: Bbob, anyone, new cadillac engine?



CadiJeff
11-07-04, 02:59 AM
Topic for discussion

Should cadillac consider a new engine? Mabe something w/ more naturally aspirated horsepower/torque than the current northstar? don't get me wrong I love the northstar, but for certian aplications (cts-v,ect) it is not quite adequit and Personally I think it is a bit insulting to be using a "fleet" engine for theese fine vehicles.

any comments/suggestions welcome

BeelzeBob
11-07-04, 04:10 AM
Topic for discussion

Should cadillac consider a new engine? Mabe something w/ more naturally aspirated horsepower/torque than the current northstar? don't get me wrong I love the northstar, but for certian aplications (cts-v,ect) it is not quite adequit and Personally I think it is a bit insulting to be using a "fleet" engine for theese fine vehicles.

any comments/suggestions welcome


Well, the Northstar for the RWD XLR/SRX/STS is a somewhat "new" engine with more power, VVT, redesigned for RWD, etc..... It is at 320 HP using a very conservative rating method that is somewhat new in the industry and was first used to rate the advertised power for the RWD Northstar LH2 engine. More importantly, with the VVT the powerband of the engine is much more broad than the TFWD Northstar and that is more important than more peak HP as the area under the torque/HP curve is what accelerates the car and provides good all round performance and driveability..not just a higher peak HP number. The RWD Northstar is quite unique and new...and higher power varients of it in RWD form are quite possible.

The CTS-V uses the Z06 Corvette engine...that engine has very high specific output especially for a 2 valve, pushrod style engine. (there is no replacement for displacement if you are looking for maximum performance...)

The CTS has the brand new "high feature" V6 with VVT.....

The Cadillac 'slades use the 6.0 pushrod engine and that particular varient is pretty much exclusive to Cadillac.....

Soooo.... Cadillac has not only considered a "replacement" for the "current" Northstar but has several of them in production already....and...more to follow...??? LOL

CadiJeff
11-07-04, 04:27 AM
....and...more to follow...??? LOL
You really enjoy doing that don't you :D

CadiJeff
11-07-04, 04:35 AM
I guess the real problem I have is that cadillac is using fleet engines in the "V" and in my opinion that just isn't what cadillac is, cadillac is the "high end" and to use an engine reguardless of the variation that is in lower end cars (corvette,coupe catera....er GTO) is a bit Bass Ackwards, the technology should "trickle down" not "trickle up". I think this is the kind of mistake that doomed Olds(w/ exception of aurora). I just think it would be more proper for the Vette owners to say "WOW! This engine is the same one in the new top of the line Cadillac!" not the reverse.

Spyder
11-07-04, 07:16 AM
You're saying that a 'vette is low end? Where would that put hondas and yotas and fords? :) hehe And Bbob, I agree with the "no replacement for displacement" theory, but if that's true, why the heck isn't there a 413 Max Wedge still being produced!?>!?!? I'd love to have a new one for my truck, instead of the 'ol 62 that's in there now. :) lol
Sorry...this caddy I've got now, my 83 I sold not too awful long ago, and *gasp* a honda accord I had as a commuter car are some of the only non-big block cars I've had...I like big motors. :)

eldorado1
11-07-04, 01:34 PM
You guys need to spit out a 5.7L DOHC v8 for the next "northstar"... And it's okay by me if you just copy the LT5 ;)

http://www.wpccc.net/images/Gathering/2003/polished%20LT5%20plenum.JPG

CadiJeff
11-07-04, 02:06 PM
The Vette is a high end for one of GM's lower brands so yes it is a low end car.

CadiJeff
11-07-04, 02:09 PM
didn't it used to go something like this?

Cadillac
Buick Oldsmobile
Chevrolet Pontiac

dkozloski
11-07-04, 03:04 PM
It was Cadillac/LaSalle, Buick, Oldsmobile, Pontiac, Chevrolet.

CadiJeff
11-07-04, 10:13 PM
point is chevrolet is the low end line, and I think it is time that cadillac retake it's position as the best, and I don't think they can honestly do this while using "fleet" engines in their top of the line vehicles.

Night Wolf
11-07-04, 10:41 PM
ummmm... how many complaints are there with the new CTS-V?.... only some bashers who say something like "yeah, but it dosn't have a Cadillac engine"

For GM to completly redesign and produce a new engine that'll atleast out perform the LS6...would take alot of money.... would you be willing to spend $80 on a CTS-V just to say it has a Cadillac engine? the price will be getting passed along to the consumer.. not to meniton, but the LS6... along with any SBC is a proven enigne... plus, the after market.... you know how long it would take to build an after market the size of a Hyandi V6... let along a SBC? just look at the NorthStar... it has been around since 1993.... and 11 years later, there is still no after market.. excpet for very few high priced specilty shops...

