How much HP? (Buick 350)

[307 Regal]

Yep. It's another "what's my HP" thread.
So anyway, I have a '76 Buick 350 (8:1 comp), .030 over, 600cfm 4-barrel, headers, glasspacks, and a 268 duration, 469 lift camshaft. Does anyone have any idea how much HP I'm making? I've read that it had 150 net horsepower in stock form. I'm hoping it's making at least 220 gross hp and I'd be kinda sad if it was less than 200hp. Any guesses?

 

[ronbz455]

Well it can't be much with that compression. I have one on the stand with good rods and used venolia 4 barrel pistons and it has about .030 to .040 deck I think. It's been a while since I checked. Sean says the power is in porting the heads and I say with Buicks it's big cam and big carb that makes them run good. My stock block 455 runs high 10's in the 1/4 big cam and 1050 Dominator.

 

[techg8]

I dont know the HP numbers as I never Dyno'd, but for reference:

I ran a Comp 268 camshaft that size in a 72 Buick 350 (8:1, .030 over) in a 72 Buick Skylark and at the track it would run 14.9 at about 90.5mph in the quarter.

Maybe someone can translate that to HP numbers?

The issue I had was that the low compression (I think it is more realistically 7.5:1 because the dished pistons were also deep in the hole) combined with the larger lift/duration and overlap camshaft softened up the low end to where my 60ft was in the 2.3s neighborhood.

I ran a 750 cfm Qjet set up for my engine on that combo, and on the street it certainly felt sporty enough and was a lot of fun to drive.

 

[lilbowtie]

I dont know the HP numbers as I never Dyno'd, but for reference:

I ran a Comp 268 camshaft that size in a 72 Buick 350 (8:1, .030 over) in a 72 Buick Skylark and at the track it would run 14.9 at about 90.5mph in the quarter.

Maybe someone can translate that to HP numbers?

The issue I had was that the low compression (I think it is more realistically 7.5:1 because the dished pistons were also deep in the hole) combined with the larger lift/duration and overlap camshaft softened up the low end to where my 60ft was in the 2.3s neighborhood.

I ran a 750 cfm Qjet set up for my engine on that combo, and on the street it certainly felt sporty enough and was a lot of fun to drive.

210hp - guessing your car is 3700 - 3800 lbs

 

[King_V]

I've read somewhere, don't know how much credence to give it, that Buick V8s typically like to have a bit more carburetor than the other makes of the same displacement. Makes me wonder if the 600-cfm carb might be a bit small for it.

The numbers I have for factory production (keeping in mind that 1975 and 1976 were LOUSY years for Detroit until they started getting a handle on working with the emissions controls - 1975 and 1976 were just "slap the band-aids on without thinking and sell 'em to the public")

These numbers are with single exhaust, and SAE Net, by the way
1976 Buick 350 2-bbl
Horsepower: 145 @ 3200
Torque: 270 @ 2000


1976 Buick 350 4-bbl
Horsepower: 165 @ 3800
Torque: 260 @ 2200


Odd that the bigger carb lowered the peak torque production slightly. But also note how that, despite the extremely restrictive single exhaust, the 4-bbl let the thing breathe better, increasing the peak-torque to peak-hp spread from 1200 to 1600 RPM.

My guess - even in 100% stock form, and with factory manifolds, even a factory-sized dual exhaust (2 inches is what they used back in the early 70s, right?) and modern catalytic converters would give 15-20 more horsepower and 15-20 more foot-lbs of torque. Headers might add another 5 to 15 to each of those numbers. Again, I'm talking SAE net.

So, even if you were running factory Q-jet, factory cam, etc., basically never changed the engine - the exhaust system alone should put you at a minimum of 190 net horse and 290 net ft lbs. That's NOT accounting for the headers. I am being VERY conservative because I personally hate when I overestimate things.

With the headers, I think you're probably hitting the 200 hp net mark.

Unfortunately, I can't judge camshafts at all - I don't know if that cam is good for a low-compression engine or not.

Additionally, I'm not sure what the (relatively) small carb is doing to the numbers. Weren't the Q-Jets all 800 CFM or thereabouts in that era? Then again, given how the 2-bbl gained torque but lost horsepower, you might be getting a SLIGHT edge on torque, but losing a small amount of hp. Not really sure.

Gross numbers are sometimes difficult to compare to net - as I recall, though, 150 net is around 230 gross (from what I remember of the early 70s Dodge 318 2-bbl)