This is info I collected from a few different websites including this one.
Do the formulas look accurate and will the stock base really support
this kind of horse power?

Personally I don't know if this stuff is accurate or not.

Stock base, stock runners 199 cfm
Stock base, Accel runners 214 cfm
Accel base, stock runners 216 cfm
Accel base, Accel runners 233 cfm
Accel base, Accel Super Ram 240 cfm
Accel base, extruded Accel runners 243 cfm
Extruded Accel base & runners 267 cfm
Stock base, Accel Super Ram 221 cfm
Stock base, Extrude Accel 217 cfm
Stock base 223 cfm
Accel base 252 cfm
Extruded Accel base 276 cfm
Stock runner 203 cfm
Accel LTRunner 242 cfm
Super Ram runner 289 cfm
AS&M long tube runners 260 cfm

Stock intake base manifold data:
Cylinder head interface: 1.14" x 1.75" = 1.99 sq. in. = 245 cfm
mid passage dimension: 1.10" x 1.55" = 1.71 sq. in. = 200 cfm
passage at runner entry: 1.48" x 1.55" = 2.29 sq. in. = 294 cfm

A stock base flows 222 cfm and should support 456 horse power.

Porting the mid passage to 1.22" x 1.625" versus the stock 1.10" x 1.55"
gives you 1.98 sq. in vs. 1.71 sq in. stock.
The equiv. flow rate is 245 cfm vs. the stock 202 cfm.

Porting and polishing the base runners will yield a flow of 255 cfm, which
will outflow any out of the box factory or aftermarked head and
should support 525 horse power.

Air flow for desired horsepower
HP / ( .25714 x #cyls ) - ( 6.37% for EFI ) = needed CFM

CFM for motor size
Cubic inches x RPM / 3456 = CFM at 100% VE (volumetric efficiency).
About 80% VE is average so multiply the figure by 0.8 then subtract
6.37% for EFI because there is no fuel in the air. We run a dry manifold.

Approximate CFM from hole size
square inches x 123 = CFM @ 28" depression

CFM to CFM by change in depression
( square root ( new depression / origional depression )) x CFM = new CFM

Horsepower from air flow
( square root ( 28 / depression )) x CFM x .25714 x #cyls = HP

 

Sometimes things look great on paper and then in practice they fall flat on their face. One of the things not included in that mess is the overall flow of the manifold when assembled, and better yet what it does to the head flow when connected to the head. The transitions in the TPI setup from one piece to another basically dont exist, and it really hurts flow. You kinda have to take a guess to figure that in unless you want to flow the whole setup. This is sorta related to that other post, I do think 500 or 525hp is entirely possible, but its neither likely or reasonable (reasonable from the standpoint of how much you are sacrificing to get that sorta power output).

 

ttt

 

Anyone else, I know things don't always go as planned, just
want to know if these formulas are sound.

I am in the middle of building a flow bench so I can work
with the entire intake assembled to a head. I am planning on
installing dowel pins to fix the components in place and use a
flexible bore scope to inspect the seams from the inside and
make the transitions from one part to another perfect.

 

When you see us raggging on the lack of transitions in the TPI manifold, we're not just talking about alignment of the seams though. What is more important is the direction that the air is moving as it makes the transition. I.E....

Runner to base - Take a look at the way the outlet of the runner faces. Now look at what direction the runner in the base goes right after the flange. Notice how the runner is basically dumping perpendicular to the engine and the base moves on an angle. Thats a sudden angle for air to have to make, especially at teh high velocities LTRs are good for.
Of course the beauty of a siamesed base is that it may effectively eliminate this problem area. Now it has a mini-plenum in the area that it used to have a sharp angle to turn (and also reducing velocity up to this point by letting both runners feed both cylinders)

base to head - This transition sucks bad (perhaps the fundamental weakness in ANY TPI set-up). Just look at how low the runner in the base is. Consider the angle of the inlet of the heads. Again, notice how there is no transitional area, air is basically flowing parallel to the ground, then has to take a sudden turn down into the head, basically by bouncing off the top of the head port. This is far from ideal as well.