... if you want a fine roadster Cadillac with a uniqe enigne... get an XLR..... the CTS-V has it's own market... and it is filling that role just fine IMO....

... back in the 50's Chevy was the cheap, peoples car..... today though, the lines are blurred so much, that it is jumpbled up..... it you consider the main GM sub divsions (and not Saturn, Saab etc...) then the Cavilier/Sun Fire are the cheapest... but you can get a new Cadillac for less then a new Pontiac.. the Bonnieville GXP is around $37k while the CTS is $30k or so... Buick strechs from $20k to $45k... which is the start of a DeVille... there is alot of blurr.... and today people buy a car more for styling, features, fuel economey then they did in the golden days where it was more of a status symbol.... not saying that either the old way, or new is bad, or better then the other... just that times change, and by saying Chevy is low-end and it is bad to have a Chevy engine in a Cadillac... IMO is wrong....

Something uniqe with Chevy... they make their cheap cars... Cavilier, and expensive cars... Corvette, SSR etc... nobody ever makes a big deal abot that... Chevy makes cars ranging from about $12k-$60k (isn't the SSR more?) and all the cars have fna clubs... they just serve different roles....

maybe they should bring back the 500.... modernize it with a few things, give it SFI, give it an honest 550hp/650tq to start out with... and stick it in the CTS-V.... nobody would ever mess with Cadillac then :)

CadiJeff
11-07-04, 11:39 PM
It used to be that Cadillac was the best of the line w/ the most innovative engines in production and while the northstar is a good engine it is not adequit for the higher power aplications such as the "v" not to mention that it (around here at least) has an undeserved bad reputation, I suppose one way around this would have been to rename the engine w/ the birth of the vvt version. As far as the aftermarket goes this has been limited by the afore mentioned bad reputation, a percieved lack if interest, and the dificulty of interfacing w/ the computers, not to mention it is a front wheel drive vehicle. The Ford 4.6 is about the same age as ours, compare the aftermarkets and tell me that 13 years isn't long enough to create an aftermarket.

I do like you idea of bringing back the 500, but make it either aluminum or some kind of composit material to keep the weight down, I suppose the easiest way to do this would be to modernize the HT design as a big block.

ellives
11-08-04, 10:16 PM
It used to be that Cadillac was the best of the line w/ the most innovative engines in production and while the northstar is a good engine it is not adequit for the higher power aplications such as the "v" not to mention that it (around here at least) has an undeserved bad reputation, I suppose one way around this would have been to rename the engine w/ the birth of the vvt version. As far as the aftermarket goes this has been limited by the afore mentioned bad reputation, a percieved lack if interest, and the dificulty of interfacing w/ the computers, not to mention it is a front wheel drive vehicle. The Ford 4.6 is about the same age as ours, compare the aftermarkets and tell me that 13 years isn't long enough to create an aftermarket.

I do like you idea of bringing back the 500, but make it either aluminum or some kind of composit material to keep the weight down, I suppose the easiest way to do this would be to modernize the HT design as a big block.

The problem with this statement "the best of the line w/ the most innovative engines in production" is the game has changed. "Best" used to mean the best quality. Well guess what? EVERYThing GM makes MUST be the best quality in it's segment. It can't survive otherwise. What about the CTS-V engine is not quality? What better engine is out there than the GM 350?

What does "Best" mean? To me it's about quality and being on the reasonable side of leading edge... but not "bleeding" edge. I don't want to see a V8-6-4 ever again but yet I see others trying it (300C HEMI comes to mind but others are doing it.) It's interesting that Cadillac was maligned for the V8-6-4 technology but only NOW it's good idea because others are doing it. This was the price of being bleding edge back then.

GM needs to focus on the value proposition. Build the Cobolt so the magazines say it's "built to last a lifetime." Nothing else will bring the market back. The mainstream buyers out there... the bread and butter... wants dependability, reliability and resale value. Only quality will provide these.

Cadillac can't afford to be so leading edge that the product isn't stable like some of the attempts of the past... HT-4100 comes to mind... This was one of the places Oldsmobile really fit the bill as a testing ground for the new technologies. And oh by the way the Aurora had nothing to do with the demise of Oldsmobile. The marketing team destroyed Oldsmobile. Did you ever notice on the first generation Aurora that the name name "Oldsmobile" wasn't on the car at all? What were they thinking? It was a great car!

