I have a 2500HD truck with the 6.0L (LQ4) that is lifted and I use it as an everyday driver for now and go to the sand dunes a lot.

I ordered this cam which comes with new lifters and I also ordered the necessary valve springs to support it: http://www.compperformancegroupstore...ode=XFIXTRTRCK

I have exhaust work done and shorty headers. But I am having trouble deciding what to do as far my heads to support the cam. I was going to just install the cam and see where it got me but I would rather do the cam and heads all in one install. So, I was wondering what heads I should get that would support such a cam, or if I should just send my stock ones out to get them ported. I am looking for the most power effective and cost effective option and am not sure what I should do. LS6, L92, Port mine, or any other options?

I hope someone here can help me out and if you need any other info about what I am looking to get or any info about my truck please let me know.

Thanks guys,
Steve

 

Hi Steve, let me tell you my experience with the same cam you bought and I installed in my 05 GMC 1500HD 6.0L 4X4. The Comp cam went in good. I used a degree wheel to make sure it was within the specs stated on the cam card. It was. I matched the cam and crank sprockets dot to dot like the stock cam was and also per the comp cams instructions. Really just a ordinary cam change. No big deal. I used the comp cams beehive springs as well as a new set of comp cams hyd. roll. lifters, dbl roll. timing chain. Longer pushrods were needed and were custom made to size. RESULTS: Using OEM replacement gaskets as needed, stock cylinder heads, headers, stock intake manifold, aftermarket cold air filter, catbacks, etc. the engine breakin done properly and a pro dyno job done, the engine had a high pitched whistle throughout the entire rpm range. VERY annoying. The vacumn would not go higher then 14mmg at idle. Cylinder leak down test showed all cylinders between 4 & 5%. Xlnt %'s. The engine had 25K miles on it when all this was done. Meaning no cylinder head leaks. A complete vacumn test was done to find any other leaks. None found. Pro dyno man stated that low vacumn and whistle is caused by the cam grind and its specs. I did increas H.P. by 46. Torque by 42RWHP. Stock for our eng. is around 305 H.P. The idle was good and I felt a definate power increase. You would need a programmer but a pro dyno is the best way to go, so save your $ and dont just rely on a preprogrammed programmer and put the $ towards a pro dyno man.
MY Opinion...Dont install the comp cam you bought, send it back. You will not be happy with the noise and low vacumn. I've had the experience and I spent the $ and my advise is to look into GM's performance parts "Hotcam", check out the cam specs(centerline is important) as well as equal valve opening heights. And by all means talk to your local hotrod shop. They will give you one on one advise on what parts will do the best for what you want to get out of your engine. By the way, I will be removing the comp cam and replacing it with a different cam from a different company. Also my advise on your cylinder heads is that you use your stock ones and have them ported and polished. Keep in mind that you want to keep the same combustion chamber size as before or slightly smaller. Hope this helps. Good luck.

 

Have you had your truck looked at by anyone else for a second opinion, that is not a very aggressive cam, the XFI lobes are mellow. Its hard to believe that cam would cause your issues. Just because he is a "Pro Tuner" doesn't mean he can diagnose problems.

 

The dyno man I used has been featured several times in hotrod magazine articles because of his specialty of building and tuning newer model computer controlled vehicles. Located in L.A., he uses the newest dyno equipment available. He travels throughout the country going to different shows keeping on top of any new ways to bring more performance into stock factory built engines. I looked at his credentials and they are the best. I trust his word. Going to a mechanic with less expertise would be wasting time. Of course the biggest mistake I made was not in contacting an expert on what cam would be best before I bought it. I learned. My upcoming "tear down" will start in mid Feb.2010. I am going to take his advice on what cam to install and I will post a reply when I know.

 

I wasn't trying to say your tuner didn't know how to tune, but, tuning is one thing. Building engines and actual diagnostics is another. There are lots of "Tuners" who do not build engines or have the ability to actually diagnose mechanical issues or even driveability issues. Those problems are totally different than Tuning. I hope the new cam works out for you. Who did the cam install by the way? Sometimes the double chains have clearance issues, things get connected incorrectly. Clearances are not checked, etc.

