I can confirm that "advertised" does not necessarily equal "actual". It's not Stage 1 455 documentation, but it's her older sister - the '67 430. Advertised at 360 hp @5000 rpm, 475 lbs-ft @ 3200 rpm. Read attached for real world results, right from Buick Engineering. Note measured vs advertised 10.25:1 static compression ratio, too...another discrepancy the sisters shared. Also note they beat the engines up and had a detonation failure even on what was then considered "high octane" fuel. Devon
FYI, I photocopied the report during a walk-in swim through the Sloan archives in Flint MI in the late '80's. There may be similar reports available for the 455, I don't remember seeing them though. Maybe someone else has taken a look? Devon
Thanks Jim for walking through this. Is the above statement relative to Carbs because the air bell is not mated to the mounting surface of the carb? In Larry's videos I see a bell that appears to be sealed via duct tape to the air-cleaner mating surface on the carb. More pointedly, from the statement above, it almost sounds like the design of the GS air cleaner was potentially optimized for the qJet despite being a base where the lowest point is below the mating surface requiring air to be pulled "up." I have no interest in moving to EFI any time soon, I am interested in projects that optimize things. For my riviera, I am casually designing a "starwars" like aircleaner with optimized flow as the goal. While I don't have a dyno, or the $s to buy dynamic modeling software for flow design, I do have a test rig planned to see what will work best. Can you clarify the carb to bell rig a little more? How is the bell mated? How large is the bell diameter that rests on the GS Aircleaner base?
Hi Chad, Risking off-topic here. While researching air cleaner design, don't worry too much about up/down as air molecules aren't influenced by gravity much. A drop-base air cleaner can provide hood clearance, but can also be your worst enemy. Rather, regarding your SW cleaner project, think more about the design of the base, how it should smoothly transition from the filter element and how it meets the carburetor, and also consider the top of your design above the carb too...how it may contribute. Please internet search for K&N flow control, that may inspire. Devon
Devon, Thanks for sharing that.. one thing to note is that Buick, like all the divisions back then, use GE Eddycurrent dyno's. No idea if they read different, but I am told that accounts for sme of the difference we see when testing these engines on a water brake dyno. The other thing is test methodology.. I did not spend a ton of time looking thru the reports, but I did not see if the tests were done use a 300rpm/second sweep, or a steady state test, where the engine is held at a specific rpm for a period of time, at WOT. Steady state tests report higher numbers on a water brake dyno, vs a sweep test, no idea if that translates back to the eddy current dynos. Chad, the issue appears to be that the taper and or the proximity of the walls of the air bell adapter (adapts the 7 5/8 bottom of the air bell, to the 5 1/8 carb air cleaner flange) interfere with the suction or on the secondary nozzles or somehow influences the secondary air bleeds. I tend to think it's the former, it loses too much fuel to be the air bleeds in my opinion, but I can't rule it out. The engine is lean, and uses less fuel when this happens. By putting the air cleaner base on first, we then remove the adapter from air bell, and duct taped the 7 5/8 opening over the center of the carb, moving the vertical walls of the air bell away from the venturi/fuel tubes. JW
Jim, You mentioned what I was about to, regarding Mark's initial question...on typical dyno testing to find torque vs rpm there is no time involved. One could hold the engine at wide open throttle at a set rpm as long as one wants. Output at that rpm remains the same...assuming the engine itself and the equipment stays the same. Regarding the report, it's fun and full of data, even camshaft profile graphed! Also mentions the engine was taken from production...then another data sheet reports vehicle specs, vehicle weight, and even exhaust pipe diameters! One might wonder about a full car roller dyno, I don't think so, and photos show bare engine mounted. Note the pages in this report are not sequential. We are looking at a report pieced together, either originally, or by the time I got my hands on it. Likely the former. We still do the same, pulling pages from other reports to produce the next; but we're careful to cite sources. Devon
Devon, Ya, your not kidding no time limitations. after they have spent 50 Hours on break in.. The sweep tests were in fact invented to give a broad analysis of engine performance in short time frame. Not to mention it's no where near as hard on the engine.. as they reported, having blown up a couple doing this testing. JW
Jim, No way the 50 hours was wide open throttle, but I'd like to think rather some kind of simulation of customer driving, or maybe worse, maybe hardcore. We may never know. One indication is that during the testing, heads were off for carbon cleanup and valves lapped. Given those questions, the engine measurements ring true to what we already know. Advertised static compression ratio is low, and now that you and others (me too) have seen excessive deck height vs piston at top dead center. Devon
Jim what causes the dyno sessions to be hard on the engine? Is it the load on the bearings? Combustion chamber temps? Oil temp rising, lowering viscosity? Coolant temps? Or a combination of the above? Reason I ask is marine engines are under load all the time even more so trying to get a hull on plane if it’s a planing hull, granted boats have unlimited cooling capacity and oil coolers also.
