Tune needed? 6.0 with 5.3 heads.

05lq4 · May 1, 2020

Will i need a retune after swapping 5.3l heads onto a 6.0 l?

Sorry if this is a stupid question. Been searching forums for awhile now and cant find an answer. Everyone does a cam with this swap and i know a tune is needed after a cam.

But is it necessary with just the head swap?

Thanx in advance!

CamGTP · May 2, 2020

I can't remember if the higher compression LQ9's ran premium from the factory or not. I wouldn't run regular 87 octane that's for sure. I've helped tune far to many of these truck with people running 87 octane, all they do is show spark re-tard with it under heavy load. 89+ octane is far better fuel.

Edited May 2, 2020 by CamGTP

swathdiver · May 2, 2020

On 5/1/2020 at 12:47 PM, 05lq4 said:

Will i need a retune after swapping 5.3l heads onto a 6.0 l?

Sorry if this is a stupid question. Been searching forums for awhile now and cant find an answer. Everyone does a cam with this swap and i know a tune is needed after a cam.

But is it necessary with just the head swap?

Thanx in advance!

Why would you not want to? A tune will optimize performance of the installed parts. That setup should make for some nice low end torque!

05lq4 · May 4, 2020

On 5/2/2020 at 11:25 AM, swathdiver said:

Why would you not want to? A tune will optimize performance of the installed parts. That setup should make for some nice low end torque!

Yes i am torque hunting. Truck won't see above 5k rpm. Just a wood hauling Daily driver.

Its eating a tiny amount of coolant so im doin head n intake gaskets anyhow. Found a cheap set of remanned 862s locally. And im 2 hours away from any place that can resurface my 317s. So in a way it seems easier haha. Hopefully it turns out that way!

Just worried about driveability without a tune. And tunes seem to be more expensive than i thought they would be.

If i was building a race car and spending thousands its a drop in the bucket. But im a budget guy for the time being.

... So... would the smaller chamber make it run rich on the stock tune?

05lq4 · May 4, 2020

On 5/2/2020 at 8:34 AM, CamGTP said:

I can't remember if the higher compression LQ9's ran premium from the factory or not. I wouldn't run regular 87 octane that's for sure. I've helped tune far to many of these truck with people running 87 octane, all they do is show spark re-tard with it under heavy load. 89+ octane is far better fuel.

I was wondering if i would have to run 89+ ! 5$ a fill up isnt gunna bother me too much. Its that big payment to the tuner that makes me cringe.

Now that you bring up lq9s... I wonder how the 2 setups (lq4 with 5.3 heads and the lq9) would compare side by side???

swathdiver · May 5, 2020

8 hours ago, 05lq4 said:

Yes i am torque hunting. Truck won't see above 5k rpm. Just a wood hauling Daily driver.

Its eating a tiny amount of coolant so im doin head n intake gaskets anyhow. Found a cheap set of remanned 862s locally. And im 2 hours away from any place that can resurface my 317s. So in a way it seems easier haha. Hopefully it turns out that way!

Just worried about driveability without a tune. And tunes seem to be more expensive than i thought they would be.

If i was building a race car and spending thousands its a drop in the bucket. But im a budget guy for the time being.

... So... would the smaller chamber make it run rich on the stock tune?

Don't think so, the computer system will adjust for it. The LQ9 requires premium fuel, it's a 10:1 motor with flat top pistons.

https://help.summitracing.com/app/answers/detail/a_id/4808/related/1/session/L2F2LzEvdGltZS8xNTg4NjU3NjE2L2dlbi8xNTg4NjU3NjE2L3NpZC9mVWpCdDd5Zmp3TjBxYXNfajNYeXM1OVlacU5yd3dic2pkTjNMQjNHR2RHcE5YVElESzN6JTdFNVFzRXNfWHRfbkl6V3lTbWFkS0hGbURkclludSU3RUN1ZHNKUzJJR05vV2VOTW1aTjlUOEczZEF4N0doeU9Bc1J2Q3B3JTIxJTIx

05lq4 · May 5, 2020

Ahh the bearer of good news!! I was hoping the computer would adjust enough to not hurt anything. Not much info out there for stock 5.3 heads onto a stock lq4.

Thanx for the link! Didnt realize the lq9 had better injectors. Thought the only difference was the fancy pistons and intake cover haha. Oh and the price tag of course! $$$.

7 hours ago, swathdiver said:

Don't think so, the computer system will adjust for it. The LQ9 requires premium fuel, it's a 10:1 motor with flat top pistons.

https://help.summitracing.com/app/answers/detail/a_id/4808/related/1/session/L2F2LzEvdGltZS8xNTg4NjU3NjE2L2dlbi8xNTg4NjU3NjE2L3NpZC9mVWpCdDd5Zmp3TjBxYXNfajNYeXM1OVlacU5yd3dic2pkTjNMQjNHR2RHcE5YVElESzN6JTdFNVFzRXNfWHRfbkl6V3lTbWFkS0hGbURkclludSU3RUN1ZHNKUzJJR05vV2VOTW1aTjlUOEczZEF4N0doeU9Bc1J2Q3B3JTIxJTIx

swathdiver · May 5, 2020

2 hours ago, 05lq4 said:

Not much info out there for stock 5.3 heads onto a stock lq4.

Remember that the LS2 is a 6.0 block with 5.3(799/243) heads. Now that I think about it, there are a few such builds over on the Performance Trucks forum. Have a look around.

05lq4 · May 5, 2020

41 minutes ago, swathdiver said:

Remember that the LS2 is a 6.0 block with 5.3(799/243) heads. Now that I think about it, there are a few such builds over on the Performance Trucks forum. Have a look around.

Didnt realize 799 243 heads were 5.3.

They have the slightly larger chambers and better cfm than the 862 706s right??

I guess i should always specify. I got LM7 heads.

Just dove down the LS rabbit hole bout a month ago. All of this is fairly new ground for me.

swathdiver · May 5, 2020

5 hours ago, 05lq4 said:

Didnt realize 799 243 heads were 5.3.

They have the slightly larger chambers and better cfm than the 862 706s right??

I guess i should always specify. I got LM7 heads.

Just dove down the LS rabbit hole bout a month ago. All of this is fairly new ground for me.

Super Chevy thinks otherwise:

http://www.superchevy.com/how-to/engines-drivetrain/1712-surprising-hp-numbers-from-our-stock-ls-cylinder-head-test/

The 799/243 were originally associated with the 5.7 LS6 as that was the first engine to use them I think. But now they are known for being on the 5.3 truck motors most and a favorite for rebuilders as the Gen III heads tend to crack and leak. Look up Castech heads.

I'm fairly new to this too, bought my first LS in 2017, came from 1970s and 1980s Buicks.

Colossus · May 6, 2020

I would go ahead and contact Justin and Jenna at Blackbear. Justin knows the 6.0 and 5.3 well and talk this over with him. You'd be happy getting a tune from them anyway even if you don't need one.

swathdiver · January 6, 2022

On 5/1/2020 at 12:47 PM, 05lq4 said:

Will i need a retune after swapping 5.3l heads onto a 6.0 l?

Sorry if this is a stupid question. Been searching forums for awhile now and cant find an answer. Everyone does a cam with this swap and i know a tune is needed after a cam.

But is it necessary with just the head swap?

Thanx in advance!

What did you wind up doing?