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07-21-2013, 02:26 PM #1
Good torque cam for "mostly stock" lq4?
Hello everyone! Due to my mis-fotune, or good fortune depending on how you look at it, the heads from my stock lq4 are going to pay a visit to my local machine shop. The previous owner broke of some exhaust manifold bolts inside the heads when he changed the clutch.. The engine is my 2003 2500hd with the NV manual tranny. While the heads are off I'd like to see about upgrading my cam and getting more torque and power from the truck. I am also going to do an electric fan conversion on it, and a kn filter. The truck has a dual 3" exhaust from the cats back using dual flowmaster 40's. It does not have a H-pipe. A future upgrade will be long tubes and a H-pipe for thr exhaust, I will be leaving the stock cats in place.
I am looking for suggestions on a good cam to use. I am toying with the idea of having some port and valve work done to the heads and possbily having them milled to bump the compression ratio a bit. Depending on cam specs and price I may leave the milling portion alone. I know that if the heads are milled a lot more work and parts (push rods) are involved with the cam.
So what are your suggestions and do you have any power numbers to back them up?"A good plan violently executed now is better than a perfect plan executed next week."
George S. Patton
07-21-2013, 03:00 PM #2
Well I don't have any recommendations (sorry) but try emailing Comp Cams. Answer their questionnaire and they will contact you and give great customer support. I emailed them letting them know I was interest in their cams and what I wanted out of it and they contacted me giving me great options and kits that were well priced instead of recommending their highest priced units.Objects in mirror are losing
2003 Chevy Silverado Z71, 5.3L, K&N 57 series, 2.5'' Flowmaster Super 10 series dual exhaust , Corvette Servo, McNew Automotive Dyno tune, SS gauge cluster, Extang Trifecta Tonneau, Pacesetter shorty headers, Goodmark cowl hood, Sony Xplod speakers, Kenwood DDX-470 exhaust tips, 16" Ultra Badlands polished wheels, Pirelli Scorpion ATR .
07-21-2013, 09:33 PM #3
Forget the long tubes. Install the H pipe, or convert to a single 3" system, maybe with dual outlets in the back. If you want low end torque, the true duals aren't helping, as you're losing back pressure across the banks. Long tubes will also not help with low end torque, as they are better for higher end. If you want headers, get some shorties. The Banks Power shorties are pretty good (but also expensive).
I don't recall which cam is in the LQ4 stock, exactly. The stock cams tend to be geared more toward low end torque than aftermarket options are, as aftermarket cams are generally ground to bump power across the range as best they can. Since GM have to try and meet certain MPG standards for their fleet, and one of the best ways to improve MPG ratings, is low end torque, the stock cams tend to try to do that pretty well in the engines they're in. Would have to find the numbers for the LQ4 cam, but another OEM cam might be better than an aftermarket for what you want there. There are a few "MPG" cams on the market though, so just look at them, and compare the numbers. Most of them aren't going to give a particularly large bump in low end torque though.
Electric fan will help a tiny bit, so I'd do that, but it will only be a very tiny bit.
As for the K&N filter, don't bother. If you've still got the stock intake tube, get the Airaid MIT, to improve flow into the engine, and stick with stock replacement filters. I installed the tube on my Avalanche, and while no major improvements, it does sound a little better, and it picked up a tiny bit of MPG (so a tiny amount of low end torque).
As for head work, porting might help a little, but I wouldn't go as far as mirror polishing them. For low end torque, a little porting work, mostly with doing port matching to the intake/exhaust. If you want to mill the heads, I wouldn't go very far with them. Maybe 0.015" taken off, at most, or maybe just use a thinner head gasket. Take off too much, and you might have to switch to higher octane gas. If you want to do that it's fine, but if not, you don't want to bump the CR up too high. If you keep the milling under 0.015" though, you should be able to use the stock length pushrods, and not have to worry about getting higher octane gas, though. I'd stick with a port match, removing of restrictions if possible, and a good valve job, on the stock heads. There are some odd bits in the ports that can't be removed on that generation head though. Another option would be to swap the heads with a different set, if you want to spend the money to do so. The Gen IV heads flow better with less restriction, but you'll need a Gen IV intake as well, since the port shape changed. Which also means a Gen IV throttle body (or an adapter plate for the smaller Gen III version. I don't recall if that year was still cable driven or electric, but if it's cable, you'd want to go with the adapter plate, or find an aftermarket throttle body for the Gen IV intake that can be cable driven.
A lot of info there, I know, but hopefully it's helpful.
08-29-2013, 07:23 AM #4
212/218 low lift or even a tr 220 cam on a 114 lsa are great cams for DD trucks. i have the 220 in mine and a 3000 stall and the truck pulls great even with 33" tires and 3.73 gears.2004 gmc sierra ext z71 5.3
KB racing hot pipes 3.5" : 76mm turbo: 4l80e : Circle-d 2b multi disk :Walbro 400 : Racetronix Hotwire kit : TB coolant bypass : Nelson 91 Pcm : Tr 220 Cam : Brian Tooley double springs kit : Ls7 Lifters : Stage 3 heads : Custom Intake Manifold :80lb Injectors : Ported TB : 40k tranny cooler: Plx dm-100 gauge: Auto meter fuel and boost gauge:
Custom Speedo : Leveling kit :Smoked led taillights and 3rd break light : Black projectors and fogs with hids : Blacked out grille : 33's on 16's : Clarion flip screen: sound que 12" subs: clerion 6x9's : Memhpis amps: Alpine componet set.
Future mods... Detriot tru-trac, deviels own stage 2 meth kit, MORE BOOST!!!!!!!!!!!!!!