 

First off I'd like to say that it sounds like you have a sweet ride. A classic muscle car, right on. I just talked to my dyno man and he is going to bring my specs up and dial in the correct cam for my application. He stated that although the specs shown on cam card make it easier to decide what cam to use ie. mellow, aggressive, etc., it dosent mean the cam will perform like expected. The entire driveline, gear ratios, tire size, valve size, TBI size, mass size, MAP specs, available fuel octane levels (many states vary on thier octane %, etc. all need to be considered in determining the right cam. These newer engines are not as home builder user friendly as engines of the past. Most of my engine building experience has been on older, precomputer engines that are easier to tune and can be done by the home mechanic. Thats why its critical to get the right cam for these newer engines. The new claims of "inside the curve" does not mean that the cam is the right one for these newer engines. All engines are air pumps, but they are not all the same when it comes to "hopping" them up. We have transcended into engines that are more in depth then in the past and with smog control being the leading factor in designing these engines, daily driven modified street machines must still meet the required ratings. Thats why specialty mechanics who work on these engines are ahead of the game and people like myself appreciate their talent.
I guess the bottom line is, know what you want from your engine and research completly before just throwing in a cam because it looks good on paper.
Your right about the dbl. roll. timing chain. It rubbed at first but after some additional work, problem was worked out. To make it easier for the home builder I suggest an aftermarket single roll. chain that is strong enough to handle higher output engines. Enjoy your sweet ride...

 

PS - My dyno man has several cars himself that he has built and enters into shows. They are not limited to one car maker, he has a 650 hp vette, shelby cobra mustang, ford PU, all modified and used as daily driven vehicles which meet smog regulations. He keeps the vehicle he is working on for about a week after he reprograms it and with the owners permission, drives it to see if any adjustments need to be made. He uses a laptop, plugged into the obd while driving so he can keep track of what adjustments need to be made. GPS is used to calibrate speedo. Its a new age for engines...

 

OP, I would get a nice pair of L92 heads/L76 intake for cheap with a custom cam for your truck torque needs. Not worth it to get your stockers ported; lost of time and $$.

Youre lucky to have the 6.0l, so you can bolton L92 for nasty powers...and yeah, take this occasion to get 1 3/4 LTs at least!!

..and put new LS2 lifter trays on your list too, cheap insurance..

 

Ya I think I am gonna get the l92 heads a the new intake just to complement the cam and make the install give me what I am loking for. I do have a custom dyno tune already on my truck that was done by ron bilyeu who designed the callaway corvette tune and he got me35rwhp from it. Unfortunatelly I wil have to have him redo it shen I get the install done but it will be worth it. They also do not make long tubes for my truck unfortunatelly. That is weird you got that sound from the cam, I wonder if it was defective or something. I chose that cam because I told a performance shop what i wanted out of the cam and that was the one they sahd was what fit my application needs. So you had to get new push rods too? Also, I thought that cam package came with pro magnum hydraulic lifters? Do you recommend a new timing chain? Do you know anywhere to get the l92 heads and l76 intake? Finally, do you have any aditional recommendations about my install or any other parts you would recommend I replace or upgrade?

Thanks for all your advice and help,
Steve

 

Ya I think I am gonna get the l92 heads a the new intake just to complement the cam and make the install give me what I am loking for. I do have a custom dyno tune already on my truck that was done by ron bilyeu who designed the callaway corvette tune and he got me35rwhp from it. Unfortunatelly I wil have to have him redo it shen I get the install done but it will be worth it. They also do not make long tubes for my truck unfortunatelly. That is weird you got that sound from the cam, I wonder if it was defective or something. I chose that cam because I told a performance shop what i wanted out of the cam and that was the one they sahd was what fit my application needs. So you had to get new push rods too? Also, I thought that cam package came with pro magnum hydraulic lifters? Do you recommend a new timing chain? Do you know anywhere to get the l92 heads and l76 intake? Finally, do you have any aditional recommendations about my install or any other parts you would recommend I replace or upgrade?

Thanks for all your advice and help,
Steve

 

Ebay for a used LS3 take-off intake. SDparts.com has good prices on the heads.

