Why oh why does the TBI 454 suck so bad.

[csdineley]

Hello,
Guess this is more of a rant then a question. I've been driving my winter beater (92 k2500 suburban 454 TBI 4l80e 4.10 gears 33" tires) since I had the trans rebuilt. It seems to run fine. But since today was so nice I decided to drive my squarebody (87 r20 Vortec 350ho quadrajet sm465 3.42 gears 31" tires). Dam that thing feels like a rocket compared to the 454. I know everyone says the TBI motors are dogs. But dam were they really this bad new? Going up the same hills on the interstate. I can move my big toe and break the speed limit in the truck. In the suburban I have to have about 35-40% throttle and hope to only be down to 65 mph's. Haven't even tried towing with it yet. Since it can barely get itself up the hills.
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[Jake Wade]

They were pretty pitiful when new.

[Mattchu60]

Is it possible that 454 is just worn out? We used to have a 94' TBI 454 2500 pickup and it would just roast the tires if you wanted. Lots of torque, i dont think it was a hp demon but had lots of grunt. Used to haul gooseneck with 3-50's era tractors on it.

I have an 87' that had a worn out TBI 350 in it. It would upshift/downshift constantly on the interstate, got really annoying. It just didn't have the power to pull itself along. I put a rebuilt 350 in it (with better heads) and its night/day difference - no issues with power now and I still am running TBI.

[csdineley]

Supposedly it a Jasper's rebuilt. According to the previous owner. But who knows. It has plenty of low end grunt. I can also spin the tires at will. Just doesn't seem to have anything else.

[wilkin250r]

I always thought that was the defining characteristic of the 454 in stock form, TBI or carb. Low end grunt, and nothing else. I don't think I've ever actually looked at the dyno curve for a stock motor, but I heard the difference between the 454 and 350 was all low end, the 454 has like 80% more torque, but only like 15% more peak HP.

(those might not be the actual numbers, but I think they were close, I'm open to correction)

[Jake Wade]

They had good low end torque, just ran out of breath about 4000, too choked

[kwmech]

Being a Jasper rebuild, I'm sure it has the most anemic camshaft installed and the dished out pistons. Compression is probably about 7.8-1. Have you checked the exhaust for flow? (no major restriction) Partially plugged fuel filter, when was the last tune-up? Try these guys also:

http://tbichips.com/?page_id=73

[LT7A]

Plus one on reading TBICHIPS info. I have a TBI 350 that has the factory round cam in it. It has responded to exhaust cat back and low restriction cat very well. Went to open element air filter, also a jump in power. Not meaning to assume that your maintenance isn't up to spec but making sure the distributor cap, rotor, coil, and plug wires are good is important. I went with an MSD 6a and advanced the timing 4 degrees (people say you can go 6) and it runs like a top. Wins no races but moves with authority. The air movement -- exhaust/intake changes are what made a big difference at speed, holding OD up a grade, able to cruise at 80 plus. 230k miles with no rebuild and I still love driving it. 4L60E and 3.73 gears FYI.

[DieselSJ]

My 87 454 TBI runs just fine. I've had it (per my GPS) over 100mph. Tipped the scales at the dump at 8400lbs last weekend and it had no trouble running 65 down the highway with that load. This is a crew cab dually. Also no problems towing our 5000lb travel trailer over the mountains on I-8 between AZ and San Diego. Only mods are replaced the cat with a 3" Magnaflow high-flow and a huge Magnaflow muffler and 3" tailpipe. That did make a difference. Cruising on the freeway, it takes very little effort to speed up to pass someone.

Start with the basics - tune up, air filter, fuel filter, and timing.

[csdineley]

So when I got it I changed the cap,rotor,plugs,wires,oil and filter, fuel filter, air filter, rear brakes, couple of u-joints, replaced a cracked exthust mainfold. New single 3" exhaust with high flow cat and muffler.

Just wish it would maintain speed going uphill.

Future plans for it are new cam, intake, carb (sorry but I'm old and it's worked pretty well on my truck). Maybe if budget allows some better heads. Not looking to make it some super high performance beast. Just needs more than it has now.

[wilkin250r]

It's unfortunate we're stuck with this age-old design of single intake and single exhaust valves. While a good set of heads will breath much better, you're STILL stuck with two valves per cylinder. If you could increase the number of valves and really let that baby BREATH, it would be very easy to get 550+ horsepower and still be a well-mannered engine.

[franken]

We aren't stuck with anything. If someone wants to engineer a better solution for whatever platform, they're free to do so.
Regarding the OPs complaint, why not put a timing light on it, or check the plugs to get an idea of what's going on?
The 454 in many years of truck apps had low compression and small heads. The 454 was only offered in trucks for many years. That's a low RPM. high torque environment. I think some of the later heads were closed chambers which actually improved performance.

Simply asking why is my life bad isn't moving toward a solution...

[wilkin250r]

Late 90s a few guys were making 32 valve heads. Dyno results showed a 10% increase in torque and a 25% increase in horsepower, made largely by increasing the peak HP almost a thousand RPM. These results weren't increases over stock, they were increases over some of the best ported aftermarket heads available at the time.

Cost was prohibitive, however. I heard the heads were about $3500, and that was over twenty years ago. Last numbers I heard, upwards of $6500 for a set.