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MotorDyne Engineering Plenum Spacer - 5/16" Iso Thermal Plenum Spacer
Part #: 516I
$335.00 For each
Free Shipping! *to continental U.S. only
Fits On:
2006 Infiniti G35 Coupe
Description:
The Motordyne plenum spacers alleviate an airflow restriction that exists above the first two intake runner inlets. The inside top of the stock plenum is very close to the top of the lower plenum runner inlets. There is only about 1/8 inch clearance between the first two inlets and the plenum cover. This creates a significant air flow restriction that reduces engine breathing and power output.
If the height of the flow area above the runner inlets were increased it by 1/8 inch it would reduce the flow restriction (pressure drop) by a factor of 4. If the height were increased once again by another 1/8 inch or to a total of 1/4 inch it would reduce the pressure drop by a factor of 9. If the plenum were lifted by a total of 3/8 inch it would reduce the pressure drop by a factor of 16. If it lifted by 1/2 inch it will reduce pressure drop by a factor of 25.
Reduction of pressure drop is asymptotic and inversely proportional to flow area. In other words this means the greatest benefit will be realized within the first 1/8 inch of added height. Fluid dynamic theory, dyno data and flow bench test data support this.
As an example, assume the pressure drop above the intake is equal to 3 PSID at high RPM. By raising the plenum even 1/8 inch the pressure drop will decrease to 0.75 PSID. That's a significant inlet pressure recovery that will translate into more horse power!
A 1/4 inch spacer will reduce that same pressure drop to 0.333 psid.
A 3/8 inch spacer will reduce that same pressure drop to 0.1875 psid.
A 1/2 inch spacer will reduce that same pressure drop to 0.120 psid.
Although pressure drop is continually decreasing, the rate of change rapidly diminishes beyond the first 1/4 inch. The same applies to gained HP. The pressure drop above the runner inlets is so dramatically reduced the added HP gains are also rapidly diminishing.
The attached plots are for three sets of tests 1/2 inch, 1/4 inch and baseline in that order with three pulls each. The results of the 3 pulls per set were then averaged together. These test conditions were very tightly controlled to provide accurate, repeatable results.
Whether the car is NA or FI, the reductions in pressure drop will always be proportional to the air mass flow rate. Thus for a given spacer size, FI applications will see even greater gains due to the higher air mass flow rates.
Weather for NA or FI, nearly any kind of plenum mod is a significant improvement from the stock configuration.
This stealth modification adds 11HP-15HP and reduces the effect of power robbing heat soak. The 5/16" plenum spacer is fully compatible with all stock and aftermarket strut bars.
The engine cover easily fits and never needs to be cut. With the engine cover and strut bar in place the engine bay looks completely stock.
The Motordyne plenum spacers alleviate an airflow restriction that exists above the first two intake runner inlets. The inside top of the stock plenum is very close to the top of the lower plenum runner inlets. There is only about 1/8 inch clearance between the first two inlets and the plenum cover. This creates a significant air flow restriction that reduces engine breathing and power output.
If the height of the flow area above the runner inlets were increased it by 1/8 inch it would reduce the flow restriction (pressure drop) by a factor of 4. If the height were increased once again by another 1/8 inch or to a total of 1/4 inch it would reduce the pressure drop by a factor of 9. If the plenum were lifted by a total of 3/8 inch it would reduce the pressure drop by a factor of 16. If it lifted by 1/2 inch it will reduce pressure drop by a factor of 25.
Reduction of pressure drop is asymptotic and inversely proportional to flow area. In other words this means the greatest benefit will be realized within the first 1/8 inch of added height. Fluid dynamic theory, dyno data and flow bench test data support this.
As an example, assume the pressure drop above the intake is equal to 3 PSID at high RPM. By raising the plenum even 1/8 inch the pressure drop will decrease to 0.75 PSID. That's a significant inlet pressure recovery that will translate into more horse power!
A 1/4 inch spacer will reduce that same pressure drop to 0.333 psid.
A 3/8 inch spacer will reduce that same pressure drop to 0.1875 psid.
A 1/2 inch spacer will reduce that same pressure drop to 0.120 psid.
Although pressure drop is continually decreasing, the rate of change rapidly diminishes beyond the first 1/4 inch. The same applies to gained HP. The pressure drop above the runner inlets is so dramatically reduced the added HP gains are also rapidly diminishing.
The attached plots are for three sets of tests 1/2 inch, 1/4 inch and baseline in that order with three pulls each. The results of the 3 pulls per set were then averaged together. These test conditions were very tightly controlled to provide accurate, repeatable results.
Whether the car is NA or FI, the reductions in pressure drop will always be proportional to the air mass flow rate. Thus for a given spacer size, FI applications will see even greater gains due to the higher air mass flow rates.
Weather for NA or FI, nearly any kind of plenum mod is a significant improvement from the stock configuration.
This stealth modification adds 11HP-15HP and reduces the effect of power robbing heat soak. The 5/16" plenum spacer is fully compatible with all stock and aftermarket strut bars.
The engine cover easily fits and never needs to be cut. With the engine cover and strut bar in place the engine bay looks completely stock.
Motordyne has worked wonders with Nissan and Infiniti engines, adding impressive numbers to their horsepower and torque figures with items such as its intake plenum spacers, Iso Thermal MREV 2 manifolds, and exhaust systems. For instance, adding just the company's basic plenum spacer will yield an 11-13-horsepower gain over the stock manifold for most applications with no other modifications! Don't you love it when simple mods that you can perform in your own driveway give such impressive results?
Q: What is a plenum spacer? Why buy one?
A: Plenum Spacers mount between the intake plenum and the motor and are designed to increase the velocity of the intake charge which improves efficiency. They also have the secondary effect of keeping the intake charge cooler which in turn helps to improve power. The nice thing about this modification lies in its simplicity. Intake plenum spacers are affordable, simple to install, and a stealth modification that cannot easily be seen. With modest horsepower and torque gains it may not transform your vehicle into a rocket ship, but it will certainly provide noticeable gains that will help on the street and track. In addition plenum spacers improve efficiency and can increase your miles per gallon as well. For such a simple design, plenum spacers provide many benefits with hardly any down side.
A: Plenum Spacers mount between the intake plenum and the motor and are designed to increase the velocity of the intake charge which improves efficiency. They also have the secondary effect of keeping the intake charge cooler which in turn helps to improve power. The nice thing about this modification lies in its simplicity. Intake plenum spacers are affordable, simple to install, and a stealth modification that cannot easily be seen. With modest horsepower and torque gains it may not transform your vehicle into a rocket ship, but it will certainly provide noticeable gains that will help on the street and track. In addition plenum spacers improve efficiency and can increase your miles per gallon as well. For such a simple design, plenum spacers provide many benefits with hardly any down side.
If you live in California, please note this item may be subject to a Proposition 65 warning. Click here to learn more.
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