For what it's worth there was a lot of buzz at the international auto show in Boston last weekend at the Cadillac display. Not one Deville of any flavor there but they had the Escalade ESV Platinum edition... $71K... ouch.... and lots looking at the XLR... nice automobile.

Aurora40
11-08-04, 10:50 PM
Heh, the CTS-V is the only Caddy that causes me to drool a bit. 400hp and 400lb-ft from a motor is pretty respectable, and any smallblock that can rev to 6,500 rpm will get my attention. It's a smooth all-aluminum V8 that makes a lot of power, gets decent economy (all things considered), and sounds wicked. What's wrong with that? How's it a fleet engine? The LS-6 comes in exactly one other car, the quickest Corvette ever. Seems like a good place to pluck an engine from. :)

CadiJeff
11-09-04, 01:34 AM
First of all I made a special exception of the aurora, an excellent car. second the ls6 (pretty much a bigger ls1) is a GM motor developed at the corperate level like the current 4cyl and 6cyl engines, there is nothing to set it apart from the corvette engine other than a cadillac emblem on the cover. Now I consider a fleet engine to be any engine that was developed to be put into many cars (coockie cutter cars) and make no mistake this is a dangerous trend and was a big complaint w/ olds vs chevy, no one wants to pay more for a different name plate on a car, I am not saying the ctsv is the same as the vette, far from it, but the point is that w/ the cutting edge design of the sigma cars they deserve both power and prestige under the hood and the ls6 only provides 1/2 of that requirement, I leave wich half for others to decide.

Aurora40
11-09-04, 09:27 PM
First of all I made a special exception of the aurora, an excellent car. second the ls6 (pretty much a bigger ls1) is a GM motor developed at the corperate level like the current 4cyl and 6cyl engines, there is nothing to set it apart from the corvette engine other than a cadillac emblem on the cover. Now I consider a fleet engine to be any engine that was developed to be put into many cars (coockie cutter cars) and make no mistake this is a dangerous trend and was a big complaint w/ olds vs chevy, no one wants to pay more for a different name plate on a car, I am not saying the ctsv is the same as the vette, far from it, but the point is that w/ the cutting edge design of the sigma cars they deserve both power and prestige under the hood and the ls6 only provides 1/2 of that requirement, I leave wich half for others to decide.

I didn't actually say anything about Auroras. ;)

And the Premium V8 is developed at the same corporate level in that it's developed by GM Powertrain. And the FWD Northstar has appeared in Pontiacs and Oldsmobiles, albeit not nearly at the same level as the smallblock is in other applications.

I do think the LS6 is different in manufacture and design from a typical truck smallblock, though (and it's the same displacement as the LS1). And I would bet it's substantially different in price as well. I guess I think it's fairly prestigious in the fact that I'd like to have a car powered by one. :)

I guess what I mean is I find an LS6 powered CTS-V a lot more alluring than if it were a 320-350hp CTS-V with a Northstar. A blown NS would bring mixed feelings as I don't associate blowers with smooth alluring powertrains, though they sure can make some boost. For some odd reason, twin turbos doesn't have the stigma I associate with blowers, but that's most likely just me being weird.

ellives
11-09-04, 09:44 PM
I didn't actually say anything about Auroras. ;)

And the Premium V8 is developed at the same corporate level in that it's developed by GM Powertrain. And the FWD Northstar has appeared in Pontiacs and Oldsmobiles, albeit not nearly at the same level as the smallblock is in other applications.

I do think the LS6 is different in manufacture and design from a typical truck smallblock, though (and it's the same displacement as the LS1). And I would bet it's substantially different in price as well. I guess I think it's fairly prestigious in the fact that I'd like to have a car powered by one. :)

I guess what I mean is I find an LS6 powered CTS-V a lot more alluring than if it were a 320-350hp CTS-V with a Northstar. A blown NS would bring mixed feelings as I don't associate blowers with smooth alluring powertrains, though they sure can make some boost. For some odd reason, twin turbos doesn't have the stigma I associate with blowers, but that's most likely just me being weird.

This is ANOTHER annoying issue! Did everyone catch the fact the N* is available in the Pontiac Bonneville? I don't mean the poor step sister in the Aurora. I mean the actual 4.6 liter N*. Why have I not seen this fact advertised?

When I was at the car show Sunday there was a Pontiac Montana on display with a sign next to it with a quote something like "the popular Montana." I watched as somebody walked up to it and said "what's this? I never heard of these before." There shouldn't be a person in this country that doesn't know what a Pontiac Montana is. (I'm not a big fan of this particular vehicle since owning my 2000 Olds Silhouette. The 3.4L engine is simply too underpowered for these size of that vehicle. ) But the point remains the same. Let's get the marketing team in gear!

