How much horsepower does a stock Z28 have?
07-27-2003, 09:42 PM
#41
Re: How much horsepower does a stock Z28 have? z-28 shoould do bout 300 to ground stock (broken in) and 350 out of engine technacially gm not lyin just givin the rwhp while givin the vetts crank hp so their just misleading and my "hard proof" was an article a couple yrs bvack done by hot rod mag comparing a vet to a trans am on the dyno along with a couple of stock ta dyno runs and as far as going past 350 unless its a freak id think your being a bit overstated mobe and according to the roush tech i spent 2 hrs talking to at the dyon day a while back sae is when they correct it the power ratigs to what it would be at 72 deg with a cetrain humdity and a certain barmeetric pressure like he told me my car did 318 raw in 94 deg heat while it was about to rain but sae it would have did 330 hp and no sharky fbods were pahsed otu beacousethey could not sell enough of them to keep the plant open their last year they sold less than 30,000 units which was wellunder the 50,000 minimun they had to meet to keep the big boys happy i personally think they did mislead for selling reasons to your avg joe the vett would not be worth the money unless it had more power so thatys why they posted the two cars hp the way they did
07-28-2003, 02:01 PM
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Re: How much horsepower does a stock Z28 have? i would have to agree with the majority about the older f bodies. they were the bomb back in the day just as ours are now but as everyone knows technology changes and so do the cars but a sweet car is still a sweet car none the less 
09-23-2005, 02:24 PM
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Originally Posted by y2k_ta
Don't forget that GM also fudged the cubic inch displacement of certain engines. The one that comes to mind first would have the be the 396 which was actually a 402. I'm sure that certainly helped with insurance issues during the peak of the muscle car.
Then there's the 350 that's actually a 346.
Then there's the 350 that's actually a 346.
The bore and stroke for the 396 is 4.096" x 3.76". The 402 is 4.125" x 3.76". All those line of motors from the 366 up to the the biggest now used 6.135 rod lengths.
As far as HP ratings they must be accurate now within I believe a 2% margin. Not sure when they mandated that. That's at the crank and is SAE. Anyone know the year that got legislated?
I grew up with muscle cars and some were vastly overrated and some vastly underrated. The 426 Hemi was well over 500 HP. You can get some idea of what their true HP rating was by using formulas for their ETs and speeds.
A 327/350 65 Chevelle would turn 105-108 on those little biased tires. I have one of those engines and trust me they turn out some serious HP. Of course with a decent cam as well as still pretty good heads even compared to todays aluminum ones and those huge pop up pistons it isn't hard to figure out why they ran so hard.
And I totally disagree with the idea that tires don't or didn't have an effect. Many of those cars didn't launch worth a hoot. That's why they didn't allow slicks in the stock classes and I think they even made you run a minimum tire pressure as well as treads being decent. I don't remember if they measured tread depth or not. Someone help me out here.
Putting slicks on a LS6 454 Chevelle made and makes all the difference in the world. Another vastly underrated car BTW.
They did fudge a little on the Corvette line regarding HP on some models giving the Vette slightly more HP than the same engine in another vehicle. But they were right on more than not. The 65 Vette with a 327/350 was the same L79 engine in the Chevelle and El Camino (yes you could special order the 65 El Camino with the L79 engine).
What amazes me today is they take the same basic engine and with a few mods have managed to massage the heck out of them getting more HP and better fuel economy to boot. And the difference in handling and safety is in another world. I'm still amazed that GM had such gifted engineers in the 50s thru 74 or before the death of the production hot rod that some of those parts are still competitive with parts requiring cnc machining. The old 461 head and intake and some of those cams are still nice parts.
The new Z06 is taking that 50s SBC to the moon.
Last edited by jobberone; 09-23-2005 at 02:27 PM. Reason: typos
