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I have an 02 Silverado with a 6.0, it's a crew cab long bed LT lifted 7 inches on 35s, soon to be on 36x15.5s and with 230k miles. So as you can imagine it needs some help with power. I plan on doing the head swap and also keeping this thing somewhat as reliable as it has been. It will be driven somewhat often but not full throttle all the time. I have done lots of searches but I can't find the information I need for my application, so Here's what I planned on doing:
L92 heads
LS3 stock intake
90 or 92 mm TB (can't remember which one I looked at)
42 lb 8.1 marine injectors
Here's where I need some input. I know that the bottom end on these motors are very strong from the factory, but with 230k miles and my truck weighing a tad below 7000 pounds (according to local scrap yard scale) will my stock crank and rods hold up to the 500+ crank hp that everyone claims to be getting from this head swap? I had planned on putting new Pistons and rings (oem) and all new bearings in it along with ARP head bolts and connecting rod bolts. But should I reuse the crank and rods? And my second question, I'm not sure what cam would be good. I don't plan on going over 5k rpms, so I'd like to find a cam that would have better low-mid power and I have no idea what would be a good choice. And my last question (for now) I plan on building my 4l80e at the same time I do the swap. How built do you guys think it would have to be? Thanks guys for any input you have!
And yes, I did try performancetrucks.net
Last edited by Steven Eaton; 03-15-2015 at 06:33 PM.
The rectangle port heads is a rather ignorant choice for a build staying under 5000rpm. Those shine at high rpm not low.
HP is a function of torque at a given rpm, with a low rev limit you won't make a big HP number, chase a HP number and the truck will not perform well in normal driving.
The crank is bulletproof a polish will suffice.
The rods could use reconditioning at which point most just go aftermarket instead.
Pistons will need to be bigger as the block will need to be bored.
I went ls3 intake with the oe 42lb injectors, l92 heads and it really pulls in 3rd above 80. I used an ls6 cam and just recently went custom and haven't used it yet. You will loose some low end torque.
I have seen several dyno sheets with these heads and different cams, so I know they don't make the 500+ until past 6k, I also like how much it makes from 3-5k rpms. It's MUCH better than the stock lq4 at its peak performance which is also in the 6k rpm range.. I Meant more that since it's driven often and I still want to get miles out of it that I won't be getting above 5k often but I guess it doesn't mean it won't happen, especially if I'm making that much power. And gagliano, I thought that since the ls3 heads had smaller combustion chambers that the compression is actually bumped up anyway? I might have just read that from someone who didn't know what they are talking about tho. Thanks for the input guys it's a great help
Last edited by Steven Eaton; 01-29-2015 at 10:28 AM.
Alright well since I'm putting new Pistons in it anyway that's no big deal to put the flat tops in. I was originally going to do that until I read I didn't have to, but It looks like you're right. Thanks for the help!
Alright well since I'm putting new Pistons in it anyway that's no big deal to put the flat tops in. I was originally going to do that until I read I didn't have to, but It looks like you're right. Thanks for the help!
Yeah, flat tops will make more of a difference in compression ratio than going to the LS3 head. 500hp at the flywheel isn't really a goal lofty enough to need an LS3 head either. Honestly, the 317 heads on there now are capable of that.
Hell you don't even need new pistons (unless you just want to take them out and refresh the motor.
Send your 317s to AI for their porting and chamber welding, then run something like 11.5 compression with a cam spec'd for your use (less than 5000rpm) and watch that thing fly and be much more responsive than 280cc port heads.
Ls3 heads are great but you will lose low end. But if you put those on, dont do a ls3 intake in that heavy truck. I would do a l92(6.2 truck engine) intake.
Ls3 heads are great but you will lose low end. But if you put those on, dont do a ls3 intake in that heavy truck. I would do a l92(6.2 truck engine) intake.
I agree and wish I would have swapped to this. I just installed a cam and wonder if it would do well with the truck intake.
Redtan, if I were to run the 317s, would the stock truck intake be ok? I have read it works pretty well for what it is. And I probably wouldn't need 42lb injectors right? The main reason I didn't plan on using the 317s is because people keep saying it's more economical to do a head swap if the head is in good enough condition to just throw on instead of shipping my heads to get ported and have all new valves installed etc. and also, if any of the dyno sheets I have seen are correct, the l92s produce more torque mid 2000s than the stock lq4 puts out at peak which is achieved mid-high 4k or even past 5k rpms I believe. And I have seen more than one dyno chart that supports this. But yes, the l92s don't even produce 200hp until around 2600 rpms and they don't peak until well past 6k rpms. I do realize the cam selection is a big variable in what the motor will do though. With all this being said, I don't see how the swap is a bad choice. I don't expect it to be a power monster in regular street driving conditions, I just want to have the power when I need it, I don't expect it to have peak power within 5k rpms. As for the l92 intake, I actually didn't even think about it because everyone else just uses the ls3/l76 (or a carb intake). But I do agree for my application that the l92 intake would be better and I will probably use it if I do the swap. Thanks for the help again guys, I'm researching hard, it's just a lot of hard choices when it comes to all this haha
Here's my dyno sheet from 2013, my peak HP was around 5400. Granted I was a novice tuner, still am. I remapped VE and MAF but never touched the spark table. I am willing to bet once I tune spark it will kick in a little earlier. This was a stock ls6 cam 204/218 .550/.550
The cathedral port truck intake is good.
Far as dyno graphs, you always use WOT right? That is why you look at dyno charts because they are perfectly representative of how an engine is used?
The newer stuff is DBW which masks a lack of low rpm less than WOT response.
For what you want from the truck cathederal ports are the way to go, you just don't want to hear it because you saw some paid advertizing magazine article.
get your stock heads ported and milled and install a truck cam from Cam Motion (don't underestimate them based on how "small" they look...that's part of why they work)
stock intake will be fine for what you're doing
rectangle port heads would be the last thing I would want to do to boost under the curve power...I won't even run them on my ls2 build in a 3500lb car
Good thread here. I agree with most of the guys about the cathedral heads for your truck. Just be sure it us cammed properly!! I been keeping up with a project truck called blue Magic by GM-EFI..... they installed a BTR truck cam 218/224 into a 5.3 motor. The cam swap alone made 64 horsepower increase and no torque was actually lost in the torque curve which is very important for a truck on 35 inch tires.
Mine uses a tiny appearing 205/210 and was already tuned before and then retuned after the cam. Gained 40rwhp peak but power and tq increased from idle to redline, no losses.
Mine uses a tiny appearing 205/210 and was already tuned before and then retuned after the cam. Gained 40rwhp peak but power and tq increased from idle to redline, no losses.
That's an awesome gain too. Heads are important.... but even with great heads we all need a great cam to match the head of choice :-)
01-28-2015, 11:28 PM
Lq4 l92 head swap advice 