Msilva954
11-09-04, 09:49 PM
BBOB is the northstar a modular engine????

For some reason I always assumed the N* was a modular engine much like the Ford 4.6....id assume if more NA power was attainable or wanted (which it always is) then the next step would be something along the lines of a 5.2-5.6 liter V8 or even a V10 of some size.........

I would love to see a 5.4 liter DoD Northstar...making around 400hp......then there would be no need for a 10 or even 12 Cylinder engine.

BeelzeBob
11-09-04, 10:40 PM
What exactly is a "modular engine".....???

Besides being a marketing name that Ford used on one of their engine families it really doesn't mean a whole lot to engine designers.... I know that Ford would have every one believe that the engine can be made in a variety of configurations but that really isn't the case..... That particular engine is about as "modular" as a "hemi" is a real hemi.....LOL LOL


Designing, developing, certifying and validating an engine costs a huge amount of money.....and that is the cheap part of the process. Buying the tooling to machine all the parts and the equipment to assemble it and the plant to build it in and the staff to man the plant...etc..can cost billions. It is hard to justify the cost of developing a specific engine for each vehicle and each marketing division....i.e...Cadillac engines and Chevrolet engines, etc.. It is impossible to cover the costs incurred for specific engines for the volumes of the specific vehicles so it is absolutely necessary to share the cost of an engine across several vehicle lines.

The important thing is to look at the vehicle and match the characteristics of the vehicle with the correct type of powerplant. Each manufacturer has a porfolio of engines and powertrains to chose from and to modify each of the engines so that it matches the character and performance requirements of the various vehicles. I think GM does a good job of matching the correct engine to the correct vehicles and providing excellent levels of performance and fuel economy for a reasonable amount of money.

One of the other posts on another part of the forum talked about overhead cam and pushrod engines quite a bit and the discussion relates to this topic also. There is a tremendous advantage in many areas to pushrod engines like the Gen3 small block chevy that is used in the CTS-V. The biggest advantage, that is seldom recognized, is the wide variety of displacements that can be achieved from a single pushrod engine. A current small block GM V8 engine, for example, could be manufactured in displacements from 4.8 liters to 7 liters using the same basic design architecture. A DOHC engine like the Northstar is restricted to a very small displacement range...the Northstar is producable in a range from 4.0 to 4.6 liters. That is all. This is because of two things that are inescapable in engine design. A DOHC engine must have large cylinder heads to house the cams and valve gear and it must have a fairly complicated/complex cam drive system that takes up lots of room in the length of the engine.

Because of the necessary large heads every effort is made in designing the lower end of the engine to make it as compact as possible. The deck surface of the engine is necessarily very low. If you look at the short block of a Northstar it is pretty small and the lower end is very compact. There is no room in the lower end for additional stroke as the piston pin already comes very close to the crank counterweights. And there is no room to increase the deck height without the cylinder heads rising up too tall. Also, length wise, there is no additional room for larger bores as the bores are squeezed as tight together as possible to allow room in the engine length to house the cam drive.

A pushrod engine has very small cylinder heads and a simple timing drive that can tuck into the front V of the engine. As a result, an engine like the LS1 can be designed with a deck surface that is artificially "high", the lower end does not have to be squeezed so tight and the cylinder bores can be spread farther apart. This leaves a tremendous amount of flexibility in the engine design to juggle displacements using the same basic component architecture.

The current GM small block is probably the closest thing to a "modular" engine on the market given the wide variety of displacements and engine characters produced.

Keep in mind that an engine is an air pump. The more air the pump can move thru it the more fuel it can burn and the more power it can make. HP and torque is all about displacment. You cannot beat cubic inches. So...if you are designing a family of engines for a variety of vehicles the biggest tool you can have in your "tool box" to give each application the correct character is a large range of displacements from the same engine family....i.e...the Gen3/LS1 small block type of engine.

Don't get the idea that all the Gen3 engines are the "same". There are huge component differences between truck versions of the engines and the LS6. Cast iron blocks vs. all aluminum construction is the most obvious. There are many many different camshaft designs for the different engines to give them the torque/HP characteristics required. Cylinder head ports, combustion chambers etc... all have to be tailored to the specific application and displacement for the engine to be as efficient as possible.

The key is to have that engine family modeled, developed and understood so that when specific parts are needed for some character of vehicle applicttion the design/development group can act very quickly and work around known technology and parts to develop the specific ones needed. There is no need, for example, to redevelop the oil pan gasket each time the pan is changed for a different chassis or application... This allows the design team to focus on the specific items that really need work and not re-do something simple over and over.

