When Bigger ISN'T Better: Plenums AKA Inlet Manifolds

 The bigger your throttle body and inlet manifold is, the more air your engine can flow, the faster you go right? Yeah nah.

A guide to throttle body sizing, getting even air distribution within 1%, major design considerations, intake volume vs capacity and if an intake/plenum chamber alone is all you need to make more are all topics Shannon Rogers from Plazmaman runs us through during our visit to The World Time Attack Challenge.

Where he and the Plazmaman team see the limitations of factory setups is also discussed along with how some head designs and packaging issues just don't allow better solutions as well as a the golden rule Shannon tries to get customers to follow which is to focus on the best combination for the application, not just a combination of the biggest parts you can find.

With this in mind an aspect that is so often overlooked when focusing on the shiny things under the engine bay is also discussed with engine builders and tuners alike forgetting to address the pedal ratio when drastically changing the inlet setup.

If you only take one thing away from this interview it should be that going for the biggest intake manifold chasing the biggest power number you can on the dyno is going to get you a nice piece of paper (noting there's always a bigger fish!) and a probably horrible car to actually drive.

Want to learn how to EFI tune? Start with some free lessons right here.

------------------------------------
TIME STAMPS:
0:00 - Common Upgrade
0:23 - Shannon Rogers - Plazmaman
0:58 - Main Design Considerations
1:37 - Reasons To Upgrade
2:04 - Aesthetics
2:21 - The Only Mod You Need For More Power?
4:04 - Design & Validation
4:50 - Overall Power Isn't Better
5:24 - Inlet Runner Length
6:31 - Volume Vs Capacity
7:09 - Throttle Body Sizing
9:09 - 800hp - 1000hp - 1500hp & 2200hp Sizing Examples
10:22 - Pro Tip: Measure Pressure Drop BEFORE Changing
11:08 - Fuel System Restrictions
11:49 - Fuel Distribution Concerns: Dual/Staged Injection Setup
13:33 - Flow Distribution: Within 1% Where Possible
14:40 - FG Manifold Example
15:01 - Don't Assume, Get Some Data
15:20 - Plazmaman, They're Everywhere
15:38 - Learn More. Do It. Now. The Old You Would Have.