[Jims_97_ETC]

the attraction to more cylinders is that higher cylinder engines tend to make more torque lower in the RPM band

That's why I said that my preferred configuration would have about 500 cc per cylinder, leaving the number of cylinders proportional to the displacement (and horsepower). That cylinder size gives a good compromise between torque and RPM potential, and specific output (hp per cc) increases with maximum RPM. For a street-only car with automatic transmission, you might want more cc per cylinder. For a race-only engine you would definitely want less cc per cylinder. The V-series Northstars have 550 cc per cylinder and ours have 575 cc per cylinder.

The best fuel economy for a given engine displacement comes from four-valve configurations because they breathe better and are more efficient. Yes, EGR reverses the fact that a four-valve engine leaves less burnt fuel and more new fuel charge per revolution, but with a four-valve engine you have better control of what you need to do to control maximum combustion temperature, which is what EGR is all about, so you will have better results in the real world with four-valve engines, as well as better emissions control. Thus I believe that the state of the art for the foreseeable future is four-valve (with variations such as three-valve and five-valve) with DFI and VVT.

I don't expect to see boxster engines in street cars because they are too wide to put where they would interfere with advantageous front suspension links, or even rear suspension links, particular the DOHC configurations. They are best in rear-engine or mid-engine configurations where they can be put in front of the rear wheels, and in cars where the loss of passenger or cargo space isn't important. Thus the ideal engine configuration becomes the V-block motor, which has the advantage that it doesn't really need a dry sump oil system.

This gets us to the GM 3.6 liter DI V6 for the normally aspirated 300 hp motor.

[Bruce from Caddy...]

I still think the 3.6L should be putting out around 330-335 hp btw. Based on the gains seen once a CAI and Sport exhaust system are added, Cadillac is not getting all the power out of this engine that they could. I suspect somewhere the CTS was 'specified' to need a 300 hp engine, and when Powertrain got to 300 they stopped worrying about more power and concentrated on noise, vibration, and harshness (NVH).

[Jims_97_ETC]

There's another reason to keep the specific output lower than one might want it to be: torque off-idle to provide throttle response and driveability without a high stall rate torque converter. Driving a car with a high stall rate converter around town at low speeds means wide RPM swings and low fuel economy. You can compensate for lack of off-idle torque with a large numerical gear ratio, one reason that we have started to see six and seven gears in automatic transmissions in modern cars instead of the traditional four. I would think that this is not as satisfactory to most people as a more gutsy engine with a four-speed transmission. One option is to have separate engine tuning for a standard shift model and this was once common, but driving a standard shift with an engine with low off-idle torque is a skill beyond what most people expect, even those who drive standard-shift cars, unless, again, a high ratio low gear is used, which requires a quick shift to second gear on startup, which I would find aggravating. Perhaps with CVT we will have yet another traditional issue go away with technology; this awaits CVT designs that are as efficient, reliable, inexpensive, and handle the horsepower as existing transmissions.

With VVT, it would seem that a way might be found to get higher specific output from the 3.6 DI engine, by varying the angle between the intake and exhaust lobes as well as moving the timing of the valve openings earlier at higher RPM.

Note that GM has a long history of not extracting the most from their high-performance engines in early production, and even then underrating the advertised outputs. In some cases, the Northstar among them, the potential is never really tapped, unless you consider teh 4.2 liter supercharged versions used in the V-series -- and even then one of them was tuned for lower horsepower for reasons that totally escape me.

[OynxSTS]

I still think the 3.6L should be putting out around 330-335 hp btw. Based on the gains seen once a CAI and Sport exhaust system are added, Cadillac is not getting all the power out of this engine that they could. I suspect somewhere the CTS was 'specified' to need a 300 hp engine, and when Powertrain got to 300 they stopped worrying about more power and concentrated on noise, vibration, and harshness (NVH).

To add to that the pending death of the 32V V8 at Cadillac... I would say that not only is Cadillac not getting all the power out of the 3.6L engine that they could... the complete future lack of a 450-500 HP 32V motor to go head to head with the best from Germany will SEVERELY limit the competitiveness and the product development at our favourite GM division...

If I had to point to one of the biggest mistakes make by Rick Wagoner and Bob Lutz it was the cancellation of a V8 replacement for the NorthStar. This terrible decision will have serious repercussions for years to come.

