"I'm baacck" As Jack Nicholson might say
I feel like I'm writing a book over here so, w/o further ado, here we go.
First, I have to say, that you can not compare a 428 to a 460 if you don't limit it to the same CI. We all know that you can get 100 more CI out of the 460. A after market FE block would be a better one to do that with @ 526 CI for the FE.
First, I'll address Brent comment with the same zeal he uses:
Two things I've learned (sarcasm) from this thread:
1: 2 * 340 = 780
2: When your "opinion" is blatantly wrong, keep digging.
Brent can either multiply, nor divide, I guess. 780 ÷ 2 = 390 or to correct Brent, 2 x 390 =
780. Based on, maybe a over optimistic porting of TF heads, with 2.3 valves. If the 2.3 will fit in 4.16 bore.
Maybe not apples to apples but the Kaase P51 heads responded to porting and a .050 valve increase (2.25 to 2.3) with 40 cfm but, I think we an safely say that ported TF heads with at least 2.25 valves, should produce, at least 370 cfm. That's up for debate..... For #2, I might point out that shovels are universal and made to fit anyone's hands.
Since we don't have a FE & 385 to build, I thought I'd see what I could do with my Sim. You
can input the block & head you will use FE vs 385 and you can input the detailed flow rates,
for the heads. I also have Pipe Max but, you can only input max flow rates with it and not low
lift figures. More info on the Sim I used:
What Are DynoSim6 and Dynomation6?
At the core of Dynomation6 and DynoSim6 is are mathematical models that
simulations four-stroke, internal combustion (IC) engines. These simulations incor-
Introduction To Version6 Simulations
The simulation incorporates a completely unique, intuitive user interface (shown using
one of several program color schemes). If you wish to change an engine component,
simply click on any component field on the left side of the screen and select
a new specification from the drop-down list or enter custom values. Engine components
are shared between both the Filling-And-Emptying (FE) and Wave-Action (WA) simulation
models. Results can be displayed in a wide variety of tables and graphs.
Main Program Screen porate two distinct simulation methods: 1) A Filling-And-Emptying
(FE) method, available in both DynoSim6 and Dynomation6 simulation packages, that provides
fast mathematical solutions to engine physics, including flow analysis through intake- and
exhaust systems, making this technique a powerful and efficient way to optimize engine
designs, and 2) A full Wave-Action (WA) method exclusively in Dynomation6 that calculates
and predicts the complex pressure-wave dynamics and particle flows in intake and exhaust
passages. The Wave-Action model picks up where the Filling-And-Emptying method leaves
off and “homes in” on the best port sizes and shapes, runner lengths, header configuration and
tubing dimensions, cam timing and valve motion, and other engine parameters, providing
unprecedented accuracy for the serious engine designer and builder.
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I couldn't find porting info for the TF heads so, I only used the out of the box flow numbers,
supplied by Brent, to Stan Weiss's site. The 385 heads that I chose are the Kaase P51's, both out of the box and ported by Evens. Those CFM numbers, went into the program.
I limited the cam lobes to CC, XFI, hyd roller lobes, for both engines, using Brent, suggested 8
deg split and a 112 LSA, installed at 108, In CL, again for both. The OP wanted a mid level
engine so, I restricted the cams to peak at 56-5800. It takes a little more cam to get the lessor
cfm head to match the higher flow flow head, as we know, so I had to increase the cam
duration on the TF, FE head. I did not change the build, in anyway between the engines. CR, CI,
850 carb and exaust, are all the same. Only the cams and heads are different.
I think what some are missing in this type build, is the benefit of low lift flow. The TF heads,
with their 1.625 Ex valve, clearly out flow the P51's, until .600+ lift and the Intake flow is better on the TF head, below .300. Most likely velocity and the flow pattern is much better, also. I can't tell you if valve shrouding is addressed but, you can choose a 352, 390, 428 or 427 block, to start with so, it may be.
Lastly, I want to point out that the program is sinitive enough to pick up +/- HP differences,
based on the rod to stroke ratio. I won't say that this Sim is totally accurate on the HP output. I
don't use it for that, I use this one and Pipe Max, to try to understand, where things might be
able to be improved.
First up was Brent's recent 4.09 x 4.25, TF engine. I could not find the cam lobe he used. The CC, HUC was closest but, the lobes are short on the lift that he quotes. There are only two other lobes that have odd numbered durations, the QXX & QXI, both have higher lifts. So, I used the XFI lobes, that are within .005 lift of his spec. But, I had to use more duration 231 vs 234 to get my numbers, in matching his HP, close enough to win one of his GTH things. I couldn't get the torque though. I was short 29 lb ft. BTW, the XFI are the same cam lobes that I used on the other engines.
I'm also adding a Blair, 469 CI, 315 CFM, small cam build. Actual dyno results.
NOTE THE AVERAGE HP FIGURES!