TBI Heads

[Pinger]

You do not have to be WOT to reach maximum torque output. All you have to do is hit barometric pressure in the intake manifold and be in power enrichment fueling. At lower rpm you can hit atmospheric pressure in the intake manifold at 1/2 throttle or less. With factory GM transmission programming you hit full load well before the PCM unlocks the torque converter or downshifts.

.

That is what a lot of people can't get their heads around.
That at around half the rpm of maximum power rpm, half throttle is WOT.

 

[LC2NLS6]

Both of my 93 454 tbi suburbans (3.73 and 4.10 geared) are complete dogs in stock form compared to all the 3.08-3.23 LS trucks and suburbans I've towed the exact same boat and trailers with. Even with new distributor, cap plugs rotors, timing etc, all runs to spec, fuel pump and pressure too. I've had tbi gm trucks since I was 17 in '93. My 88 1500 got edelbrock everything - cam headers intake chip in '99. It wasn't really much faster in grand scheme of things. The tbi heads are garbage. The reason I did cam intake and Holley efi on my blue 93 was it couldn't tow my little boat up a hill this summer when I started the hill at 65 mph it was 35 mph at the top at WOT. My 09 burban had no such issue on same hill same boat.

 

[LC2NLS6]

That is what a lot of people can't get their heads around.
That at around half the rpm of maximum power rpm, half throttle is WOT.

If you have enough fuel to maintain correct afr out. RPM is moving air, air pushed in, and if it can get around the half open throttle blade, then its what it is, and slapping on a dominator 1050 cfm throttle body won't make you go faster if the engine manifold heads and cam can't move that amount of air being pushed in. So tbi heads are garbage, get vortecs or alum.

 

[LVJJJ]

Had an '88 3/4 ton Suburban 454. Was a bit of a dog with low compression. Had to add a bunch of bolt ons to get it to tow our big Arctic Fox travel trailers, Thorley headers, MSD adjustable timing control, two 4" air intakes, Doug Nash underdrive/3.42 gears and other things I can't remember. Now have a '94 1/2 ton 4wd GMC Suburban. Original 350 was a total piece of junk, now have a 383 stroker with JBA headers and two 4" air intakes. Out-pulls the 454 with 3.73 gears. Great torque at low rpm which is what you need to tow.

 

[L31MaxExpress]

Both of my 93 454 tbi suburbans (3.73 and 4.10 geared) are complete dogs in stock form compared to all the 3.08-3.23 LS trucks and suburbans I've towed the exact same boat and trailers with. Even with new distributor, cap plugs rotors, timing etc, all runs to spec, fuel pump and pressure too. I've had tbi gm trucks since I was 17 in '93. My 88 1500 got edelbrock everything - cam headers intake chip in '99. It wasn't really much faster in grand scheme of things. The tbi heads are garbage. The reason I did cam intake and Holley efi on my blue 93 was it couldn't tow my little boat up a hill this summer when I started the hill at 65 mph it was 35 mph at the top at WOT. My 09 burban had no such issue on same hill same boat.

I had a TBI 350 in a G20 van. Never had a problem climbing long grades even with a 3,500 lbs car in an enclosed trailer going into new mexico and colorado. I had 1.6 rockers, thorley tri-y headers, dual 2.5" exhaust with a X-pipe, a 454 TBI, 1" open center spacer and a chip at the time. 700r4 and 3.08 gears. It went up those grades at altitude as fast as I felt like going. At 70 mph if I wanted to accelerate or have power to climb a grade, I could still catch a downshift to 2nd gear. It had no reservation spinning 4,500+ rpm and pulled well to 5,500 rpm.