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My previous thread in the pushrod performance section was trying to go off topic, so I am going to start one with a broader topic range. I admit it is difficult for the majority of people to do a comparison between parts from different companies due to marketing and equipment. By using the same flowbench here at WOT-Tech, I hope this takes some of the guess work out.
First and foremost, an explanation of what a flowbench does and its importance. A flowbench measures airflow through any part, both in air flow (cfm) and depression (inches of water). The standard years ago was 10" of water, but 28" has been the preferred measurement for quite some time now. For cylinder heads, it is common practice to use clay to create a rounded entrance to the port. This is done to utilize the entire port rather than have turbulence at the port opening limiting the flow. For exhaust, a tube is attached for the same reason. The same method is repeated for all parts.
No one has more time researching the 3100, 3400, or 3500 heads and manifolds on a flowbench than WOT-Tech. Our closest competitor doesn't even use a flowbench to test porting! I have a copy of the flow numbers they advertise offline (you wont see them posted on their site), and its substantially higher than any numbers recorded here at WOT-Tech. This could be for any number of reasons, none of which are especially important because we won't be comparing with those numbers.
This is all well and good, but flow numbers certainly aren't the only thing to compare outside of dyno/track results. Designing heads and manifolds is much more than the most flow (unless you are boosted, then flow is what you want under boost conditions). Velocity is what keeps the intake charge rushing into the combustion chamber even after the piston has reached bottom dead center, and has started to move back up the cylinder. This little bit of extra air/fuel is what gives more power. Velocity in the ports are measured with velocity tubes and there are more in depth issues with flow shape and fuel drop out. The easiest way to compare velocity however, is to measure the ports displacement. A larger port will have slower air speeds. If this was not the case, everyone would run the largest heads possible on their V8s.
The first comparison is between the WOT-Tech Competition 3400 heads and the MMS Stage 2 heads. Below are the displacement measurements
Stock 3400 Intake = 111.4cc
WOT-Tech Competition Intake = 113.5cc
MMS Stage 2 Intake = 117.2cc
Stock 3400 Exhaust = 70cc
WOT-Tech Competition Exhaust = 72cc
MMS Stage 2 Exhaust = 76.2cc
That should give you a good idea of the size difference between the 2 heads. Now for the flow numbers, which are at 28” depression using a 3.700” bore size. I list this because it is impossible to compare numbers to another bench without having this information. Bore size is critical to testing for real world results. More important on straight valves, the same principle holds true for the canted valves of the aluminum head 60V6 heads. As the valve opens, it moves away from the cylinder wall. However, the airflow past the combustion chamber wall is still influenced by the bore, creating its own dynamic flow pattern vs valve lift off the seat.
The following is not going to format well on this forum, but the first row is the valve lift off the seat in .050" increments, followed by the MMS S2 and then the WOT-Tech Comp series 3400 head. You can also check out this link to see it formatted better, along with the WOT-Tech Race series numbers
3400 Intake
Lift / Stock/ MMS S2 / WOT-Tech Competition
0.050..... 31.6..... 33.2..... 35.3
0.100..... 55.4..... 60.9..... 63.4
0.150..... 78.1..... 85.3..... 89.9
0.200..... 101.3..... 109.5.... 116.7
0.250..... 125.4..... 133.1.... 142.9
0.300..... 148.1..... 155.7.... 166.7
0.350..... 170.0..... 176.6.... 187.3
0.400..... 187.8..... 194.2.... 203.6
0.450..... 201.1..... 210.6.... 217.4
0.500..... 210.1..... 224.8.... 227.7
3400 Exhaust
Lift / Stock/ MMS S2 / WOT-Tech Competition
0.050..... 27.1..... 28.4..... 25.2
0.100..... 53.0..... 56.4..... 51.8
0.150..... 78.4..... 83.5..... 87.6
0.200..... 98.4..... 105.1.... 112.6
0.250..... 116.8..... 123.2.... 131.2
0.300..... 133.8..... 135.8.... 148.1
0.350..... 144.4..... 144.9.... 158.4
0.400..... 151.5..... 151.0.... 167.1
0.450..... 155.1..... 157.1.... 174.0
0.500..... 157.0..... 160.6.... 178.8
The WOT-Tech heads have smaller ports that flow more. The exhaust side is important for NA and Turbo applications, because smaller ports keep the exhaust gas hotter. Hotter exhaust travels faster, and spools a turbo quicker. Our race heads have the exact same exhaust ports because of their efficiency.
