I recently picked up a 92 K1500 with a 350 TBI and Manual trans, and I want to beef up the power from the engine. I will be leaving the engine stock and building the heads and preparing everything so I can knock out everything in one long weekend so I’m not constantly tearing the engine down. What I currently have in mind is headers with a custom 3 inch exhaust, L31 Vortec head swap (with machining to allow more cam lift) a cam, not sure on lift and duration, and a vortec intake manifold to match the heads, strengthened push rods, as well as upgraded fuel and oil pump. Any advice on cams would be very appreciated, as well as other things I may have missed. Also will i need a professional tune, and if so, what’s my best route for that? I’m trying to keep costs as low as possible, like junkyard heads, but I know things like the cam will need to be purchased new, so I’m trying to keep cost in mind.
CK5
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350 TBI Build, input needed
- Thread starter amelbeach
- Start date
ps : The other option is to ditch the factory TBI and move to something like a Fi-Tech or Holley Sniper system (about $1200 US to get it up and running). The wiring is pretty basic, and there is a direct replacement high pressure fuel pump (Edelbrock 3581) to feed the system. You'll likely need to change the fuel lines to handle the pressure, unless you already have hardlines all the way up.
Having done it both ways, I vote for Fitech/Sniper route, whichever you prefer. If you're going to vortec heads and a better cam, you may want to look at Trick Flow heads they have better flow numbers and aren't too expensive, although vortecs from the junkyard are going to be cheaper. Your throttle body will need to be bored out, as well as higher fuel pressure and possibly even new injectors You'll need a fuel pressure regulator, and a gauge you can see while you're on the gas. An AFR gauge will help, and learn to use your ALDL data stream and you can tune pretty close to where you need to be. And you'll never get it timed right, since the ICM won't know what cam you have....which is the nice part of the all in one tbi systems. You can tune on the fly as much as you want for free.
runamok151
1 ton status
I had the Edelbrock performer intake and cam in my truck w/ stock heads and Thorley (iirc) long tube headers into a 2.5" dual exhaust. I thought the cam was a perfect fit. Tq and HP ranges were spot on for these trucks ('89 w/ th 700, 4.46 gears and 35s). Great grunt down low and held rpms at highway speeds w/out hunting or downshifting on grades.
Bigb55
1/2 ton status
The stock TBI system will be the crutch. It is a great system from the factory, very reliable and does the job. It has a very small window for self learning and adjustment. Mods to the heads and camshaft will be to much and will require a tune and fuel system mods.
The stock system can be tuned and mods made to make it work. The stock system with pressure upgrades, new injectors, and a tune is good for up to 250-270 hp. After 250-270 hp, you will have to get the intake bored and use a 454 TBI or a bored out 350 TBI to increase the CFM of the intake.
The easiest way to get the ECM tuned and up and running is to use a upgraded ECM From DynamicEFI. It even has a common starter tune for the L31 engine that will get close to what you plan to do.
Or just buy an Edelbrock proflo4 and call it a day.
Also depends on if you need to keep it SMOG legal wherever your are located
The stock system can be tuned and mods made to make it work. The stock system with pressure upgrades, new injectors, and a tune is good for up to 250-270 hp. After 250-270 hp, you will have to get the intake bored and use a 454 TBI or a bored out 350 TBI to increase the CFM of the intake.
The easiest way to get the ECM tuned and up and running is to use a upgraded ECM From DynamicEFI. It even has a common starter tune for the L31 engine that will get close to what you plan to do.
Or just buy an Edelbrock proflo4 and call it a day.
Also depends on if you need to keep it SMOG legal wherever your are located
x2 on the pro flo 4 system
and read up on my holley sniper unit from HELL story https://ck5.com/forums/threads/my-h...m-the-start-update-the-story-ends-now.335419/
and another member here just ditched the fitech and went pro flo 4 edlebrock .
