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hi; this is something I've been working on as a potential help to someone who is wondering if the LS4 is the right engine for their project. It is mostly general rather than specific but does say if you can or can't do 'certain things'...
Right now (I'll remove this caveat later when my level of confidence is satisfied - I'm hoping for input from others on the forum) it is based on info gathered from all over and put into one place, specific to the LS4.

As noted below I got burned by a feature of a V6 engine that wasn't apparent to me until I got quite a bit deeper into the project. So this is meant to be an overview, but also a 'what you can and can't do' - with this motor. Tuning the ECM might turn out to be one of the bigger things. Transmissions are a limiting factor and I don't go into them, either.

I hope forum members will come forward and add to it and help get the info corrected where it isn't right - I have made every effort I think to get good info but I haven't tested ANY of this yet - not in a running car, at least.

Feel free, of course, to ask questions; that is the purpose of this. If something isn't clear then it will get 'looked at'.


Preamble:
This is intended only to be a ‘primer’ for people curious about, or considering, the LS4 for a project of some sort. I ‘discovered’ the LS4 almost by accident and set about pursuing information on it – after being burned by a single-but-important detail of the 60*V6 I had been planning on using... If I wanted to use a different cam in it, I had to go to an earlier ECM; at least OBDII and likely OBDI. It was a show-stopper for me.
I wanted to see if there was some issue with the LS4 that would impact its use in my project. (Happens to be a fiero swap-in but that is irrelevant here).
In my research, I found myself checking almost countless threads on an almost equal number of forums, websites, testimonials etc. This is a sort of compilation of all that: I haven’t tried, tested or proven any of these things; I have just tried to get the info I found into one place.
For the above reason, I invite editing and input from anyone and especially those guys who have years of experience under their collective belts. I don’t intend to go into a lot of detail, especially where items are well detailed elsewhere. If I can, I’ll point to some of those sites. I don’t intend to discuss the weakness of the LS4 – the auto transmission – leaving it as ‘outside of this scope’. I also won’t go into a lot of detail on the other members of the LS family for the same reason.
So, all that being said, I hope this saves someone some time and effort and maybe also saves some of the acknowledged wizards of this engine some time in sending individual emails and PM’s as they did so helpfully with me!
Thanks to all the people who have taken the time to put together the tons of threads and articles that simply helps all of us!
Resources:
Read also: https://ls1tech.com/forums/ls4-perfo...-4t65e-hd.html
And
https://ls1tech.com/forums/ls4-perfo...formation.html
For some good technical info.
Some resources: (I haven’t used any of these, at least yet; no doubt there are lots more!)
http://www.ls4store.com/
http://www.briantooleyracing.com/
http://www.neweraperformanceparts.co...d=46&Itemid=53
http://www.guerragroup.com/#!camshaft-help/c1mq5 for cam recommendations; (Pat G)
RockAuto has many/most parts for this engine series, including brand names.
Will Handzel's "How to Build High-Performance Chevy LS1/LS6 V-8s" is a well-regarded reference book on interchangeability of parts among (at least) the Gen III engines.
Background:
The LS-x series of engines was a brand new and complete departure from the decades-old small block chev series of engines that shared an extensive array of parts and features. It was introduced over time in various ‘Generations’ – we are currently up to 7th Generation - with at least 30 different iterations in the family; including both aluminum and cast iron truck blocks that are generally termed ‘Vortex’ engines. There is lots of interchangeability but it is not total. Happily, lots of stock GM parts can be used in achieving significant HP increases for the LS4!
Overall LSx family displacements range from 4.8L to 7L and all are of the small block configuration, albeit with all-new architecture. This thread addresses the car engines, specifically the 5.3L LS4, which was specially designed to sit in a transverse, front-mount, front wheel drive arrangement in the 2006-2009 Chevrolet Impala SS, 2006-2007 Chevrolet Monte Carlo SS, 2005-2008 Pontiac Grand Prix GXP and the 2008 Buick LaCrosse Super. It is a Gen IV engine with ‘cathedral port’ heads. All of these cars had automatic transmissions exclusively; there were no manual options. ECM’s will reflect that (TCM’s are used). The LS4 ONLY has a metric bell housing/bolt pattern – it will bolt to the 60 deg V6 manual transmissions (if you can figure out the clutch and flywheel reqts!) and is NOT readily bolted to almost any other transmission (ie for rear drive cars). Otherwise the stock automatic is the usual and only choice...... The starter motor bolts to the transmission, as a last item; not to the engine.

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to finish (it was too long)

The first versions had an economy feature named Displacement on Demand (DoD) by GM; this term was changed to Active Fuel Management (AFM) after about 2007. There are numerous articles on this feature elsewhere in this and other forums. The extra oil volume required by the DoD system requires a higher volume oil pump than others in the series. It also uses a drive by wire (DBW) throttle body setup.
The LS4 has a shorter crankshaft (shorter at both ends) and unique ‘front end’ attachments such as the harmonic balancer and accessory drive items (single belt) as well as special ‘shallower’ water pump – all so that it can be shoe-horned in between the shock towers of these front drive cars. It also has a structural aluminum oil pan that (edit: does NOT feature!) special internal baffling to help keep the oil pump pickup immersed under hard acceleration and cornering. (EDIT: there seemed to be confusion on this item but there is no evidence of any baffling in the oil pan after all.) It is not easily (or at all) interchangeable with other LS pans. As with other LS engines it is part of the 6 bolt crank mains support system.
One restriction of these all-aluminum V8’s is that they have relatively thin cylinder (liner) walls. They can’t be freely overbored as with the older SBC’s. They are very limited in how far they can be upsized. They feature a well-regarded cylinder head – the 243 casting – which is the same as the LS6 heads. These will support significant power increases as-is (ie with cams or other upgrades). Head bolts are torque-to-yield types; they cannot be reused. ARP makes bolt and stud kits that fit. Head bolts are 11mm x 2mm threads, for purposes of chasing threads prior to rebuild.
(Edit) Cam:
For 05-06 the stock cam was 3 bolt. Then it was switched to 1 bolt for 07. This cam and timing set is a 4 reluctor, single row, 1 bolt system that has relatively few stock-type upgrades although there are some available which will retain the DoD (or AFM) function. Sources include Competition Cams, Cam Motion and a number of others. Eliminating DoD/AFM can be done, providing lots more selection. The location of the cam sensor needs to be checked and taken into account. (Input needed!). The stock rockers are needle bearing shaft mounted rollers with a 1.7:1 ratio. They can be upgraded with a ‘trunnion kit’ but there seem to be mixed results with some of these wearing out or failing early. Research req’d. The stock lifters are hydraulic roller type, individual lifters. There are ‘special’ ones that work with the DoD that can be replaced with conventional if the DoD is being deleted.
Biggest ‘bang for the buck’ for more power is to upgrade the cam; often in conjunction with a DoD delete as it ‘opens up the field’ to a very wide selection of cams. The engine front configuration means a single row timing set and this can’t readily be upgraded to a double roller or other as a deeper cover won’t fit (info needed!). A well-respected timing chain seems to be the Katech C5-R which apparently was developed in racing corvettes.
Swapping in an LS1, LS2 or LS6 intake manifold is another very common update as the stock, plastic LS4 intake is restricted at its neck by the oil pressure sending unit (OPSU) and it takes some work to eliminate this restriction. It is noted that the LS4 has its intake ‘swapped’ end-for-end compared to other LS engines; the throttle body actually opens over the transmission instead of the front of the motor (accessory belts and pulleys etc).
This intake manifold update is usually paired with a throttle body and fuel rail update; again to an LS1, LS2 or LS6, depending on what is to be done about the DBW system. The MAF effect on a swap or upgrade is significant in a number of ways that go far beyond this article. (See the sticky on MAF’s; also a Link to a good article/thread?) Simply LOCATING the MAF in a good spot for linear, laminar airflow is a challenge given the plumbing limitations of the underhood area. Attaching it directly to the airbox seems to be one approach that at least eliminates possible turbulence at entry. Smooth transition leaving the MAF is still needed.
There is a seemingly significant complaint about oil consumption that GM finally addressed – in a fashion - by recommending an upgraded oil pan gasket that incorporates an oil ‘deflector’ that stops oil from spraying on the undersides/sides of the pistons and (long story short) ‘plugging up’ the ring grooves in the pistons, which contributed to oil consumption of about 1 qt/1000 miles or worse! This is partly in conjunction with the DoD but at this time it is not clear what else might be done. The GM bulletin also recommends soaking the ring lands in solvent to help ‘free up’ the rings – then changing the contaminated oil etc etc as part of the ‘fix’.. The new oil pan gasket is GM P/N 12643081.
A suggested part of a DoD delete is to install a stock LS2 oil pump which is ‘standard’ volume and pressure.
Performance Upgrades:
This is simply a list of what I have seen people say they either will do or have done. A search of LS4 upgrades will give any number of links etc. A reliable contributor to this forum is getting about 385 WHP in his swap and retains the DoD function for highway driving. My goal is over 400WHP; cam yet to be decided.
All of this appears to be doable with relatively little cost given the HP increases that can be realized. The common sentiment is that the LS4 bottom end can support to mid-400’s crank HP without failing. I don’t know what proof there is of this. Beefing up the rod and main bearing bolts seem to the first item of business if more hp is wanted. Note that GM parts from other LSx engines can be used in a number of situations, for bonus availability and reliability!
• LS2 or LS6 intake manifold (stock or aftermarket); note that ‘certain’ aftermarket ones won’t fit;
• OPSU mods to help intake ‘neck’ restriction;
• Cam upgrade; A not-too-aggressive cam should give more than 400 WHP according to a very knowledgeable source;
• Valve spring upgrade to suit cam;
• Port matching;
• DoD delete; replace with all-stock roller lifters; Valley pan replacement; stock parts can be used;
• LS2 or LS6 throttle body; DBW or cable as preferred;
• 88 mm MAF (upsized from stock; use another from the LSx series!)
• Exhaust – freer flowing in some fashion; stock LS7 exh manifolds are a great upgrade.
• Larger injectors to suit HP goals; again stock ones can work!
• ECM tuning.


Hope this helps!
GP

ghlkal

iTrader: (1)

GP, this is a great idea! Thanks for taking the time to put this together. I'm sure it will be helpful for folks who are considering the LS4 for their project.

SteveCZ28

iTrader: (1)

this is great information here. thank you for taking the time to put this all together for us

spawne32

iTrader: (2)

I was under the assumption that ALL LS4's are 3 bolt cams, not just 05-06.

lVloses

iTrader: (1)

07-09 are 1 bolt. You can easily change that though. I'm running a 3 bolt cam in my 08.

91parkave

iTrader: (4)

The 07 08 v8s went to a 58x system, single bolt cam setup. This was the case for other vehicles as well to utilize the e38/e67 pcms

spawne32

iTrader: (2)

Just running the 3 bolt timing gear set cloyes sells? I assume the cam position sensor pickups are still the same?