What makes the 1970 Buick 455 make so much Torque?

For most of you who have read my posts, know I'm new to the Buick 455 and new to the forum.

I now own my first 1970 Buick GS 455. I've been having a lot of discussions with my best friend who is also a gear head.

We can't figure out what the Buick engineers did to be able to create an engine that delivered 510 pounds of Torque, when nobody else could, with the exception of Cadillac, but it wasn't a performance car.

What is the key to this Torque, is it the heads?
Or is it the combination of Stroke and Bore?
Or something else.

Also, why did Buick make a dished shaped pistons. As far as I can tell, there is almost no squinch area with this piston design.

I had a 1965 Chavelle (327ci) that had 10.1 compression pistons (factory stock) and it had almost no performance to it. Of course, the 2 speed, slip and slide Powerglide didn't help either.

Hope somebody has the answer to my Torque question....

 

The engine was designed to move land barges at low RPM. Tq gets it rolling and HP keeps her moving. Most of that Tq comes in before 3000 rpm. As to the how its done I couldnt tell ya for sure. large bore and stroke would be the key. The Thawk engine recently completed at TriShield has a 4.40 stroke and 4.500 bore which made 707 Tq

 

Thank you Larry.

So bigger is better in the automotive engine world.

So, tell me about the Buick piston design.

why did Buick make a dished shaped pistons. As far as I can tell, there is almost no squinch area with this piston design.

I just took a look at the Stage 2 piston last night, huge improvement.

Last night, I also found the mystery pistons that are in my 455.

The piston on the left is a Federal-Mogul hypereutectic alloy cast piston.

I'm researching the company to see if they still make it. So far, no luck, they must be a discontinued model.
I may never find out what compression ratio they are.

It's the piston on the left. Tired to copy the image, it won't let me. So I copied the link.

Larry, know anything about this particular piston???

https://apis.mail.aol.com/ws/v3/mai...lNorrin&downloadWhenThumbnailFails=true&pid=2

 

The beauty of the Buick 455 as opposed to Olds and Pontiac is the shorter stroke 3.90....allows for bigger valves and better for higher rpm than the Olds/Pontiac 4.25 stroke and still making similar torque. Unfortunately it's revving potential was likely the demise for many 455 Buicks. At least it had forged rods as opposed to Pontiac cast junk.

 

Thank you both. I'm getting educated.

Larry, you said, When rebuilding the engine, it is best to shoot for zero deck.

So, when you add the .025 head gasket, wow that is close. I know most guys shoot for .040 clearance.

BQUICK, thank you for your comments. I agree, I raced small block chevy engines (327ci Covette 365 HP engines) and routinely shifted
at 6,500 to 6,700 rpms. I did run forged pistons and crank. I never broke an engine part but I did burn-up a lot of
clutches.

I'm told not to exceed 4,600 rpms with the 455. I'm so amazed Buick ran a 13.38 et in 1970. That's fast back in the day with Poly street tires.

I've seen John Chamberlain's Buick (old videos) run in the mid- 12's with slicks (stock class). He outran all the Mopars (Hemi's too), Chevys and Fords.
I love watching that video. I've only seen one chevy run in the mid-12's and it was a 1968 Camaro, much lighter than the Buick.
But, John outran him too.

 

4,600?? Stock Stage 1s shifted at 5500 in drive. I bet the magazine testers were shifting closer to 6K. Unfortunately stock cam peak hp at about 5300.

 

My opinion is that the rod angle on the 455 Buick is superior to all of the other big blocks including the Chevrolet 454.

 

Larry, yes, I'm thinking of the original .025 steel shim gaskets.
Maybe I've mis-read something. I thought the 1970 Stage 1 455 came with the .025 head gaskets?
I wouldn't feel safe running a head gasket that thin. .040 to .045 is what I would go with.


BQUICK, you have to remember I have the Base model TH400 BA model trans. It doesn't shift at 5500 rpms.
I believe only the Stage 1 BB trans shifts at the 5500 rpm.

I found this info on-line. What is amazing to me, Max horsepower is @ 4600 rpm, that's hard to believe.
What also is amazing, 510 lb-ft Max Torque is only @ 2600 rpm, you're not even out of first gear yet.
You need drag slicks on the street just to get any traction.....

"The 70 BB Stage 1 was unique. The later valve bodies were not setup like it, though close. Not all 70 Stage 1 BB's had the 6 clutch drum, it depended on the build date as it was used after a certain point. A lot of 70 BA's had the 6 clutch drum too. The BB's used a different direct piston which improved the 3 gear shift.