Yup, at no time in a car will your engine be subjected to full load against an immovable object. Nor will it be asked to accelerate against an immovable object. The cylinder pressures during those times will be the highest they will ever be, and for longer. Which is why we protect every new "pump gas" engine with a 50/50 mix of 110 octane race fuel and pump premo. Even though that fuel does cost us some power. Most of the reason is that there is no converter or gearing involved to help the engine move the vehicle. Oil and water temps are monitored and controlled, so that is not an issue. JW
From what I have read is the LS6 engine in the Chevelle has awful restrictive exhaust manifolds. The same engine in a 70 Vette is more of a screamer because the exhaust manifolds are so much better in the Vette I read that adding headers t o the LS6 in a Chevelle makes a world of difference The Chevelles LS6 was dynos at 350hp. or close gross but headers really woke it up.
PGSS, this is a very interesting piece of information. Difficult to believe that Chevy would build the LS6 in the Chevelle that allows the exhaust headers to be that restrictive but NOT the 70 Corvette. However, if this is true, for the Chevelle, this would explain why Buick kicks their ass at the strip. I will have to look up the 1/4 mile times between the 70 Vette LS6 to and Chevelle LS6 see what the difference is between the two. Also, I'm curious to see what the curb weight of a 70 Corvette is. The Chevelle and Buick Stage 1 are very close to being the same curb weight. Vet (Navy).
Update: This is what I found of the LS6 Corvette. According to Car Craft Magazine: 1/4 mile time = 13.2 @ 107 mph. Curb weight = 3,685 with Th400 Trans. Curb weight = 3,641 with 4-Speed. The Corvette is lighter than the Buick Stage 1. Vet
I just looked it up too, I think it’s garbage info, says weight it 3200 lbs ( believable) but 454 LS 460 hp Regardless, Chevy rated the big block higher hp in the Corvette because they knew they could get away with it, IT WAS A FEW HUNDRED POUNDS LIGHTER than a Chevelle with the same big block.
I agree Mark. But I knew the Vette is a lighter weight car. What I didn't know, that the exhaust headers on the Chevelle are supposedly a very poor design. This is difficult to believe. GM making up mystery performance numbers is normal, i'am not surprised. Thank you for your research too. Vet
They probably figured most people were going to put headers on so why put alot of R&D into manifolds. Also the Corvette manifolds may not have fit in a Chevelle. Another thing to consider re: lower advertised HP is that insurance is cheaper. Knew a buddy in HS that had a LS6 Chevelle and he paid twice what I paid in insurance than my GSX. Also, his got stolen twice FROM HIS GARAGE. My X was left outside and never was bothered.....
You are right-on with everything. When you're young and dumb, you buy the car with the most HP advertised rating. When you're older and mature, you realize the performance cars are being overrated on HP, lol. I have to admit, I think Buick is the only one's that advertised Torque on their air cleaners. When I was a teen, that was very confusing, I didn't realize that number was torque, lol. Now that i'am mature, I have to sort that the factory BS from what is real. Never read so many car mags. Vet (Navy)
Ha, I have one of these for the Pontiac OHC 230 L6 https://drive.google.com/file/d/16iT6PHzTnbold6TtWTdnBY8NExxGZBYD/view?usp=sharing Jim, going back to the dyno video of Mark's engine, on the EFI run, the EGT sensors seem to move around A LOT, what's going on there?