First and foremost, an explanation of what a flowbench does and its importance. A flowbench measures airflow through any part, both in air flow (cfm) and depression (inches of water). The standard years ago was 10" of water, but 28" has been the preferred measurement for quite some time now. For cylinder heads, it is common practice to use clay to create a rounded entrance to the port. This is done to utilize the entire port rather than have turbulence at the port opening limiting the flow. For exhaust, a tube is attached for the same reason. The same method is repeated for all parts.
No one has more time researching the 3100, 3400, or 3500 heads and manifolds on a flowbench than WOT-Tech. Our closest competitor doesn't even use a flowbench to test porting! I have a copy of the flow numbers they advertise offline (you wont see them posted on their site), and its substantially higher than any numbers recorded here at WOT-Tech. This could be for any number of reasons, none of which are especially important because we won't be comparing with those numbers.
This is all well and good, but flow numbers certainly aren't the only thing to compare outside of dyno/track results. Designing heads and manifolds is much more than the most flow (unless you are boosted, then flow is what you want under boost conditions). Velocity is what keeps the intake charge rushing into the combustion chamber even after the piston has reached bottom dead center, and has started to move back up the cylinder. This little bit of extra air/fuel is what gives more power. Velocity in the ports are measured with velocity tubes and there are more in depth issues with flow shape and fuel drop out. The easiest way to compare velocity however, is to measure the ports displacement. A larger port will have slower air speeds. If this was not the case, everyone would run the largest heads possible on their V8s.
The first comparison is between the WOT-Tech Competition 3400 heads and the MMS Stage 2 heads. Below are the displacement measurements
Stock 3400 Intake = 111.4cc
WOT-Tech Competition Intake = 113.5cc
MMS Stage 2 Intake = 117.2cc
Stock 3400 Exhaust = 70cc
WOT-Tech Competition Exhaust = 72cc
MMS Stage 2 Exhaust = 76.2cc
That should give you a good idea of the size difference between the 2 heads. Now for the flow numbers, which are at 28” depression using a 3.700” bore size. I list this because it is impossible to compare numbers to another bench without having this information. Bore size is critical to testing for real world results. More important on straight valves, the same principle holds true for the canted valves of the aluminum head 60V6 heads. As the valve opens, it moves away from the cylinder wall. However, the airflow past the combustion chamber wall is still influenced by the bore, creating its own dynamic flow pattern vs valve lift off the seat.
The following is not going to format well on this forum, but the first row is the valve lift off the seat in .050" increments, followed by the MMS S2 and then the WOT-Tech Comp series 3400 head. You can also check out this link to see it formatted better, along with the WOT-Tech Race series numbers
3400 Intake
Lift / Stock/ MMS S2 / WOT-Tech Competition
0.050..... 31.6..... 33.2..... 35.3
0.100..... 55.4..... 60.9..... 63.4
0.150..... 78.1..... 85.3..... 89.9
0.200..... 101.3..... 109.5.... 116.7
0.250..... 125.4..... 133.1.... 142.9
0.300..... 148.1..... 155.7.... 166.7
0.350..... 170.0..... 176.6.... 187.3
0.400..... 187.8..... 194.2.... 203.6
0.450..... 201.1..... 210.6.... 217.4
0.500..... 210.1..... 224.8.... 227.7
3400 Exhaust
Lift / Stock/ MMS S2 / WOT-Tech Competition
0.050..... 27.1..... 28.4..... 25.2
0.100..... 53.0..... 56.4..... 51.8
0.150..... 78.4..... 83.5..... 87.6
0.200..... 98.4..... 105.1.... 112.6
0.250..... 116.8..... 123.2.... 131.2
0.300..... 133.8..... 135.8.... 148.1
0.350..... 144.4..... 144.9.... 158.4
0.400..... 151.5..... 151.0.... 167.1
0.450..... 155.1..... 157.1.... 174.0
0.500..... 157.0..... 160.6.... 178.8
The WOT-Tech heads have smaller ports that flow more. The exhaust side is important for NA and Turbo applications, because smaller ports keep the exhaust gas hotter. Hotter exhaust travels faster, and spools a turbo quicker. Our race heads have the exact same exhaust ports because of their efficiency.
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