Marky Dissod
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@Mudsport96, would you mind expanding on what makes high compression daily driver trucks no fun?
How'd the SSR / TrailBlazer SS / 9-7X Aero get away with the LS2's 10.9-to-1?
LQ4 refresh...looking for guidance
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How'd the SSR / TrailBlazer SS / 9-7X Aero get away with the LS2's 10.9-to-1?
Mudsport96
Full Access Member
SSR was "light at 4600ish lbs", therefore the engine loads were not what you would see in a "heavy" suv. You would be more likely to spin the tires than to load the engine to a point it would knock. The TBSS and Saab had the e38 computer that has far more processing capabilities than the P01 could dream of and still more than the P59 so the fueling and timing strategies could handle the higher compression. They had better gear ratios than even the 5.3 extended trailblazers to help with mechanical advantage. One of my good friends just sold his SS because he was tired of "feeding" it 93.
The biggest deal is the fact that he will be required to run at a minimum of Premium fuel at that compression, and in a Burb with the fuel mileage that will be expensive. Could he run 87? Sure, but he will constantly be on the knock sensors and performance will suffer. Could he get a custom 87 tune and get some back? Probably, but at that point you are negating the power you bolted on in the first place. Rule of thumb when engine building. If you can get close to the same power from a bolt on that a jump in compression will gain you... save the compression for last. He if wanting more should do long tubes and exhaust.
Plus he specifically said for towing .. which in itself adds load stresses to the engine. Why did the 2500 and 3500 HD trucks get the LQ4 and not the higher compression LQ9 if power was needed and compression didnt matter? Because one they knew the customer was not going to use premium fuel when towing. I know after looking at the ignition tables of my father's 2002 2500 GMC that there is a large gap between the low octane and high octane spark adjustment tables. So he ran a couple tanks of 93 to see what would happen. Empty bed and no trailer saw minimal effect. Towing however, saw almost a 2mpg gain on average over 300 miles. Tandem axle trailer loaded with a Dodge Dakota. Why the gain? Could be many things, but data logs showed about a third of the knock counts on 93 vs 87. So the truck could stay on the more aggressive timing table and get more power and mpg.
And two, the ecm processing capabilities were not there yet and they would have to crutch the engine with less timing to stave off detonation. After already ( in my controversial opinion) ham-stringing the LQ4 with the LS1 cam. Yeah it makes more power up top, ( and FAR more than the LM7 at EVERY RPM) but I think the L33 cam would have been better. Buy they used that cam anyway. Why? Maybe they needed to bleed off cylinder pressure at lower rpm to avoid knock so they used the Camaro cam to do that.
At this point I forgot what we were talking about and look like an old man yelling at clouds....
The biggest deal is the fact that he will be required to run at a minimum of Premium fuel at that compression, and in a Burb with the fuel mileage that will be expensive. Could he run 87? Sure, but he will constantly be on the knock sensors and performance will suffer. Could he get a custom 87 tune and get some back? Probably, but at that point you are negating the power you bolted on in the first place. Rule of thumb when engine building. If you can get close to the same power from a bolt on that a jump in compression will gain you... save the compression for last. He if wanting more should do long tubes and exhaust.
Plus he specifically said for towing .. which in itself adds load stresses to the engine. Why did the 2500 and 3500 HD trucks get the LQ4 and not the higher compression LQ9 if power was needed and compression didnt matter? Because one they knew the customer was not going to use premium fuel when towing. I know after looking at the ignition tables of my father's 2002 2500 GMC that there is a large gap between the low octane and high octane spark adjustment tables. So he ran a couple tanks of 93 to see what would happen. Empty bed and no trailer saw minimal effect. Towing however, saw almost a 2mpg gain on average over 300 miles. Tandem axle trailer loaded with a Dodge Dakota. Why the gain? Could be many things, but data logs showed about a third of the knock counts on 93 vs 87. So the truck could stay on the more aggressive timing table and get more power and mpg.
And two, the ecm processing capabilities were not there yet and they would have to crutch the engine with less timing to stave off detonation. After already ( in my controversial opinion) ham-stringing the LQ4 with the LS1 cam. Yeah it makes more power up top, ( and FAR more than the LM7 at EVERY RPM) but I think the L33 cam would have been better. Buy they used that cam anyway. Why? Maybe they needed to bleed off cylinder pressure at lower rpm to avoid knock so they used the Camaro cam to do that.
At this point I forgot what we were talking about and look like an old man yelling at clouds....
tooleyondeck
Full Access Member
Besides replacing gaskets/components that show wear, the only change you should have to do mechanically is remove the clutch fan from the 03 LQ4. Your 05 Burb should have efans, so keep your ECU and harness from your 05 and have it reflashed with a 6.0 tune that retains the efans and you should be good to go.
That's exactly what I'm thinking about now.
I will get the oil analysis done and take a look inside the valve covers to see what it looks like
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