Stock 1970 Buick Horsepower???

Sorry Jim, I should have been more clear: by GS I mean "stock GS".

I would never claim that anything is faster than a 1970 GS Stage 1.

Interesting. I've read that the 71 and 72 engine was the same and the only reason for the lower effect is that it's measured in SAE Net instead of Gross.

I get the impression that the engines got less and less effect from 1970 and forward due to stricter environmental rules/demands, with compression playing a part in this.

 

If I rember right the Hemi was rerated by NHRA according to its performance in pure stock, at 465 or there abouts.

Dave B

 

When you say engines were the same I do not think so. In 72 the belt driven air injection pump was installed and things like intakes were recast with air rails etc. These mods must have reduced performance relative to the 1971 models.

 

Maybe not, though, Jim.
High Performance Pontiac just did an interesting article comparing the late '70's 4bbl intakes to the '68-'72 intakes (which have generally been considered Pontiac's best stock intakes).

The later intakes have EGR provisions, along with what appears to be restricted secondary ports. They found no appreciable change in flow or performance (on the stock heads), apparently proving that the older intake manifolds were 'more than enough' already.

I realize I'm comparing engineering staffs and powerplants from different parts of Michigan, but I found it interesting. The entire "advertised horsepower" thing has been a controversial mystery for many years now, it seems.

 

Well, I don't even remember where I read it so I won't argue with you.

Does this mean that it's harder to get my 72 to crank out more effect or would it make it easier as all I have to do is install parts from a 1970 GS 455? :grin:

 

i was suprised to see this old thread brought back from the archives. It's funny but although there has been lots of talk, no one has answered my question. Has anyone ever dynoed a stock 1970 Buick engine? I had to assume that no one on this board ever did or just didnt want to talk about it.

 

Well, I stumbled upon this thread on my search for an answer to the question on how much a stock 1972 GS 455 actually outputs.

From what little I've had chance to read on this forum (there's a *lot* of information in here ) and on the web the closest you'll get to an answer right now is the Stage 1 GS 455 at 376 HP on the dyno as Jim (Weise and Lore) stated in this thread.

It's not to late though; just get hold of a stock 1970 GS 455, get the engine out of the car, put it on a dyno and record the results for the world to see.

 

re skylark 350

I had a brand new 70 gs 350 4 spd at age 18-- (yes I am a relic)-the skylark had 280 hp and the difference was compression ratio-----------ram air and dual exhaust. Also a word worth mentioning. One could buy a skylark 4 door with the gs 350 engine with :beer :beer :beer dual exhaust as an option. Did anyone know that??? Mike

 

Been there and done that. So did Muscle Car Entusiest Magazine last year. They used a stock Stage one cam and I thin JW's was a little better than stock. I recall the figures to be very close to what the Buick factory led by Dennis Manner found and which we posted --376hp.


http://www.v8buick.com/showthread.php?p=773388#post773388

 

So a 1970 stock non-Stage 1 GS 455 output 376 HP? I thought that figure was for the Stage 1 engine.

Color me even more impressed.

 

TTT I'd still love to see a dyno sheet on a stock built 350

 

Well, just so happens that the latest issue of the GSCA newsletter (just received two days ago) has the info you want. They took an original 1970 GS350 (advertised HP 315) with only 33,437 miles on it and pulled the motor to detail the engine bay and restify the chassis. Before replacing it they decided to run it on the dyno. They checked the compression, verified the original carb and distributor and only replaced the plastic dash pot on the quadrajet and the worn out advance stop bushing in the distributor. They changed the oil then put it on the dyno.

For comparison sake, they mentioned an article from Super Chevy magazine in 1997 where they tested two original Chevy small blocks that were bone stock. One was a 1968 325 HP 327 and the second, a 1970 300 HP 350. Horsepower was 276 @ 4800 for the 327 and 272 @ 4700 for the 350. Torque was 378 @ 3300 and 385 @ 3200 respectively. Gas used was Sunoco 94 octane.

The Buick 350 was tested with 93 octane gas and timing was set at the factory spec 6 deg initial. Two pulls were made and HP and torque was within 3 HP and 3 lb. ft. between the runs. Horsepower was 271 @ 4650 RPM and torque was 386 @ 3100 (highest of the two pulls).

They also did a mild performance build on a 1977 Buick 350 motor to show what simple mods would do. Mods consisted of 10:1 .030 over pistons, heads milled to give 9.45 to 1 true compression, 3 angle valve job on the heads with no porting, and a mild Howard H203-215/112 cam. Timing was set at 8 deg. initial all in at 3000 RPM. The stock smogger quadrajet was overhauled with new gaskets and rejetted with no other mods. The dyno run produced 302.6 HP @ 4800 RPM and 408 lb ft torque @ 3200.

It was a very interesting article.

 

I assume these results were under the SAE net standard which is today's and the post 71 model SAE standard. The pre 72 factory ratings were under the SAE gross ratings. They would need to be reduced by about 20% to convert these to today's SAE net standard.

 

No. The Super Chevy magazine tests were done in 1997 on an engine dyno and the Buick motor tests were done at Wildcat Performance on their engine dyno within the past year. So, everything should be apples to apples. Assume that alternator and water pumps were installed but not A/C or power steering.

 

Ray I think you meant to say "Yes" since I was comparing the results I referenced to the original factory ratings which were performed pre 72. My use of the word "they" refers to the original factory ratings.

 

Oh. I see what you meant now. So, if I reduce the 1970 GS350 rating of 315 HP by 20%, I get 252 HP. I don't see that it jives with any of the dyno tests performed in 1997 and 2015. I always thought that the difference between SAE gross and SAE net was that gross was measured with no accessories and open headers and SAE Net was with all accessories and standard exhaust. Maybe a detailed definition of the difference between gross and net is appropriate here.

 

That is correct.

And we also have another important variable which is what rpm was used on each occasion a test was performed.

So due to drive train loss a stock 70 GS 350 ("315 HP") should dyno around 220 hp to the rear wheels ("RWHP"). Just as a frame of reference to today's muscle cars, 2013-2014 GT 500s dyno around 600 RWHP and stock 2015 or 2016 Hellcats dyno around 660 RWHP. Stock 69 or 70 Boss 429 Mustangs dyno today around 325 RWHP.

 

So, just to keep things in perspective, all the motors I referenced in my answer to 70aqua_custom's post asking for the real HP of a 1970 GS350 motor were measured on engine dynos produced between 1997 and today. And, those tests (including the Chevy motors) were done without any accessories so, in theory, the HP figures should be similar to HP ratings taken in 1970 which were also without any accessories (gross HP).

To take things a bit further, it was often the case, back in the day, that actual horsepower of production engines was less than the specs that the manufacturers published. So, a 1970 GS350 engine rated at 315 HP (gross) back then and that measures 271 HP today (presumably gross on a dyno) is entirely believable based on ratings vs. actual horsepower.

 

Yup. And, that LS6 as tested by Car And Driver magazine in Feb of 1970 also ran 103. (103.8, in fact). While the 1970 Stage 1 tested by Motor Trend in Jan. 1970 went 105.5 MPH. Many would argue that the Stage 1 was a "prepared" car as most other tests of the Buick in 1970 were in the 102 to 104 range. Isn't bench racing fun? :laugh::laugh: