This posting is one in a series. If you have not yet read the earlier postings in the series, you’ll need to, as this posting won’t make much sense without having done so! Just do a search using the word “SLURP”.
In postings 11,14, and 15, I described how a salvaged GM LQ9 6.0 liter engine was selected to serve as the basis for Red’s new “heart”, and how the new camshaft which will change its personality so completely was chosen from a field of literally thousands of candidates. In this posting, I’ll describe in some detail how that camshaft, and some of the components needed to make it effective, were installed last evening.
Bear in mind as you read this that ALL the work described within this posting can be duplicated, with only minor changes (e.g. exact profile of the camshaft) on ANY (yes, any) of the GM LS series engines. Since the LS series has been the V8 used in virtually all GM products since about 1999 (except for Cadillac Northstar engines for example), that means this posting is literally applicable to almost any GM V8 of recent vintage. As I have discussed in numerous earlier postings, all the LS engines use either identical or almost identical parts that vary mainly in displacement dimensions, ability to sustain high rpm, and strength under high-stress conditions. For example, the LS2 engine used in recent Corvettes and SSRs differs from this LQ9, which came from a Cadillac Escalade SUV, only in block material (aluminum versus the LQ9’s cast iron), camshaft profile (higher rpm focus versus the LQ9’s torque focus), compression ratio (10.9 versus the LQ9’s 10.1) and intake manifold (higher rpm/lower physical profile than the one on the LQ9).
It’s important to understand that the entire LS series is high quality. I am not replacing low quality components with higher quality ones when I do this hop-up. GM’s selected components are very good ones, whose important attributes center around reliability and durability under the ambient and rpm conditions that its vehicles were designed to work under. However, we hot rodders tend to place our focus more on performance and a little less on durability than GM. The changes made are intended to support that different focus.
In general, that means either enabling the engine to reliably spin at faster rpm, OR increasing the amount of work it can do each revolution. The reasons are simple. An engine does a certain amount of work each revolution of its crankshaft. Work done per minute by an engine is equal to the amount of work it can do each revolution of its crankshaft times the number of revolutions per minute. If we increase the work done each revolution (e.g. via a supercharger), we increase the engine’s power output. Likewise, if we spin its crankshaft more often per minute, we increase the amount of work it can do.
On my last project vehicle, my 2004 Chevrolet SSR, I did BOTH, by installing a supercharger (more work per revolution) and improving the engine’s ability to spin faster via higher rpm camshaft, free flowing exhaust, and cleaned up intake tract (more revolutions per minute). The SSR NEEDED both, as its curb weight with half a tank of fuel, supercharger, and driver exceeded 5000 pounds.
On Red, doing BOTH is ridiculously unnecessary.
Red weighs only 3000 pounds dry, or 3275 pounds with half a tank of fuel and me, because he is a very simplistic vehicle compared to the SSR. He is lighter than a Corvette Z06 for example. He is also rather front end heavy, seriously limiting how much power can be applied through his rear tires before they merely spin and turn rubber into fumes. Because he is so light weight, he will be as quick as my SSR was if I equip him with just 375 crank horsepower and manage to get 78% of that power to the ground. In other words, the STOCK LQ9 (345 hp at 5200 rpm) would make him almost as quick as my SSR, and anything I add to the LQ9’s power will make him even quicker.
The engine simulation software says that the changes we will make to that LQ9 will increase its work produced per revolution slightly, and its number of revolutions per minute dramatically (from 5200 rpm peak power to 6500 rpm). The software says this should cause it to produce a minimum of 425 crank hp, if we are space-limited in our ability to accommodate exhaust headers and if the dual carb Edelbrock RPM Air Gap Performer manifold does not work as well as the single carb one does (don’t laugh – that IS possible). If we DO have room for the exhaust we want, and if that dual carb setup really works as well as it looks, the work per revolution will rise a LOT, and the software says we’ll see 505 hp at the crank at 6000 rpm and above, and Red will flat FLY.
Besides the Edelbrock dual carb 1000 CFM setup and the MSD reluctor-triggered ignition that comes with it, we need a few other key pieces to be able to reliably spin our LQ9 to 6500 rpm versus the stock 5600 rev limit and the stock 5200 rpm point of peak power. They will include:
- Crane camshaft part number 144HR00053, which likes the 2400 to 6500 rpm range to work well in, but generates strong power even at 2000 rpm (over 130 crank hp at 2000 rpm) or below. This cam will work with factory exhaust manifolds, but will really shine with headers and large free-flowing exhaust system. This cam needs much stronger valve springs than stock to handle its more aggressive lift (0.551” at valves versus 0.479” stock lift) and moderate ramp acceleration rates. The higher spring pressures and higher working rpm necessitate stiffening up the pushrods to avoid their bending or deflecting at high rpm (which will lower actual valve lift, destabilize the valve train, and eventually cause a failure).
- Competition Cams valve springs, part number 26918. These are the very best springs Comp Cams offers. They are beehive shaped, like the stock springs, so they will not resonate and so do not require a dampening inner spring, making them lightweight while strong. They have MUCH higher spring rates than the stock springs, generating 125 pounds with the valves seated and 367 pounds fully compressed. Since the springs chosen by Crane itself for their cam generate only 112 pounds closed and 303 pounds open, the Comp Cam springs are easily an overkill. They also have an easily visually discernible advanced micropeened finish. They can handle up to 0.625” lift – way beyond the 0.551” we need here. Note that they are NOT lighter than the stock valve springs, being 2.6 ounces each versus 2.5 ounces for the stock ones. As I said, the stock GM parts are good ones! However, these Comp Cam springs are visually MUCH larger and stiffer, and so the fact that they weigh almost nothing more is very impressive.
