Re: OT-Vortec 4.3 improvements over regular4.3

Posted by jdemaris on February 22, 2005 at 20:13:17 from (209.23.30.42):

In Reply to: OT-Vortec 4.3 improvements over regular4.3 posted by DCM on February 22, 2005 at 19:39:40:

Vortec is supposed to have better low-end torque and better mileage, partly due to the more direct injection of fuel. I don't believe the better mileage claim. Early 94 engines and older 4.3s have throttle body injection, then for around two years -starting in 94 CPI was used, then CSFI. CPI still uses one central injector like TBI does, but uses separate hoses that run to each port. It also uses a high-pressure 60 PSI fuel system unlike TBI. It is expensive to fix and is replaced as a unit. The later CSFI has a separate injector for each port and has some replaceble parts and is less trouble prone than the CPI.
I had a 92 TBI 4.3 Blazer, I have a 94 AWD Astrovan AWD 4.3 with CPI, and two of my sons have 2000 Blazers with 4.3s with CSFI. My older 92 non-Vortec 4.3 Blazer with TBI averaged 14 MPG in the winter in all around driving and got around 19 on the highway under the best conditions. My 94 Astrovan with the 4.3 CPI system gets 14 MPG average and 18 highway, and both of my sons' 2000 Blazers with the CSFI 4.3s are averaging 12 MPG and 18 highway in winter driving.
So, I haven't seen any whopping differences in mileage, and I haven't noticed a power increase either. If anything, the mileage has been a little worse with the newer Vortecs. I live in a hilly area, maybe the gains would be different in highway/flatland driving. I will say that all the 4.3s have been more powerful and slightly better in fuel than my 86 Blazer with the 2.8 TBI was.
My 6.2 diesel Blazers both will get around 21 MPG on the highway and 16-17 around town, so that beats all the Vortec Blazers.

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