Built tbi vs ls swap

[Schurkey]

The Gen 5 block was an engineered disaster in terms of head-swaps using original Mark IV heads (not so much a problem with aftermarket heads) and engine-driven fuel pumps. A one-piece rear main seal, and the re-routed oil passages were actual improvements.

The Gen 5 ports and valves weren't any worse than the Mark IV "small port" "round-port" "peanut port" heads. The net-lash valve train was unwelcome. Standard cast aluminum valve covers were nice, though.

Early TBI 454s were based on the Mark IV--up to 1991(?)

The Gen 6 "Vortec" 454s used crappy swirl-port heads like the TBI small-blocks. Those heads are not the great leap forward that some magazines have implied. They were marginally better than the round-port heads they replaced.

 

[Tomahawk 309]

My son has a 2010 with a stock 4.8 in it. Honestly it runs much harder than my 94 5.7 tbi. Both are bone stock and his has about 20k more miles on it than mine (130k).
I used it to pull two Harleys from S FL to SE GA and it didn't break a sweat. I'm sold on the LS swap.
Imo by the time you get new heads, cam, throttle body tune etc... to be where the ls is stock, you're well into what an LS swap would cost. That's my take on having spent time with both platforms.
Of course the LS swap is way more time and work but my time is cheap.
I will also add you can get 4.8's dirt cheap.

 

[Schurkey]

My son has a 2010 with a stock 4.8 in it. Honestly it runs much harder than my 94 5.7 tbi. Both are bone stock and his has about 20k more miles on it than mine (130k).

What transmission, and what gear ratio in each truck?

 

[Tomahawk 309]

What transmission, and what gear ratio in each truck?

I see where youre going....4l60e for both trucks 3.42 for the 5.7 and 3.23 for the 4.8 and tire size is basically the same albeit 15" rims vs 17".

 

[L31MaxExpress]

5.7 Vortec eats a 5.3 alive for torque and has similar HP. 4.8 is a gutless pig, with the cruise set they have to double downshift to hold 70 mph uphill in an unloaded Express van. My 5.7 with bolt-ons would climb the same hill in overdrive despite the heavy conversion package. The 4.8 van had 4.10s to my 3.73s at the time as well.

A stock L31 with a 300 hp marine cam will make over 400 ft/lbs across a fairly broad powerband as well as 320-360 hp depending on the intake, headers and exhaust. The 395' 300 hp marine cam is the same one the HT383 uses and also used in the Ramjet 350 with 1.6 rockers.

https://www.hotrod.com/articles/how-to-build-a-cheap-small-block-chevy/

I have built this exact same engine setup except used a F/Y-car aluminum head LT1 cam(prefer them over the 395' cam), comp 787 retainers and pac1218 springs with 1.6 rockers. Used a dual plane spreadbore intake and a good 850cfm Q-Jet that I rebuilt and recalibrated. With headers and 2-1/2 exhaust it pulled like a freight train backed to a 700r4 and a 3.08 rear gear. Was in a 92 AWD Astro van that formerly had a 4.3 CPI in it. Drive it on the primaries alone and it got great fuel mileage, open those massive secondaries and hang on to something. Well tuned Q-Jet will beat most injected engines in fuel economy and also have suprising power.

Actually just taking a break from building one. I generally add the primary enrichment tubes that most Q-Jets lack and drill the airhorn for the fuel disharge ports that connect to them. Allows me to run a leaner calibration on the primaries and still get enough fuel under heavy part throttle. Adds 0.020" fuel discharge per primary venturi at about 1/2 throttle rather than having to add that much more in the main jets.

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[[email protected]]

I went the Holley Sniper route, and it runs the engine just fine. The distributor is plugged in, but the factory ESC is in a box on the shelf. The stock ECU is still there to control torque converter lockup, but when I get done rebuilding the original engine I'll add a vacuum switch and a relay to control it off of throttle position and the 4th gear pressure switch. Then I can yank the stock ECU and wiring. Eventually I'll plug in a Hyperspark distributor.

I looked into the cost for tuning my own setup, and it was half of what I'd spend on the Holley. I'd already spent money trying to fix the stock TBI, and it was a fiddly mess. You have to hold your tongue just right when bolting it together or it leaks. To get near the power capacity I needed, I also needed to bore it out. If you include the prices of an adjustable FPR, the mini-gauge kit, a pod spacer, a rebuild kit, new injectors, an adapter cable for tuning, and the custom ECU, you're getting near the cost of a Holley Sniper, which can support 600hp out of the box. The only issue I had with the Sniper was the TPS failed - and apparently they all do. All the other issues I've had with it were my own doing: exhaust leak, dorked a cable end, ignition module crapped out, ignition coil fell off.

That said, I'm impressed with what some people can accomplish with the TBI. It's just not for me, although I've considered trying to bolt together a two-TBI setup for my Cadillac-powered crapcan-racing Jaguar.

Plow-flow 4, is that a John Deere fuel injection setup?

Thanks Erik I have looked all over on how to wire these .I found a few videos on the install butt they leave out the wirering

 

[Erik the Awful]

Wiring's easy for me, so the install went quick. The biggest problem I had was running the plug for the handheld through the firewall. I ended up using the firewall grommet for the antenna, and a split piece of fuel hose as a shim to get the handheld cable up to the size to fit the grommet. That's also how I dorked up the cable end, but I used some fine needle nosed pliers and got it working again.

 

[badco]

Wow some of the answers are crazy and I skipped last two pages. I have built SBC's almost my whole life after 12 and in the business of building hp with stock stuff. First TBI is horrible to build power from, ditch it and do either a Holley 4bbl tbi system, port injection or a good carb. Flow = hp and stock tbi just dont support hp or fuel delivery very well not to mention it's really hard to tune a chip controlled truck unless you have a chip burner even then it's a pain. Could do a vortec 5.7 with the ls 0411 pcm and it will do 300 flywheel stock on dyno. 5.3 is a dog in stock form but add timing and take away all its factory limitations and they will outrun any of the stock 5.7s now they are lacking in bottom end grunt and even the 6.0 with a tune didn't outpull my junk 96 5SPD truck loaded but smokes it down highway.

 

[RDF1]

Ive always said for low end just go with the older 5.7 Vortec engines. They do feel like they have made more torque off idle till ~3000 RPMS
The LS engines dont make much torque from idle to 3000 rpms but they do come alive from 3500+ rpms.
Kinda complete opposites from one another.
Best thing is the power potential per dollar for the LS family.
Ive only messed with 1 TBI engine.
we put a 355 together for a friends '95 truck and went thru 6 different Tuners and never got it right. Went ended up going with a Carb
The next year we just did a 370ci LS engine, i knew a little more about it since thats all i was use to messing with.

 

[badco]

Old tbi is simple and serves its purpose. The 96-97 system makes great torque and low end power but difficult to tune, 98-99 was a little better but the gen 3 pcm on these trucks is amazing. If someone actually made a adapter harness would been even btr. I made one at the cost of a junk pcm but it was a pain. Only reason I didn't unpin was I drive mine daily and it took me a while to get tune like I wanted it. So I'd swap between them alot.