Z06kern

iTrader: (18)

I just installed a LS2 stroker in my Z06. I have spent the last two weekends dailing in the ve and spark tables. All my fuel trims are very close to zero and I'm running 24-27 degrees of timing from 2500 up to 6800 rpm. My LC1 afr is in the 12.8 to 13.1 range in the upper rpms. Last week I put it on the dyno and the car made 490RWHP and 441RWTQ.

I think the problem is the heads I'm using. They are Patriot LS6 Style castings that TSP race ported. These heads are about 1 1/2 years old and have 59cc chambers setup for smaller bore motor. I'm pretty happy with the peak horsepower numbers, but the torque should be better in my opinion. Below are the rest of the deltails on the setup:

402 LS2 Shortblock 12cc Mahle Pistons 11:1 Comp
TSP/Patriot Race Ported Heads 59CC Chambers 2.08 int 1.60 Ext
GM MLS Head Gaskets
TSP Texas Gaint Cam 248/254 611/613 113 LSA
Comp 7.425 Pushrods
NGK TR6 Plugs (plan on spraying 150 shot)
Stock Rocker Arms
Fast 90mm
Nick Williams 90mm throttlebody
Halltech Stinger Intake
Kooks 1 7/8 Headers no cats
Borla Stinger Exhaust

The car feels strong to me on the street and runs very well. Any suggestions on why I'm down on torque?

kumar75150

what size intake valves are in the heads?

Patrick G

iTrader: (14)

A good motor should make its cubic inch displacement in torque by 3000 rpm and 1.25x its cubic inch displacement at peak torque. You should be above 500 rwtq. I would expect your cam has little to no advance ground in and/or a wide LSA. Your dynamic compression is probably low and I would expect your area under the curve to suffer.

Do you know what the LSA and the intake centerline of the cam is? Unless the heads are bad, you can probably get your torque back with a cam change.

Z06kern

iTrader: (18)

Valves are 2.08/1.60. LSA 113 Zero advance

Z06kern

iTrader: (18)

I can't post up the sheet, but it does make its displacment in torque by 3000 rpm. It just does not make the torque up top where it should.

11sHSV

If you want torque, try running a cam on 108/110LSA. Something that you also consider is intake runner length. We are currently playing with 8 throttle bodies setups and by changing trumpet length you pick up torque and hp or loose it.

Slowhawk

iTrader: (12)

Did you try different timing across the range on the dyno? I just say that because a 408 we recently did made 475hp with 25 degree's of timing then made 530rwhp with only 19 degree's.

Also was the lifter preload checked during the build? The reason is because I find myself ussing 7.350 rods with milled heads.

Z06kern

iTrader: (18)

I did drop the timing back to about 21 degree's in the upper rpms and picked up a couple of horsepower. Also, the heads have not been milled they partroit ls6 style castings with welded 59cc chambers. I have checked the preload and 7.425 pushrods are what it required.

Anybody have any ideas as to what cam I should run to get some of my torque back?

JakeFusion

iTrader: (7)

Comp LSK. 243/247 110+1.

The lobe specs are as follows:

Lobe#, Dur. @ .006", .050", .200", & Lift
2131 293 243 168 .653"
2132 297 247 171 .656"

The TX Giant should be on a 112 and marketed for 427+ engines. Otherwise, it'll just kill torque. But, people want big cams and wide LSAs to keep overlap down for decent drivability. That's fine if you're going to run a custom intake and tons of compression. But with a FAST 90, you need to aim for a peak of 6300 (because the intake will restrict you to that anyway) and not fight against it. That way you'll maximize the area under the curve. This cam does that and will help bring your DCR back up. Your static compression is still too low, but you'll have a lot more torque with the cam I recommended. Also, I'd look into going with a Cometic .040" gasket. That'll get your compression up to around 11.4:1 and the DCR will end up around 8.3:1 with the Comp LSK cam.

Patrick G

iTrader: (14)

What Jake said!

Z06kern

iTrader: (18)

Great info. Thanks!

Z06kern

iTrader: (18)

I am currently running Patroit Gold springs with only 1500 miles on them. Should I upgrade the springs if I should choose to run this cam?

JakeFusion

iTrader: (7)

Should be able to shim them within .050" of coil bind and be okay. If not, the Comp 921s will work. Patrick, your thoughts?

Patrick G

iTrader: (14)

The Patriot Gold have enough spring pressure when shimmed to within .050" of coil bind. The Comp 921s are preferred mainly because they have a little bit more breathing room before coil bind. This allows them to be shimmed a little more for additional valve control.

SlickVert

iTrader: (5)

About how much seat and open pressure will 921 have when shimmed to within .050 for a cam with .650 lift?
Bob

Patrick G

iTrader: (14)

About 155 seat and 410 open.

SlickVert

iTrader: (5)

Thanks Patrick

=ZoomZ=

iTrader: (1)

Patric ,, Jake ,, i have the same basic setup but with AFR 225's and im running a 3600 stall in an automatic FLP tranny .

I need 500+ rwhp to drive from day to day .

What cam would you suggest .

=ZoomZ=

iTrader: (1)

Would this cam work well on a 113-114 lda for torque and power with a 3600 stall ?

JakeFusion

iTrader: (7)

I'd put it on a 114+4. It should work well with a 3600 stall. Sometimes putting so much advance in kills the power after the peak and since you have an automatic, you may only want to put it on a +2.