Reliable - Fuel economic TBI Power

[datmony]

I am starting to think about a new motor for my '91. I will not be doing a LS swap..... just too many other projects at the moment and I am looking to move to a new place where I will be doing a lot of shop renovations and house renovations this summer.

I want to keep this to be a very simple, fresh, reliable engine that will work within the confines of TBI. I drive this thing a lot as a daily driver and this winter it will be a snowboarding rig, so I want to keep the fuel economy in check. Current motor actually runs like a champ. My only complaints are climbing mountains at freeway speed, merging onto the highway at 70 with a semi barreling down in the right lane, etc. Normal around town, or offroad the power is fine. I also do not want to lose any of that low end power that makes the TBI a great truck motor.

Bearing these thoughts in mind, what are folks recommendation on a formula for the engine. I will upgrade the stock pump, adjustable fuel pressure, injectors. and do ecm/pcm programming as required but I don't want this to be a science project of tuning the TBI to milk the last little bit of power by pushing the confines of the system.....

Simple reliable, but makes good power..... what would you build..... good torque more important than high HP but still able to accelerate well at freeway speeds up steep grades (cascades, sierras, rockies, etc)......

Interested to hear your thoughts.....

 

[frankin5]

My question is what gear ratio and size tires do you have?

 

[dyeager535]

I'd agree with frankin5. Gears will probably get you close to what you want with none of the TBI mods.

In proper tune, the same K5 with a carbed 305, 350, and fuel injected 350, will all net nearly the exact same MPG.

My best so far in my truck, on non-flat ground, going 60-65MPH, has been 16.7MPG (that's injected...I got 17MPG with the carbed 350 under ideal conditions...cool weather, completely flat ground, 50MPH).

I think I'd scrap the TBI and go with TPI if you don't want to go full LS. Even on the low-end, TPI buys you around 30ft-lbs of torque at the peak, and it certainly feels snappier to me throughout the power band. A good set of long tube headers may net you about the same gains.I know you said TBI, but you are changing out just about every component anyway. Without changing the induction system (heads, intake, TBI, etc.) there is no other way to increase the torque without increasing displacement or spinning the engine faster. A larger cam is going to make more power, at a higher RPM.

TPI setups have started to get cheap because no one cares about them anymore, the LS is where it's at.

 

[Bent77]

Going to agree with everything @dyeager535 just posted, and the mileage numbers are consistent with what I’ve gotten as well

 

[454Sub]

I do throughly enjoy my TBI 454. It's dead nuts reliable, perform as expected and isn't terrible. It's got some upgrades but nothing serious.

That being said I would never rip the motor out and try and squeeze more out of it. I don't know where your located and your particular emissions hangups but I would go straight to LS and be done. Once decently tuned and limp mode tuned it, it's a rock solid reliable platform as well. Not to mention it can be serviced by any shade tree outfit, the TBI and carb like it or not isn't as easy to find parts for at AutoZone. We may dislike AutoZone, but convenience is hard to beat.

 

[datmony]

Thanks for the thoughts folks. It is not a matter of desire, cost, nor actually skill. The wiring doesn't scare me.... none of the additional work is daunting. I have all the tools, I have all the know how to do it. It is a simple item, time. My goal is to bench build a TBI and simply swap it in fast.

I have SOOOOOOOO many other projects in the hopper that I don't want this one to get any additional scope creep beyond what it already has. This is just a daily driver, with only 285s. Gears are only going to net me marginal improvements due to the small tire size.

 

[dyeager535]

Go buy a GM L31 crate for ~$1900, drop it in, and have 45 more HP and 30 more ft-lbs of torque.

Minimal changes to the TBI needed. Reprogramming of course, intake, maybe TPI/Vortec pump and AFPR here (might be able to get away without, just have to see) but that's it.

Now I wasn't TBI in the first place, but it was pretty much impossible cost-wise to beat the L31 crate engine (with warranty) by rebuilding an old block, which I already had. Throw headers on and you might be in the 70HP+ range over TBI. Realistically, the L31 has all the "goodies" most want when they build an engine anyway, it's just a complete package...high compression, good heads, roller cam, better HP/TQ than stock older motors, and brand new parts.

Don't get me wrong, I like building things too, and I put my last motor together, but I knew nothing about the crate engines at the time. For minimal hassle, and modest, reliable improvements in power with no real downsides, I see this being the best route.

 

[datmony]

Now we are where my head is at!!!!

I as well love building things, this is a not that showcase, I will do nice things to it for sure (see my build thread on it) but it will not be the take it down for 2 months thing. This K5 is right now the hammer of my tool box. "I love it, use it all the time" but it is utilitarian.

So with something like that and headers are a definite update (three wire O2 sensor with them) what else would someone do for simple, slap it in and go scenarios. I am also ok buying a built crate engine and slapping a few goodies into it (cam, throttle body spacer, injectors, etc) if it makes sense.

Eventually this will get a wizbang motor. But I am frankly planning on putting on enough road miles before that additional move that this won't be wasted. And I have a backlog of projects to finish first..... my Cj7, my new shop, the updated house for the wifeypants, my 63 Jag, a new lathe..... etc etc etc.

I simply want bolt in improvement that I can do in a weekend, weekend + because the snow is already flying.....

 

[dyeager535]

https://www.ebay.com/itm/3015672963...e9e366f85e2&bu=43203886955&cp=1&sojTags=bu=bu Where I got mine. $50 Visa gift card doesn't hurt, somehow I got free shipping to the house.

You could *probably* drop that in and be able to drive it lightly until the tune is done, which would make it potentially a weekend project. I wanted to do some things to it from stock (larger cap. oil pan, oil temp bung, BBC oil pump, etc) but as my engine already had Vortec heads, it was essentially a drop in. If talking about TBI spacer and what not off the bat, then buying a carbed Vortec intake and using a TBI adapter to the carbed intake, you wpuld then NEED what you WANTED.

As far as I'm concerned, there isn't much reason to change things on the L31. You can throw on roller rockers, which aren't a huge improvement in power, and you could do cam, but again the cam changes the powerband and will almost certainly screw with the tune more than the L31 does since the stock cam is so mild. but it makes torque at a lower RPM, which is useful getting these trucks moving. And if your freeway RPM's are fairly low, will pull pretty good in OD.

 

[runamok151]

Throw a mild cam in it. I absolutely loved the Edelbrock Performer after I put it in my truck. My '89 had 35s and 4.56s and it was the perfect match for all around driving. 65-70 mph put it right around 1850-2000 rpm, right in the heart of the torque curve, and never hunted for gears on the highway or hills.

 

[Stomis]

If you're chasing injection upgrades but sticking with a smallblock consider the fitech or holley sniper units. Either one is going to perform/tune better (easier I guess is really the right word) and would let you throw whatever you want at the motor in dribs and drabs.

If I wasnt doing my s10 on such a budget I would toss the TBI and put a big cap HEI and a holley sniper on top. For a DD its really hard to beat a 10:1 355 with vortec heads and an "RV" style cam