So I've been reading my butt off trying to figure out cam specs and what I should be looking for when I do my heads cam setup. I'm finding out I can go a million different ways, but it all depends on my induction/exhaust setup and how much overlap the cam has that would depend on the power I'm putting down.

So with that said, I have a 98 TA LS1 stock bottom end. I have a LS6 intake manifold, ported stock TB, EGR! and will be looking at getting the PRC Stg 2.5 5.3L heads from TSP. I currently have Flowtech headers with ORY and SLP LM1 catback...will be installing a single cutout after ORY and eventually upgrading to QTP's 1-3/4 headers with their ORY..still keeping the single cutout.

So I understand that desired overlap really depends a million different things, but for my application with my top end mods (maybe going to a 90/90 setup eventually) should I be looking at something with a higher overlap initially? Somewhere in the 20-30 range? I'm basing this off a T Rex cam of 242/248 608/612 110lsa

So if I have the formula right... ([242+248]/4 - 110)*2 gives me 25 of overlap. Is that desireable for my setup or should I be looking for something with less overlap initially. Then upgrade my headers, then my intake manifold/tb, and then get another cam with more overlap?

Is my logic correct here?

I'm still gonna keep reading...but am I on the right track or am I confusing myself?


Side note for those interested...it's an autox car I drive on the street...so I'm looking for low-mid range power and my "makes me feel good" end goal after everything is 450 rwtq...hp is nice...but I figure i get torque...I'll have enough hp


**Addition**
I also would like to go with a little higher LSA ONLY to have a more aggressive idle, and I can play with the number to get back to the correct overlap number...is it that simple that to get similar power with a "slightly" choppier idle like if I went with a Texas Speed Texas Giant 248/254 Camshaft with a 113 lsa also giving me a 25 overlap?


**ANOTHER EDIT***
The Giant Cam referenced above is just for reference...i really wouldn't be putting that cam in my car

 

Ok...so I'm looking at Texas Speed's site, and they're 220/220 112 lsa cam supposedly has a choppy idle but 1200-6200 RPM Power Band with -8 overlap....i'm getting confused again...haha


Ok...so looking at the Texas Speed Torquer 2 232/234 .595/.598 with 112 lsa...that'll give me 9 overlap...does that sound like a good platform with the PRC Stg 2.5 5.3L heads to build on?

 

Not to be negative but you are looking at this the wrong way and putting WAAAy to much emphasis on overlap when as you stated there are many other things to consider (gear, intake, exhaust, heads, desired powerband etc...). It is admirable you want to learn but get a pro to spec a cam for you.... If you have a shop you trust talk to them or contact Patrick G or Geoff at Engine Power Systems on here. They both have a worksheet you fill out and they tailor a cam to match your mods and meet your goals.... Well worth the $25 they charge...

 

Yeah I think I need some serious help...haha. the more I read last night the dumber I felt...and I'm still lost.
So I'm thinkin my plan is do a torquer v.2 112 lsa cam only swap...then upgrade to the qtp headers/y...then look at getting a set of heads with a professional helping spec out a cam that would like account for a 90/90 setup if he thinks its worth it.

 

Just abit of a note any tuner can make any cam sound choppy so id pick a cam with the intended powerband in mind and get the tuner to put in as much or as little chop as you want.
Obviously with more overlap you will have a much more agressive and choppier sound but ive seen even small cams like 224 228 tuned to be really choppy and you wouldnt pick it was only a small cam its all how good the tuner is.

 

Ah yes...good point...I'll be having frost tune on a friends dyno in louisa

 

buy the heads and cam together in a pkg for a little better price.

 

@ 98 TA emlc were did you get that formula it is correct. The easiest way to find overlap is to take your exhaust valve closing and your intake valve opening and add them togethter that will give you the overlap all this should be given by camshaft manufactuer on cam card. Also LOBE SEPARATION plays a Huge role in overlap tighter the lobe seperation more overlap wider the lobe seperation less overlap. Also overlap deterimines overall powerband of engine VACUUM for brakes,torque curve, idle characteristics sure tight LSA sound cool but dnt always give you best performance also do you have headers exhaust what gears any other mods heads stall tire size weight all will play a role also what is the intake lobe centerline for this determines also torque curve if you are looking for low end power. Note your Exhaust valve closing is one of your most important valve events it helps determine Overlap


Another edit also restrictive intake and exhaust tracts will cause a loss of power due to reversion. If you are looking for torque 5.3 heads are great for this due to smaller combustion chamber also an ICL that is a little advanced will help generate more torque and cylinder heads that have small volume intake ports help in torque due to velocity of air moving into cylinder. It is up to what you want try calling Bullet Racing Cams

also have buddy with 98 Z28 tsp 5.3 stage 2.5 heads with an Ms3 its a rocket out of the hole he also runs an SCCA class

I hope all this helps good luck with your build man

 

([{Intake Duration + Exhaust Duration}/4] - Lobe Separation) x 2

I got the formula out of the advanced engineering tech...they were going off on hypotheroetical symposiums of efficency in making poop in their pants or something like that.....about 99% of it was over my head but I'm trying to figure it all out.

Gears are currently 3.42's. I'm interested to see how the car feels coming out of tight turns after the swap, but I'll probably end up getting some 3.73 or 4.11's. I kinda wanna wait on getting a 12 bolt and just do it all together....shimming gears is not something I know how to do accurately....so really don't wanna screw up my rear end which so far has performed fantastically

Other mods are in sig...add Ported TB, Flowtech headers/ORY/Cutout that I'll have installed before I finish all this.

Yeah still don't understand everything, but I'm working on it, and thank you for your input. It does help. I'm definitely going for low to mid range power for now, and as someone else stated, I can adjust the sound of the idle with the tune....so I'm not so hung up on lsa for idle as I am for the desired power in that rpm range.

So even though I "think" I could guess at a decent cam, I'll end up confirming with a shop who will be able to help me get exactly what I'm looking for without me have to understand 100% of it.

Vacuum is something I never took into consideration, and since my car also drives on the road...yeah...that's kinda important. That's exactly what I"m talking about as to why I'm just going to contact a shop once it's time to pull the trigger. Price won't change for a custom grind.

 

yea i know the formula but the only thing is it not accurate due too it is advertised and not actual duration measured @ 50 that will give you seat to seat time also have you thought of changing flywheel weight and an LSA of 112 would be great and the tuners way being a fellow tuner is to idle down really low and this could possibly damage IAC

 

If you are looking for low and mid range and muscle under the curve your are going in the wrong direction. Something in the mid to high 220"s duration will do what you want. All the cams you are listing are top end peak HP cams and not really auto X friendly. Remember that horse power is for show but it is TORQUE that really hauls your azzz. Good luck.