oh my word, is this true?

[blazin_blazer]

i just read a thread that said the 1987 tbi 454 has 200hp @ 3600 or 3800 rpm & 364 ft lbs of torque at 1800 rpm. if that is the case, why in the world would/should i try to keep the tbi and all when i put said bbc in my 85 k10, seems like a warm cam, dual plane aluminum intake/q-jet, & headers would/could really change those #'s. any thoughts or comments?

anyone know where a good hp calculator is online, so i can see what it would make w/268 or 272 cam and a carb? anyone know the compression ratio on a stock 87 454?

 

[Stomis]

Keep the TBI cause the TBI's not whats limiting those numbers. Unless of course your gonna go to a propane setup, in which case I say go for the carb for simplicity.

I'm no bigblock guy but the appeal to those motors is that those peak numbers come in super low in the rpm range, wheras a sbc would have to be brought up to 3500-4000 before you saw peaks like that. Plus I think those heads are a major limiting factor.

 

[original balzer]

I recall one of the mid 70's 454 truck engines being below 150hp. Its always been weird to me to have such low HP numbers in stock big blocks.

For what its worth, stock GM TBI is rated to support up to 220HP even those on a 454. There are several upgrades that can be done to the TBI to bring that up *some*

 

[Stomis]

I recall one of the mid 70's 454 truck engines being below 150hp. Its always been weird to me to have such low HP numbers in stock big blocks.

For what its worth, stock GM TBI is rated to support up to 220HP even those on a 454. There are several upgrades that can be done to the TBI to bring that up *some*

Hey dont knock the TBI. Theres guys on thirdgen.org running 11's on 4xx hp motors with tbi.

 

[original balzer]

Like I said its all in the rateing Im not knocking it just stating the fact GM sugests.

 

[4X4HIGH]

i just read a thread that said the 1987 tbi 454 has 200hp @ 3600 or 3800 rpm & 364 ft lbs of torque at 1800 rpm. if that is the case, why in the world would/should i try to keep the tbi and all when i put said bbc in my 85 k10, seems like a warm cam, dual plane aluminum intake/q-jet, & headers would/could really change those #'s. any thoughts or comments?

anyone know where a good hp calculator is online, so i can see what it would make w/268 or 272 cam and a carb? anyone know the compression ratio on a stock 87 454?

For a truck engine that is being used as such (towing, slow wheeling) torque is what you're looking for, not HP and look at the RPM of that 364 ft/lbs it is down low where a truck will benefit from it. Now if you run sand or mud bogs then you want upper RPM HP. I can't stress enough how people are too concerned with HP numbers when almost everyone here is out wheeling low speed stuff and needs torque.

 

[moneypit_K5]

You could get more juice out of that engine by getting rid of that "2 barrel TBI" and replacing it with a good carb/intake. As stomis suggests, those tbi heads are a big power suck.

 

[4X4HIGH]

You could get more juice out of that engine by getting rid of that "2 barrel TBI" and replacing it with a good carb/intake. As stomis suggests, those tbi heads are a big power suck.

The heads are bad ONLY if you're looking for HP, they makes LOTS of low end torque though.

 

[moneypit_K5]

right..I shouldve added that.

 

[b454rat]

Bump the compression up a little, mild RV cam, headers and good exhaust will wake a 454 up enough to obliterate the rear tires. My old 89 with a TBI454, TH400, 3.73 gears and 40" boggers would lite the tires up. Big blocks rule.

 

[Stomis]

You could get more juice out of that engine by getting rid of that "2 barrel TBI" and replacing it with a good carb/intake. As stomis suggests, those tbi heads are a big power suck.

What year did the 4barrel tbi start on the 454's anyway?

 

[b454rat]

Never had a 4 barrel TBI, just big TB itself. 47-48mm for 350 and smaller, and 52mm for the 454. Injectors were bigger too.

 

[82355]

What year did the 4barrel tbi start on the 454's anyway?

The guy you quoted was suggesting to replace the TBI with a carburetor. Stock TBI units are all "two barrels".

Martin

 

[Stomis]

The guy you quoted was suggesting to replace the TBI with a carburetor. Stock TBI units are all "two barrels".

Martin

Huh idk why the hell I thought 454's came with a 4barrel tbi stock... too much reading smushing together in my head...

 

[original balzer]

Holly makes a 4bbl TBI. Also summit has an upgraded TBI that flows 675cfm rather than the stock 500cfm.

 

[Fabrimacator21]

Holly makes a 4bbl TBI. Also summit has an upgraded TBI that flows 675cfm rather than the stock 500cfm.

It's a nice tbi system but by the time you pay for a standalone 4bbl tbi you could have had MPFI. If you looking for more cfm a bored stock 454 tbi seems to be the way to go. Apparently holley tbi's have some serious problems.

Tbi is not a horrible setup but when you start approching 400hp... MPFI just makes a lot more sense for the money. IIRC TBI nets more off idle torque then a carb.

 

[ScottMH]

its the governments fault we lost so much horsepower in the mid 70s. by 1973 pretty much everything made horrible numbers compared to their earlier counterparts. the government wanted the emissions to go down and the only way GM could do this was to drop the compression from 10:1 to 7.5:1 and restrict the exhaust with cats and heavy backpressure. If you have a big block thats made in the mid 70s early 80s i would change the heads, piston, cam, and exhaust. then you will be back into real BB numbers. the same goes for SB.

 

[thewestwon]

I'm currently rebuilding that exact motor from my 87 k30 crew cab. From the way it ran before, those numbers sound correct. It could pull a house but definitely wasn't quick about it. After dealing with all the tbi and emissions bs trying to get it out, I was strongly considering building a monster. However, after seeing a very small amount of wear, I hated doing much to the block so I got her cleaned up, got some headers, and bought an rv cam. I'd say she'll be pretty stout when she's running again.

 

[Thunder]

Just FYI

The LT9 454 engine in 1987 and all the rest of TBI trucks was rated at 230 Hp 385 torque. Aprox 8.3to 1 cr
The TBI engines had the same HP as the carbed truck 454s plus 25 more ft lbs torque.
The stock TBI on 454 engines will support aprox 325 FWHP with proper tune and fuel pressure

LO5 TBI 350=210 HP. 300 Tq. Light duty 2 bolt main in 1/2 ton trucks. 9.3 to 1 cr
L05 TBI 350= 190 HP. 300 Tq Heavy duty 4 bolt main in most 3/4 and 1 ton trucks 8.5 to 1 cr
350 TBI will support aprox 280 HP with proper tune and fuel pressure.
TBI 350 made significantly more HP and torque than the earlier 73-86 truck LS9 350s which were rated at 175 HP. 275 TQ.


L03 305 TBI 170 HP 260 TQ.

 

[dyeager535]

its the governments fault we lost so much horsepower in the mid 70s. by 1973 pretty much everything made horrible numbers compared to their earlier counterparts. the government wanted the emissions to go down and the only way GM could do this was to drop the compression from 10:1 to 7.5:1 and restrict the exhaust with cats and heavy backpressure.

The way HP/TQ was measured changed, which reduced the numbers much more than the change in compression and emissions components.

Not saying the stuff wasn't "detuned", however IIRC, you can multiply the '73+ numbers by 20% to get close to the net numbers. Everything afterward is SAE, which is all accessories on and operating, through stock exhaust.