Lr4 4.8 vs Lm7 visuals?
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If they do not test for output, a good way to gain power in that 5.3 would be a stock 2003ish LQ4 /LQ9 cam. They idle like stock, retain almost all the OEM low-end torque of the 5.3 and gain close to 40 HP at redline. The later LQ4 and LQ9 engines have the same cam GM put into the 2001+ LS1 engines.
The only visual difference in a 4.8 and 5.3 would be the crank casting number, connecting rod number, and in some applications a dished piston rather than a flat top. But some 5.3s also have flat tops.
Last edited by Fast355; Jun 13, 2019 at 07:51 AM.
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Summit does not show a different cam or injectors for earlier LR4/LM7's. It's possible the EGR might have lowered the HP those years.
The only Gen III 5.3's with flat tops are if they have 243/799 heads.
The only Gen III 5.3's with flat tops are if they have 243/799 heads.
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https://www.onallcylinders.com/2018/...ads-cam-specs/
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From: Central Cal.
All the specs you could want about a 5.3 or 4.8 for that matter since they are the same minus crank, rods & pistons.
https://www.onallcylinders.com/2018/...ads-cam-specs/
https://www.onallcylinders.com/2018/...ads-cam-specs/
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99 has a 115.5 LSA and a 2000+ a 114 LSA. That adds overlap to the same cam and I am fairly sure causes the intake valve to close sooner trapping more cylinder pressure. I don't recall the ICL but IIRC the 2000+ cam is moved about 2° advanced compared to the 99 Cam.
The 99s had a different cam than the 2000+ and smaller fuel injectors. The first couple of years also had EGR. The tunes are also substantially different between the 1999 and 2002 I have compared. I actually used the 2002 4.8 Police Tahoe tune in a 99 after changing the injector sizing in the file and it ran ALOT better.
If they do not test for output, a good way to gain power in that 5.3 would be a stock 2003ish LQ4 /LQ9 cam. They idle like stock, retain almost all the OEM low-end torque of the 5.3 and gain close to 40 HP at redline. The later LQ4 and LQ9 engines have the same cam GM put into the 2001+ LS1 engines.
The only visual difference in a 4.8 and 5.3 would be the crank casting number, connecting rod number, and in some applications a dished piston rather than a flat top. But some 5.3s also have flat tops.
If they do not test for output, a good way to gain power in that 5.3 would be a stock 2003ish LQ4 /LQ9 cam. They idle like stock, retain almost all the OEM low-end torque of the 5.3 and gain close to 40 HP at redline. The later LQ4 and LQ9 engines have the same cam GM put into the 2001+ LS1 engines.
The only visual difference in a 4.8 and 5.3 would be the crank casting number, connecting rod number, and in some applications a dished piston rather than a flat top. But some 5.3s also have flat tops.
