Why no TBI Engine thread?

89 K2500, TBI 454 here. I put a cold air intake (I spent good money on one years back, im gonna use it), factory Y pipe into single side pipe with a Harley-Davidson muffler (it was free), currently has a broken driveshaft and a giant coolant leak. Even though gas is friggin' crazy, I still try to daily it because its just fun. Someday I'll put in the money for a 496 stroker kit and put a massive supercharger on it, paint it bass-boat style purple with electric blue flames, and make it into a Mud racer. Yes, all that without doing a LS/Vortec swap

Minn95Dually said:

That's what I was thinking. With the gads of info why not be in one place? I am trying to figure out performance upgrade paths and seems to be alot of options. Like, is it worth upgrading, should I do TBI mods, what intakes to use, manifolds to use, should I consider a crate engine, things like that.

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...have you not looked at the stickies? There are TBI performance threads.



https://www.gmt400.com/threads/the-ultimate-88-98-performance-toolbox.12428/ This one covers both but has a ton of TBI info

Here's a different viewpoint. I personally would take a factory bone stock TBI K motor over ANYTHING else for certain aspects. They were MORE dependable than anything I ever saw before or since. If I needed the least expensive to maintain truck that could go 300,000 miles it would be a K 350 TBI. But as soon as someone starts dickin' with them, they are no longer good for that.

Is there faster stuff? Absolutely. Can you have your cake and eat it too? Nope. Whatever small or large gains you get in horsepower, you will lose more than you gain in terms of long term reliability, around town driveability, fuel mileage, and the expense of all the parts to try to make it all work like converters, headers, gears, etc.

I want all the smooth low speed torque and dependability I can get, and you can't get that with a bumpy cam and similar modifications.

The BEST modifications are the most expensive. Displacement and compression. A cammed 8.5 to 1 350 is a dog at most usable rpm's.

The BEST all around cheap dependable long lasting FI engine combo was the GM TBI engines from '87-'95. I've been a professional tech since '82.

Tom

I have the normal stuff on mine. Headers 2.5” mandrel exhaust with x pipe. It isn’t loud at all. TB spacer good air cleaner and a little bump in timing. Fires right up gets it’s 13-15mpg and will roast 35’ tires.

C30454 said:

Here's a different viewpoint. I personally would take a factory bone stock TBI K motor over ANYTHING else for certain aspects. They were MORE dependable than anything I ever saw before or since. If I needed the least expensive to maintain truck that could go 300,000 miles it would be a K 350 TBI. But as soon as someone starts dickin' with them, they are no longer good for that.



Tom

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I know you! You're one of those people that uses your truck as though it were a truck. Practical, sensible and adult like. I agree with you. I didn't know anything about TBIs when I bought my clean and stock 1993 K1500. I 'm pretty happy with it but the performance wasn't what I expected from a Chevy 350. Rummaging through lots of bad information I finally understood that Chevy built it this way for reasons that Tom elucidated. It's a truck engine for a fairly light duty full size truck. It gives you the reliable low end torque and it is low maintenance. The worst aspect is the gas mileage.
When I first got it I was a little surprised by the lack of aftermarket performance parts and information. Here I had just bought a Chevy small block for the first time in years and I wanted to try some performance ideas. The TBI is a transition away from the old science and cautiously and humbly it edges toward the new science. The TBI doesn't breath, and it doesn't rev. It's low compession.The throttle body has built in air/fuel flow limitations The manifolds don't flow. It has a very mild cam.It's almost like the engineers had a specific application and market in mind and it wasn't hot rodding. I realized that if I wanted a performance motor the TBI was a poor choice to start with. Bolt on modifications like a set of headers wouldn't do much. You would need to upgrade fuel delivery and injection, get heads that will flow, camshaft, headers and exhaust. But it still has the 8:5 to 1 compression ratio. It was easy to see why the LS is such a no-brainer.
I'm glad I didn't modify it. I don't know what the original mileage was supposed to be when new but mine gets between 10 and 12 MPG. With the current gasoline reality I'm very interested in whatever will improve the mileage. My answer to the price spike is to not drive it so much and consider other ways to get things done. It's my daily driver and it's got me remembering what a lovely economical car my 1969 VW Beetle was. It got me through the OPEC oil embargo of 1973. That shock changed the world and lots of folks dumped their low milage gas guzzlers in exchange for ANYTHING that got over 20 or more MPG. That was a period of adjustment for everyone. There were plenty of rumours flying around and waiting in long line to get gas was a drag. Once in a while somebody would get shot, the is America after all but by and large folks realized that they were all in the same boat and managed to get through it okay. I can imagine what would have happened if people had reacted to the oil embargo the way they reacted to the pandemic. Oh that would have been hilarious. I just might park the truck and get a bug for the time being.
So what can be done to improve the economy of the TBI?

Wait a minute, did I miss the Vortec Engine Thread?

Caman96 said:

Wait a minute, did I miss the Vortec Engine Thread?

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Don't need one, vortec's are made out of real tornados.

I enjoy reading the TBI discussions;
I intend to keep my truck stock looking, and running the OEM computer;
I have understood that our heads don't flow well, but that goes along with the tiny cam, and measly (cfm size) throttle body.
I would love to have more power, but more power requires two things:
1) increased airflow
2) increased fuel flow
And I'd like to stick with the mileage I have, and not make that worse - that second point means mileage would invariably go down.

TBIs respond well to basic small block hot rod tricks. They are 9.3:1 unless they are an 8800+ GVW engine, then they are 8.75:1. My TBI engine was an 8.75:1 4-bolt main unit with 810 heads. Headers into the factory catless 2.5" duals with an added X-pipe and 1.6 roller rockers along with an Edelbrock intake bored to 2", a 454 TBI ubit and 454 air cleaner really perked it up. Also changed the cam for a factory LT4 Corvette roller cam. NONE of it hurt the mileage and it still knocked on 20 mpg highway on 87 octane in a heavy 83 G20 van. I also ran it with both ZZ4 heads and cam as well as a set of ported 906 Vortecs, custom comp cam and a single plane victor jr manifold. Even with the Vortecs, bigger cam and single plane it still had factory like driveability and 19+ MPG.

Forgot to mention my other TBI, 94 GMC Sierra 1500. No real mods I’ve done. Previous owner put in dual side pipes with a really odd H Pipe set up. He also put a massive dent in the door and added a very sporty slipping transmission. My plans for this; make it into a good mix of everything. Daily driver that I can also use to do work and go hunting with. My old Toyota is now gone... NOT (it just won’t break). I like using this as a runabout and yard mule. I’m thinking of a dual carb setup but that ruins the good mix of everything. I might downgrade it to a Vortec 305, I don’t need so much displacement for this or lots of power (S10 Blazer Xtreme is for that).

Only issue with the engine is not having an issue. Transmission is going out and the transfer case is absolute shoot.