Another area where the pushrod type of engine has a huge advantage is the relative ease that technology like displacement on demand can be incorporated. It is far far easier to put the DOD hardware on a pushrod/cam-in-block engine than on a DOHC engine. This provides tremendous flexility to gain fuel economy and provide the correct power levels for each vehicle application and duty cycle while maximizing the fuel economy potential of the vehicle. A vehicle like a heavy duty pickup that is set up to tow 10,000 pounds needs lots of torque/displacement to be able to handle that load yet when empty the truck can operate on much less displacment and optimize fuel economy.

DOHC engines are high on the "cool" factor and I like them but the pushrod engines really give them a run for the money. About the only advantage that can be touted for the DOHC engines is the ability to run variable valve timing on both the intake and exhaust cams separately. A pushrod/cam-in-block engine benefits from cam timing changing also but not to the extent that a DOHC engine does. The DOHC arrangement allows separte control of intake and exhaust valve timing as well as valve event overlap. This lets the designer have excellent torque AND HP characteristics as well as control exhuast emissions and have good solid idle quality. The single cam pushrod engines are definitely not as good at this.

Time will tell but once the media worship of the "high tech" overhead cam engines starts to wane I suspect that pushrod engines will once again be just as "cool". When you can put a 400+ HP V8 into a car like the CTS-V and have it perform as well as it does people will, sooner or later, start to question the need for all the extra parts, cost, complexity and lack of flexibility with the DOHC arrangement. I know that BMW and such would have you believe that DOHC is the only way to go but let me tell you that pushrod engines are knocking on the door in terms of performance of the best DOHC engines for far less money and in a far smaller package.

Too bad the public are not all engineers or pushrod engines would be an easy sell.

Any and all of this could be debated forever. I tried to put Engine 101 into several paragraphs....each of which deserves a book into itself so don't take things too much out of context here to pick nits....LOL

SHERIFF
11-09-04, 11:30 PM
I think GM does a good job of matching the correct engine to the correct vehicles and providing excellent levels of performance and fuel economy for a reasonable amount of money.


Not to dispute what you say.... but can you explain why Cadillac would choose to put a 275 and 300 horsepower V-8 Northstar in the Cadillac Devilles? They certainly knew the majority of the Deville drivers would be senior citizens who would never keep them dusted out and performing up to par.

Don't get me wrong, I enjoy my DTS and I enjoy the 300 horsepower. I just wonder what Cadillac was thinking when they put such a powerful sophisticated engine in a Grandpa mobile. :)

(Hope I didn't offend anybody. But 99.5% of the people driving Devilles where I live have gray hair and are on the way to the bank to deposit their Social Security checks. A 72-year-old man owned the DTS I bought.)

JimD
11-10-04, 12:46 AM
....

It is impossible to cover the costs incurred for specific engines for the volumes of the specific vehicles so it is absolutely necessary to share the cost of an engine across several vehicle lines....

....Too bad the public are not all engineers or pushrod engines would be an easy sell.

Any and all of this could be debated forever. I tried to put Engine 101 into several paragraphs....each of which deserves a book into itself so don't take things too much out of context here to pick nits....LOL

I don't nitpick intentionally (it's only one of my basic character flaws).

But it sounds like maybe the GM Headshed spent the bucks to put the DOHC 3.6L (LY7) engine in play without consulting the pushrods-forever powerplant engineering group. DOD is easier / less expensive with pushrods, right?

For as long as CAFE is the law of the land, the consumer will be offered only a "torque / fuel economy / emissions" compromise for street-legal wheels. But don't get me started on automobiles / powerplants designed by politicians....

CadiJeff
11-10-04, 04:39 AM
I didn't actually say anything about Auroras. ;)
It wasn't you that the comment was directed at.

As good as the lsx series of engine are I am just tired of hearing people say that Cadillac is incapable of a 350+ hp engine and it needs the engine from another branch to get there, and I know plenty of people that think this.

I have no problem w/ pontiac using the northstar in fact I think it it well overdue as the nearest competitive offer w/in gm is the 3800II S/C v6.

I also have no problems w/ OHV pushrod engines and think that they are excellent powerplants.

Ijust believe that if cadillac wants to revive it's King of the mountian then they should be producing their own engines, to me it says very little for cadillac to make an excellent, unique vehicle and put an engine in it that is available in a chevy, as I stated above there are people I know that think cadillac is a joke because of this very fact.

