Pros
We liked the fact that MotorDyne's 5/16-inch plenum spacer kit comes as a complete all-in-one package which includes new nuts and bolts, as well as spacers to reinstall your factory strut bar. Hell, they even include Loctite for all you knit picky individuals. Also included within their kit is a trick bypass valve. This special bypass valve can be adjusted so that hot coolant does not pass through the throttle body, which helps minimize power-robbing heat as air enters the throttle body. Combining the plenum spacer, iso thermal intake gasket and bypass valve allows both the upper and lower intake manifold to run at a cooler temperature while increasing airflow efficiency to the intake runners. MotorDyne states their 5/16-inch plenum spacer works best when used in conjunction with their MREV2 lower collector. As shown on our dyno tests, these guys know what they're talking about.
Cons
There's not much to complain about when it comes to the iso thermal plenum spacer. The only issue we might see isn't related to MotorDyne, it's the owners of the vehicle attempting to install the products themselves and breaking parts in the process. While the installation is a relatively simple process, you can always count on ghetto fabulous mechanics to break a few bolts here or there.
Parts
5/16 spacer, 30mm flange bolts, throttle bolts/washers, plenum washers, strut bar spacers/washers, 70mm hex cap screws, 35mm hex cap screws, 55mm hex cap screws, iso thermal plenum internal spacers, iso thermal aramid manifold gasket, iso thermal coolant control valve Loctite
Tools
4-, 8-,10 and 17mm socket, ratchet, extension, adjustable crescent wrench, screwdriver, needle nose pliers, allen wrenches, torque wrench, scissors, Teflon pipe thread
Installation time 60 minutes
Notes
Immediately after we installed the plenum spacer, we began our dyno pull and encountered some pleasant numbers. Torque numbers over our previous MREV2 dyno pass showed a gain of 11 lb-ft of torque at 2500rpm while an average of 4 to 5 lb-ft of torque was increased throughout the entire power band.
The gains continued to remain at a consistent rate in horsepower numbers at again 2500rpm showed a pickup of 5hp while the plenum spacer helped improve the higher rpm powerband and deliver a gain of 4.6 peak horsepower over our previous run. This new iso thermal system combines MotorDyne's aluminum plenum spacer with thermal management components that substantially reduce upper and lower plenum temperatures. Cooler intake air temperatures increase air density, while reducing the tendency for detonation (ping) can create more engine power.
Dyno 3: MotorDyne 5/16-inch
Iso Thermal Plenum Spacer
PEAKHP 237.4 / PEAKTQ 230.7
Horsepower Gain
1500 to 3500 HP range: 5 to 2
3500 to 5500 HP range: 3 to 5
5500 to redline HP range: 8 to -5
Torque Gain
1500 to 3500 TQ range: 2 to 11
3500 to 5500 TQ range: 5 to 5
5500 to redline TQ range: 4 to -3