[PAUL T]

My 94 Concours Northstar went at 166,000 miles. I denied it for a long time but eventually had to accept it. (IMG:style_emoticons/default/unsure.gif) (IMG:style_emoticons/default/connie_mini_wipetears.gif)

[Jims_97_ETC]

I put in a reman at 116,500 miles and plan to drive the car several more years. I've had it 12+ years now. The most I had other cars was 7 years (the 1959 Chevrolet 235 cid 6 and the 427 cid Cheverolet wagon). The 1959 had three engines and the wagon had two. I'm way ahead with the Cadillac.

[davek]

Another reason to prefer a V8 (or more) in a luxury car is the smoothness, both a lack of vibration and a soften the pulses of the exhaust noise. Back in the days of the V16, lots of makes had a V12, because they were easier to balance. Everything is built to a price and purpose, and the Northstar had many objectives when it debuted, and the primary one was to steal Lexus' thunder. The LS400 debuted in 1990 with a 250hp 4.0l DOHC V8 when that sounded downright exotic. The dowdy, indifferently-assembled Cadillac models with their impotent 4.9 OHV and 185hp weren't in the same league. The Lexus was better than a Mercedes and cheaper, too, but Cadillac wasn't. The '92 Seville was surely meant to debut with the Northstar and instead it was delayed one year. Compare the '93 STS overall to the '91 and it's crystal clear what was going on, and I feel it was pretty successful. In fact, the initial Northstar's swaggering exhaust note so put off buyers that it was tamed one year in. Its power and advertising were as subtle as a concrete block thrown from an overpass.

Sadly, it took 10 more years for the Northstar to progress much, and it took a RWD platform. More than 300hp was probably thought dangerous in FWD settings and too much for the 4T80E anyway. While the '93 Seville was a revelation, the '98 was not. By 2004, it badly needed replacing, and the RWD one was appropriate and as fabulous looking as the '93 had been. Cadillac's lineup today is better than it's ever been.

I agree with the above statements that canceling the Northstar's replacement (suggested name: Northway) was a big mistake. The LS is a fantastic engine in its own right, but it's much too famously Chevrolet to see good acceptance in mainstream Cadillac models. Luxury buyers are fickle. If any part of a Cadillac is seen as technically deficient, the buyers will stay away for that reason. The 3.6 is an excellent engine, and any V8 has its work cut out besting it in any way. That optional engine is an important step-up in luxury buyers' minds. Witness the premium that Mercedes and BMW charge for V8s over the same model with 6. Luxury cars are not about adequate, and the 3.6's competence is not the big deal as much as any V8's superiority.

Cadillac will need V8s through their lineup to compete, not just in its cheeky European foray, but increasingly in the US, too. A clean turbo diesel will be vital in the next 5 years, too. Cadillac can't rest on its laurel and sell only to people who want Cadillacs, but cater to all lux buyers. They've seemed to know that for the past few years, but they also can't afford to ignore it for ANY length of time. The one-two punch of the V8-6-4 and early HT4100 would not be survivable today.

[Jims_97_ETC]

Note that the BMW M3 has a V8. Roger Smith is long gone so you can forget airy thought at the top leading to things like the 368 cid V8-6-4 or a 4.1 liter engine in a 5,000 pound car. I agree that Northstar has another generation in it to cover where the High Value V8 would have taken over. Some of the thinking that I was seeing in the High Value V8 was modular thinking, like the Ford Modular V6-V8 family where the same factory builds engines based on castings for V6 and V8 engines that share many parts such as pistons, rods, valves, timing chains and sprockets, dampers, flex plates, etc. and the 3.6 liter DI V6 seemed like it might be the first of the line, or at least a precursor like the Quad 4 was a precursor of the Northstar, which took its timing chain concept but not its 80 hp/liter specific output in HO trim, which would have given it 365 hp. In a FWD, the problems that we have with the exhaust manifolds and crossover pipe don't exist and it seems likely that a 360+ normally aspirated Northstar could be cobbled together using Quad 4 HO cam profiles and a returned intake manifold and exhaust. A fresh look at DI with VVT and the FWD configuration should give an easy 400 hp for a normally aspirated 4.6 liter V8 using the existing Northstar except for the heads, intake manifold, and exhaust system back through the cat. That would give them the three years that they need for a new V8, or to combine the V6 and V8 factories.

Wouldn't you rather see a Northstar V10 in the Escalade rather than an LS? That could provide 600 hp, normally aspirated, and *that* would be a 350 to remember. It would very likely beat the 6.2 liter (378 cid) LS for fuel economy and, with a 6-speed, for driveability. Put *that* in your hybrid configuration.