You know, when you really think about it, why would you try to upgrade and make 20 year old technology work like today's technology? For less money, you can get an exponentially faster computer controlling better injectors that are all engineered to work together with each other. Plus you can tune it while you're driving using better software than even existed when the TBI was cutting edge. Even the FI-tech system is way, way better than the stock GM TBI system can be upgraded to, and it will cost less and be less of a headache. It really sucks when you realize how stupid you were when you made the decision to start upgrading your TBI, because you only want a little better performance, and you end up writing this post because you realize how wrong you were! Don't be me!
2 sides to this for me. I love the Stock TBI system. Basic, reliable, and can still get parts for them. But they are limited in what they can do. So this really depends on what you want out of it. Maximum performance will not happen with the stock TBI. Yes, there are things you can do. If you stay with the TBI, I wouldn’t waste money on heads. But a good roller cam, that’s designed to work with EFI will definitely help. There are several companies that can still program chips to help with add ons. But again, limited.
However, my ONLY counter point with aftermarket EFI systems, is long term parts availability, and technical support. Years ago, I was in the same situation. Wanted EFI, but had a mild 454. Holley Projection 4! Worked awesome! Spent the money on Oxygen sensor upgrades...
3 years later, the computer crapped, sent to Holley...
could not repair, or replace. Only solution, new digital control with the mandatory digital components. Cost as much as the original system did.... worked great.... again. But in a few years, parts started going again... and once again. The system was obsolete!!!!! Now what!!! Choices....
Buy yet another EFI system? No...threw a carb on it!
technology is always changing, and these companies are here to make money! Today’s technology, is replaced within a year! The long term support isn’t there. They are going to want to sell you another system in a few years...
So..... what is your long term goal! How much power do you honestly expect to gain?
However, my ONLY counter point with aftermarket EFI systems, is long term parts availability, and technical support. Years ago, I was in the same situation. Wanted EFI, but had a mild 454. Holley Projection 4! Worked awesome! Spent the money on Oxygen sensor upgrades...
3 years later, the computer crapped, sent to Holley...
could not repair, or replace. Only solution, new digital control with the mandatory digital components. Cost as much as the original system did.... worked great.... again. But in a few years, parts started going again... and once again. The system was obsolete!!!!! Now what!!! Choices....
Buy yet another EFI system? No...threw a carb on it!
technology is always changing, and these companies are here to make money! Today’s technology, is replaced within a year! The long term support isn’t there. They are going to want to sell you another system in a few years...
So..... what is your long term goal! How much power do you honestly expect to gain?
From what I've seen so far, none of the aftermarket is putting anything out there that hasn't been done before, by others, outside of a few hard parts.
They aren't using special injectors, they are using stock OEM sensors, but with proprietary ECM/PCM's, and providing a wiring harness. Digital data displays for factory OBD1 have been out for at least 10 years, as has wideband O2 support, self tuning, etc.
There is definitely some benefit to be had from buying systems turn-key. As long as they keep working and don't continuously become obsolete and unworkable. Some of the hard parts (intakes, rails) are really nice to have available, and there should definitely be kudos to the aftermarket for bringing that stuff out.
At least so far, it seems the factory injection stuff is still getting some love, the real impediment IMO is the TBI specific stuff. The original ECM's are super slow, and the throttle body is limited pretty heavily. All of that can be worked around relatively easily.
They aren't using special injectors, they are using stock OEM sensors, but with proprietary ECM/PCM's, and providing a wiring harness. Digital data displays for factory OBD1 have been out for at least 10 years, as has wideband O2 support, self tuning, etc.
There is definitely some benefit to be had from buying systems turn-key. As long as they keep working and don't continuously become obsolete and unworkable. Some of the hard parts (intakes, rails) are really nice to have available, and there should definitely be kudos to the aftermarket for bringing that stuff out.
At least so far, it seems the factory injection stuff is still getting some love, the real impediment IMO is the TBI specific stuff. The original ECM's are super slow, and the throttle body is limited pretty heavily. All of that can be worked around relatively easily.
