ArcticZ28

iTrader: (14)

My current specs are as follows:

HPE 408
11:1 SCR
244/248 635/627 112 (installed 4 degrees advanced for the restrictive heads)
Eagle crank
Callies rods
Diamond flat top pistons w/ 2cc reliefs
Stock 6.0 heads (317)
SVO 42 #'s
LS6 intake
P/P stock TB
Edelbrock 1 7/8 stepped LT's/ORY (soon to be catted with high-flow magnaflow bullet cat's)
LM catback

Made 425/445 with 12.1-12.9 AFR (nothing substantial gained by leaning it out anymore so I played it safe). I'll be sending my heads to TEA to get them ported (with 225cc runners) and a valve job (2.02/1.55) that will supposedly flow around the 320's on the intake. I'm sure I'll be more than happy with them, it's just that I want to address my cam while I'm at it. This car is a daily driver (use 93 octane) and I'd like it to be pretty streetable. My calculated SCR is 11.1:1 and my calculated DCR is 7.33 but I'm not sure if I'm using the DCR calculator correctly (because it also shows that I'm only at 10.94:1 SCR ). If others could clear up this confusion it would help a lot. But if this information is correct, it looks as if there is a lot of room for improvement with a different cam. *enter cam guru advisors* What cam specs should I be looking for in wanting a streetable car that won't rev past 7k rpm? I realize gears factor into this equation as well and I'm running the stock 3.42's with an M6 but am considering moving to at least 3.73's (sitting in a box in my garage) or possibly 4.10's.

Here's links to dyno graph 1 and dyno graph 2 to help you visualize where I'm at.

Thanks!

JakeFusion

iTrader: (7)

Well, I don't know the advertised duration on that cam (numbers at .006") so I'll just make a guess on what your DCR is. But first, let me say that I like the cam choice.

Your IVC is at 50 at .050" which is optimal for a FAST 90 intake (if you plan to go to that) to make the most peak power at 6300rpm while not sacrificing power under the curve. But, the advance will make it fall off after peak, but it should carry fairly well due to the duration. I doubt it'd go to 7k, but you can probably see 6700 or 6800 holding power effectively.

The TEA heads will probably net you a solid 40-50rwhp and a ported FAST could net you another 15-20 for a solid 480-495rwhp, which is very respectable considering your torque will be very solid as well. With that setup, you can install the 3.73s and have a very lively car with a very stout midrange. You wouldn't need to gear it much lower than that.

I'd recommend you have TEA mill the heads .018" for a 69cc chamber and 11.5:1 CR (my figures have you close to 11.1 if your quench is .040"). That'd give you an 8.5:1 DCR if those lobes are similar to an LSK or XE-R at .006". That'd probably give you another 10rwhp.

I think pushing for 530-550 is going to be hard to do on your setup, so I'd just maximize what you already have. 500rwhp in a very streetable package is going to be a ton of fun.

If you want a different cam, I'd recommend a Comp LSK 243/247 110+1 and a milling of the heads .024" to 68cc.

ArcticZ28

iTrader: (14)

Thanks a lot for that info Jake, I really appreciate it. My numbers at .006 are 304.3/306.3 and my quench is at about .037 with the GM MLS .045 gaskets and pistons .008 outta the hole. I was contemplating having them mill the heads as well to bump SCR up a bit but wasn't sure how that would affect my DCR and being able to drive it on 93 octane. My main goal is to have a 500+ rwhp streetable car, so I want to make sure everything going along with these heads will get me AT LEAST to that point.

JakeFusion

iTrader: (7)

In that case, I'd change the cam. It seems too lazy for my taste. You'd have to mill the heads quite a bit to get DCR up. Try the LSK 243/247 110+1 and it'll peak about where you peak now, but it'll carry it much better. Plus, with the additional aggressiveness off the seat, the LSK lobes will provide more total power over the curve. I'm also willing to bet the LSK lobes are more aggressive from .050 to .200".

ArcticZ28

iTrader: (14)

Yea, that's what I figured. The cam was originally intended for a 375 iron block that I had a while back but transferred it over to this new 408. I've attached the data sheet for the cam with all the numbers. Why do you suggest this particular cam? What are the lift numbers? I want to make sure the cam fully utilizes the way TEA says they'll port my heads. If you could explain every particular reason you can think of I'd appreciate it. I'm just trying to get a grip on what exactly I need and why, so I can better understand.

JakeFusion

iTrader: (7)

Oh, I see that it was 112+1 when I had figured it 112+4. But I missread the original post as being installed at 108 ICL. But anyway.

Less advance will carry the power past peak more effectively. The IVC at .050" should be close to 50 to produce a cam that peaks where the LSx series manifolds force the engine to peak; so in essence, you peak naturally with the manifolds, instead of fightning against them. This will allow you to maximize the power under the curve.

My suggested cam does both: it provides for a good peak and under the curve and allows the power to carry through. Also, it provides a good DCR if you mill the heads down to 69 or 68cc.

The Comp LSK lobes look like this:
Lobe#, Dur. @ .006", .050", .200", & Lift
2131 INT 293 243 168 .653"
2132 EXH 297 247 171 .656"

That compares to what you already have:
INT 304 244 161 .635"
EXH 306 247 162 .627"

As you can see, the LSK is more aggressive off the seat and provides more total area as the lift increases. Overall, the LSK lobe will make more power. On a 110+1 it will peak at 6300 and carry it very well, while providing for very good VEs.

ArcticZ28

iTrader: (14)

Who carries (or grinds) this cam?

JakeFusion

iTrader: (7)

Thunder Racing can order the grind for you. I've provided the Comp lobe numbers.

2131/2132 110 LSA 109 ICL.


Also, your overlap will be a little more with this cam (which also means more power). With the better ramp rate, it should drive the same as your current cam, if not better.

ArcticZ28

iTrader: (14)

Awesome, thanks for all the info

Anyone else care to chime in or provide any suggestions?

ArcticZ28

iTrader: (14)

What about a cam suggestion without XER/LSK lobes?

Patrick G

iTrader: (14)

JakeFusion gave you solid advice. Nail the correct valve events (like he recommended) and prepare to have a huge grin on your face the moment you go WOT.