choke point?

[bc]

Ok now Im confused about just where the choke point should and why it is the choke point. I was going though some old post by Darin Morgan and found this.


viewtopic.php?t=874&highlight=sb2
The port length on the SB2.2 is roughly 5.800 inches long through the center. If your shooting for an 8000rpm peak power and a shift point of 8500-8600rpm then the runner length on your sheet metal manifold should be right at 5.900inches long with a 2.500 diameter opening in the plenum (4.900SQin). The valve sizing for a 4.155 bore will be 2.180 intake and a 1.580 exhaust. With a 400cid engine on alky in that rpm range a 3.580 SQin opening at the port entrance tapering down to a choke of 3.300SQin. If you use a single plane manifold I would use the 88958617 from Wilson manifolds. I think the other manifolds would be to restricted on alky. I would NOT use IR runners like Kinsler. Your better off using some type of throttle body on a properly tuned manifold whether it be a sheet metal tunnel ram or the 88958617 manifold. Just my opinion from what I have seen in my lifetime. anyone else care to chime on that one?
_________________


Now when you figure what the throat should be for a 2.180" valve it will roughly be 3.09sqin. correct? So if you have a port opening of 3.58sqin like he suggest tapering done to a "choke" of 3.30sqin some where between the throat and the opening and then the throat is around 3.09sqin. Doesnt that make the throat the choke point since it would be the mininum cross section point in the port. I thought the best possible place for the choke point to happen is at the throat and then taper out from there. Which in the port Darin decribes it does do that but he is calling the point where the 3.30sqin happens the choke point. Anyone know why and where should that point be?

[dbusch]

3.3 at the throat seems very large to me for a 2.180 valve...

[maxracesoftware]

you didn't Post all the Specs of your Engine PipeMax would need to give you more accurate Data results, but just from a quick Simulation,
Darrin gave you good advice.

if its a 400 CID w/4.155" Bore then your Stroke = 3.688 ???
6.000 C-C Rod ???
Cam Specs ??
Compression Ratio ??

Simulation shows for a 400 CID making Peak HP at 8000 RPM
you would need =>

Code: Select all

-Recommended Camshaft Valve Lift-       - Induction Tuned Lengths -
         Minimum  Normal  Maximum	Best Length= 12.152    2nd= 9.565
Intake  = 0.752   0.802   0.852		3rd Best= 7.761   4th Best= 6.529
Exhaust = 0.745   0.794   0.844		Plenum Runner Max Entry Area = 4.752


Current Intake Valve Curtain Area / Time Choke RPM = 7628 RPM
Minimum Intake Valve Lift to prevent Choke = .768 Lift  @  8000 RPM
Cylinder Head Intake Port Sonic-Choke  min. cross-area = 2.549 sq.inches

Intake	Intake	Curtain Area		Recommended Port          Lift/Dia
Valve	Choke	Square Inches		Cross-Sect. Area           Ratios
Lift	RPM	Intake	Exhaust		Intake	Exhaust		 Int	 Exh
.050	505	0.342	0.248		0.214	0.151		.023	.032
.075	758	0.514	0.372		0.322	0.226		.034	.047
.100	1010	0.685	0.496		0.429	0.301		.046	.063
.125	1263	0.856	0.620		0.536	0.376		.057	.079
.150	1515	1.027	0.745		0.643	0.452		.069	.095
.175	1768	1.199	0.869		0.751	0.527		.080	.111
.200	2021	1.370	0.993		0.858	0.602		.092	.127
.225	2273	1.541	1.117		0.965	0.677		.103	.142
.250	2526	1.712	1.241		1.072	0.753		.115	.158
.275	2778	1.883	1.365		1.180	0.828		.126	.174
.300	3031	2.055	1.489		1.287	0.903		.138	.190
.325	3283	2.226	1.613		1.394	0.978		.149	.206
.350	3536	2.397	1.737		1.501	1.054		.161	.222
.375	3788	2.568	1.861		1.609	1.129		.172	.237
.400	4041	2.739	1.985		1.716	1.204		.183	.253