[Jan Olsson]

Many testers feel that the Cadillac V6 isn't as smooth as the competitors V6 engines, then they test the Northstar engine (IMG:style_emoticons/default/tongue.gif)
Personally I feel that a 90° V8 that can be fully counter balanced with respect to the 1:st AND 2:nd order of vibrations always will be superior to a V6 who in many cases need to be counter-balanced for a smooth run.
Nothing wrong with the current V6 but a V8 should be offered for those who wants the "little extra"..after all Cadillac is a luxury car maker. A V8 based on the technology used in the V6 should be nice.
Everyone is making a V6, Cadillac on the other hand have had V8 engines since 1915. A V8 on the other hand will always sell on the luxury market. It isn't all about top horsepower, it is also about available torque at any rpm.
Admit that it is a certain feeling in having a V8 engine that performs just as well as many screaming twin turbo engines. I am not a fan of technique for its own sake.

Less heat, lesser parts, better feeling.
They should at least offer Northstar engines in the future to fill the gap between the V6 and the V-models.

[BodybyFisher]

Many testers feel that the Cadillac V6 isn't as smooth as the competitors V6 engines, then they test the Northstar engine (IMG:style_emoticons/default/tongue.gif)
Personally I feel that a 90° V8 that can be fully counter balanced with respect to the 1:st AND 2:nd order of vibrations always will be superior to a V6 who in many cases need to be counter-balanced for a smooth run.
Nothing wrong with the current V6 but a V8 should be offered for those who wants the "little extra"..after all Cadillac is a luxury car maker. A V8 based on the technology used in the V6 should be nice.
Everyone is making a V6, Cadillac on the other hand have had V8 engines since 1915. A V8 on the other hand will always sell on the luxury market. It isn't all about top horsepower, it is also about available torque at any rpm.
Admit that it is a certain feeling in having a V8 engine that performs just as well as many screaming twin turbo engines. I am not a fan of technique for its own sake.

Less heat, lesser parts, better feeling.
They should at least offer Northstar engines in the future to fill the gap between the V6 and the V-models.

Hear hear!, I congratulate you

[Julio]

Mine went at 70K its a 97 eldorado dealer wanted a ton to fix it I did mone in the driveway Itook it out the top it cost me about 700 with the helms manual gasket set rear seal I did the 1/2 case while it was out gasket set and bolts, the time cert kit its self was a little over 300 at the time.

Take your time you only want to do this once.

[TDK]

Dear all,

I feel that Jims 97 ETC, Dave K, OnyxSTS, Jan and Bruce himself have submitted some of the finest supporting posts in quite some time. I found myself nodding to the screen as I hope many of you were as well. I certainly agree and can only hope that GM/Cadillac is reading this forum as well.

Do the math; a state of the art DI, VVT, 3.6 liter V6 with 300hp at 50hp per cylinder makes a fine 4.8 liter V8 with an easy 400 hp. Then do the supercharge thing for the next couple hundred hp.

To paraphrase another author; Cadillac is not about being adequate!

Bruce, please consider sending GM this thread with the above authors' contributions in particular.


There is no better "Focus Group", than this forum.


For the record, Our '94 Concours was over 215,000 miles with NO engine or tranny work and only 2 green coolant changes that I know of. It was wound up as tight as I could find asphalt for it to run, and it NEVER gave up. I can only hope our 99' Deville now at 60,000 miles - is as legendary.



Regards,

[Jims_97_ETC]

When they do the DI head design, they can look at the port and valve angles and get better breathing. They need to surpass the best LS heads. With the current 4-valve heads they are close but the design is more for mid-range. The bottom end is good to go. I'm assuming that they have better O-rings and head gaskets now.

[Bruce from Caddy...]

TDK -- I concur.

(IMG:http://www.caddyinfo.com/2010%2030L%20LF1%20CTS.png)

Back to my 3.6L V6 HP rant -- the new 3L LF1 DOHC DI VVT V6 makes 270 hp in the CTS. Scale that up to 3.6L and you would have a 270 x 3.6/3 = 324 hp 3.6L instead of our 304hp 3.6L LLT.

So get with it Powertrain, why do we have a 304 hp LLT and not a 325 hp LLT?

We are also still missing the 4L V6 variant, which is the upper planned limit of the design, although due to fuel economy concerns I fear we'll never see it. Theoretically a 4L DI V6 could make 270/3 x 4 = 360 hp.

The missing new tech V8 was referred to as the Ultra V8. It possibly would have been a 4.6L DOHC VVT V8 variant for 375-400 hp. It was in development before the Direct Injection was deployed, so I am not certain if it was planned as a DI engine or not.

With a terrific engine in the 430 hp LS3 or the Escalade's 403 hp, 417 ft-lb torque L94, which is Cadillac-exclusive, I would honestly use that instead of developing a new DOHC VVT V8.