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Will TBI give better gas milage over a carb?

COCHEV

COCHEV

1/2 ton status
Joined
Jul 9, 2002
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Location
Washougal WA
All things being equal- lift, tires, gears, motor cam etc, would swapping to tbi over my 600 edelbrock net me any gain in mileage/economy? enough to be worth the hassel of doing?
 
The short answer is Yes and yes.

The long answer is do it. Theres more reasons than just economy. Your also gaining superior cold start ability, less cranking on your battery due to that. Plus you'll pick up fuel mileage. Plus you'll gain offroad capability because the TBI isnt phased by offcamber situations like a carb.
 
I have a 95 GMC 1/2 ton with a 350 that has TBI. I also have a 75 K-5 with the originial carbed 350. In GM's 20 years of truck building, they managed get exactly the same mileage, 11. In answer to your question, no.Save your money,install a LS.
 
buefchris said:
I have a 95 GMC 1/2 ton with a 350 that has TBI. I also have a 75 K-5 with the originial carbed 350. In GM's 20 years of truck building, they managed get exactly the same mileage, 11. In answer to your question, no.Save your money,install a LS.
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Something is wrong with your 95 if it is only getting 11. That truck should get an easy 15, upper teens on the highway if all is running right, being stock or near it.
 
Well, it use to get 15 mpg, [it's best]. when it was new on the highway. My Blazer use to get 13 but as time went on those numbers began to fall.
The 95' is bone stock height and tires. Tune-up's,filters,water pump,starter and alt changed but that's it.
My point is if your looking for mileage numbers to change for the better, I don't see a big difference from a stock carbed motor to a stock TBI one. A lotta work with a small payoff.
Other benefits mentioned, yes. I'm a huge fan of EFI engines.
My LS conversion made a big difference in power and mileage. And when the time comes, the 95' will see a ls1,2or3.
 
I would'nt change it to save money on fuel, it may be years to recoop! But all the other reasons make it well worth the time.

Cleaner oil at oil change time is enough for me. They run SO much better cold start it's incredible. My 90 Suburban literaly runs great at cold start and drive away, just like it was warmed up. :waytogo:
 
My '91 Blazer in stock form on 31" tires used to only get 10-12 mpg when i bought it, rebuilt the throttle body and replaced just about every sensor and I'm consistently averaging 16 mpg, and one highway trip it actually hit 18 mpg, next on my list is a k&n filter and a high flow cat... I'm hoping to get it closer to 20 mpg on the highway. If your '95 is doing that poorly I'd do some serious investigating as to why... However, I used to have a '96 f150 that would get 17 mpg, I put Slightly bigger tires on and it dropped to 13 mpg...
Two of my coworkers have '08 silverado's, the only difference between them is one is a regular cab and the other is an extended cab. We all have similar commutes, the regular cab gets 15 mpg consistently in drive, and the ext cab gets 18 to 20 in overdrive... The guy with with the regular cab swears that we are going to ruin our transmissions driving in OD almost all the time... I argue that the money we save on gas will more than pay for the trans rebuild.
 
smier said:
My '91 Blazer in stock form on 31" tires used to only get 10-12 mpg when i bought it, rebuilt the throttle body and replaced just about every sensor and I'm consistently averaging 16 mpg, and one highway trip it actually hit 18 mpg, next on my list is a k&n filter and a high flow cat... I'm hoping to get it closer to 20 mpg on the highway. If your '95 is doing that poorly I'd do some serious investigating as to why... However, I used to have a '96 f150 that would get 17 mpg, I put Slightly bigger tires on and it dropped to 13 mpg...
Two of my coworkers have '08 silverado's, the only difference between them is one is a regular cab and the other is an extended cab. We all have similar commutes, the regular cab gets 15 mpg consistently in drive, and the ext cab gets 18 to 20 in overdrive... The guy with with the regular cab swears that we are going to ruin our transmissions driving in OD almost all the time... I argue that the money we save on gas will more than pay for the trans rebuild.
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That guy should be taken out back and shot for being so ****ing stupid. And please tell him I said that.
 
Stomis said:
That guy should be taken out back and shot for being so ****ing stupid. And please tell him I said that.
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It'll be a cold day in hell when he burns that transmission up running it in 3rd all the time. All those poor turbo 350's that died early, only because they didn't have OD?

The guy is still an idiot, but he's right, the transmission is stronger in drive then OD...not that it matters at all in the way he's using it. That's like saying a half ton truck isn't strong enough to commute to work, so you should drive a mack dump truck everywhere.
 
Yes, the cost and time of retro-fitting tbi is my concern. My truck does everything i ask it to...except get good mileage. it is lifted, which does not help- work or mileage, however, its what i have to roll in so i use it. not really wanting to get rid of perfectly good working rig for a different one, but gas is killing me.

a tbi, th700r setup would be more ideal. or diesel. again- that requires another intial purchase or expesive retrofit. anyone have what i want and want to trade? :deal:
 
I love the TBI, but the only way I would do it is if I had a complete, perfectly running donor to swap everything over from. It would still be time consuming and frustrating in my opinion. The other issue is if your current setup is "computer friendly", or would you be swapping cams etc... Dang this site!!! Now I'm daydreaming about swapping a tuned port setup onto mine.
 
my crew was getting close to 14 when it had the stock tires on. im not sure that tbi would be a huge gain in mileage with a lifted truck on larger than stock tires.
with that said- there are alot of tbi subs and trucks at pic-n-pull lately. that would make it easier, except that you would need 13psi to the engine from those dual tanks. external pump would be the easiest route. or grab the units from a tbi pickup.
my k5 used to get 13 highway on 35s with a q-jet and alot of dizzy mods.

maybe thats an option. play with the dizzy to possibly squeak some more mpg from the current set-up.
im not sure if swaping to a q-jet would really help or not. 600 edel's get pretty good mileage
 
I have a q-jet i got from a member here, just haven't had time to do it. also wanted to swap to a spread bore manie when i did so.

I've even concidered returning the rig to stock hight or at least 2" lift as it has add-a-leafs in the rear, and running 33s.

I don't know. mostly, it is what it is. :thinking:
 
With the way things normally go…. I would leave it alone if it’s running great. You try to “make it better” and often create problems and it runs like ****.

My truck was a TBI that was converted back to carb by the PO. Standard 350 with a edelbrock 600 and intake. Runs perfect. Crakes up in 2 seconds after sitting for 3 weeks in cold temps. I think the key to it all regarless of TBI or carb is proper turning. Carb maybe doesn’t get the best gas millage, but I say screw it …. Runs like a top.
 
Yeah my 86 gets decent mileage with the quadrajet but the tuning is what makes or breaks it. TBI is cool but the time and cost(not to mention the hassle of dealing with a smog ref for emissions in my state) make it a losing situation.
 
K5_Fla said:
With the way things normally go…. I would leave it alone if it’s running great. You try to “make it better” and often create problems and it runs like ****.

My truck was a TBI that was converted back to carb by the PO. Standard 350 with a edelbrock 600 and intake. Runs perfect. Crakes up in 2 seconds after sitting for 3 weeks in cold temps. I think the key to it all regarless of TBI or carb is proper turning. Carb maybe doesn’t get the best gas millage, but I say screw it …. Runs like a top.
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dude, just use the stock font.. that sh*t's micro, hard to read..
 
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