The 70 BA valve body is VERY close in design to the 70 BB and only a spring in the 1-2 accumulator valve needs to be removed to make it the same. No waved steel plates were used in the 2nd and 3rd gear clutch packs on the Stage 1 trans, and the 3rd gear valve body accumulator spring was softer to firm up the shift. The governor was setup to shift at approx. 5500 rpm and was specific to 1970 BB only (some model of Pontiac and maybe Olds used it too). Later governors were ok, but closer to 5200 rpm. The valve body separator plate has larger holes in places to increase pressure to the clutches. Am pretty sure that 70 was by itself and 71-72 was different."


Engine: Buick 455 V8
Displacement: 455 cu in (7.5L)
Configuration: 90° V8
Bore x Stroke: 4.3125″ x 3.90″
Compression Ratio: 10:1 or 10.5:1 (1970) 8.5:1 (1971-1974) 7.9:1 (1975-1976)
Firing Order: 1-8-4-3-6-5-7-2
Max Horsepower: 350-370 HP @ 4600
Max Torque: 510 lb-ft @ 2600

 

Buick had 2 advantages.
1. The intake passages were smaller but very efficient.
The 454 70 chevelle intake had huge passages that slowed the flow and killed low end torque.
The Hemi Mopars were even larger and had even less torque (no torque below 5000 rpm).
2. The Buick had a slightly larger bore than Olds and Pontiac. Also a shorter stroke. This allowed room for larger valves. Nice balance on bore-stroke ratio allowing a 50 hp advantage to the Buick no matter how you build them from 14 seconds to 10 seconds in the quarter mile.
2001-2002 Motor Trend magazine did a engine shoot out with 6 engines.
Buick won!

 

Gary, My gear head friend and I have been wondering for a long time how Buick made so much Torque.

My friend is a huge believer that power & Torque comes from well designed heads.

Thank you for the info, mystery solved.

 

Was rated at 4600 but made 376 at 5200 from what I remember.

 

I remember reading the 376 HP and the 5200 rpms sounds right to me.

I have to admit, I have read a lot of performance articles on the 455 Buicks and they can have difference specs.
GS 455/HP 350 and a BA TH400 transmission. Has 5 clutches where the BB has 6 clutches.
GS Stage 1/HP 360, but this engine has a lot more performance add-on's, including the BB TH400 transmission that shifts at a higher rpm.
Here comes the GS Stage 1 Riveira - HP/370 - Really???

My guess is the real HP is 376 like you said.

I have never seen a TRUE STOCK Stage 1 engine stand Dyno test for HP and Torque. Everyone I have seen, has some type of performance add-on.

Here's the kicker - 1970 Stage 1 has a 750 Qjet.
The 1971 Stage 1 (detuned Compression) had a 800 Qjet, try and figure that one out???

 

During that 6 engine shootout:
The Buick engine was the only one of the 6 engines that still pulled a vacuum all the way up!
It was begging for more air (a bigger carburetor please)!

 

I have an old article (from the Pontiac camp) charting the int/exh airflow of various V8 heads and the balance between. Buick's were at the top~

Intake CFM / ext CFM / ratio
B-455 standard : 80 / 70 / 88%
B-455 STG 1 : 97 / 80 / 83%
B-455 STG 2 : 97 / 90 / 93%
Olds 455 W-30 : 85 / 65 / 77%
PMD 455 standard : : 85 / 68/ 80%
PMD 455 RA IV : : 97 / 66 / 68%
PMD 455 SD : : 105 / 70 / 67%
Chev standard BB oval port : 130 / 85 / 65%
Ford 428 CJ : 95 / 65 / 68%
Chrylser B Wedge : 100 / 80 / 80%
Chrysler Hemi : 150 / 90 / 60%

I do not know the circumstances under how those above numbers were generated, as to how a std B-455 head is listed above @ 80/70, when elsewhere I have them at 220/150 (for only a 68% ratio). Article was written by Pontiac tech writer Gene Scheer.

 

Gentlemen, fantastic stats.

I have never read either one of these articles, I admit, Buick engine engineers really surprises me!

I'm amazed that Buick came up with very powerful engines starting with the 400, 430, and the 430 bored to the 455.

We all love these engines, Buick ONLY started building these engines in 1968, while phasing out the nailheads in 1967.

Buick made the nailheads for a very long time. My father had a 1953 Buick with the first V8 nailhead, I believe it was a 322ci called the Buick Fireball V8.

Thank you both for sending me this information. VET (Navy)

 

I was always taught that increasing port velocity was good for torque in any engine, the big block Buick's seem to do that well.

 

Never knew that Buick had better velocity than the rest of the factory built performance cars (Ford, Chevy & Mopar).

My gear head buddy has always said, there must be something special about the Buick heads, but couldn't figure out what Buick did to increase velocity. Vet (Navy)