Intake	Intake	Curtain Area		Recommended Port          Lift/Dia
Valve	Choke	Square Inches		Cross-Sect. Area           Ratios
Lift	RPM	Intake	Exhaust		Intake	Exhaust		 Int	 Exh
.425	4294	2.911	2.110		1.823	1.279		.195	.269
.450	4546	3.082	2.234		1.930	1.355		.206	.285
.475	4799	3.253	2.358		2.038	1.430		.218	.301
.500	5051	3.424	2.482		2.145	1.505		.229	.316
.525	5304	3.596	2.606		2.252	1.580		.241	.332
.550	5556	3.767	2.730		2.359	1.656		.252	.348
.575	5809	3.938	2.854		2.466	1.731		.264	.364
.600	6062	4.109	2.978		2.574	1.806		.275	.380
.625	6314	4.280	3.102		2.681	1.882		.287	.396
.650	6567	4.452	3.226		2.788	1.957		.298	.411
.675	6819	4.623	3.351		2.895	2.032		.310	.427
.700	7072	4.794	3.475		3.003	2.107		.321	.443
.725	7324	4.965	3.599		3.110	2.183		.333	.459
.750	7577	5.137	3.723		3.217	2.258		.344	.475
.775	7830	5.308	3.847		3.324	2.333		.356	.491
.800	8082	5.479	3.971		3.432	2.408		.367	.506

Intake	Intake	Curtain Area		Recommended Port          Lift/Dia
Valve	Choke	Square Inches		Cross-Sect. Area           Ratios
Lift	RPM	Intake	Exhaust		Intake	Exhaust		 Int	 Exh
.825	8335	5.650	4.095		3.539	2.484		.378	.522
.850	8587	5.821	4.219		3.646	2.559		.390	.538


