is there any difference between a pontiac 455 sd and a 455?

http://en.wikipedia.org/wiki/Pontiac_V8_engine -- check out the 455 portion of this link it should give you some insite into the differences.

In 1973, a further refined and even stronger version, the Super Duty (SD) engine was introduced with "only" 310 hp (231 kW)/231 kW (SAE Net) using a similar camshaft specifications to the Ram Air IV 400. The 455 SD used round-port cylinder-heads similar to those used on the 1971 and 1972 455 HO, with specific "LS2" intake and cast-iron exhaust header-manifolds. Still, it was the strongest American engine offered that year. Its power was achieved through bending of EPA emissions-testing procedures, which led engineers to de-tune the engine to 290 hp (220 kW) via a camshaft change to the same profile used in the early RA III 400 engines for mid-1973 and 1974, after which point it was discontinued. While an evolution of the RA IV and H.O. engine designs, the 455 SD was a much improved engine. In addition to the more refined cylinder heads, block casting reinforcements in the lifter galley and main bearing oil pan rail area along with the addition of forged connecting rods with larger 7⁄16-inch-diameter (11 mm) bolts, the SD was made with a provision for dry sump oiling from the factory. This truly was a racing engine, detuned for use in passenger cars.

Super Duty 455's used Pontiac's legendary round port cylinder heads while the non Super Duty used standard D-port heads. The SD blocks utilized 4 bolt mains, forged connecting rods and pistons, and the blocks were cast with a provision for dry sump oiling. The lifter galley was reinforced with additional bracing to prevent cracking as well. Pontiac used a revision of it's standard 455 emissions rather than classify it as a brand-new engine. Since the standard 455's were already emissions certified, it allowed Pontiac to skip the certification process required of all new engine's. Without that it's highly unlikely that the SD-455 would have been approved for production. The SD-455 was the last of the true muscle cars. They were genuine 13 second cars when other so called '73 and '74 cars were struggling to manage 15 seconds in the 1/4 mile. It's a miracle that the SD-455 was even considered much less produced considering the market for high performance cars was definitely on it's last leg.

The only "13 second" SD455 cars were the prototypes that were issued to the magazines of the period for testing. They significantly different from actual production cars, as documented here: https://www.hotrod.com/articles/pon-0505-inside-455-super-duty/ MOTOR TREND tested a later regular production SD455 and couldn't get out of the low 15s with it. These cars weighed nearly 3,800 pounds. Combined with 290 SAE Net HP (Actual product engine specs), they just weren't fast.

I had a 1974 SD 455 Formula Firebird, no air,Turbo 400, 3.42 rear, ran consistent Mid-13's over 105 mph. Also would run over 150 mph. SD Firebirds were the real deal in 73 and 74 I added a shift kit , rejetted carb, and recurved distributer, ran Low 13's . Awesome car.

GuruVDYBF is right on the money, the SD455 has become over hyped folklore. The camshaft was a pollution cam, the manifold had EGR, and the carburettor ran ultra lean, put that all together and it struggled to get under 15's unmodified!

GuruC2TVH - Thanks for your thoughtful reply. I can only laugh at the other comments such as this one: "I had a 1974 SD 455 Formula Firebird, no air,Turbo 400, 3.42 rear, ran consistent Mid-13's over 105 mph. Also would run over 150 mph." As it rolled off the showroom floor, a 14.5 @ 98 MPH from that 3,800 smogger would have represented the absolute best case. As we know, the SD455's block was strong and featured nice provisions for subsequent lubrication mods. Other than that, the engine made some 25 HP less than the uncelebrated 1971 455 HO, which was actually capable of running very high 13s in the 102 MP range (Firebird and low content T-37 Tempest) straight off the showroom floor. The 455 SD really suffered in terms of its low compression ratio and compromised cam, carburetor, and ignition specs. The magazine test cars got the RA IV cam, milled heads, thinner head gaskets, functional hood scoops, optimal ignition specs and perfected carbs fitted with larger secondary jets and optimized metering rods. :-)

These two guys are above me I'll total dumb fuck bench racers. Even detuned without headers high- compression the bigger can bigger gears the car still in clock 13:5. Now the other 455's that year and later we're just passenger car engines that will only run 15. They didn't pick the SD 455 to be the top 5 muscle car engines ever for nothing. Don't listen to these two smucks above. https://oldcarmemories.com/5-best- high-performance-v8s-muscle-car-era/

