The main reason for the hp difference there is they switched from gross to net hp ratings in 72.

 

Is that right? It makes more power with a carb?

 

Why shouldn't it? EFI is just a finely regulated form of fuel entrance into the airflow.

Carbs, from what I hear, just allowed as much as possible to flow. Which begs the question about intake and throttle body sizing.

No real regulation but what your foot said no to, no matter the rpm, or gear.

 

Yep and so does the LS2. GM rates it at 440 with a 4bbl.

 

Thats why the 69 model year was extended to Feb 1970? Are you serious? Youre off by a year.

 

Yes however the beauty in EFI is in the gains from manifold/port redesign, is it not?

 

Yes sir, I'm serious.... and we're talking about Muscle Cars, not Camaro.

However, since you bring up the 1969 Camaro, here's some tidbits to help put you on the right path :

1. The 1969 Camaro ran from September 1968 till November 1969! It did not run till February 1970. If it had, it would have had to qualify for 1970 model year standards. Something GM was NOT about to spring for with a new Camaro coming up in a matter of months. Just to reinterate.... the 1969 Camaro was in production for 14 months.

2. The ONLY reason the 1969 Camaro end date was extended from the summer of 1969 to November of 1969 was.... get ready for this..... the all new 1970 Camaro wasn't ready in time. The new Camaro didn't hit the streets until February 1970.

3. Sales of the 1st gen Camaro it's 1st 3 years:

Camaro SS sales for '67, '68, '69:
34,400; 27,800; 33,900 (with 3 additional months of production).

Camaro RS sales for '67, '68, & '69
64,800; 41,000; 37,700 (again with 4 extra months of production)

Finally, base Camaro hardtops, again for '67, '68, '69
160,600; 176,800; 165,200 (with 3 extra months of production)


If you ever entertained the fantasy that the 1969 Camaro's model year was extended because of popularity, hate to bust the ole bubble. You're dead wrong.

Blame Fisher Body.

The rear quarter panel dies for the new 1970 Camaro (and Firebird) could not get it's stampings right. It produced wrinkles and cracks in the sheetmetal stamping. At first, Fisher Body tried to correct it by modifying the dies, but it made the problem worse. Finally, they scrapped the dies and started all over again, delaying the 1970 Camaro production by 4-6 months depending on what point you use (production start or showroom delivery).

Some of the really old timers will recall GM's mad scramble to extend contracts for suppliers (and to get them to hold off or make space from their new comittments) to continue making parts for the '69 Camaro. GM 1st tried to spin the mess and blame other things. But word got out what really happened.


Don't feel too bad. It's a common misconception that '69 production continued into 1970. Many of the last cars made in November '69 didn't find their way to dealers till January 1970 and quite a few people make the mistake of misreading that as the car was in production till then.... but it wasn't.


Now, as to my statement that muscle cars (cars similar to GTO by the big 3 US automakers) started crashing no later than the 1970 model year, feel free to pick a popular muscle car.... your choice.... and I'll post the annual production figures showing the rate of sales decline starting in 1969 if not sooner.

 

All due to a change in the way horsepower was rated.... as pointed out already.

Emissions standards didn't start carving out serious power from engines till at least the 1974 model year when GM began bolting bead-type catalytic converters on most cars in 1974 ahead of the new 1975 standards. Chrysler's "Lean Burn" electronics help Chrysler escape from catalysts on alot of it's V8s till the late 70s. Ford's V8 engines never lost their torque due to better breathing and honeycomb cats, but the horsepower they made went directly into powering emissions gear like the smog pump.



One final note about muscle cars and the engines they were famous for. Top engines were barely anything less than factory race prepared motors. In ALL instances they were the top optional engine. In many instances, they were all but impossible to get unless you were close friends with a dealer. In most all cases, they cost nearly as much as the base model of the car the muscle coupe was based on. Kind of like a Chrysler 300 having a performance engine option that cost $15,000.

The REAL engines that were in these muscle cars, the ones that you could easily check in the option box, that you could easily get from the dealer, and comprised the 98% of the engines that were in Muscle Cars held up well in power output till well into the emissions era, at which time they were phased out in favor of fuel economy.

Chrysler Hemis died because they were too expensive to make, but Chrysler's 440s and 360s carried high performance parts inside many years till they were killed off. Ford's high performance big blocks made it into pickups and big cars. LT1s were made into lead-free friendly L82s that still had quite a few exotic parts and lasted till the end of the 70s.

 

Holy off topic batman. Although some very interesting info in this pissing match, you guys are light years off the topic and have managed to hijack the post. Take it elsewhere man.

 

So you guys are trying to tell me that the 455 needed 135+ horsepower and 150 lb-ft of torque just to drive its accessories and pump the exhaust through its mufflers?

 

No. But it is perhaps a glaring example as to why horsepower ratings were standardized to the new SAE net standard. Not all ratings were honest or at least, measured consistantly.

 

I suspect that it isn't the carb bumping the hp rating, but the carb manifold itself, being less restrictive in the high end, as compared to this particular EFI manifold.

 

Hmm, I doubt it will make 525 after being neutered for production. I'll estimate ~475 hp.

 

It'll need to make more than that. The 6.1 is being bumped to 435 shortly.

 

So another 40 horsepower isn't enough from an additional .3L? The 6.2L LS3 only got 25hp over the 6.0L LS2