Need help with LQ4 cam selection
 

Hey guys. Awesome site here. Ive been doing a ton of reading and research for my engine swap, but i could use some insight on a couple things. First of all I have a 2003 RCSB silverado 4.8 auto. Currently the truck is stock except for a set of 4.10's and a truetrac as well as a flowmaster 40 series.

I have a LQ4 shortblock 6.0L with 71k miles on it. I also just bought a set of factory 317 heads which im going to have ported and milled .030 along with these I got a smokin deal on new LS6 springs retainers and locks. I know these are not "243s" but there what my budget allows so I plan to stick with them.

SO....that brings me to cam selection. This truck is a DD and will see some occasional track use. I know im going to be limited by lift and seat pressure with the LS6 springs. But would like to get some insight on the "best" cam available if that makes sense. My goal is around 400RWHP These are the 3 that I have been looking at.


#1 Lunati Voodoo 55003
Lift .526/.534
Duration : 218/221
RPM Range:2000-5000

#2 Comp 54-412-11
Lift: .522''/.529''
Duration @ .050'': 212°/218°
RPM Range: 1200-6000

#3 Thunder Racing TR220
Lift .551/.551
Duration: 220/220
RPM Range: 1500/6500

So what do you guys think? Im all ears for insigth and suggestions. Im always will to learn!
Thanks.

Is there a reason you would want to shave .030 off the heads. With that kind of mill work, I think you might need to clearance your pistons with the cams you selected. You might run into issues with the Intake sealing up right as well.

I love the 212/218 in my "lil engine that could" (4.8L), but If I had the LQ4, I would go with #3 choice. With the cam, you will need the supporting Mods to compliment it as well ...Headers, Stall TC, Tune

All of this is my .02

Welcome to the site and Good luck with your build. Keep us updated. :cheers:

The LQ4 with dished pistons yields a CR of 9.4:1 with the 317 heads. By milling to heads .030 should get compression up to about 10:1 which is a little more ideal for my N/A build.

I should have enough PTV clearence but I will check that once I finally choose the cam. I really dont want to have to flycut the pistons.

I forgot to add that I plan on picking up a stock Trailblazer TC and ofcourse will get a tune as well. What kind of numbers does your 4.8 make?

I have the 212/218 high lift in my 4.8 rcsb it runs hard. I would run the tr224 or tr220 for your set up then you could still run the ls6 springs, both cams have put out great numbers and track times.

get a bigger cam like 23ish 23ish an get some good springs that will hold 650 lift

I like cam #3 but you limiting factor after that cam will be the converter . I'm sure the 220 cam will like yanks trt2600 stall if you every went that route.

Or since you already have the yellow springs, maybe look into a used ls6 cam. I think those are arounf .525 lift. That cam will have silky smooth idle and more power everywhere vs any stock lq4, or ls1 cam.

If you are on a budget the ls6 cams can be found cheap. I would definitely mill the 317s for some more compression.

Save the money with the ls6 cam and put that towards the trt2600 stall.

4.10's
trt 2600
ls6 cam
lq4

that would sound like a very streetably setup with great power. I would think you will see 360+ to the tire, but with alot more usuable low and mid range power.

Im on a budget, or this would be an option. I think I mentioned that in the first post. I have seen alot of positive things on the TR220. Anybody have dyno number or an idea where this would put me at with RWHP?

Thats the feedback im looking for! I was under the impression the stock TrailBlazer 4.2L TC stalls at 2800 behind a 6.0 is that not enough? It seems that the stock ls6 cam makes power to high up in the RPM band. I dont really want to sacrifice that much of off idle torque for high rpm HP. Does anybody here have experience first hand with the TR220 with LS6 springs in a LQ4?

IDK about the 4.2l TC. never worked with one.

I always thought that anytime you went aftermarket on the cam you need the good aftermarket springs/pushrods/etc for the faster ramp rates of the aftermarket cams.

Look into it but I thought the ls6 cam would make more low tq then any of the cams you have listed above.

What size converter is the 4.2L? is it a full 12in. converter? The trt2600 is an 11inch converter making it about 10lbs lighter. litther quiker revs.

If you went to a 2800 10inch stall most of those are around 20lbs lighter then the 12 in. converters.

I had a 2800 in my camaro a few years back and loved it...drove really nice, but when I put in my 224 cam my 330 foot was the same at the track, it wasn't until after the 330foot untill the car started gaining time over my stock ls1 cam. I went 3600 on the stall and the car cam alive, spun to a faster 1/4 mile by .2 tenths..

If I put a stall in my ls1 ram I'll go 2800 on a 10in converter. I found a ls6 cam last night from a guy that I'm going to run.