'70s rides, decade of disaster or delight?

[hotlap]

I consider the 1970 model year as a carryover from the 60s. Performance dropped yearly from 1971 on.

I started driving in 81 and my second car was a 76 Trans Am with a 455 4-speed. Stock it had 7.5:1 compression and made only 200 HP but swapping 400 heads alone raised the compression to 9.5:1. Add a 72 or earlier intake, cam, headers and dual exhaust and you were right back to 1970 performance levels. Those Pontiac 400 and 455 engines were pretty easy to hop up and available through 79. Then the bottom really fell out

[ChrisBlair]

Originally Posted by hotlapZL1

I consider the 1970 model year as a carryover from the 60s. Performance dropped yearly from 1971 on.

I started driving in 81 and my second car was a 76 Trans Am with a 455 4-speed. Stock it had 7.5:1 compression and made only 200 HP but swapping 400 heads alone raised the compression to 9.5:1. Add a 72 or earlier intake, cam, headers and dual exhaust and you were right back to 1970 performance levels. Those Pontiac 400 and 455 engines were pretty easy to hop up and available through 79. Then the bottom really fell out

But it is worth mentioning again, don't get fooled by "hp" ratings as the '70s progressed.

Yes, smog motors were down on power because of compression and cam profiles. However. In 1970 this was 'hp' rated in 'gross' terms, then we went to SAE net hp in 1972.

Gross hp, which for example was how a Chevy Chevelle SS LS6 engine was rated in 1970, was rated per SAE standards J245 and J1995. Corrections for temp humidity etc were in 'ideal' environments and the engines also were rated with little if any parasitic accessories such as a fan belt or a transmission. Many times long tube headers were installed. The test engine cited for the rating was also typically "one of the good ones"; they'd test a few and you can be sure they didn't select the lowest result. This as actually a type of brake hp, but with a stacked deck.

In '72 we swapped to SAE net hp, which comforms to SAE standard J1349, and while a trasnmission was still not part of the equation, belts and smog pumps etc were, and this test obviously lowers the rated numbers compared to SAE gross hp. If the same smog engine from say '73 were rated per the 1970 SAE specs J245 and J1995, the smog pumps and other accessories would not be robbing power.

Today we use what we call 'bhp' or brake hp, which is a slight confusion, as it seems we hadn't been using some type of bhp all along...so if we fast-forward to 2012, here's how Chevrolet touted the LFX equipped Camaro (boldface by me for emphasis):

"New, standard 3.6L “LFX” V-6 with SAE-certified 323 horsepower (241 kW), which is 20.5 pounds (9.3 kg) lighter and helps maintain fuel economy of up to 30 mpg highway (2LS model)"

SAE certified means certified per SAE spec J2723 which is a validation of other SAE specs such as our old friends J1349 (from SAE net hp, above) or J1995 (from SAE gross hp, above). This does not necessarily mean an inflated rating for the engine, but it can mean some change from previous ratings.

So as you can see, bhp, SAE Certified, SAE gross and SAE net are all from various eras and are related but at the end of the day "400 hp" from 1970 is not quite the "400 hp" of 2014 and when you see a "200 hp" 455 from 1976, consider how many horses were negated by the changed SAE spec used to rate the engine.

[ilirg]

Originally Posted by LBreezie

1972 Road Runner, I love the new concept design for it and would probably be next next purchase if it would happen.

I would buy that!

[hotlap]

Originally Posted by ChrisBlair

But it is worth mentioning again, don't get fooled by "hp" ratings as the '70s progressed.

Yes, smog motors were down on power because of compression and cam profiles. However. In 1970 this was 'hp' rated in 'gross' terms, then we went to SAE net hp in 1972.

Gross hp, which for example was how a Chevy Chevelle SS LS6 engine was rated in 1970, was rated per SAE standards J245 and J1995. Corrections for temp humidity etc were in 'ideal' environments and the engines also were rated with little if any parasitic accessories such as a fan belt or a transmission. Many times long tube headers were installed. The test engine cited for the rating was also typically "one of the good ones"; they'd test a few and you can be sure they didn't select the lowest result. This as actually a type of brake hp, but with a stacked deck.

