Northstar Engines and System Technical Discussion Discussion, LD8 L37 comparison...which is really quicker? in Cadillac Engine Technical Discussion; After much reading and researching I still can not find the simple answer to which of the two engines is ...
After much reading and researching I still can not find the simple answer to which of the two engines is better. I got a chart i will attach that a lot of you most likely have seen before. I personally have the L37 engine and never rode in a car with the LD8. Is there noticable difference in 0-60 and quarter-mile times? Let this thread decide the truth behind the better NORTHSTAR.
The original design engine is one, in 1997, producing 275 hp @ 5600 rpm and 300 lb*ft @ 4000 rpm (the LD8). It's standard in Seville SLS, Eldorado, DeVille, and DeVille D'Elegance. A slightly more powerful engine (and with slightly less torque, the L37) came equipped in the STS, ETC, and DeVille Concours and made 300 hp @ 6000 rpm and 295 lb*ft at 4400 rpm. Northstar V8 Torque Curves (Image captured from gmpowertrain.com)
The actual field performance of these two engines is very similar. The L37 revs a little easier when running up to redline (and comes with a 3.71:1 transaxle) and the LD8 (with a 3.11:1 transaxle) has more low-end grunt when you're cruising down the boulevard. There is approximately a 5% difference in measured acceleration times between a 275 hp car and a 300 hp car. As you can see, the high-zoot engine actually makes less power and less torque through most of the operating range than its "less powerful" sibling.
If you look at the chart, the difference in hp, in egards to rpm, is still in favor of the L37. It makes the same 275hp the Ld8 makes at about 5000rpm. That means that while the LD8 peaks at 275hp at 5600rpm, the L37 makes that mcuh hp at around 5000rpm, and then continues to climb to 300hp at 6000rpm. I thihk this indicates a clear advantage the L37 has in hp, and when it's developed, over the LD8.
Peak torque, and when it is achieved is a different story though. The LD8 make 5 lb ft of torque more than the L37, but it's only 400rpm lower than the L37. It does appear to reach that amoutn of torque a little fater that the L37 though.
I think that overall, the differnce in torque is not so much a deciding factor in speed, as the hp is. The Northstar rev's very quickly, and will reach it's peak hp quite fast. This is why the L37 will in the end, overtake the LD8. The LD8 is more drivable around town, while the L37 performs better on the highway, or at WOT.
The LD8 clearly makes more horsepower until about 4500RPM, at which the shift in favor of the L37 is pretty dramatic. Still, this suggests the LD8 would be a more responsive driver when you're not blasting through the gears - except for the axle ratio, which IMHO tilts the whole picture solidly in favor of the L37 no matter the speed. 3.7 vs. 3.1 is pretty significant...
From real world STS vs SLS experience. The two SLS N*s I took on were both neck and neck off the line from the green light, but by 1/8 of a mile my STS pulled ahead and opened up. On the open highway, the SLS and Devilles I came up on, all faded after the 90 mph kick down. The LD8 does not stand a chance at WOT on the open highway.
Do you believe the biggest difference would be the transaxle? I know there is different gearing between the two. The L37 has the 3.71:1 and the LD8 has the 3.11:1 transaxle. There is significant difference there. It looks like the transaxle is what it really comes down to when comparing the versions of the northstar. From what we have got so far on this thread the L37 looks like the winner in the long run. The area just before redline is greatly in favor of the L37. It is interesting though that the LD8 is actually a bit faster on the low end.
Just to throw in my .02 worth - I had a '99 Deville with the 275HP, my G/F has an 02 Deville with the 275, and I just last week traded the '99 on a '01 ETC with the 300 HP engine. I haven't really had the chance to run the ETC through the wringer yet, but I have noticed some differences, some of which may be due to other influences (weight, suspension, etc...) between the Deville(s) and the Eldo
1) The Eldo engine is like silk up until around 3500 when you can DEFINITELY feel the juice kick in. It is one of the most free-revving engines I've ever been behind. The tach needle just jumps from 3K to 6K without even thinking about it.
2) The Devilles seem to have a more "uniform" response - there is no real jump in the power at any one RPM - snap it in second, and floor it and they both take off pretty briskly. By comparison, the Eldo seems more like a 'slingslot', for want of a better term. It seems to smoothly slide from 1500 to about 3000 rpm, but then it almost feels like a turbo kicks in - there is a definite difference in feel.
Which is better? Pick 'em - flip a coin - I don't think you'd be disappointed with either of them.
If you are just talking engines, in a identical heavy cars with the same gearing in most cases the 275 h.p. engine would win. In light cars with the same gearing the 300 h.p. would probably win. Of course if the gearing were really high(low numericially), that would favor the 275 because of torque curve, the opposite would be true with really deep (numericially high) gears. There is no pat answer for this question!