JSMeloche
11-10-04, 09:52 AM
Not to dispute what you say.... but can you explain why Cadillac would choose to put a 275 and 300 horsepower V-8 Northstar in the Cadillac Devilles? They certainly knew the majority of the Deville drivers would be senior citizens who would never keep them dusted out and performing up to par.

Don't get me wrong, I enjoy my DTS and I enjoy the 300 horsepower. I just wonder what Cadillac was thinking when they put such a powerful sophisticated engine in a Grandpa mobile. :)

(Hope I didn't offend anybody. But 99.5% of the people driving Devilles where I live have gray hair and are on the way to the bank to deposit their Social Security checks. A 72-year-old man owned the DTS I bought.)

My guess is the N* is a prestige engine and a Caddy needs a prestige engine. A caddy needs to move!!! If youve ever driven a 4.1 L v8 powered Fleetwood (125hp for a 4000+ pound car) you know you need some HP to move a big boat lol
The N* was the beginning of putting Cadillac back on the right track after scaring away a lot of customers in the 80' with underpowered car with complicated and often unreliable electronics. Ex: early variable displacement engine V8-6-4, 4.1 underpowered car, etc...

Msilva954
11-10-04, 10:04 PM
"Northstar is producable in a range from 4.0 to 4.6 liters. That is all. This is because of two things that are inescapable in engine design."

BBOB, was the N* developed from the begining as a 4.6l or a 4.0??.....just wanna know if it was designed from the top down or viseversa.

BeelzeBob
11-10-04, 10:39 PM
Not to dispute what you say.... but can you explain why Cadillac would choose to put a 275 and 300 horsepower V-8 Northstar in the Cadillac Devilles? They certainly knew the majority of the Deville drivers would be senior citizens who would never keep them dusted out and performing up to par.

Don't get me wrong, I enjoy my DTS and I enjoy the 300 horsepower. I just wonder what Cadillac was thinking when they put such a powerful sophisticated engine in a Grandpa mobile. :)

(Hope I didn't offend anybody. But 99.5% of the people driving Devilles where I live have gray hair and are on the way to the bank to deposit their Social Security checks. A 72-year-old man owned the DTS I bought.)


This proves that you cannot satisfy the customers....half of them bitch that the car is too slow and the other half bitch that the car is too fast...LOL LOL


Seriously, the engine was sized for small displacement to maximize fuel economy and the specific output target was high to provide the performance people expected of a Cadillac. Cadillacs had typically been know as very powerful cars and Cadillac took a great deal of flack over the relatively poor performance of the 4.1 liter pushrod engines. Even though the engine delivered excellent fuel economy and had "adequate" performance for most people for toddling around it was obviously not up to Cadillac standards in the eye of the customer. The performance levels of the 4.5 and 4.9 were much closer to the expectations of the customer and the Northstar's aim was to exceed that. Based on the earlier performance complaints it was expected that more people would "use" the Northstar engine than apparently do.......

BeelzeBob
11-10-04, 11:08 PM
I don't nitpick intentionally (it's only one of my basic character flaws).

But it sounds like maybe the GM Headshed spent the bucks to put the DOHC 3.6L (LY7) engine in play without consulting the pushrods-forever powerplant engineering group. DOD is easier / less expensive with pushrods, right?

For as long as CAFE is the law of the land, the consumer will be offered only a "torque / fuel economy / emissions" compromise for street-legal wheels. But don't get me started on automobiles / powerplants designed by politicians....


The 3.6 is a very high tech, high output engine. It is less probable to put DOD on smaller engines as they cannot operate for very long or very far on lesser numbers of cylinders and it is much more difficult to DOD a V6 as it will run very roughly on 3 cylinders or 4 cylinders. On 3 cylinders a 3.6 liter engine in DOD mode (operating on the equivalent of 3 cylinders or 1.8 liters) would not have enough torque to stay in DOD mode for very long so it's usefullness would be very limited and not something to go after. So...for a smaller displacement V6 for that market the specific output and high tech image of the DOHC design do make some sense......

Just like the Vortec inline 6 with DOHC for the smaller trucks (and it's "modular" brother the inline 5 cylinder for the Colorado/Canyon trucks) makes a lot of sense due to the packaging advantage of an inline engine, lesser maching costs of one deck surface on the block and only one cylinder head makes a lot of sense for that application. There is sufficient volume for that line of vehicles to justify an "application specific" type engine. The VVT on the exhaust cam of those engines helps torque and idle quality and allows emission control of engine out emissions without an EGR valve or external EGR nor a supplemental AIR pump. With manueverability being a prime consideration of the light trucks the inline engine family allows a very narrow engine bay thus allowing the front wheels to turn sharply allowing very small turning radii. Plus....pushrod inline engines do not make as much sense as the cylinders are necessarily side by side (without the stagger between the banks of cylinders in a V engine)thus there is no room for the cam drive to "hide" in and putting the cam beside the engine makes it wider..which is why you wanted an inline engine for that application...to get a narrow engine. Cam-in-block pushrod engines work well for packaging when they are in a V so that the cam can package between the banks in the V and thus service both banks of cylinders. With an inline engine the cam has to be as long as the bank of cylinders are so putting it on top actually makes sense as it has to go somewhere and it is just as easy to put it there.


