jemarshall64

I am building a 99 LQ4 for a 5000 ish pound 4wd rig. I am using a set of 799 heads that I had a .005 clean up pass done on them, and I am looking into running the Deatsch 38 lb injectors on it. I am new to dealing with LS engines and I am having a hard time figuring out which cam I should run, and the more I try to figure it out and read into it, the more I get lost. I am looking for low to mid range HP/TQ out of it, nothing to huge and up in the high rpm's. It'll be mainly off road with occasional trips around town. What should I be looking at here?

Mercier

iTrader: (15)

If you are looking for low-mid power(the right path for a 4x4 IMO), I wouldn't go very big. Start looking at something like this:

http://store.cammotion.com/60l-truck...00-compression

This will also work well with $60 GM valve springs for low cost and long life.

jemarshall64

thank s for the link. I had come across some in that range, but was not sure if it was worth the money to go from stock to that, with the small change in lift.


On the springs, are you talking about this set?

GM Springs Amazon

GM Springs Summit

JoeNova

JFR Triple 12.

Mercier

iTrader: (15)

Yes; those springs. For the same price, Cam Motion will grind any spec you want, so you could ask them for that cam in .600" lift if you wanted, and run something like a PSI LS1511 spring. .650" and you would run BTR .660" "Platinum" duals.

From what I have seen, stock heads, even 799s/243s, don't flow much more above about .550" lift until you do some work to them. That is, flow increases a lot from .400" to .500" but after that, the gains taper off. Perhaps .550" is a better compromise. It still allows you to use stock-type valve springs, keeps things in the reliable and affordable range, and gives you yet more lift. Again, CM will grind you whatever you want. There is some effect of a .620" lift cam getting to the high-flowing lifts(.400+) faster but I think the benefit there is marginal in a mild build.

Duration is really what was going to give you more power in such a cam. It keeps the valve open and flowing longer. IMO, a lot of guys just max out the lift because they can. That last little bit is that last little bit..

See below for some flow data I snipped from another website(link below that):

243 Stock Head Flow Numbers
------------------------0.100---0.200--0.300--0.400---0.500---0.550---0.600
Intake 210 cc------------62------126----184----224-----251----256----257
Exhaust 75 cc------------57------108----143----163-----176----180----183

See, we go from 224(intake)/163(exhaust) at .400" to 251(+12%)/176(+8%) at .500" yet from .500" to .600" we only gain 2%/4%.

Make sense? There is a lot more to it and that's why my day job is NOT spec'ing cams but this gives you food for thought. Also don't judge cams just based on lift/duration..especially not stock vs. aftermarket. CM could give you a cam that actually specs out to the same advertised numbers as a stock cam but perform MUCH better. The reason is these cams are ground to a specific need(performance) rather than all the compromises that OEM deals with(emissions, mileage, etc.). This gets into ramp rates/lobe shape/etc.

Source:

http://houstonperformancetrucks.com/...h-flow-numbers

WaLsFan

I think a BTR Stage 1 Truck cam would also work well for you and can be run with a set of the gm performance springs...it's the cam I am looking at for my heavy suburban with 5.3

jemarshall64

I have noticed looking at cam's allot of the lift numbers stop at about .55, yet they advertise them as being allot different, looking at it this way it now makes allot of sense.

jemarshall64

Thank you, that does look like a pretty decent set up. Lookig at the stage 2, 3 and 4 you can really see on them how the lift numbers top out at ~.55, but the duration is increased for each stage.

HioSSilver

iTrader: (8)

I think it's cam motion that has some drop in cams that work well

JoeNova

I still vote this, even over the LJMS and BTR truck cams.

CAMMOTION PERF

Thanx Guys.

Yes, we have some excellent drop-in truck cams that can bring big power improvements and have even better than stock drivability. Check out this thread on our customers success story: https://ls1tech.com/forums/dynamomet...hp-22rwtq.html