during the first few thermal cycles? Because some people have never heard of it and others have, but have never experienced it because I guess they checked the bolts after everything has settled?

Also, I had been tightening the bolts back to the torque specification because it thought the bolts were coming loose. After two attempts at resetting them, I decided to over torqued them a little to try and keep them in place. I checked them last night and they haven't moved after putting about 220 miles on the car. I don't notice any idle problems so should I just leave them as they are, slightly over torqued? Or should I just set the torque back to the original specs?

 

Not necessarily. I say this because they aren't always installed exactly the same way by everybody who installs it. ...and there are over 10,000 of them installed on VQ engines all over the world.

As evidenced by the number of units in service, statistically, the success rate of the Motordyne plenum spacers is extremely high.

They are purposefully designed for high reliability, but with over 10,000 installations there are bound to be some exceptions or variations in how they are installed.

As long as your idle is good, this is what you want. Idle is by far the best indicator of a good plenum seal. If your idle is good, the seal is good.

Even as tension relaxes after the first few thermal cycles, there is still a great deal of tension holding the upper plenum in place.

That plenum won't move until you intentionally take out the bolts to remove it.

 

i guess i dont understand how a bolt is loose, but yet its not....

 

Ahhhh Mikeyson,

Confucious say it is good to ponder the mysteries of life. Like women as well. Like the bolt thing, good luck with that!!

 

but this is expected of people who follow the motordyne install directions properly?

 

Yes. Just follow the detailed instructions and it will provide a problem free installation for the life of the car.

 

cool. does the spacer lean out the to engine since air is getting through better?

 

Not really. By itself, it can raise the A/F by ~0.25 point but its not significant.

Its not until you stack a bunch of breather mods that it starts to add up.
Intake, spacer, headers, test pipes, exhaust.

And then there is the car to car variation...

Some cars come from the factory lean (14.5). Some come from the factory very rich (11.0). And you won't know until you dyno it.