Swap a 6.1L Crank into a 5.7L HEMI for 440-hp

3rd Gen HEMI how-tos, tips and tricks.
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Swap a 6.1L Crank into a 5.7L HEMI for 440-hp

Post by scottm » Thu Feb 09, 2017 10:39 pm


Swap a 6.1L Crank into a 5.7L HEMI for 440-hp
http://www.hotrod.com/articles/swap-6-1 ... mi-440-hp/
Here’s the recipe: buy a 5.7L Hemi from a crashed Ram truck, swap in a factory forged 6.1L crank from eBay, add a “drop-in” forged piston and rod combo from Wiseco, fix the heads, slap in a mellow cam for your EFI, and you have a 440hp, bulletproof, street Hemi for not a lot of cash. It’s perfect for that Dart swap or late-model bottom-end upgrade, right? Later, you can port the heads and bomb the thing with nitrous because now you have forged internals. Want in? Here are the vitals.

The basis for this build is the 5.7L Hemi found in 2003–2008 vehicles. We found this complete core on eBay for $1,400 about five years ago. We used a swap-meet carb and intake for dyno testing to avoid the cost of a stand-alone EFI box, but this combo will work using the existing intake and ECU on your late-model 5.7L Challenger, Charger, or Ram.

Hemi haters talk about the pistons being the weak link in this engine series, but the reality is the intake valve seats will likely fail first, detonating your piston and shifting the blame. Fix that.

The real secret: The factory 6.1L crankshaft is a forged version of the 5.7L crank. It’s like Clark Kent and Superman for purposes of metaphor. Spot one using the four-bolt reluctor wheel with 32 teeth as a guide—the 5.7L has only three bolts.

Wiseco’s piston and rod combo gives you a flattop with a zero deck using a 5.7L block. Depending on the cylinder head cc, it yields a compression ratio between 9.0:1 (85cc) and 11.3:1 (65cc). Lower compression allows for cheap fuel and room for copious boost from cheap turbos later.

The cam is a Crane roller with 210/216 degrees of duration at 0.050 with 0.550-inch lift. Note the timing marks line up on opposite ends of the timing chain and the exhaust lifter is first on cylinder No. 1 when degreeing the cam.

Stock, non-Eagle 5.7L Hemi heads flow 280 intake/183 exhaust cfm at 0.550 lift from the factory. It’s a respectable number for a small Hemi head. At a minimum, repair the valve seats, or go all out and port the heads.

We bought a 6.1L balancer and flexplate and had the entire rotator balanced at Revco Precision in Long Beach, California. Prepare to shell out about $185 for that. Joe Jill at Superior Automotive helped with Hemi specific tools and advice.

For some reason, the only thing that prevents the factory rocker arms from sliding laterally off the valve tip is a spring wrapped around the rocker shaft. These rocker-arm spacers from Superior Automotive Engineering solve that problem and are good protection against crazy nitrous over-revs that are likely going to occur later.

Another trick is using a 6.1L timing chain on the 5.7L engine. It requires the timing-chain cover to be clearanced to fit.

If you were wondering, the oil pump on the late-model Hemi is driven by the crankshaft because there’s no distributor.

This was a non-VVT engine equipped with MDS only. Mopar sells the delete kit for the solenoids and you must change to non-MDS lifters to get this to work.

JBA builds a nice set of shorty headers for the Gen III Hemi. It has a ball flange already, making us think of how that will fit the new ball-flange turbos we’re seeing on the internet.

How is this better than a 5.7L crate engine? It makes 60 hp more, it has forged guts instead of nodular iron castings, and best of all, you built it yourself.

Parts List

Description PN Price
32-tooth reluctor TR-32 $47
ARP crank bolt ARP-147-2501 $37
Balancer 6.1L 594-325 $39
Crane hydraulic roller cam 1989501 $438
eBay 6.1L cranks 2008 2 for $100
Gaskets set CS 26284-1 $107
Holley Ultra XP carb 80803HBX $809
Head gaskets HS 26284 PT1 $89
Intake manifold MOPAR $950
Main bearings MS 2220H $108
Melling oil pump MEL-M342 $117
Milodon oil pan 31002 $412
MSD HEMI-6 120-6013 $520
Rod bearings CB 1808HN $95
Roller lifters P53021720AE $99
Spark plugs LZTR5A(16) $85
Shaft rocker system Superior Automotive CALL
Take Out HEMI 2006 $1,000
Trick Flow pushrods TFS-21457000 $119
Timing chain (5.7L) TC-CLO-9-0704S $76
Valve springs 99831-16/1989501 $214
Wiseco H-beam rods DH6243ANLB8-A $666
Wiseco forged pistons K466XS $825
Scott Moseman
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