6.2L headgaskets
LS3 intake rockers
LS3 rocker stand
MAP relocation kit

 

Hey Steve, good luck with whatever you decide. As a fellow truck owner, 4X4 offroader, and engine builder I would like to give you suggestions pertaining to your specific vehicle. Your original post says daily driver and sand dunes, lifted. I too love sand dunes. I go have fun as often as I can. There are 3 amazing dunes in Ca. They are Pismo State Beach, Dumont Dunes(Death Valley), and Glamis Sand Dunes, all within a short drive from where I live. Why am I telling you this? Simple. I know what your trying to accomplish,. You need more torque, power on the low to mid range to turn those tires and keep you floating over the sand. You know what I mean. Anyone who drives offroad in the sand knows that if you give too much gas, you will bury your rig down to the axles and then its dig out time. You also need a good idle on your engine so if you have to rock it back and forth, it wont stall on you. Keep in mind what you want from your engine. I've gone thru what your doing so this is experience and simple advice I'm giving you. Take it or leave it.
If you want to keep it simple then the best way to go, but maybe the most expensive is to leave the engine alone except for the installation of a supercharger. I have a magna charger(eaton style) on my engine now. They are designed for stock engines and come with a programmer inputted with your vehicles specs. Intake is part of the assembly and it is easy to install and has incredible power and torque gains while keeping a smooth idle.
There are 2 heads that are made for our engines. Casting #317 (9.5:1)is what you most likely have. It has a 72cc combustion chamber. The other head is installed in the dinali's. Same head except that it has a 65cc (10.5:1)chamber. Small chamber = higher compression. Thats why the dinali's have a higher output engine. Everything else is the same for both engines. I found it was easier to trick out my heads, knowing that all the parts will fit when I put it back on. You can install other LS heads onto your block, but you may need to change alot of the parts and may have to do some pushrod hole drilling and grinding to get things dialed in. Check on this before you get different heads. You could end up spending alot more time and money then you first thought. Replace your timing chain, you went to alot of work installing a cam so dont take a chance on using your old part. Chains are pretty cheep but critical to the operation of your engine. Get a pushrod checking tool. Yes, if you change cams you will need new pushrods. There is no valve lash adjustments that can be done on our heads. If you have had your obc reprogrammed before, talk to dynoman and see if your new cam will work with those settings, at least until you can get it to him to adjust properly. You can install other intakes onto your engine but check to see if there is alot of rerouting or relocating of parts. The main jist of this is to really know what you want to do, how much you want to spend, and reliability of the end product.
A little about myself: I am a career Firefighter for the largest Fire Dept. west of the Rockies. My title is Apparatus Operator, I drive, maintain, and operate the Fire Engines(pumpers) and Trucks(ladders). I have been in the fire service for 29 years and have worked with and around the Fire Depts. highly trained mechanics. Although I am a first responder, my job is to make sure that the Firefighters on board arive to and from the incident safely, and that the apparatus and equipment onboard all operate perfectly. I am telling you this so you'll know that I'm not just spitting into the wind. Again think of your intended use, going at the speed of light down a dragstrip or having a big smile on your face as your rig sails smoothly but powerfully and reliably over the dunes. I'll be happy to help you any way I can by my own experiences with the same type vehicle you have. Good luck, have fun, tread lightly, and smooth sailing!

 

The truck 6.0L heads are not different. The increase in compression ratio is from the pistons.
LQ4, basic truck engine, 6.7cc dished pistons. 9.4:1
LQ9, Denali, Escalade, SS, flat top pistons. 10:1

 

My 2005 GMC 1500HD 6.0L regular factory output(305HP)has flat top pistons. Not dished. I've seen them with my own eyes.

 

I am not going to argue about it. If you have a VIN U for the engine it is a LQ4, dished piston engine. VIN N LQ9. That is all there is to it. Just trying to keep the OP from getting incorrect information. What is the casting s number on your cylinder heads. It can be seen without removing the valve covers.

The attached pick is the LQ4, not much of a dish, but it is a dish. The LQ9 is completely flat, no valve reliefs.

