[Z06] Cylinder head flows on Mercury 32-valve, DOHC LS7
#1
Drifting
Thread Starter
Cylinder head flows on Mercury 32-valve, DOHC LS7
Saw in my recent SuperChevy magazine an article about the Mercury 32-valve, DOHC LS7. Great article and picutres, the engine is an engineering feat in and of itself.
That said, I'm not exactly impressed with the flow rates of the heads, even compared to stock (already CNC'd) LS7 heads. Additional ported LS7 heads far exceed the SB4 7.0 cylinder head flow rates. Not sure I care much for flow rates below .500 lift on an engine that boasts 8,000 rpm redlines?! My AHP hand-ported LS7 heads flow 390cfm+ at .700 lift.
http://www.superchevy.com/how-to/181...50hp-dohc-ls7/
That said, I'm not exactly impressed with the flow rates of the heads, even compared to stock (already CNC'd) LS7 heads. Additional ported LS7 heads far exceed the SB4 7.0 cylinder head flow rates. Not sure I care much for flow rates below .500 lift on an engine that boasts 8,000 rpm redlines?! My AHP hand-ported LS7 heads flow 390cfm+ at .700 lift.
http://www.superchevy.com/how-to/181...50hp-dohc-ls7/
Last edited by BigVette427; 01-17-2019 at 03:11 PM.
#2
Saw in my recent SuperChevy magazine an article about the Mercury 32-valve, DOHC LS7. Great article and picutres, the engine is an engineering feat in and of itself.
That said, I'm not exactly impressed with the flow rates of the heads, even compared to stock (already CNC'd) LS7 heads. Additional ported LS7 heads far exceed the SB4 7.0 cylinder head flow rates. Not sure I care much for flow rates below .500 lift on an engine that boasts 8,000 rpm redlines?! My AHP hand-ported LS7 heads flow 390cfm+ at .700 lift.
http://www.superchevy.com/how-to/181...50hp-dohc-ls7/
That said, I'm not exactly impressed with the flow rates of the heads, even compared to stock (already CNC'd) LS7 heads. Additional ported LS7 heads far exceed the SB4 7.0 cylinder head flow rates. Not sure I care much for flow rates below .500 lift on an engine that boasts 8,000 rpm redlines?! My AHP hand-ported LS7 heads flow 390cfm+ at .700 lift.
http://www.superchevy.com/how-to/181...50hp-dohc-ls7/
Also, flow rates dont really mean much without other data, cylinder bore, with pipe, without pipe ect
Last edited by Millenium Z06; 01-17-2019 at 03:15 PM.
#3
Drifting
Thread Starter
#6
This illustrates the benefits of being able to rev well beyond 7000 RPM comfortably without concerns about valvetrain stability.
That 750 crank horsepower is a result of an engine that is revving to 7500+ to make that 750 crank horsepower without valve train deflection or crazy big cam shaft profiles.
Awesome engine.
That 750 crank horsepower is a result of an engine that is revving to 7500+ to make that 750 crank horsepower without valve train deflection or crazy big cam shaft profiles.
Awesome engine.
#7
Melting Slicks
Also shows you the value of the mid lift flow numbers.
#8
Modern HEMIS are in the 390's also with the 5.7 Eagle head being the best of the non SRT heads. The SRT 6.2/6.4 heads flow slightly better
Last edited by Millenium Z06; 01-18-2019 at 10:08 AM.
#9
Drifting
Thread Starter
Again, 2 (two) 1.7 valves, thats 2.4 total area and a smaller valve will increase port velocity which equals torque so 2 smaller ports and 2 smaller valves will easily outflow a larger single port/valve. The mid lift numbers, where you are 90% of the time would also be far better than the single port and I'd bet its capable of well over 400cfm.
Dodge now offers four different Hemi heads, the early 5.7 (like the ones we tested), the 6.1, the later 5.7 Eagle, and the 6.4 Apache heads. The early 5.7 heads we tested, offered the lowest stock flow-rates of the bunch, topping out at 269 cfm at .700-inch lift. All of the later heads offer significantly more flow in as-cast form, with each easily exceeding 300 cfm. Flow numbers for the 6.4 Apache heads are said to reach 340 cfm, a big number even for ported 5.7 heads, as our ported early castings from Total Engine Airflow (TEA) checked in at 329 cfm. The improvement in airflow offered by the porting from TEA was significant, as the ported heads flow enough to support over 650 horsepower. The question now was; would the mild engine be able to take advantage of the extra head flow when it was making only 400 horsepower? The answer was not really, as the stock heads were already sufficient to support the current power level. The ported heads improved the power output slightly, to 413 horsepower at 5,700 rpm, and 439 lb-ft of torque at 4,600 rpm, but it was another case of the mild combination holding the heads back. The results would change in test two.
https://treperformance.com/i-2390084...-lift-630.html
I was more so referring to the aftermarket Gen II Hemi heads (ex. Edelbrock) for the 426 and up motors; they have heads that flow 400cfm as cast.
https://www.rodauthority.com/tech-st...26-hemi-heads/
#11
Drifting
Pro tip - marine heads aren’t designed for peak RPM power. They are designed for peak torque in the mid RPMs for sustained use/load.
If those heads could make their way to Greg Good then feelings would be hurt for sure.
If those heads could make their way to Greg Good then feelings would be hurt for sure.