As far as I know the base 455 is rated at 350 hp the Stage 1 is rated at 360 hp (which is laughable) and the big car 455 is rated at 370 hp Hope that helps. Mike
The big car motor is the same at the motor rated 350 in the GS. Per the chief Buick engineer the stock output on the stage 1 was around 376 hp in reality and the small valve engine was only about 15 hp less.
Has anyone (or magazine) documented a stock '70 Stage 1 engine rebuild (to original specs) and then dyno'd the engine? I know one of the car mags a while ago had a series of stock rebuilds in order to verify the claims of the manufacturers back in the day. I know we have to have a tremendous amount of respect for Dennis Manner's recollections on this subject, but there are just some pieces of the puzzle in which the calculus doesn't add up ... and the fact that Buick Motor Division's official ratings were misstated doesn't help the cause, either. I can accept that the '70 GS 455 engine and the large bodied Buicks had the same engine because the parts can be verified to be the same ... Regarding the 376hp figure on the '70 Stage 1, was that hp figure based upon a 5200 redline? 5300? 5400? 5500? I do not think anyone know's for sure, or at least that these numbers are from a lower than max redline which appears to have been a manufacturer's favorite trick back in the day - to quote a lower than max hp figure which could be true at a lower rpm. It would just be nice to get some modern verification, if it exists. The questions will continue, for sure.
It is based on more than his recollection. He has shown many of us the graphs from the factory dyno runs. I may be off a bit in my recollection but this data was at 5000-5200 rpms plus or minus. Also recall JW ha never built a stock 455 that ever made 510 ft ibs. They all seem to come in beween 450 - 500. JW interviwed Cliff Studaker and he admitted that a thumb could like have been on the scales. Rcently I was lookig at some data on a repro MOPAR 440 magnum rated at 375 hp. It made less the 450 hp peak and like the Buick 455 the peak torque never was near 500 ft lbs.
Hawken About 5 years ago in Musclecar Review Magazine my firends Built and Dynoed a bone stock 70 GS Stage 1 455 engine out of a 70 GS Stage 1 car I own. If I recall correctly it made 382 horse and 505 Foot LB's of Torque.
Rich, Do you know what RPM's the peak HP & Torque figures were achieved? This is the issue I suspect the variations in figures derive from .... the RPMs used to get the HP & Torque figures. I can see the Denny Manner figures at the lower RPM 5000 or low 5's, but I have just seen too many figures and quarter mile times that seem to indicate higher numbers than officially stated. The point is that the extra RPMs will likely be where the higher HP figs come from.
In the article bone stock Stage 1 455 made 382 horse at 4700 rpm and 506 Torque at 3,300 rpm This article is in Musclecar Enthusiast Magazine Dec 2004
The advertised numbers are as follows; 1970 Buick Skylark/GS powerplants; 350-4V 315hp @4,600rpm and 410ft-lbs. @ 3200rpm 455-4V 350hp @4,600rpm and 500ft-lbs. @ 2800rpm 455 S1 360hp @ 4,600rpm and 510ft-lbs. @ 2800rpm other 1970 GS optioned cars (Riveria, Wildcat, etc.) 455 4V 370hp @ 4,600rpm and 510ft-lbs. @ 2800rpm The media at the time and since then have tried to determine what the actual "real" maximum output really was or is. In several articles with the engineerign staff they arrived at the 376hp number by taking the lowest output of all of the engines used in ther certification dyno testing. I don't recall how many engines they thought there might have been, but good scientific method and engineering practice would indicate 12 to 20 engines were used in the certification. Here is my opinion, It would not suprise me to find that a select fit and assembled engine could make 50hp more that that 376hp number and have a similar increase in torque as a percentage; that equates to about a 14% improvement. What would the insurance rate have been on a Stage 1 with 425hp and 565 ft-lbs? Chevy hp and Cadillac torque from the brand that is in the middle and NOT the performance brand (i.e. Pontiac) And It can safely assumed that the Olds W-30 was capable of very similar numbers.
You have to be careful on this subject because Denny (Dennis) Manner is THE MAN regarding Buick 455 engine design - literally ... the Father of the Buick 455. All I can say is that there seems to be room in the RPM range to account for some degree of variation in this equation. While it is true that Buick appeared to have a state-of-the-art engine assembly and testing program in the early '70's, I would stop short of calling it some type of "select fit" program like the Olds W Machines or the Hemis. They were "specific" parts, but I do not beleive the Stage 1 engines were sequestered from the regular engine assembly process (other than Stage 1 engines were built in Flint only for '70 (and '69?)).
Some of the difference could be due to the SAE convetion change for 72 from SAE gross to net. So a 70 engine measured back in 69 would have to be knocked down 20% to get to SAE net which we use today.