 

hicks I do not question your knowledge one bit, and I GREATLY appreciate your help and advice man. I wish I could afford a supercharger, that is my dream, but I am thinkin just doing some of the cheaper motor stuff right now and then hopefully getting the funds for a supercharger once I finish college and get a steady job. If I could even find a used one that would be awesome (selling yours soon by chance? haha). I am just looking into every option I have right now so I can decide which one I want to go with. I have just heard those L92 heads are the cats a** and work well on the LQ4 decribed in this article. Let me know what your opinion on this article is cause I do value your knowledge and experience, especially since I am just getting into the technica aspects of engine building and truck performance (http://www.carcraft.com/techarticles...ads/index.html)

 

I don't see any reason why the cam you have selected wouldn't perform in a stock LQ4. It is pretty small in my opinion. Usually the trucks like smaller cams to keep that bottom end torque that is needed. Also the 4L80E tranny doesnt help matters being such tall geared.

Your stock cylinder heads are a good base to start with. The ports are nearly identical to LS6 heads only with slightly larger combustion chambers. You can get those 6.0L heads ported and milled but for the money it would be best to do the LS3/L92 heads. The cam you have chosen would probably need changed to optimize the use of the LS3/L92 style heads. The newer heads like a bigger intake exhaust duration split than the cathedral port heads do.

So basically you need to lay out a plan of exactly what you are wanting and match the parts. The cam needs to match the cylinder heads and combo.

 

Okay I understand. So if I am going to stay with this smaller cam, I should probably stay with my stock heads and not do anything but the cam and required components like springs, valves, etc...If I do go with the L92 heads, and the L76 intake, what cam would you recommend to keep the torque and power on the low end? I havent bought the cam yet but I chose it because I didnt plan on doing heads with it. But hearing what I have heard from you and my other experienced buddies, If I am going to do the cam, then I might as well go big and do it all at once and spend the extra money. I just dont want to fork over $700-1000, get like 30-40hp, and wish I did more. So i figure I should probably chose a different cam that should support those L92 heads that everyone is saying are bad a**. Thanks for your help guys I am really learning a lot from what u have been saying and I just really wanna make sure I know what all I am going to have to do/buy before I get into this project

 

The LS3/L92 heads have impressive flow numbers and all but they arent "That Badass". In my opinion I'd stay cathedral port for your case due to the smaller intake runner which will increase port velocity to help your bottom end torque.

The big question is do you pull/tow/haul alot or is this just a truck you are daily driving and want more umph?

With those things considered if you tow/haul alot then you need to keep the cam below 220 duration. The good thing with this is you can get by with yellow LS6 valve springs which can be had for under $70!

If you don't tow/haul alot and just want to be quite quicker than you are now then I would look into something in the low-mid 220's duration. I have a buddy here in KY that is running an LS1 with a 224 cam in his 1500 2wd SCSB truck and run's 12's with it! Thats not gonna really be your result if you are 4wd with a 4L80E cause of weight and powertrain loss. But still something to consider on your setup cause it should still increase power significantly without sacrificing bottom end.

Another question... are you going to put a convertor in this truck or keep the stocker? That will ultimately determine how big you can go on the cam as well!

 

Originally I was just going to do the comp cam 54-452-11, springs, and lifters, but now I have decided to get long tube headers instead of the cam for right now, use the money i saved from the cam purchase to fix the motor on my jetski to sell, and then use the $2200 + from selling the ski to fund this project to get it done right.

I wasnt planning on a new converter and I do tow with it a few times a year. Ultimately, I want to get this project to get me as much power for the least amount of money, but also want it to be done right (so I will pay extra $ to do so). What would you say should be my parts list for the project to get me the most low end torque, work as a daily driver, give me as much umph as possible, and still allow me to tow on occasion (from your professional opinion) What make/model cathedral heads? what cam have u heard works well with them? what type of intake if I have to change to compensate the new heads? And any other parts you think I need to include to match?

Sorry for all the questions but you guys seem real knowledgeable about this stuff and I am just starting to really get into it and learning as much as I can so I am really trying to pick your brains and expertise. Thanks again guys you have taught me a lot so far