Crank	Head	Piston	Piston	Piston	Volume	Crank	Rod-to-	Rod-to-
Angle	CFM @	CFM @	Depth	Speed	CC per	Rotate	Bore	Crank
Degree	28 in.	28 in.	inches	Ft/Min	degree	TimeSec	Angle	Angle
72.6	371.8	391.3	1.5564	8048.1	345.81	.00151	17.05	90.35
72.7	371.8	391.4	1.5598	8048.7	346.56	.00151	17.06	90.24
72.8	371.8	391.4	1.5631	8049.3	347.31	.00152	17.07	90.13
72.9	371.8	391.4	1.5665	8049.8	348.06	.00152	17.08	90.02
73.0	371.9	391.4	1.5699	8050.3	348.80	.00152	17.09	89.91
73.1	371.9	391.5	1.5732	8050.8	349.55	.00152	17.10	89.80
73.2	371.9	391.5	1.5766	8051.3	350.30	.00153	17.11	89.69
73.3	371.9	391.5	1.5800	8051.7	351.05	.00153	17.12	89.58
73.4	372.0	391.5	1.5833	8052.1	351.80	.00153	17.13	89.47
73.5	372.0	391.5	1.5867	8052.5	352.54	.00153	17.14	89.36
73.6	372.0	391.6	1.5901	8052.8	353.29	.00153	17.15	89.25
73.7	372.0	391.6	1.5934	8053.1	354.04	.00154	17.16	89.14
73.8	372.0	391.6	1.5968	8053.4	354.79	.00154	17.17	89.03
73.9	372.0	391.6	1.6002	8053.7	355.54	.00154	17.17	88.93
74.0	372.0	391.6	1.6035	8053.9	356.29	.00154	17.18	88.82
74.1	372.0	391.6	1.6069	8054.1	357.03	.00154	17.19	88.71
74.2	372.1	391.6	1.6103	8054.2	357.78	.00155	17.20	88.60
74.3	372.1	391.6	1.6136	8054.4	358.53	.00155	17.21	88.49
74.4	372.1	391.6	1.6170	8054.5	359.28	.00155	17.22	88.38
74.5	372.1	391.6	1.6204	8054.5	360.03	.00155	17.23	88.27
74.6	372.1	391.6	1.6237	8054.6	360.78	.00155	17.24	88.16
74.7	372.1	391.6	1.6271	8054.6	361.52	.00156	17.24	88.06
74.8	372.1	391.6	1.6305	8054.5	362.27	.00156	17.25	87.95
74.9	372.1	391.6	1.6338	8054.5	363.02	.00156	17.26	87.84
75.0	372.1	391.6	1.6372	8054.4	363.77	.00156	17.27	87.73
75.1	372.1	391.6	1.6406	8054.3	364.52	.00156	17.28	87.62
75.2	372.0	391.6	1.6439	8054.1	365.27	.00157	17.29	87.51
75.3	372.0	391.6	1.6473	8054.0	366.01	.00157	17.29	87.41
75.4	372.0	391.6	1.6507	8053.8	366.76	.00157	17.30	87.30
75.5	372.0	391.6	1.6540	8053.5	367.51	.00157	17.31	87.19
75.6	372.0	391.6	1.6574	8053.3	368.26	.00157	17.32	87.08
75.7	372.0	391.6	1.6608	8053.0	369.01	.00158	17.33	86.97
75.8	372.0	391.6	1.6641	8052.7	369.75	.00158	17.33	86.87
75.9	372.0	391.5	1.6675	8052.3	370.50	.00158	17.34	86.76
76.0	371.9	391.5	1.6709	8051.9	371.25	.00158	17.35	86.65
76.1	371.9	391.5	1.6742	8051.5	372.00	.00159	17.36	86.54
76.2	371.9	391.5	1.6776	8051.1	372.75	.00159	17.37	86.43
76.3	371.9	391.5	1.6810	8050.6	373.49	.00159	17.37	86.33
76.4	371.9	391.4	1.6843	8050.1	374.24	.00159	17.38	86.22
76.5	371.8	391.4	1.6877	8049.6	374.99	.00159	17.39	86.11
76.6	371.8	391.4	1.6911	8049.0	375.74	.00160	17.40	86.00
76.7	371.8	391.4	1.6944	8048.4	376.48	.00160	17.40	85.90
76.8	371.8	391.3	1.6978	8047.8	377.23	.00160	17.41	85.79
76.9	371.7	391.3	1.7012	8047.2	377.98	.00160	17.42	85.68
77.0	371.7	391.3	1.7045	8046.5	378.73	.00160	17.42	85.58
77.1	371.7	391.2	1.7079	8045.8	379.47	.00161	17.43	85.47
77.2	371.6	391.2	1.7113	8045.0	380.22	.00161	17.44	85.36
77.3	371.6	391.1	1.7146	8044.3	380.97	.00161	17.45	85.25
77.4	371.6	391.1	1.7180	8043.5	381.71	.00161	17.45	85.15
77.5	371.5	391.1	1.7213	8042.7	382.46	.00161	17.46	85.04
77.6	371.5	391.0	1.7247	8041.8	383.21	.00162	17.47	84.93
77.7	371.4	391.0	1.7281	8040.9	383.95	.00162	17.47	84.83
77.8	371.4	390.9	1.7314	8040.0	384.70	.00162	17.48	84.72
77.9	371.4	390.9	1.7348	8039.1	385.45	.00162	17.49	84.61
78.0	371.3	390.8	1.7381	8038.1	386.19	.00162	17.49	84.51
78.1	371.3	390.8	1.7415	8037.1	386.94	.00163	17.50	84.40
78.2	371.2	390.8	1.7449	8036.1	387.69	.00163	17.51	84.29
78.3	371.2	390.7	1.7482	8035.0	388.43	.00163	17.51	84.19
78.4	371.1	390.6	1.7516	8034.0	389.18	.00163	17.52	84.08
78.5	371.1	390.6	1.7549	8032.8	389.92	.00164	17.53	83.97
78.6	371.0	390.5	1.7583	8031.7	390.67	.00164	17.53	83.87
78.7	371.0	390.5	1.7616	8030.5	391.42	.00164	17.54	83.76
78.8	370.9	390.4	1.7650	8029.3	392.16	.00164	17.55	83.65
78.9	370.8	390.4	1.7683	8028.1	392.91	.00164	17.55	83.55
79.0	370.8	390.3	1.7717	8026.9	393.65	.00165	17.56	83.44
79.1	370.7	390.2	1.7751	8025.6	394.40	.00165	17.57	83.34
79.2	370.7	390.2	1.7784	8024.3	395.14	.00165	17.57	83.23
79.3	370.6	390.1	1.7818	8022.9	395.89	.00165	17.58	83.12
79.4	370.5	390.0	1.7851	8021.5	396.63	.00165	17.58	83.02
79.5	370.5	390.0	1.7885	8020.1	397.37	.00166	17.59	82.91
79.6	370.4	389.9	1.7918	8018.7	398.12	.00166	17.59	82.81
79.7	370.3	389.8	1.7952	8017.3	398.86	.00166	17.60	82.70
79.8	370.3	389.8	1.7985	8015.8	399.61	.00166	17.61	82.59
79.9	370.2	389.7	1.8019	8014.3	400.35	.00166	17.61	82.49
80.0	370.1	389.6	1.8052	8012.7	401.10	.00167	17.62	82.38

so at 8000 RPM

the Engine is trying to move 391 CFM at 8000 RPM

3.432 sq.inch area looks correct
3.300 sq.inches = approx 7800 RPM

PipeMax Plenum Runner Max Entry Area = 4.752
Darrin = 4.900 sqinches

PipeMax Best Total Induction Length= 12.152 at 8000 RPM
Darrin = 11.700"

for Power between 8000 RPM to 8600 RPM like Darrin posted
average Total Induction Lengths= 12.152" + 11.305" = 11.715"

so 11.715 works between 8000-8600 (Darrin = 11.700)


however, at 8600 RPM Engine is trying to move = 421.0 CFM at 28"

