spazegun2213

So as i dive deeper into tearing the heads off my car I'm realizing that a) while I'm here I really should take my time and upgrade anything i think should be upgraded. and b) why not add some trick bits I've been drooling over for a while.

Here is my problem, I'm running in NASA's ST-2 class, so i need to keep peak power and TQ from 350-370. However, midrange is WIDE open. I was thinking about a Cam of some sort that would take the power to ~400, and all the supporting mods (valve springs, push rods, double roller timing chain, etc). I figure that's ~1200 and really, not that hard while I have 80% of the motor torn down at the moment.

However, I'm really wondering if i good tuner could pull timing/fuel at the top end to take my peak power down? Because if not, its not even worth spending the money.

Thanks guys!

AU N EGL

YES

But no matter where you highest HP is on the dyno chart, 6500 or 5600, that is the number they will use.

varkwso

I would go with reliability mods only - I also have 8.7/1 in TTA.

I have seen some strokers in NASA do well since they make more torque under the curve - but not sure it is worth the $$$.

spazegun2213

This would NOT be a stroker... just a cam at most.

varkwso

I would keep the stock cam...and meet the min wt....just my opinion.

I did go back with ARP bolts and forged pistons...

DALE C

I would do a 224 cam and detune peak power. C5R timing chain with tensionor and a set of CTSV lifters. Texas Speed has great prices on cam kits that include a good set of push rods and some nice springs and retainers for smaller cams.
If you dont do anything else I would do the CTSV lifters while you have it apart, we swear by them.

spazegun2213

I've heard the C6Z lifters are also nice.

Alright well i called up another tuner and he said not to worry about the cam, but since I have the heads off, may as well P&P them, larger valves, and do that. Sound reasonable?

AU N EGL

That will quickly put you out of ST2. The Stock C5Z motor and maybe the 224 cam with conservative tune, will put you close to the 8.7:1 limit. In most cases the create LS6 with tune will put you close to the limit for ST2

Better to be close to BUT NOT over the 8.7:1 limit.
Can always add some ballast.

Nothing worse then being in the Low end of ST1 or low end of SU.

I have a 224r cam in an LS6, polished but not ported heads, TPIS PP 84mm TB LTs and I am at 400 RWHP.

Dont have the cars wt, or what it will weigh with the cage goes in.

varkwso

I have them in one of my motors.

0Randy@DRM

Very interesting. Bigger ports, bigger valves = low port speed. Lower port speed=less mid range. Bigger margins can sometime get the end user with parts they don't need. Spending money going backwards isn't the best idea, unless you have too much cash.

Randy
Put a damn cam in there, Road Race cams are much different then Drag cams too!!!

wallyman424

i keep telling ross to just get the damn motor together and drive the damn car. the guy has some severe racecar attention deficit disorder.

spazegun2213

as usual, the two people i trust the most chime in... Odds are I'll just put the motor back together and jump in and have a good time

J.R.

My original ST2 engine was an LS6 with MTI IIE heads (i.e. larger valves) and a 224/228 cam on a 114 LSA detuned to meet 8.7 to 1. It does not work efficiently.

Per AU N GEL a stock LS6 will give you approx. 370 RWHP and a better torque curve. Remember they only measure HP no matter where it is at.

Keep the LS6 243 heads for better port velocity and if you want to change cams go to an approx.205/219 .525 to .550 lift on a 112 LSA (there is a COPO cam very similar to this). Use single valve springs for a lighter setup and you will be impressed with very flat torque curve. To add a little more torque go to a .040 Cometic head gasket for a slight compression increase. You should then be able to run around a 12.0 AFR on the upper end to keep the engine alive longer.

WBHighwind

Take a look at my cam specs. Ive been told several times that its a good road racing cam. It doesnt make a ton of power at the peak, so its not a good dyno cam, but it has good area under the curve and the torque line is strait across.

In my little knowledge of the subject, I would keep the heads you've got.

DALE C

Why do heads before maxing out cam (for stock heads)

The CTSV lifters have a little better oil control to the top.