- Manley pushrods, part number 25735. These are 4130 steel, 5/16” diameter pushrods with 0.080” wall thickness and swedged ends. They are identical in length to the stock pushrods, at 7.400”. These guys are stiff and tough, and Randy liked them a LOT when he examined them prior to installation. At 1.9 ounces each, they are, like the valve springs, heavier than the stock 1.8 ounce pushrods, but again, their stiffness is very superior, and their swaged ends are on a different planet in terms of quality.
- To help make up for the slight increases in valve spring weight and pushrod weight, we went with Titanium valve spring retainers. These are so light they challenge the postal scale I use, but the scale showed them at 0.2 ounce each, or half the weight of the stock retainers which scaled at 0.4 ounces. These guys, despite their diminutive size, cost more than the pushrods and more than the valve springs, because of that exotic Titanium construction!
- Because the engine will be now making much more power and much more heat, we needed colder sparkplugs to prevent a sparkplug meltdown or engine pre-ignition as a result of too hot plugs. And, unfortunately, you don’t just go down to your local auto parts store and ask for plugs suitable for “a modified LQ9 in a 1955 Chevy 3100 pickup”! You make an educated guess, and you try to go TOO cold versus not cold enough, as the penalty for an incorrect guess is only fouled plugs if you guess too cold, but damaged engine if you guess too hot. I went with NGK TR6 plugs, which are what I used successfully in the hotter SSR engine, so at worst, they may foul prematurely.
This, and a number of gaskets and seals, are all we needed to make this rather dramatic change in the LQ9’s personality. Here’s a photo:
http://i252.photobucket.com/albums/hh16/JimGnitecki/Engineupgrades001components.jpgBut, don’t let anyone tell you “cam changes are cheap”. The cam, springs, psuhrods, retainers, gaskets, and seals cost almost $1000. Notice that this does not include a dual heavy duty timing chain nor reworked water pump or ported oil pump, as these kinds of additional precautions are only warranted when you anticipate prolonged high rpm use - like roadracing – and the thought of a high center of gravity 55 pickup with leaf springs doing roadrace laps SHOULD be enough to make any sane person giggle.
I also needed a few hours of Randy’s VERY skilled time, even though the engine currently being on a stand versus installed in a vehicle certainly cut the time needed very dramatically.
The $400 cost of a good roller tappet cam is truly “the tip of the iceberg”.
So, how did we actually do the install? Like this:
- Removed valve covers
- Loosened and then removed rocker arms on each cylinder bank
- Removed rocker arm base on each cylinder bank
- Removed all pushrods
- Removed the crankshaft harmonic balancer (not for the faint of heart – torqued to 240 ft lb among other things)
- Removed the front engine cover
- Removed timing chain (don’t disturb the oil pump and especially its pickup tube bolt)
- Removed cam retainer
- Threaded bolts into camshaft end and SPUN the camshaft a couple of revolutions. (This is a critical step that raises the hydraulic lifter assemblies so they don’t interfere with extraction of the cam. On any LS engine, the lifters will behave this way and will STAY up for “a reasonable period of time”. If you screw this up, you are forced to remove the HEADS to fix the error, so don’t screw it up)
- Gently and carefully slid out the stock camshaft, being careful to not damage the internal bearings during the process.
- Cleaned and carefully prelubricated the new camshaft (roller tappet cams like this one need only engine oil prelubing, but FLAT tappet cams require a special break-in lubricant and very specific engine startup and rpm procedures!)
- Carefully and gently slid the new camshaft into the engine
- Re-installed the frontend parts removed, using new gaskets and seal, and observing all torque specifications for all bolts
- Used a special valve spring compression tool to remove the old springs and retainers, and install the new ones. Here’s a photo of the tool in use:
http://i252.photobucket.com/albums/hh16/JimGnitecki/Engineupgrades005valvetoolinuse.jpg- As we worked on each cylinder: We applied air to the cylinder via an air compressor. This kept the valve from dropping into the cylinder when the valve spring keeper and retainer were removed. With the tool compressing the spring, the TWO keeper halves were removed via a miniature magnet, which released the retainer and spring. The retainer and spring were removed and replaced by a new spring and retainer. With the new spring and retainer under tool compression, each keeper half was inserted by hand until it “snapped” into its correct position. With both keeper halves in, the tool pressure was released. After both valves in each cylinder were done, the air supply was moved to the next sprark plug hole, and the entire process repeated. All sixteen valve springs were done this way.
- Randy commented on how much stronger the spring force against the tool was with the new versus old valve springs. It was a dramatic difference. In this photo, you can see both the larger sixe and the unique finish on the new spring (end position) versus the old spring right beside it:
http://i252.photobucket.com/albums/hh16/JimGnitecki/Engineupgrades004newspringvsold.jpg- Each valve cover got a new Felpro gasket:
http://i252.photobucket.com/albums/hh16/JimGnitecki/Engineupgrades007newvalvecovergaske.jpg- The re-installation of the front cover is a precision operation, as the cover bears on BOTH the front of the engine and the structural oil pan. You can see the 90 degree junction of those two separate sealing surfaces here:
http://i252.photobucket.com/albums/hh16/JimGnitecki/Engineupgrades008frontcovermounting.jpg- Finally, knowing that I would be doing a lot of VERY messy wirewheel cleanup of the chassis and axle assemblies, we wrapped the engine inside two separate “engine bags” to keep the dirt and grit out during the festivities:
http://i252.photobucket.com/albums/hh16/JimGnitecki/Engineupgrades009baggingtheengine.jpgAfter all this, Red’s new engine is ready for insertion into the chassis, but before we can do that install, we need to finish cleaning the chassis components, and reattaching Red’s suspension. But, the suspension will be brand new, and the subject of a future posting coming up.
Jim G
