I've done search, can't find "REAL WORLD" answers. I am looking to buy a Buick 455 '70-'72 GS, Skylark, or maybe even a GSX in excellent condition. The advertised difference in Horsepower between the Stage I and 455 standard engine is 10 (TEN) HP, I don't believe it o No: Does anyone know of a site with actual dynos on these stock engines? What were the actual differences between these 2 engines? I would like to know the details, pleaaaaaaaaaaaaaaase. :grin: I was told the 1970 engines do not run on PUMP gas, is this correct? Thanks so much in advance. Mac
Here's a little casual reading while you're waiting on help from someone more qualified to answer your questions. GS 455 GS 455 Stage 1 Valve pic, half way down page And of course lots of performance info at Tri-Shield Performance Valve size, camshaft, and a little fudging for insurance purposes made the differences in HP ratings Lotsa guys here doing very well on pump gas:laugh:
Thanks I saw the first 2 sites before, but the 3rd was new. It stated the Stage I on a dyno saw 422 FWHP or about 370 RWHP. Nice numbers. From what I can tell: Stage I has higher compresssion (Pump gas problem?) Larger valves (intake/exhaust) Different Carburerator Different Distributor Different Oil Pump? Axle ratios? Both produce 510 lbs of Torque :beer Now I need to know what kind of numbers a Standard 455 (Non Staged engine) puts out?
The advertised hp during that era was dictated by insurance rate problems and a GM company policy of limiting the power to weight ratio to 10 to 1. Hence, a 3600 lb GS hardtop got a rating of 360hp. The father of the 455 engine, Dennis Manner, is reported to have said the stage 1 engine on the GM dyno was 376hp. I would not get too caught up by the numbers published in factory literature. Do not overlook the big Buick torque advantage only beaten by the 472 and 500 cid Cad engines.
Dennis told me that the 1970 STG 1 motor made 376 Hp at 5400 rpm on the dyno's at Buick Engineering. It was rated at 370 HP at 5000 rpm, because that was exactly what it made at that RPM, and since the advertised curb weight of a '70 GS 455 was like 3700 or so, they needed to keep the HP/weight ratio safetly below the dreaded 10 lbs per hp, to keep the insurance folks and GM from seeing red. That's gross crankshaft HP. No way your going to see anywhere near that at the rear wheels. The Stage motor in an of itself is not all that tremendously different than the GS 455 motor, so a difference of 10-20 HP would be something I would not have any trouble believeing. Bit bigger cam, and the bigger valves are going to be the only thing that makes any more power on the dyno. The Stage 1 package also came with other equipment, and since it was a limited production, it is more valuable to find an original Stage car than just a regular GS 455. But there is not a *huge* difference in performance of the Stage car, vs the standard GS 455.
That 379 HP on the GM dyno, was that Rearwheel or Flywheel? What is your bests guess on HP difference between 455 and Stage I? I understand the Underrated 455, my LS1 in my Trans Am is rated at 310 FWHP, in the real world they dyno 310-325 Rearwheel HP :eek2:
Jim, You are the man :TU: Just spent 1 hour visiting your site :grin: Is that GSX for sale yet? I am adding several cars to my collection, I need a BIG BLOCK I found several GS Stage I (some from this site) and some standard 455 engine cars. I am looking for a weekend driver, maybe 2,000 miles a year, has to be a 12 second ride or better. This whole Stage I thing has been driving me NUTS :stmad: I could care less about my car appreciating in value, I have other investments that do far better than than any car ever will. I want a nice, clean, kick ass ride that will beat 95% of the cars on the street. 12 seconds shoud do it. I'll probably go to the strip once or twice just to get some ET's. Without starting any flame wars, are you saying that between the standard 455 and Stage I that the difference is maybe 20HP. I personally would rather save the money from buying a Stage I and upgrading my Stock 455. Don't get me wrong, I love Stage I cars, but for my purpose I would rather invest in more HP. I am now debating buying a stock 455 and dropping it off at your shop for several weeks and have you do some MAJIC :grin: Thanks. Mac
Mac, My suggestion to you, considering you above post, would be to find the absolute nicest 70 GS 455 you can.. Running 12's with a healthy small valve motor, and the rest of car in good shape, is not a problem. Stage 1 valves in unported cylinder heads are the most over-rated perf mod in the 455. For the money it takes to convert the head casting to the stage 1 valve size, (there was only 1 casting, in 70-71, with a few different numbers on it) I would take a set of street/strip ported small valve heads, any day.. Plan ahead on the motor build, if you go that way... there is a line at the moment..:eek2: Best time to start a motor project... October/November.. I don't think Chris will be selling his X anytime soon.. after going thru hell with a GN hot rod he got into with some other shops after we finished the X for him, I think he is glad to have a an 11 second car to drive, anytime he wants.. And he has been offered big $$ for it a couple times, and turned it down. JW
Jim, I will contact you Monday at your shop. I want to find a 1970 GS 455 hardtop with buckets and automatic on the floor, in excellent shape. If anyone has this ride and wants to SELL, please contact me (cash in hand). I then want you to add new heads or port the stock heads, add a bigger cam (slight lope), headers, and torque converter. This should put me in the 12's with good streetability. Till Monday Mac :beer
Mac, You can call me tomorrow, this time of year, we work 7 days a week around here.. Typically start at about noon on Sundays. JW
I think you might be overlooking that after 1970 the convention was changed so as to measure and report Hp downstream and not at the flywheel. I think that applied to all of the GM line.
First, was '70 or '71 the last year before the change ? And second, it was still measured at the flywheel, The difference was that before they ran the engine on the dyno without the accessories or the restrictive factory air intake and exhaust, called "gross hp", as opposed to later when the engine was ran essentially how it was in the car, called "net hp" (which the factories still use today).
$$$$$ Hi Mac- Welcome to the board! Just curious, what are the investments that you have that are doing so well??? We could all use a little help in that regard! :Brow: - Bill
