4.9L or Northstar

[MAC]

I am having a slight disagreement with a member of Lincolnvscadillac.com concerning which is faster from a dead stop—Is the 4.9 faster than the SLS and STS from a dead stop? I said the SLS is as quick or a even quicker than the STS from a dead stop and is quicker than a 4.9. He contends the 4.9 is quicker from a dead stop to about 20-30 mph. Would anyone have any insight on this?

[The Fred]

No one will agree with me but with good front tires a 4.9L Cadillac will beat a northstar off of the line for a short time.

[Bruce Nunnally]

Mostly it will depend on the drivers. Cars are difficult to launch properly, especially if you have not practiced with a timer.

These are numbers from different cars and on different days, and with some mods to the 4.9L (exhaust, chip, intake) and not the 4.6L at that point, but the same driver and same location:

The stock 4.9L numbers from contemporary magazines were 8.1-8.5s 0-60, so not as good as my modified 92 STS ran. Keep in mind that the 4.9L powertrain is lighter than the 4.6L northstar package all other things considered by 100+ pounds.

My later tests with my 96 after it had a borla exhaust showed 2.69s-2.71s 0-30mph, similar to the modified 92. Example my air filter study: http://www.caddyinfo.com/airfilterstudy2.htm

So, it depends, but a 4.9L can be quicker or as quick to 30mph as a Northstar, (about 60 feet), but not after that.

My 2005 CTS V6 is quicker than either of my previous V8s:

http://www.caddyinfo.com/2005CTScorsavolant.htm

but a large part of that is likely the different transmission torque management, and the advantage of rear wheel drive launches.

[MAC]

Based on your numbers it’s very close to even. However, what about the SLS? Would the SLS be slightly quicker up to about 20-30 mph than the STS due to better torque? Better yet, what about a 94 Eldorado (270HP/300lb.-ft torque)?

[Bruce Nunnally]

I have not tested an SLS. Let me repeat again, my intuition is more will depend on the drivers ability to get off the line quickly than on the difference in the cars. I feel the secret to quick starts in the Seville/El Dorado is by 'chirping' the tires, no more wheelspin than that.

However, the problem with getting the STS off the line is not a lack of torque. The problems are torque management to protect the 4T80e transmission, and front wheel drive dynamics.

The STS/300 hp package has a taller final drive ratio of 3.71:1 which makes as much of the difference in acceleration than the hp difference.

[JasonA]

I agree with Bruce -- ALL of these cars are so close in the short range that you really can't make a definative distinction. In the long run, either Northstar car will easily outrun a 4.9L, but the STS/SLS distinction is, again, really too close to call.

The SLS has more torque, at a lower RPM, but also a taller final drive. I can easily burn the tires loose on my SLS, so even with the SLS, you have to "feather" the throttle to get a proper launch. Again, I agree with Bruce...that abruptly going to 1/2 throttle to chirp the tires, and quickly going to full throttle seems to produce the best launch.

In theory, the STS will be the faster car, but we're talking about 10ths of a second to 60. Production tolerances and the state of tune/maintenance of the car is more than enough to overcome the technical advantage of the STS. Again, look at this sampling of measured acceleration results from magazine publications.

http://www.jnjhome.net/cadillac/images/caddyperf.gif

A '95 SLS outran, by a slim margin, many STSes, including 98+ cars and 97 and previous cars. Of the three SLSes they tested, the average time to 60 was 7 seconds. Within a 10th or two of the average for the STSes. One of the slowest marks on there was posted by an STS, with a 0-60 time of 7.2 sec and a 1/4 mile time in the mid-15s. I G-teched my '97 SLS and the best I got to 60 was 6.7 seconds. That's at least as quick as most STS times. I did not have the room (public roads) for a 1/4 mile test.

[MAC]

The base 95 SLS with 275HP/295lb.-ft is quick even in the quarter as it outpaced even the STS. So generally, it’s pretty much a toss up (often depending on driver skill) between the 4.9 and Northstar in the first 20-30 ft but after that a well-maintained Northstar rules. Though it could be that by the luck of the draw one identical Northstar may perform a bit better as they are not all exactly the same.

Thanks for the input everybody, I appreciate it.

[JasonA]

The base 95 SLS with 275HP/295lb.-ft is quick even in the quarter as it outpaced even the STS.

That particular '95 model did outrun many of the STS cars tested. Another SLS model went as slow as 7.3 seconds 0-60.

Though it could be that by the luck of the draw one identical Northstar may perform a bit better as they are not all exactly the same.

That's it right there. There are so many variables to acceleration times, including with the car (production/manufacturing tolerances, state of tune, previous maintenance) and with the track/environment. Technically, the STS *should* have the mechanical advantage, with the shorter final drive ratio. But as shown, you can really have anything happen as these cars are so close. On average, you can see the STS is slightly faster, but on an individual basis, it's up in the air.