Blox Racing Spacer
 

So I was looking at Plenum Spacers for my 03 Sedan. I noticed that the Motordyne spacer is well over $200, while a spacer from Blox Racing is only about $100. Is there any real difference between the two? To be fair they are just plastic. If any of you guys have expirience with these, let me know. Very interested in buying one. Also, what size is best?

Thanks!

Motordyne is aluminum.

How big of deal is plastic vs aluminum?

Peace of mind knowing that your MD spacer won't crack and break into pieces sending chunks of plastic directly into the motor. Your choice..........

There's also an issue of thermal transfer and thermal expansion. Aluminum on aluminum on aluminum transfers heat very effectively and expands/contracts at the same rate so gaskets will last a very long time. When you are aluminum on plastic on aluminum the plastic acts as a thermal insulator and you end up with varying expansion rates as the motor heats up. You will likely need to re-torque the plenum spacer flange bolts occasionally, maybe twice a year at worst just to ensure the gasket isn't getting wierd.

Blox even tries to spin this as a performance improvement lol, this is quoted directly from their website.

Personally I would NEVER go with a plastic spacer.

u can get motordyne spacers on ebay for a little cheaper and usually free shipping

Motordyne kit also comes with a copper TB gasket and an aramid lower plenum gasket, which insulates the plenum from the runners/block. After the install there was a HUGE reduction in intake manifold temps while driving. Before the install I could barely rest my hand on the top of the plenum after a short drive, but with the gasket the top of the plenum is cool to the touch (until it heat soaks of course).

I have had a Skunk2 thermo-polymer composite spacer on mine for close to 10 years now and not a single issue with it. The plenum top is always cooler than the bottom and after the first heat/cooling cycle I have never had to touch the bolts on it again.