Whether it is a written law like CAFE or just high fuel prices (Europe) ALL engines are designed as a compromise between power/fuel economy/emissions. There are no exceptions. For instance, in Europe, the engines were/are heavily taxed above 2 liters so smaller engines prevailed. The drivers still wanted to go as fast on the autobahn so high engine speeds were the only answer. High engine speeds naturally mandated overhead valve trains that were more stabile/stiffer/lighter and could easily be made to endure the continuous high operating speeds of European use. So....the overhead cam "movement" was primarily a result of European tax laws influencing engine design.

With the development of improved friction reduction techniques (such as roller cam followers), DOD, pumping loss improvements/reductions via EGR and cam phasing control, etc... the idea of larger displacement/slower turning engines for maximum fuel economy while maintaining the performance capability desired is coming back into vogue for many vehicles. With that type of engine pushrod valve trains make a lot of sense.

It is NOT a "pushrod forever" mentality, believe me. It is simple engineering logic. The idea is to determine the smallest/lightest/most cost effective/most efficient/etc. device that will do the job required. "Pushrod" or cam-in-block engines can do the best job in many situations.

Not to side line the discussion but a somewhat esoteric point about multivalve engines is that they are not always the best thing in the world for engine out HC emissions. Since the spark plug is in the middle of the chamber in between the valves the multivalve engines are pretty much the "hemi" that seems so desireable. The disadvantage of this is that when the combustion starts the initial pressure rise in the chamber due to the onset of combustion forces unburned HC into the crevice volume around the perimter of the piston (between the piston and the cylinder wall and above the top ring). This is the major source of unburned HC emissions from the engine as those HC trapped in the crevice volume escape during the exhaust stroke. With two valve/pushrod engines the spark plug is usually located more to one side of the chamber in a typical "wedge" arrangement. This causes the chamber to burn assymetrically which is good in that part of the chamber where the plug is close to the cylinder wall burns before the pressure rise is great so that a portion of the end gas forced into the crevice is already burned material that is basically inert. This can casue up to a 30% reduction in engine out HC with a two valve engine. Surprised..??? Thought those high tech 4 valve engines were the greatest thing since sliced bread for emissions, eh...???? I say this is esoteric because the catalyst is capable of sufficient cleanup and is responsible for the majority of the unburned HC cleanup anyway so it kind of doesn't matter....but it is a fact and flys in the face of what most people believe.

BeelzeBob
11-10-04, 11:14 PM
Ijust believe that if cadillac wants to revive it's King of the mountian then they should be producing their own engines, to me it says very little for cadillac to make an excellent, unique vehicle and put an engine in it that is available in a chevy, as I stated above there are people I know that think cadillac is a joke because of this very fact.


Cadillac used to just produce large cars......

Today Cadillac has a very very broad product line that runs from the CTS to the Deville to trucks like the Escalade line. There is no single engine that is going to meet the requirements of all those vehicles. And it is not possible to develop specific engines for each product line within Cadillac. It makes perfect sense to utilize the entire portfolio of GM Powertrain engines and pick the best of each engine for the Cadillacs. There are some special features added to the Cadillac engines that they "share" with other platforms. It also makes sense for Cadillac to leverage the use of the Northstar in other platforms (like the Aurora and the GXP Bonneville) to maintain sufficient volume on the Northstar engine line to keep the costs within reason.

Back many years ago it was common for hotrodders to go after Cadillac engines as they were the most powerful. Slowly that trend may be returning......

BeelzeBob
11-10-04, 11:27 PM
"Northstar is producable in a range from 4.0 to 4.6 liters. That is all. This is because of two things that are inescapable in engine design."

BBOB, was the N* developed from the begining as a 4.6l or a 4.0??.....just wanna know if it was designed from the top down or viseversa.

