There is a dead air spot in front of the rocker stud boss in the LS head.. some funky reversion is happening there.
That and the smooth runners do not lend their self to good MPG.
That is one reason why GM stuck a swirl port in there to help fuel atomize.
That runner needs more heat also to get MPG up.
You can get such good MPG from the early 350's in stockish form in trucks that would trump the LS.
Been there done that.
22MPG from a heavy 1/2 with 4 speed granny trans and iron intake with a Q jet.
Adjust APT lower and recurve the distributor..quick timing curve.
That iron intake was rough and ran hot.. perfect for making MPG.
LS has plastic cool air intake and cooler running aluminum heads.
My son has a 2014 5.3 truck and 13-14 MPG is what it normally gets I towed my bayliner to gore with it and got 11-12 MPG it has the automatic 6 speed. None of the gears turned in any better MPG.
My 6000 lb Ford van on the same trip with Boat in tow would get 17 MPG with 302 and 2 barrel cruising with NO overdrive at 2800rpm.
The higher rpm put me in the power and air velocity was high through the runners.
Keeps fuel atomized and does not lugh the engine. I did have a comp 260h cam and I ported my heads
.
My 47 dodge and 57 chevy with my 350" with 268H cam would pull down 18 MPG same boat same river.
These LS engines spray fuel into the runners not far from the back of the valve.
You put more RPM in them they spray more fuel and that fuel does not have time to absorb heat so you get worse MPG the higher you rev them.
Throttle body injection had the benefit of allowing the fuel to run through a long path and tumble and break up the droplets and many of those trucks got very good MPG.
If your heads are off yu would benefit from a porting and roughing up the intake runners all the way to the bowl
That and the smooth runners do not lend their self to good MPG.
That is one reason why GM stuck a swirl port in there to help fuel atomize.
That runner needs more heat also to get MPG up.
You can get such good MPG from the early 350's in stockish form in trucks that would trump the LS.
Been there done that.
22MPG from a heavy 1/2 with 4 speed granny trans and iron intake with a Q jet.
Adjust APT lower and recurve the distributor..quick timing curve.
That iron intake was rough and ran hot.. perfect for making MPG.
LS has plastic cool air intake and cooler running aluminum heads.
My son has a 2014 5.3 truck and 13-14 MPG is what it normally gets I towed my bayliner to gore with it and got 11-12 MPG it has the automatic 6 speed. None of the gears turned in any better MPG.
My 6000 lb Ford van on the same trip with Boat in tow would get 17 MPG with 302 and 2 barrel cruising with NO overdrive at 2800rpm.
The higher rpm put me in the power and air velocity was high through the runners.
Keeps fuel atomized and does not lugh the engine. I did have a comp 260h cam and I ported my heads
.My 47 dodge and 57 chevy with my 350" with 268H cam would pull down 18 MPG same boat same river.
These LS engines spray fuel into the runners not far from the back of the valve.
You put more RPM in them they spray more fuel and that fuel does not have time to absorb heat so you get worse MPG the higher you rev them.
Throttle body injection had the benefit of allowing the fuel to run through a long path and tumble and break up the droplets and many of those trucks got very good MPG.
If your heads are off yu would benefit from a porting and roughing up the intake runners all the way to the bowl
Had the 98 Suburban throw a rod and trashed the block at just over 400K miles. Had my mechanic drop a GM crate 350 Vortec back in. Cost a total of $5,000 between the motor and install. Runs great and should last another 400K+ miles.
There is a dead air spot in front of the rocker stud boss in the LS head.. some funky reversion is happening there.
That and the smooth runners do not lend their self to good MPG.
That is one reason why GM stuck a swirl port in there to help fuel atomize.
That runner needs more heat also to get MPG up.
You can get such good MPG from the early 350's in stockish form in trucks that would trump the LS.
Been there done that.
22MPG from a heavy 1/2 with 4 speed granny trans and iron intake with a Q jet.
Adjust APT lower and recurve the distributor..quick timing curve.
That iron intake was rough and ran hot.. perfect for making MPG.
LS has plastic cool air intake and cooler running aluminum heads.
My son has a 2014 5.3 truck and 13-14 MPG is what it normally gets I towed my bayliner to gore with it and got 11-12 MPG it has the automatic 6 speed. None of the gears turned in any better MPG.
My 6000 lb Ford van on the same trip with Boat in tow would get 17 MPG with 302 and 2 barrel cruising with NO overdrive at 2800rpm.
The higher rpm put me in the power and air velocity was high through the runners.
Keeps fuel atomized and does not lugh the engine. I did have a comp 260h cam and I ported my heads
My 47 dodge and 57 chevy with my 350" with 268H cam would pull down 18 MPG same boat same river.
These LS engines spray fuel into the runners not far from the back of the valve.
You put more RPM in them they spray more fuel and that fuel does not have time to absorb heat so you get worse MPG the higher you rev them.
Throttle body injection had the benefit of allowing the fuel to run through a long path and tumble and break up the droplets and many of those trucks got very good MPG.
If your heads are off yu would benefit from a porting and roughing up the intake runners all the way to the bowl
LOL
