TBI vs Vortec

It runs well throughout the RPM range. (Keep in mind the stock tbi is dual plane) The only time I've seen it as a problem is if it is a completely divided plenum. Most of the tbi systems fire all of the injectors in sync so to get proper fueling all of the cylinders need access to all of the throttle bores all of the time. So run a manifold with a cut down divider, or single plane.I use edelbrock PN 2716.

In some ways the Vortecs are like tbi its a central injector feeding the poppet valves also nick named spider injection. The Vortec does have a mass air flow sensor for much better fuel targeting based on air mass entering the intake. There are also really nice kits that allow the poppets to be re-placed with injectors at each cylinder. Vortec also has faster starting and snap excelleration due to the fuel being delivered closer to the cylinder chamber vs. spraying way up the intake taking the same long trail as carburetors did. Also the vortec heads are superior in flow characteristics when compared to those TBI smog heads. Just my 2 cents vortec the way to go.

I've owned several of both. As stated repeatedly here, TBI is nearly bulletproof. Vortec is more fun to drive and tow, and gets a little better mpg.


I prefer the simplicity of the old TBI but I drive two Vortecs right now. And I'm happy with them.

I have a 95 and 97, both trucks are identical besides the engine obviously, color, and tire size. 275/60r15 on the 95, 255/70r16 on the 97. The 97 has more power as expected, the 95 consistently gets 1-2mpg more... which is interesting considering several people on this thread claim the vortec is better on fuel.

With that said, I think people put too much weight on the differences between the two, considering both are underperformers compared to more modern engines like an LS.

Buy the one that is the better deal and enjoy it, don't worry about it.

I agree with Thunderstruck. Take care of the one you find a good deal on!

Truck 1: 1995 K1500 RCSB Chev with a new roller-cam upgraded 5.7 TBI that I helped install 3 years ago. Had it 12 years and I love that truck. It is not a race truck and I am keeping it as stock as possible. It is a very obedient and predictable servant, but not a race truck. It is a Z71 with 3.73 gears and a NV3500 manual transmission that is still tight.

Truck 2: 1998 C1500 RCSB GMC that was bought with two broken connecting rods BUT STILL RAN AND THREW NO CODES (but it did throw a lot of oil out the oil pan holes). It's new engine was put in two years ago and has the MPFI upgrade, headers, dual exhaust and an RV cam. It came with 3.42 gears and I gave it a 4/6 drop. I love that truck too.

Their engines each have slightly different personalities. The TBI is quite torquey at low RPMs, but that may be because of the lower 3.73 gears but it's no screamer. The MPFI C1500 is no slouch off the line but has much "longer legs" than the TBI with its 3.42 gears. It is true that the MPFI engine does start almost instantly while the TBI takes about a second to crank before it starts. Neither engine requires longer cranking even if it is -30 degrees Celsius (thirty degrees BELOW FREEZING here in Canada). They're not exotic. They're just reliable.

I keep track of mileage in EVERY tank of gas in a spreadsheet I made a long time ago. The K1500 TBI takes me back and forth to work and stays pretty close to home. It rarely sees highway speed and delivers 16 miles to the IMPERIAL gallon reliably. The C1500 MPFI recently went on a long trip of about 1200 miles and peaked at 24 miles to the IMPERIAL gallon. Not bad at all.

Being as I really like both of my trucks and am not one to smoke tires or abuse them I can't say that I have explored the "limits" of their capabilities and I don't even want to. But I'll listen and learn while some of the other guys try to prove why one is better than the other. Maybe I'm getting old but it just seems wiser to do a good job on the maintenance and make them last. I wish I had TWO of each!

This isn't an MPG thread but many have cited Vortec doing better on gas than TBI. Perhaps that's true but on a road trip I just took I netted 18.4, 19.1 and then 19.4. Previous best was 17.xx. Truck is an '89 SB/RC five speed 4x4 with 3.73's and a tree-fiddy. I kept the speed mostly between 55 & 65 to net numbers in the 19's. Blew me away, that's for sure.

