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Will TBI give better gas milage over a carb?
- Thread starter COCHEV
- Start date
There's only one reason to convert to EFI - because you want to.
That being said...add up all of the costs to do your planned conversion. Then compare that to a Junkyard LS engine with computer and stuff. Make the sure the conversion is a lot cheaper than the swap.
That being said...add up all of the costs to do your planned conversion. Then compare that to a Junkyard LS engine with computer and stuff. Make the sure the conversion is a lot cheaper than the swap.
DrkZide
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How will that LS do underwater? lol I am legitimately curious due to the many water crossing we have over here. Like water over the hood.
Pookster
1/2 ton status
Im voting for the LS swap. A good number of reasons:
TPI is more efficient than TBI, which is more efficient than Carb.
TPI keeps your oil cleaner by keeping fuel out of it- there is no cylinder that gets more fuel than another (in theory, I know the rails can put of different amounts depending on location). This also makes fuel metering more efficient.
TPI uses Mass air flow to measure air charge- not so good on the TBI. Think its after the plate. So you get better more effiicent air/fuel mixture ratios.
LS motor is substantially lighter. couple hundred lbs, and that can vary more depending on aluminum or cast iron heads.
Easily pass emissions if you have it.
Work is obviously more, but if your motor is already tired.. this might be a better swap.
TPI is more efficient than TBI, which is more efficient than Carb.
TPI keeps your oil cleaner by keeping fuel out of it- there is no cylinder that gets more fuel than another (in theory, I know the rails can put of different amounts depending on location). This also makes fuel metering more efficient.
TPI uses Mass air flow to measure air charge- not so good on the TBI. Think its after the plate. So you get better more effiicent air/fuel mixture ratios.
LS motor is substantially lighter. couple hundred lbs, and that can vary more depending on aluminum or cast iron heads.
Easily pass emissions if you have it.
Work is obviously more, but if your motor is already tired.. this might be a better swap.
x2
COCHEV
1/2 ton status
Thanks for all the replys. my motor is far from tired. in fact its only a few years old and runs great. Like i said, it does everything well- except get good mileage- which is normal for a carburated 350.
I will most likey switch it over to a q-jet and just leave her be. The LS swap sounds sweet, but is no where neer in the budget any time soon.
I will most likey switch it over to a q-jet and just leave her be. The LS swap sounds sweet, but is no where neer in the budget any time soon.
DrkZide
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My question is how do you snorkel an LS without creating a HUGE bend in the intake piping therefor disturbing airflow. I wonder if you can mount the manifold backwards.
Okay, so here's my left field question...what are your gears?
If you're still trying to motorvate the thing with 3.73 gears you're definitely contributing to the problem right there.
If you have all the parts to drop it down to stockish and 33's I'd say do it unless you regeared to a deeper gear for the 35's. Taller = poorer wind drag. Bigger tires = heavier, harder to move, engine/trans working harder, more friction with the road, etc.
I'm no expert on this stuff but seems to me you'd be hard pressed to get a carbed small block, TH400 having, 3/4 ton 4x4 on 6" of lift and 35's with a ton of craftsman equipment in the bed (think you said you set tile?) get good gas mileage. Just isn't going to happen. That truck new and stock would have been happy to get 13mpg. Now you have a large number of factors weighing against it getting anything decent.
P.S. What are you getting anyway?
Yes you can.
probably not, I wouldn't expect to see any mileage gains. My brother converted his 81 C10 from carb to TPI and it didn't gain squat. When he did see a gain is when he swapped the OD trans in after that. If you are loooking for better mileage, get an OD trans. (700R4, 4L80E, NV4500)
COCHEV
1/2 ton status
Okay, so here's my left field question...what are your gears?
If you're still trying to motorvate the thing with 3.73 gears you're definitely contributing to the problem right there.
If you have all the parts to drop it down to stockish and 33's I'd say do it unless you regeared to a deeper gear for the 35's. Taller = poorer wind drag. Bigger tires = heavier, harder to move, engine/trans working harder, more friction with the road, etc.
I'm no expert on this stuff but seems to me you'd be hard pressed to get a carbed small block, TH400 having, 3/4 ton 4x4 on 6" of lift and 35's with a ton of craftsman equipment in the bed (think you said you set tile?) get good gas mileage. Just isn't going to happen. That truck new and stock would have been happy to get 13mpg. Now you have a large number of factors weighing against it getting anything decent.
P.S. What are you getting anyway?
yes, i've all but resigned myself to this. Its no surpise, i've been driving these trucks to work for years. I've always just paid the price cause you need a truck to do what I do. With the economy and rising gas prices, its starting to get expensive to get to work- plus i live in the damn city now (not by choice) so, just looking for ways to squeeze a little mileage out of the deal.
to answere you're question, i run 4.10s with my 35s which seems to be fine. i don't spend much time over 60- nor do i like to anyways with that setup. the th400 isn't helping either.
otherwise, like i said, its a great rig. starts every day and gets the job done. but if we get to 4 bucks a gallon i'll need a second job to cover getting to the first one!
shovelbill80
1/2 ton status
700R4 has a 3.05 first compaired to the 2.5 of the 400.....helps to get things moving a bit easier.
if you don't go over 60, 4.56's would probably get you a little better mileage too. i like TBI for the cold weather better. mine sucks on gas cause it don't leave NYC much, have remote start. sometimes i get 7 mpg, sittin in traffic yealds 0 mpg though. i'm going to do some mods this spring to help a bit. my bro, the PO, consistantly got 14 on the highway for 20 years.....'90, 31's and geared 3.73.
if you don't go over 60, 4.56's would probably get you a little better mileage too. i like TBI for the cold weather better. mine sucks on gas cause it don't leave NYC much, have remote start. sometimes i get 7 mpg, sittin in traffic yealds 0 mpg though. i'm going to do some mods this spring to help a bit. my bro, the PO, consistantly got 14 on the highway for 20 years.....'90, 31's and geared 3.73.
