Plenum Volume? - Is bigger better?

[TURBOPOWERED68]

I currently have 1/2 inch spacer and was considering installing another 1" spacer above it.
The reason for the second spacer is, Thats where all of my vacuum ports will be.
So what do you guys think about a total 1.5 inch spacer between the intake and plenum?

 

[nonoss38]

If your shifting at 7,800 or greater maybe. I would say that's a bit over kill.

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[1952ray]

If your shifting at 7,800 or greater maybe. I would say that's a bit over kill.

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A total waste of money and time

 

[V6sleeper]

I run a 1" spacer just so my fm intercooler pipe lined up perfect with the throttle body, I didn't notice any difference in drivability ,but I wouldn't stack 2 spacers on top of each other..

 

[Nick Micale]

I.....................So what do you guys think about a total 1.5 inch spacer between the intake and plenum?

You actually have 2 questions with this post, your title asks "is bigger better?", and as with many things, it most likely is better, at least to some yet un-defined level.

Even with a total spacer dimension of 1-1/2" I do not see that as an issue in your build, nor do I see it as much, if any, help with your build.

I consider the plenum volume as an air "reservoir" which feeds each cylinder as the intake valve opens. The larger volume may lessen turbulence and give a more even air flow into the cylinders? As air flow increases with RPM, the larger volume would help air flow, but even with "spirited" street driving you it may be difficult to notice any difference?

Another possible benefit with the larger volume is the incoming air charge temp would be less, but again this would be a very small gain.

My personal opinion is I want the largest plenum volume I can achieve within the physical restraints, accessibility, and still be visually appealing.

But I do not want a bird house, or small dog house, on top of my engine!

 

[SHADOWII]

I prefer the larger volume myself and as stated not a big advantage unless you're moving a lot of air. The biggest reason not to go 1 1/2" is your dog-house to hood clearance. Especially if you have a hood pad, it reduces the clearance even more. I settled for the 1" champion spacer for my champ. intake, even tho I don't run a hood liner for weight reduction. You may have to cut part of the support bracing for clearance.

 

[Pronto]

Stacking will also add another place to have a vacuum leak.

 

[Chuck Leeper]

The guys in the "know", say the plenum volume should be 60% of the engine displacement.
You have 1 gallon of engine disp. What's the volume of an intake??

 

[V6RACER]

1.5" spacer with stock lower intake? seems a bit much, I'd stick with the 1" and be done.

 

[belsie]

I run a 1/2" spacer for clearance purposes only, w/ RJC plate above the spacer as recommended!! Vacuum is available from other sources w/o disturbing air flow so be careful in your choices, good luck............

 

[TTipe]

In my case the spacer allows the air more space to turn coming from the Hemco into the lower manifold.