In '72 we swapped to SAE net hp, which comforms to SAE standard J1349, and while a trasnmission was still not part of the equation, belts and smog pumps etc were, and this test obviously lowers the rated numbers compared to SAE gross hp. If the same smog engine from say '73 were rated per the 1970 SAE specs J245 and J1995, the smog pumps and other accessories would not be robbing power.

Today we use what we call 'bhp' or brake hp, which is a slight confusion, as it seems we hadn't been using some type of bhp all along...so if we fast-forward to 2012, here's how Chevrolet touted the LFX equipped Camaro (boldface by me for emphasis):

"New, standard 3.6L “LFX” V-6 with SAE-certified 323 horsepower (241 kW), which is 20.5 pounds (9.3 kg) lighter and helps maintain fuel economy of up to 30 mpg highway (2LS model)"

SAE certified means certified per SAE spec J2723 which is a validation of other SAE specs such as our old friends J1349 (from SAE net hp, above) or J1995 (from SAE gross hp, above). This does not necessarily mean an inflated rating for the engine, but it can mean some change from previous ratings.

So as you can see, bhp, SAE Certified, SAE gross and SAE net are all from various eras and are related but at the end of the day "400 hp" from 1970 is not quite the "400 hp" of 2014 and when you see a "200 hp" 455 from 1976, consider how many horses were negated by the changed SAE spec used to rate the engine.

Absolutely true. Change in ratings distorted what was happening and even the good old days weren't as good as remembered. Most of the top performers from then were low 13 sec cars at best.

[Erik427]

360 hp was about all they made.....and it was either very peaky or short lived on the tach.

[ChrisBlair]

Originally Posted by hotlapZL1

Absolutely true. Change in ratings distorted what was happening and even the good old days weren't as good as remembered. Most of the top performers from then were low 13 sec cars at best.

Yeah, and a lot of the cars that people think were so fast were just also-rans even back then.

What I think is cool is that it took 30 years to surpass those cars. That's like a stock 1940 Ford DeLuxe stomping a 1970 440 Roadrunner.

[hotlap]

Originally Posted by motorhead

Wow this one isn't mine, I had one of these rare cars. Very few were made.

This is the 455 4-speed 76 TA I bought in 82 and sold in 09. Very few of these were made too. Its a real Y82, 455 car

Can you say cowl shake, body flex and axle hop?

[motorhead]

Originally Posted by hotlapZL1

This is the 455 4-speed 76 TA I bought in 82 and sold in 09. Very few of these were made too. Its a real Y82, 455 car

Can you say cowl shake, body flex and axle hop?

Love it. I've owned many trans ams, and while I know they are not the performance kings we have today, they still hold a very special place in my heart.

[hotlap]

Originally Posted by motorhead

Love it. I've owned many trans ams, and while I know they are not the performance kings we have today, they still hold a very special place in my heart.

Thanks! They really were the best car available in the 70s and I'd still love a 73 SD455 4-speed, Brewster Green TA. The holly grail of TAs IMO.

[ChrisBlair]

I'd settle for a '69 Trans Am convertible

[kevinw]

i still have brown bomb, a 1977 grand prix. it has a 301 V8 and the car is so heavy it takes an hour to get to 60 mph. but once its going, it rides like a tank.
my parents bought it new in 76 and now i use it as my truck as it has a huge trunk.
but, it is grossly underpowered as many vehicles were back then.

[Angrybird 12]

Originally Posted by ChrisBlair

I'd settle for a '69 Trans Am convertible

I guess you would since there were just 8 total built. 4 manuals and 4 automatics.

[big hammer]

Originally Posted by hotlapZL1

This is the 455 4-speed 76 TA I bought in 82 and sold in 09. Very few of these were made too. Its a real Y82, 455 car

Can you say cowl shake, body flex and axle hop?

that looks great. I have a 75 455 TA.

while they weren't great performers stock, Pontiac gave you a solid foundation to build on. cam, headers and exhaust and you're on your way with that big 455.

Pontiac kept it real better than anyone else in the 70's.