Again: The only "13 second" SD455 cars were the prototypes that were issued to the magazines of the period for testing. They significantly different from actual production cars, as documented here: https://www.hotrod.com/articles/pon-0505-inside-455-super-duty/ MOTOR TREND tested a later regular production SD455 and couldn't get out of the low 15s with it. These cars weighed nearly 3,800 pounds. Combined with 290 SAE Net HP (Actual product engine specs), they just weren't fast. Put a 100% PRODUCTION LINE STOCK (please read that at least 4 more times) on a modern inertia chassis dyno and you'll see something on the order of 230 HP at the wheels. Combined with a 3,800 pound car (plus driver), that's an upper 14 seconds/98 MPH car. The only "stock" SD455s that turned mid 13s @ 105 were the specially prepared prototypes that were tested by a few of the period magazines back in the day (CAR AND DRIVER and HOT ROD being two of them).

Attention GuruSSY6N So you're saying that a relatively recent article that's primary based on nostalgia is more significantly than actual empirical evidence from known production line stock SD455s? Here's a vintage MOTOR TREND road test of production line stock (not to be confused with the specially prepared 1973 magazine prototype). 0 - 60 MPH: 7.3 seconds 1/4 mile: 15.0 seconds @ 96 MPH Top Speed: 124.3 MPH Link to the actual article's test results page: https://www.flickr.com/photos/141864703@N03/47966612963/in/album- 72157689935719041/ People writing modern articles about old cars are typically doing little more than regurgitating old myths than can easily be disproved my more reliable and original information. HIGH PERFORMANCE PONTIAC drag tested a known 100% production line stock 1973 SD455 back in the 2007-2008 timeframe. That car ran upper 14s @ 98 MPH, though it id have a recurved distributor, K&N air filter element and was fitted with wider than stock modern rubber at the back. 100% production line stock vs. same, something as innocuous as a 2013 Honda Accord V6 automatic sedan would out accelerate a PRODUCTION LINE STOCK (not to be confused with the prototype magazine ringers I've recently detailed with a link that included interviews with the SD455's original engineers) SD455 with room to spare. https://www.caranddriver.com/reviews/a15116988/2013-honda-accord-sedan-v-6-test- review/ That's because the Accord's horsepower to weight ratio is superior.

guruVDYBF- I would have to respectfully disagree. My uncle had one back in the day. We would talk Pontiac all the time. He has since passed...but he was a wealth of information as I am too young to remember, (man...I miss those conversations) . Are you talking about the standard Trans Am issue 455? That was 250HP from factory. It rans numbers better than those I see above. My uncles was no AC, automatic with 3.42 gears. It was definitely a high 13s car. With simple mods it was obviously faster. There was nothing that Ford, Chrysler or the rest of GM had in 73-74 that was comparable. It was a great muscle car of the day, whatever the quarter miles times are. Now a SD455 with AC had a 3.08 sounds like what you are talking about. All AC SD's had 3.08. Thx

Guru as much misinformed about the SD. Now a regular 455 was slow and ran 15's but the SD was a much different animal, I will call bullshit on this one. DD

I guess I guess this fool didn't realize the little SD Cam they used there's the same Cam that went in a ram air lll 400 and it was rated 366 hp. I'll also add that a stock SD is probably 400 horse with open headers. And would stomp a muddy hole in a ram air lll. In fact it would easily beat a Ram Air IV. That's why the SD 455 is picked to be one of the top 5 muscle car engines of all time. You can really get some horsepower out of this with some compression in a bigger cam.

No test car with ram air IV ever left the factory. Once they realized it wouldnt pass the emissions with enough cushion they destroyed the Ram Air IV cars and no one got to test one outside of the factory. The no it all is blowing smoke up your asses.

I'll say it again as stock SD that's running properly can run a 13.50. This guy above me is an idiot and it's never owned one. Nunzi Romano took a completely stock SD and put headers and gears on it and his tune and it ran 12 70s and made the front page of 1984 Pontiac magazine. People are so full of shit. This car from the factory it was 400 horse with shitloads of torque. Imagine what you can do to it. But the 74 455 probably ran 15 but it was just a passenger car engine and not a SD

The SD 455 cars easily ran high 13's. They were not in the 15's. Period. L-78 base 400 75-78 TA 400 autos ran 15's. An anemic 400 W72 4-speed T/A ran high 14's right out of the box. The SD 455 block was much stronger than the base 455, they were safe to rev higher, it had better rods-pistons-head and exhaust manifolds. It was a true performance engine. They were fast, and they are now valuable as H*ll.

