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PERA Core Corner
Intro To DaimlerChrysler’s 4.7L: No Prerequisite Required
By Roy Berndt
The planned demise of all LA Chrysler engine configurations was already in the wind for some time when the Power Tech 4.7L SOHC
engine was introduced in the Jeep Grand Cherokee in 1999. Not only was it the first clean sheet design V8 for Chrysler in 41 years, but it was the first full production Mopar with aluminum cylinder heads (we are not counting the 1965 Hemi).
Well, here we are in 2003 and guess what? They are coming out of
warranty, so where are they starting to show up? In each and every one of our shops throughout the country! So we thought it might be a good
time to take a look at some of the changes and some of the things that stayed the same.
There are three different flavors of this engine: Standard, HO and NGC (Next Generation Controller). Where did Chrysler put this engine and when? In 1999-2004 the Grand Cherokee got the Standard engine and in 2002-’04 the HO was an option on certain models. The Standard engine was also in the 2000-’02 Dakota and Durango with the Ram P/U being added in 2002 as well. In the latter half of 2002 the Durango received the NGC engine and in 2003 Dakota and Ram were added to that collection. To the best of our information right now, certain models of the Grand Cherokee are the only HO applications.
We have seen the blocks three different ways: without detonation sensor bosses in the valley; with detonation sensor bosses but not drilled and tapped; and with detonation sensor bosses drilled and tapped. What we have ascertained to this point is that the detonation bosses are required for the HO applications only.
All blocks carry the same casting number – 53020661AB, AC.
The crankshafts are the same for both the Standard and NGC engine
applications except for one little difference – the bolt-on spark trigger or reluctor ring. By the way, the reluctor rings are not available anywhere except on a crankshaft so they have two different part numbers. The Standard and HO have 16 points of reference and the NGC has 32. So if you’re going to scrap any 4.7L crankshafts you may want to pull the reluctor ring (see Photo 1). These crankshafts have c/n 53020683.
The crankshaft for the HO is forged steel and has forging number 53021409AA. Both cast and steel crankshafts have a common rod journal but there is a narrow ridge in the center thereby controlling each individual connecting rod side play and oil bleed out (see Photo 2).
The camshafts are different between the Standard and HO, yet we have not been able to verify if there is a difference for the NGC application. However, the cam gear on the right side of the engine does change in the NGC application, but is clearly identified by NGC stamped right on the gear (see Photo 5).
Lastly, we will look at the cylinder head. The same heads are used for both the Standard and NGC applications c/n 53020801 7L for the left head and c/n 53020802 3R for the right head. The head for the HO has different combustion chambers and the engine uses different pistons. HO is cast right on both cylinder heads along with the chamber difference making for easy and quick identification. (see Photos 3 4, 6,).
Well, that should give you enough to chew on for a bit. I am certain that some time in the future you will see a complete article on this engine because production numbers are huge. In the mean time this is the kind of information research that takes place for PERA’s SourcePERA software. So if you’re interested in the "Yellow pages" of casting information, contact us at www.pera.orgor email me directly firstname.lastname@example.org and we will find a way to help. This information and collection of photos would not have been possible without the help of Bruce Chapman of Ontario Reman and Doug Anderson of Groom’s Engines.