Hemi_Express2013
Senior Member
- Joined
- Aug 4, 2013
- Posts
- 728
- Reaction score
- 375
- Location
- Nantucket, Ma
- Ram Year
- 2013
- Engine
- Hemi 5.7
Is it a real Hemi? That was the cry nearly 10 years ago when the daring engineers at Chrysler slapped the sacred Hemi slur on the valve covers of their new V8 engine and unceremoniously dropped it into a truck. The trolls on the Web were so busy complaining that they overlooked what has to be the best mass-production Hemi cylinder head Mother has ever produced. Now, after corporate bloodbaths, government meddling, and bratwurst in the company cafeteria, the Hemi is really getting good. Especially the heads. Let’s take a look.
As this is written, there are four cylinder head designs. In 2003, the 345-inch 5.7 Hemi received the first, followed in 2005 by the 6.1 hemi design. After 2009, the 5.7 Hemi Eagle and 6.4 Hemi Apache head appeared along with Variable Valve Timing (VVT) and the larger 392-inch engine. As the engines got larger, the heads improved with the help of larger valve sizes and improved ports. As cams got bigger, the beehive springs got more aggressive and capable of handling more lift. The current king is the Apache head that is reported to flow more than 340 cfm.
We’ve been playing with the heads on the eBay 5.7L Hemi that we are currently plumbing into the ’71 Demon project car. Car Craft fabricator Grant Petersen and Jimmy White from Circle City Hot Rods created the headers for the turbos using 5.7L flanges from Stainless Works. During this process we began bench-racing upgrades for more power and quickly realized we had the smallest heads available. Of course, we wanted more so we called Dave Weber at Modern Muscle Performance to see what would fit and how far we could go.
5.7 Hemi 2003–2008
The 5.7 hemi cylinder head can be found on Dodge trucks and non-SRT passenger cars, making it the most common head in the family. It has a 161cc intake port that flows between 250-280 cfm at 0.600 lift, depending on the flow bench. We’ve seen published numbers stating 265 cfm, and we’ve independently tested the stock pair off the ’06 eBay Hemi from a Dodge Ram truck and saw 259 cfm. The intake valve is 2.00 inches and range from 4.850–4.900 inches in length.
The exhaust port is a small square with a 50cc port volume and flows around 180 cfm at 0.600 lift. Again, using independent testing, we saw 160 cfm through the port. The valve measures 1.55 inches in diameter and, like the intake valve, is roughly 4.850 inches long and has a solid stem.
5.7 Hemi Flow Chart*
Lift Intake CFM** Exhaust CFM** I/E Percentage
0.100 71 38 54
0.200 168 109 65
0.300 239 163 68
0.400 270 180 67
0.500 284 183 64
0.600 285 185 65
0.650 285 186 65
*Flow testing performed by Dave Weber at Modern Muscle Performance using a 4.060 bore plate, no exhaust flow pipe on a Superflow 1020 flow bench at 28 inches test depression.
**Rounded to the nearest decimal
5.7L Eagle 2009–Present
The Eagle Hemi cylinder head arrived in 2009 with VVT on non-SRT Dodge passenger cars and trucks. As with the early head, the Eagle uses rocker shafts and 1.65:1 ratio rockers, but there are big differences in the size and shape of the intake port and the rest of the valvetrain. The Eagle uses 2.05-inch intake and 1.55-inch exhaust valves that are not only larger, they are also longer than standard. The rocker support is taller, and the valve-guide support boss sits higher on the top side of the head, moving it out of the intake port. The Eagle uses a larger square port like the 6.1L that flows a massive 331 cfm right out of the box.
5.7L Eagle Flow Chart*
Lift Intake CFM** Exhaust CFM** I/E Percentage
0.100 82 45 55
0.200 175 110 63
0.300 243 160 66
0.400 300 180 60
0.500 323 181 56
0.600 331 183 55
0.650 331 186 56
*Flow testing performed by Dave Weber at Modern Muscle Performance using a 4.060 bore plate, no exhaust flow pipe on a Superflow 1020 flow bench at 28 inches test depression.
**Rounded to the nearest decimal
Read more: Inside The G3 Hemi Cylinder Head - Car Craft Magazine
As this is written, there are four cylinder head designs. In 2003, the 345-inch 5.7 Hemi received the first, followed in 2005 by the 6.1 hemi design. After 2009, the 5.7 Hemi Eagle and 6.4 Hemi Apache head appeared along with Variable Valve Timing (VVT) and the larger 392-inch engine. As the engines got larger, the heads improved with the help of larger valve sizes and improved ports. As cams got bigger, the beehive springs got more aggressive and capable of handling more lift. The current king is the Apache head that is reported to flow more than 340 cfm.
We’ve been playing with the heads on the eBay 5.7L Hemi that we are currently plumbing into the ’71 Demon project car. Car Craft fabricator Grant Petersen and Jimmy White from Circle City Hot Rods created the headers for the turbos using 5.7L flanges from Stainless Works. During this process we began bench-racing upgrades for more power and quickly realized we had the smallest heads available. Of course, we wanted more so we called Dave Weber at Modern Muscle Performance to see what would fit and how far we could go.
5.7 Hemi 2003–2008
The 5.7 hemi cylinder head can be found on Dodge trucks and non-SRT passenger cars, making it the most common head in the family. It has a 161cc intake port that flows between 250-280 cfm at 0.600 lift, depending on the flow bench. We’ve seen published numbers stating 265 cfm, and we’ve independently tested the stock pair off the ’06 eBay Hemi from a Dodge Ram truck and saw 259 cfm. The intake valve is 2.00 inches and range from 4.850–4.900 inches in length.
The exhaust port is a small square with a 50cc port volume and flows around 180 cfm at 0.600 lift. Again, using independent testing, we saw 160 cfm through the port. The valve measures 1.55 inches in diameter and, like the intake valve, is roughly 4.850 inches long and has a solid stem.
5.7 Hemi Flow Chart*
Lift Intake CFM** Exhaust CFM** I/E Percentage
0.100 71 38 54
0.200 168 109 65
0.300 239 163 68
0.400 270 180 67
0.500 284 183 64
0.600 285 185 65
0.650 285 186 65
*Flow testing performed by Dave Weber at Modern Muscle Performance using a 4.060 bore plate, no exhaust flow pipe on a Superflow 1020 flow bench at 28 inches test depression.
**Rounded to the nearest decimal
5.7L Eagle 2009–Present
The Eagle Hemi cylinder head arrived in 2009 with VVT on non-SRT Dodge passenger cars and trucks. As with the early head, the Eagle uses rocker shafts and 1.65:1 ratio rockers, but there are big differences in the size and shape of the intake port and the rest of the valvetrain. The Eagle uses 2.05-inch intake and 1.55-inch exhaust valves that are not only larger, they are also longer than standard. The rocker support is taller, and the valve-guide support boss sits higher on the top side of the head, moving it out of the intake port. The Eagle uses a larger square port like the 6.1L that flows a massive 331 cfm right out of the box.
5.7L Eagle Flow Chart*
Lift Intake CFM** Exhaust CFM** I/E Percentage
0.100 82 45 55
0.200 175 110 63
0.300 243 160 66
0.400 300 180 60
0.500 323 181 56
0.600 331 183 55
0.650 331 186 56
*Flow testing performed by Dave Weber at Modern Muscle Performance using a 4.060 bore plate, no exhaust flow pipe on a Superflow 1020 flow bench at 28 inches test depression.
**Rounded to the nearest decimal
Read more: Inside The G3 Hemi Cylinder Head - Car Craft Magazine