Been a Pontiac Guy all my life and sorry, but you clowns stating this is a 15 second 1/4 mile car are morons. Nowhere in the referenced article does it state this. You are either a.) drawing conclusions based on changes made from the test cars; b.) confusing it with a standard 455 TA which DID run 15 sec 1/4's or c.) flat out unintelligent. I guess there could be another reason - your Corvette guys. The SD was a magical car in an uninspiring time for muscle cars. Quit misleading people by trying to sound intelligent on a subject you know nothing about.

What? No more? That’s it?

Just the statement that there were no RAIV cars ever released, shows their stupidity. There were many RAIV cars, I have 2 of them, and I also have a 73' SD455 TA. What you 15 second knuckleheads are incorrectly mentioning was the RAV motor which could only be offered over the counter in the Pontiac Parts department. Not the RAIV ! Duh! All SD455 Trans AM were mid to high 13 second cars Period. The Super Duty 455 or for that matter the earlier Super Duty 421 engines were race motors detuned for the street. The (NET) HP a couple of guys referenced was what the car did with all accessories running on a fully released as sold engine. There was only one engine in the muscle car era that had higher NET hp rating then the SD455 (310hp net) and that was the Chrysler 426 Hemi, that came in at 350 NET hp. The gross or BHP of the same Hemi was considered to be way over the 425 it was rated at. Does this not tell you the SD455 was one hell of an engine?? The following year 1974 The net rating became (290) camshaft change and further emission detuning. All SD455 carbs are different then previous Quadrajets and flow 850 cfm. The RAIV carbs were also hi-performance carbs, and flowed about 750 cfm.

Bill- Both the 1973 and 1974 SD455's were 290HP net.

OK - I have the SD-455 w/ round port heads in a 3000 lb. 1970 Pontiac Tempest. It has been "tampered" with a bit and runs 10.70s at 4000 feet here in Montana. All original.

As an old guy who bought his '74 SD new back in the day, and as someone who now is fortunate enough to own a fairly sizeable collection of cars including Ferraris and Lamborghinis, I had to laugh at the 'benchtest' comment and the magazine idiots who somehow couldn't manage to get the car out of the 15's. I agree with the others who actually owned these cars. Mine ran 13.80 all day at 102 mph on street tires totally stock (I still have the time slips to prove it). After rejetting the carb and recurving the distributor I managed to get it down to 13.6 at 104-105 mph everything else bone stock including the GR-70-15 radials. These motors were obviously putting out more than 290 net horsepower. BTW, my sales/ship-to sheet shows a dry weight of 3,704 lbs.

ok the 1976 Trans am with a 455HO 200net hp 330 ft lbs 4075lbs test wt. 3.23 rear gears 0-60 8.4 sec 1/4 mile 15.9 @ 87 mph road and track june 1976. and that was with a 4 speed trans. that would be about 207net hp the 1977 TA 400 200 net hp 325 fl lbs 3820 lbs 3.23 gears ran the 1/4 in16.3 @ 82 mph which would put it at about 163 hp you also have to factor in thing like temp, altitude and driver skill. I have seen SD455 cars run 13's stock hell the 1979 W72 TA was rated at 220 net hp and 320 ft lbs , 3.23 gears the they ran 15.3 to 14.61 @96.6 mph that is 265 hp which is right in line with what NHRA rated the engine at 260 to 280 net hp. so yes the SD 455 cars were in fact 13 sec. cars NHRA rated them at 370 -380 net HP

Title of this article is "Is there a difference between 455 SD and 455 non SD" that is "YES" Price a SD block, SD round port heads, SD intake, exhaust manifolds, connecting rods, more internals ... ALL different. from standard 455. Either motor a good performance motor or "build for a street car" candidate. The SD block would most likely hold more HP, 1000HP might not be out of the question where a stock block becomes iffy around 650HP. I dont have any SD stuff and never have but do some due diligence on researching my 650 HP goal. Pretty sure 650HP will get my 10's goal for my 64 GTO. Most likely my single digit goal for my Astre wagon, and for 11's for my 71 Formula. Talk is cheap tho, proof is in the puddin' As for the paper-weight imports with nitrous or boost or whatever else, go race in your own country if you want to spend thousands to make a gas guzzler out of a 4-banger. Maybe you too can be on "Fast and the Dubious". :)