Code: Select all

Crank	Head	Piston	Piston	Piston	Volume	Crank	Rod-to-	Rod-to-
Angle	CFM @	CFM @	Depth	Speed	CC per	Rotate	Bore	Crank
Degree	28 in.	28 in.	inches	Ft/Min	degree	TimeSec	Angle	Angle
72.6	399.6	420.7	1.5564	8651.7	345.81	.00141	17.05	90.35
72.7	399.7	420.7	1.5598	8652.3	346.56	.00141	17.06	90.24
72.8	399.7	420.7	1.5631	8653.0	347.31	.00141	17.07	90.13
72.9	399.7	420.8	1.5665	8653.6	348.06	.00141	17.08	90.02
73.0	399.8	420.8	1.5699	8654.1	348.80	.00141	17.09	89.91
73.1	399.8	420.8	1.5732	8654.7	349.55	.00142	17.10	89.80
73.2	399.8	420.9	1.5766	8655.1	350.30	.00142	17.11	89.69
73.3	399.8	420.9	1.5800	8655.6	351.05	.00142	17.12	89.58
73.4	399.9	420.9	1.5833	8656.0	351.80	.00142	17.13	89.47
73.5	399.9	420.9	1.5867	8656.4	352.54	.00142	17.14	89.36
73.6	399.9	420.9	1.5901	8656.8	353.29	.00143	17.15	89.25
73.7	399.9	420.9	1.5934	8657.1	354.04	.00143	17.16	89.14
73.8	399.9	421.0	1.5968	8657.4	354.79	.00143	17.17	89.03
73.9	399.9	421.0	1.6002	8657.7	355.54	.00143	17.17	88.93
74.0	399.9	421.0	1.6035	8657.9	356.29	.00143	17.18	88.82
74.1	399.9	421.0	1.6069	8658.1	357.03	.00144	17.19	88.71
74.2	400.0	421.0	1.6103	8658.3	357.78	.00144	17.20	88.60
74.3	400.0	421.0	1.6136	8658.4	358.53	.00144	17.21	88.49
74.4	400.0	421.0	1.6170	8658.5	359.28	.00144	17.22	88.38
74.5	400.0	421.0	1.6204	8658.6	360.03	.00144	17.23	88.27
74.6	400.0	421.0	1.6237	8658.7	360.78	.00145	17.24	88.16
74.7	400.0	421.0	1.6271	8658.7	361.52	.00145	17.24	88.06
74.8	400.0	421.0	1.6305	8658.6	362.27	.00145	17.25	87.95
74.9	400.0	421.0	1.6338	8658.6	363.02	.00145	17.26	87.84
75.0	400.0	421.0	1.6372	8658.5	363.77	.00145	17.27	87.73
75.1	400.0	421.0	1.6406	8658.4	364.52	.00146	17.28	87.62
75.2	400.0	421.0	1.6439	8658.2	365.27	.00146	17.29	87.51
75.3	399.9	421.0	1.6473	8658.0	366.01	.00146	17.29	87.41
75.4	399.9	421.0	1.6507	8657.8	366.76	.00146	17.30	87.30
75.5	399.9	421.0	1.6540	8657.6	367.51	.00146	17.31	87.19
75.6	399.9	421.0	1.6574	8657.3	368.26	.00147	17.32	87.08
75.7	399.9	420.9	1.6608	8657.0	369.01	.00147	17.33	86.97
75.8	399.9	420.9	1.6641	8656.6	369.75	.00147	17.33	86.87
75.9	399.9	420.9	1.6675	8656.2	370.50	.00147	17.34	86.76
76.0	399.8	420.9	1.6709	8655.8	371.25	.00147	17.35	86.65
76.1	399.8	420.9	1.6742	8655.4	372.00	.00147	17.36	86.54
76.2	399.8	420.8	1.6776	8654.9	372.75	.00148	17.37	86.43
76.3	399.8	420.8	1.6810	8654.4	373.49	.00148	17.37	86.33
76.4	399.8	420.8	1.6843	8653.9	374.24	.00148	17.38	86.22
76.5	399.7	420.8	1.6877	8653.3	374.99	.00148	17.39	86.11
76.6	399.7	420.7	1.6911	8652.7	375.74	.00148	17.40	86.00
76.7	399.7	420.7	1.6944	8652.1	376.48	.00149	17.40	85.90
76.8	399.6	420.7	1.6978	8651.4	377.23	.00149	17.41	85.79
76.9	399.6	420.6	1.7012	8650.7	377.98	.00149	17.42	85.68
77.0	399.6	420.6	1.7045	8650.0	378.73	.00149	17.42	85.58
77.1	399.5	420.6	1.7079	8649.2	379.47	.00149	17.43	85.47
77.2	399.5	420.5	1.7113	8648.4	380.22	.00150	17.44	85.36
77.3	399.5	420.5	1.7146	8647.6	380.97	.00150	17.45	85.25
77.4	399.4	420.4	1.7180	8646.7	381.71	.00150	17.45	85.15
77.5	399.4	420.4	1.7213	8645.9	382.46	.00150	17.46	85.04
77.6	399.3	420.4	1.7247	8644.9	383.21	.00150	17.47	84.93
77.7	399.3	420.3	1.7281	8644.0	383.95	.00151	17.47	84.83
77.8	399.2	420.3	1.7314	8643.0	384.70	.00151	17.48	84.72
77.9	399.2	420.2	1.7348	8642.0	385.45	.00151	17.49	84.61
78.0	399.2	420.2	1.7381	8641.0	386.19	.00151	17.49	84.51
78.1	399.1	420.1	1.7415	8639.9	386.94	.00151	17.50	84.40
78.2	399.1	420.1	1.7449	8638.8	387.69	.00152	17.51	84.29
78.3	399.0	420.0	1.7482	8637.7	388.43	.00152	17.51	84.19
78.4	398.9	419.9	1.7516	8636.5	389.18	.00152	17.52	84.08
78.5	398.9	419.9	1.7549	8635.3	389.92	.00152	17.53	83.97
78.6	398.8	419.8	1.7583	8634.1	390.67	.00152	17.53	83.87
78.7	398.8	419.8	1.7616	8632.8	391.42	.00153	17.54	83.76
78.8	398.7	419.7	1.7650	8631.5	392.16	.00153	17.55	83.65
78.9	398.7	419.6	1.7683	8630.2	392.91	.00153	17.55	83.55
79.0	398.6	419.6	1.7717	8628.9	393.65	.00153	17.56	83.44
79.1	398.5	419.5	1.7751	8627.5	394.40	.00153	17.57	83.34
79.2	398.5	419.4	1.7784	8626.1	395.14	.00153	17.57	83.23
79.3	398.4	419.4	1.7818	8624.6	395.89	.00154	17.58	83.12
79.4	398.3	419.3	1.7851	8623.2	396.63	.00154	17.58	83.02
79.5	398.3	419.2	1.7885	8621.7	397.37	.00154	17.59	82.91
79.6	398.2	419.1	1.7918	8620.1	398.12	.00154	17.59	82.81
79.7	398.1	419.1	1.7952	8618.6	398.86	.00154	17.60	82.70
79.8	398.0	419.0	1.7985	8617.0	399.61	.00155	17.61	82.59
79.9	398.0	418.9	1.8019	8615.4	400.35	.00155	17.61	82.49
80.0	397.9	418.8	1.8052	8613.7	401.10	.00155	17.62	82.38