DerekTheGreat said:

This isn't an MPG thread but many have cited Vortec doing better on gas than TBI. Perhaps that's true but on a road trip I just took I netted 18.4, 19.1 and then 19.4. Previous best was 17.xx. Truck is an '89 SB/RC five speed 4x4 with 3.73's and a tree-fiddy. I kept the speed mostly between 55 & 65 to net numbers in the 19's. Blew me away, that's for sure.

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Good mileage for a TBI. I logged the fuel mileage on a road trip in my 97 Express conversion van back in 2016 with a 395' marine cam, tri-y headers, high flow cats backed to a 4L85E and 3.73 gears. Averaged nearly 19 mpg for the whole 2,200 mile trip. Alot of that trip was rolling hills and ran for nearly 3 hours at 90+ mph. We were running better than 70 mph for most of the trip.

I bought LD K2500 ECSB with the NV3500 with 9800 mi on it in 1992. The NV3500 was a absolute POS, replaced once under warranty, again at 150k, and when I sold it at 285k the trans was in the process of fragging 5th gear....again. I really liked that truck—the rest of it was almost flawless and gorgeous.

With apologies to the Mopar 318 and FOMOCO 1st gen 302, the 5.7 TBI motors may be the longest lived cast iron gas V8 ever devised by humankind. It’s no secret, it’s a low RPM motor. The TBI’s outlast the 5.7 Votecs, and the 5.7 Vortecs outlast the 3rd gen 4.8/5.3/6.0’s which operate at even higher RPM’s.

Stoplight to stoplight my 5.3 beats my 5.7’s, but running up the mountain passes the 5.7’s have a wider power band, don’t hunt and peck through the trans as much, and pull the hill at lower RPM’s.

Also, that 91 TBI got better fuel mileage than the 5.7’s and as good as my 5.3.

Problem is, the TBI’s don’t have the power needed to negotiate Mtn highways at altitude here in Colorado.

L31MaxExpress said:

Good mileage for a TBI. I logged the fuel mileage on a road trip in my 97 Express conversion van back in 2016 with a 395' marine cam, tri-y headers, high flow cats backed to a 4L85E and 3.73 gears. Averaged nearly 19 mpg for the whole 2,200 mile trip. Alot of that trip was rolling hills and ran for nearly 3 hours at 90+ mph. We were running better than 70 mph for most of the trip.

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Yeah, I didn't believe it and so I reverified mileage logging on the trip odometer and such. Was always told 4x4 will do a little worse than 2wd, yet I can't squeeze more than 16.xx out of my wife's '92. Other things to note about my truck is that I kept the front tires at 38 psi and rears at 32. Completely new exhaust (3") with Walker high flow cat, which wasn't installed for the trip.. Truck seems just as happy at 80mph as it does at 60. Not sure what it would net at those speeds for an entire tank though.

alpinecrick said:

...the 5.7 TBI motors may be the longest lived cast iron gas V8 ever devised by humankind. It’s no secret, it’s a low RPM motor...
...Also, that 91 TBI got better fuel mileage than the 5.7’s and as good as my 5.3...

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Low RPM and low compression, I'm convinced that helps longevity as well. Easier on the bottom end when things go boom in the combustion chamber millions of times over..

I am really happy with the TBI in my truck, to think I almost sold the thing shortly after I got it.. I might even play with timing after logging knock counts as it currently is at factory spec. However, it's already doing fantastic. The only other cars in my fleet which do better are my Town Car and the Fireturd, but only the Lincoln does so by a noticeable margin- 24.xx. It's also a very smooth running engine, but starts to burn lots of oil after about 1000 miles into an oil change. For the whole ~2,500 miles my truck just did on it's current oil change, it used maybe 1/4 of a qt. Compared to my other oil slurpers, that's equivalent to zero oil burn for me.