[Cliff R]

[QUOTE=Cliff R;6343810]Here are a few things I've found testing intakes. ALL single plane intakes require at least a 1" spacer or you leave considerable power on the table.

The T-I is a complete "turd" and we saw a 59hp improvement back to back dyno testing one w/o a spacer vs my "modified" factory iron intake.

The T-II in contrast is excellent, and with a 1" spacer it makes the most power for bragging rights on dyno runs almost every time. Downside is that it doesn't have a spread bore pattern.

The Tomohawk is also a nice part, spacer required.

I like the RPM and have made good numbers with it but the added 1" height makes it difficult to use with many Shaker and factory Ram Air set-ups without special parts and considerable "cobbling".

The Performer is a "turd" on a 455 build at or past the 430-450hp mark, too restrictive.

The factory iron is a very good part and a good fit for most applications. It is heavy, but to 500hp not much out there that will outrun it.

At the track back to back testing the intakes mentioned above the Tomohawk with a 1" spacer topped with my 4781-2 850DP carb ran the highest MPH for all testing, and that was on two different 455's in different vehicles.

My "modified" factory cast iron intake at the same outing produced the best ET even though it gave up nearly 2mph to the Tomohawk with a 1" spacer.

455's also like big CFM carburetors. A 450hp 455 needs at least 750cfm and will pick up on the dyno or at the track going to 800-850cfm even though the "math" doesn't show it needing that much carburetor.

In almost all cases a single plane intake with at least a 1" spacer will win bragging rights on a dyno test.

For example, a well built 455 with 10.4 to 1 compression, Edelbrock round port heads, RAIV cam and a Torker II with an 850cfm carburetor produced 505hp. Installing an Edelbrock RPM with no other changes netted 487hp on the very next pull.

On the street doing any sort of "seat of the pants" assessments the single plane intakes win every single time. They produce STRONG power in the upper mid-range and really start showing their colors from about 4500rpm's to the shift point. The blast of power feels much like a small shot of NOS so noticable transition. The power produced by a dual plane intake is more "locomotive" like and smooth/strong/flat with little if any felt transition. The "butt meter" very quickly favors the single plane intake even though at the track with traction they often give up enough 60' and short times that the car will ET quicker than it will with the single plane intake..........Cliff