06pbmKC

I’m LS swapping my bronco. Lq9 rebuild and nothing fancy because it won’t see boost. I’ll be running 823 heads. If anyone is in the Kansas City area JPI has some really nice ported heads. My question is should I go the ported route? My concern is loss of low end power. This is a truck so low end is the big concern. It will never see over 4500 if I’m being honest. I also remember how well the rectangle port heads flow from when I swapped them on my ls2 gto.

my cam is the cam motion version of the truck norris cam. Titan 2 truck cam.

Che70velle

iTrader: (6)

Ethan, do not port the heads. They already are “almost” too big for what your doing. Porting them will only slow down airflow, which hurts torque.

Doug G

They used LY6 motors in trucks (basically what you're building)...you should be fine as is for how you plan to use.

Those heads as is can support 600+HP...no need to port.

Ls7colorado

iTrader: (3)

I would throw some 862 heads on there with a tbss (new style cathedral truck intake) and enjoy the extra 50ft lbs of tq down low.

RB04Av

I think 243/799 would be a better head choice.

Ls7colorado

iTrader: (3)

not better for power below 4500, but still better than rec ports. Im running 799s on my lq4with "truck norris" cam but if I would have had a set of 862/706 I certainly would have used them instead.

RB04Av

The 4.8/5.3 heads will give YYYYYYUUUUUUJJJJJJE compression on a LQ9. Great for power, not so great to find fuel for. If that's not an issue then they're fine.

95wannabe

iTrader: (20)

Do you have a dyno graph on that?

Ls7colorado

iTrader: (3)

No sorry

Doug G

LY6 Applications

LY6 Applications VIN 8th Digit Year Make Model
K 2007-10 Chevrolet Silverado 2500 HD, 3500 HD K 2007-10 GMC Sierra 2500 HD, 3500 HD K 2007-09 Chevrolet Suburban 2500 K 2007-09 GMC Yukon XL 2500 K 2008-09 Chevrolet Express 2500, 3500 K 2008-09 GMC Savana 2500, 3500

Pretty sure that's what's in UPS trucks also

I don't think GM would put it in trucks if torque was an issue... are there better option, sure.

old motorhead

iTrader: (10)

If you don't over cam the combo, 823 heads will work great. Truck norris cam is not even close to an over cam.

06pbmKC

I have the cam motion version of their cam. It should be a solid performer.


Duration at .050: 212/220
112 Lobe Center Angle with a 108 Intake Centerline
Lift with 1.7 Rocker Arm Ratio: .553"/.553"
Recommended Displacement: 4.8-6.2 Liter Engines
Cylinder Heads: Cathedral or Rectangle Port
Recommended Compression Ratio: 9.4-10.5:1

Ls7colorado

iTrader: (3)

That cam will be fine, id still stick with the cathedral heads since your main goal will be power BELOW 4500.

I agree they used the rec port heads on the 6.0 HD trucks but they also had that 6 speed to assist with keeping the engine rpms up under load and the VVT cam to aid in low end torque.
While the rec ports will be fine, anyone who has ever looked at a dyno graph would agree the cathedral would be better.

Ls7colorado

iTrader: (3)

You can just throw this put the window if you don't trust it but...... here it is....

RB04Av

706 heads on a LQ9 will give compression well up into the 11s.

Not at all the same results as putting them on a LQ4.

Not a good recipe for a low-RPM truck torque kind of build. Not a good idea for a street-driven truck on pump gas. Not a good idea for the OP's stated purpose and intent. Regardless of how much power they can make. "Most power on a dyno" isn't always the single and only guidepost to a successful build.