2000 1500 5.3 vs 2002 Tahoe 5.3

[Fast4.7]

You're correct about the hp rating. However, you're incorrect about the camshaft being a "smaller cam." As a mechanical engineer that worked at the largest aftermarket camshaft company for over 22 years, I can 100% confirm that your statement is false. If you said that the tighter LS camshaft makes more a little more cylinder pressure at low rpm, I would agree with you. Here's a good video that will help you with the basics of valve opening events.

I do not care where you worked. I am not wrong in this respect. I am very well versed in camshafts. Change the LSA by moving the valve timing events and you change the overlap. Change the overlap and you change both idle vacuum as well as the VE of the engine. Both of which require VE table changes. As I previously mentioned even changes in intake and exhaust system also change the VE tables. I have run the same exact Comp grinds with 4* tighter LSA. Idle vacuum was down, low speed VE was down, and it moved more air overall though the same MAF sensor with the same MAF calibration once it had a little RPM in it. I have also had to retune for higher ratio rocker arms because the VE table is altered enough to warrant changes. Overlap also happens to be my first consideration when picking a cam rather than merely a number that exist off other specs.

[kevin87turbot]

I do not care where you worked. I am not wrong in this respect. I am very well versed in camshafts. Change the LSA by moving the valve timing events and you change the overlap. Change the overlap and you change both idle vacuum as well as the VE of the engine. I have run the same exact Comp grinds with 4* tighter LSA. Idle vacuum was down, low speed VE was down and it moved more air overall though the same MAF sensor with the same MAF calibration once it had a little RPM in it.

After reading your post again, it appears that we are now in agreement that a tighter LS angle will help peak torque on a mild application such as the one that we are discussing. Maybe that's how you determine that it's a "bigger cam?" Regardless, I thank you for your patronage.

[Fast4.7]

After reading your post again, it appears that we are now in agreement that a tighter LS angle will help peak torque on a mild application such as the one that we are discussing. Maybe that's how you determine that it's a "bigger cam?" Regardless, I thank you for your patronage.

I determine bigger cam off overlap more so than duration. Anything that will alter the MAP sensor reading in relation to throttle position and rpm is a bigger cam to me. Duration and thus airflow also change the VE but what really shifts the VE table is lower vacuum. Put a cam in an engine like my 383 has that makes substantially less vacuum and the fueling will be extremely rich at idle and lean above idle.

[2xLS1]

Because somewhere along that time frame there is a break in the production where GM shifted the cams. I have personally pulled factory 2000 year model 4.8 and 5.3L files with tuning for the smaller injectors. The smaller OE injectors are supposed to be indicative of the smaller cam. If that is the case, why did these 2000 YM calibrations have them? Hint, they had the smaller 99 cam when they were opened up despite being a 2000 year model.

The break in is the 99 model year. Then pose a 2000 5.3L calibration file that has 19lb injectors with correct CVNs.

Still waiting to see those multiple files you've pulled.

[DodgeZ]

The 12613412 flex fuel injectors would be a great upgrade over the stock injectors and will flow 50 lb/hr. They typically cost less than $100/set and The injector data is easily found for them as well.

can they handle a Truck Norris cam and still run e85?

[kevin87turbot]

Still waiting to see those multiple files you've pulled.

I've never seen a 2000 model Silverado that has the 21.8 lb/hr injectors from the factory. I own a 99 model that still has the little injectors in it.

Now that I think about it, I've never seen any difference in rwhp numbers on the 99 model and 2000 model Silverados after tuning them. With the stock cal files, the 2000 models typically have another 2-3 degrees of timing at upper rpm. That seems to be the primary difference in the HP ratings. After tuning they seem to be the same power.

[kevin87turbot]

can they handle a Truck Norris cam and still run e85?

Yes they can.