3.090 sqinches is more for 7300 RPM

[maxracesoftware]

GM SB2.2 NASCAR SBC in ported shape

Port CenterLine Lengths =
Intake =5.758
Exh=3.623

• Cylinder Head's Exhaust Port CenterLine Length in Inches { Default= 3.200 }
  
  Example=> Roof= 4.200 Floor= 2.200 Total= 6.400 / 2 = 3.200 CL Length
  {use Scotch 3M 218 Fine Line Tape to measure Roof and Floor Lengths}

[bc]

So the throat doesnt count as the choke point? Because that is the smallest area and I would think that would be the choke? What determines the choke point if it is not the smallest area in the port? If you have a valve that is 2.18" the throat area should be about 91% of that making an area of 3.091sqin. So way is a place in the port that measure 3.30sqin the choke point and not the throat area? Im missing something and just trying to figure out what it is. Thanks

[maxracesoftware]

So the throat doesnt count as the choke point? Because that is the smallest area and I would think that would be the choke? What determines the choke point if it is not the smallest area in the port? If you have a valve that is 2.18" the throat area should be about 91% of that making an area of 3.091sqin. So way is a place in the port that measure 3.30sqin the choke point and not the throat area? Im missing something and just trying to figure out what it is. Thanks

yes , correct , the 3.091" would be in the seat insert area - throat area

the 3.300 to 3.432 sq.inch area would be the "Port's"
recommended CSA for that RPM

you want the absolute min CSA to be at the seat insert area
and not placed somewhere further up in the port away from the Bowl area

the further the min CSA is away from the seat,
the more it will disrupt Wave tunning, and the more the HP/TQ loss

ideally, the min CSA should be located at the insert area

example=> some Chevy and Pontiac SS engines
at pushrod areas....if the min CSA occurs at the pushrod area
theres a very good probabilty the Engine will not make
the HP the FlowBench CFM numbers suggest it would.

if you then fix the pushrod area , and move the min CSA to the
seat area...all probability, the engine will now have a better chance at making the HP the FlowBench suggests

likewise if the min CSA is at the insert area,
but the Short Turn/Apex area velocity is too high,
the engine will not make the correct HP for FlowBench CFM

its not just getting the correct CSA and min CSA , Port Taper, but having the correct velocities everywhere inside the Port and port-to-chamber transition

[maxracesoftware]

one more thing ?

at what Crankshaft degree
are you running out of Intake Port Volume ??

at what Crankshaft degree
are you running out of Total Induction Volume CC's ?

in the case of a pushrod area Choke point ....at what Crank degree
would Port Vol CC's catch up to the Pushrod Area distance away from the Valve ?

[bc]

Wow thanks! So now that I have that staight. Two more thing. If the seat area is the smallest point and the port should taper out from there. Then the "ports" CSA would always be at the short turn correct? From I what have always done or tried to do was funnel the port down as it approaches the seat area. Which would mean the 3.300 to 3.432 that has been refered to would be around the short turn area, correct? So my other question is (and Im guess I have been calculating this wrong) but the seat are is not used as the CSA to determine where hp will peak, correct? The seat area doesnt determine rpms but the smallest point in the runner does correct? Using the above stated port with a throat or seat are of 3.09 and a choke of 3.300 and a port opening of 3.58 that were used, it would be 3.30 and not the 3.09 to figure max rpm then. I have to get me a copy of the PipeMax software! Thanks for the help

[bc]

Basically Im now confuse as to way the mininum cross sectional point (the seat area) doesnt dictate peak rpm and that some larger area up stream for the seat area does.

[dbusch]

its funny how so many aftermarket CNC heads are designed with the cross sectional area at the pushrod being way smaller than the area at the throat. I guess they are all designed for low lift stuff, like .600" and less???

[bc]

That is kind of what I was thinking. Why are all these street heads and CNC heads out with these larger valve which pretty much make the pushrod the smallest point and not the seat area?

[larrycavan]

Larry,

I'm looking at the output from PipeMax. Is column 5 piston speed? If it is, aren't those speeds excessively high?

Larry C.

[John Wallace]

I figure it should be rpms

[maxracesoftware]

Larry,

I'm looking at the output from PipeMax. Is column 5 piston speed? If it is, aren't those speeds excessively high?

I figure it should be rpms

Sorry for some unknown reason the Post didn't properly Format/Paste
as it should have..its hard to read.

Column 5 = Instantaneous Piston Speed in Feet per Minute FPM

Average_Piston_Speed_FPM = Stroke * RPM * .166666667
5284 FPM = 3.688 * 8600 * .166666667

Peak Instantaneous Piston Speed in Feet per Minute FPM = approx 8600+

if you mean those speeds are excessively high in terms of stress on Engine components...yes , its getting there

[bc]

So what is used to calculate where the hp will peak rpm wise? If it isnt the smallest point which should always be the seat area (I got that much). Then where should it be? The short turn area? I thought I had these worked out but Im still learning and still confused.

For example, Im working on a head now that is for a 496 (4.31x4.25). The intake valve is 2.15, seat area is 3.02, the area at the short turn is 3.15 and the area at the pushrod pinch is 3.22. So using those specs where about will the engine peak at? Thanks for all the help