Neither....it was designed as several different displacements at the same time. The original layout work for any engine will always take into account the complete range of displacements anticipated. The use of the Premium V engine in the Cadillacs and in the Aurora was part of the game plan from the very beginning so the basic engine parts were designed for both displacements from the very onset of the design. Admittedly, most all the testing and development took place with the 4.6 liter parts, however, since this was the most highly stressed situation. In fact, most all the development and validation took place on the 300 HP L37 as it puts the greatest stress on the parts. If the engine lives at 300 HP as a 4.6 then is it a far easier job to make it work as a 250 HP 4.0......... Plus the fact that the Northstar debued as a 4.6 in the Cadillacs in the 1993 model year and the 4.0 didn't start production until the 1995 model year meant that the final development and validation of the 4.0 varient followed the 4.6. But the design was there from the beginning.

Interesting tidbit is that the forged powdered metal con rods with the cracked caps were included as part of the Northstar design "reach" from the early development of the engine components. The technology of the powdered metal rods was just not mature enough however to include them in the 1993 version so the forged rods were developed as an interim step for 1993/94. The powdered metal rod development and testing progressed toward implementation in the 1995 model year...concurrent with the 4.0. If you put the powdered metal con rod down the cylinder bore of a 4.0 you will see that there is very little room to slip the big end of the rod thru the bore to stuff the pistons. The basic bore dimension of the 4.0 was limited by the big end of the powdered metal rod size....that is why it would be very inconvenient to make the engine smaller than a 4.0. The bore can not get any smaller due to the rod size (unless a completely different rod and bearing diameter and crank were developed) and making the stroke less would make the engine a very space "in-efficient" sub-4.0 engine due to the now-excessive deck height. It could be done but the engine would be somewhat ill fitting. So that is why I said that it is limited at 4.0 for the lower end of the displacement range.

CadiJeff
11-11-04, 12:30 AM
Bbob you deserve a beer just for all that typing :worship: , and a bonus from gm for PR work on this site :thumbsup:

SHERIFF
11-11-04, 11:44 AM
Seriously, the engine was sized for small displacement to maximize fuel economy and the specific output target was high to provide the performance people expected of a Cadillac..... Based on the earlier performance complaints it was expected that more people would "use" the Northstar engine than apparently do.......

That pretty much answers the question. While my father owned a brand new Cadillac every year until his untimely passing at the age of 64, I never drove any of them very much and was not really familiar with the "lack of power" (I always had Corvettes, Trans Ams and IROC-Zs at my disposal, why would I want to drive his Cadillacs :D ). My mother still currently has the last new Cadillac my father bought, a 1988 Coupe Devile FWD, 4.5 V-8, and to me it seems to have plenty of power. But it's a smaller car than the current Devilles too of course. Such a shame for a car to go to waste, I don't think it has over 33,000 miles on it right now (last time I looked). Even worse, the car simply isn't worth anything now because of it's age. If the Northstar in my DTS goes south, maybe I can transplant the 4.5 V-8 in my car. Probably not though. :)

ellives
11-11-04, 12:07 PM
That pretty much answers the question. While my father owned a brand new Cadillac every year until his untimely passing at the age of 64, I never drove any of them very much and was not really familiar with the "lack of power" (I always had Corvettes, Trans Ams and IROC-Zs at my disposal, why would I want to drive his Cadillacs :D ). My mother still currently has the last new Cadillac my father bought, a 1988 Coupe Devile FWD, 4.5 V-8, and to me it seems to have plenty of power. But it's a smaller car than the current Devilles too of course. Such a shame for a car to go to waste, I don't think it has over 33,000 miles on it right now (last time I looked). Even worse, the car simply isn't worth anything now because of it's age. If the Northstar in my DTS goes south, maybe I can transplant the 4.5 V-8 in my car. Probably not though. :)

Funny you talk about the size of the current De Ville. My son recently started to taking a liking to those (the DTS particularly) over the STS... I always found it curious that people would complain about full sized Cadillacs being a "boat" and they'd never drive one when those same people would happily run out and buy an SUV! It's "herd mentality" at it's best. To me the only real benefit (that I do appreciate) is the AWD/4WD in an SUV. Now that Cadillac (and GM in general) has dipped it's toe into the AWD space (Yeeeah!) there's really no reason to consider an SUV unless you really need the overall space and towing capacity.

SHERIFF
11-11-04, 03:40 PM
Funny you talk about the size of the current De Ville. .....there's really no reason to consider an SUV unless you really need the overall space and towing capacity.
The party might be over for the Deville, DHS and DTS though. There's rumor the Deville line is going to downsized into a rear wheel drive 2005 STS clone soon. Why even have CTS, STS and Deville lines if they are all going to look identical? I hope the rumor doesn't pan out though. :)

CadiJeff
11-12-04, 03:10 AM
I second that, I hated that in the mid 90's when chevy did that