- 01-15-03 05:14 AM #16
I agree. I think there will be a V12 Cadillac very soon.. They want to compete with BMW so that will be important..
So Cadillac is tampering with displacement on demand again, eh? Cool.. Those 4-6-8's had a lot of problems, so I hear.. I bet a new version would be great nowadays...
- 01-15-03 11:01 PM #17
Displacement on demand
Let me say something about the "displacement on demand" engine.
I bought the 1981 Fleetwood BECAUSE of this feature. Back in the day it was called the V-864 and it was a technological marvel for its day. The engine would operate as a V8 at all times until cruising speeds were attained. As proper torques allowed, the valvetrain would shut the valves to 2 or 4 cylinders to save fuel.
I drove this car 330,000 miles without incident!!! Throughout this time I heard all sorts of bad press about this engine. The truth is that most people can not think for themselves... they will repeat any little thing they hear as fact. Somebody talked up Hondas and now there are millions of broken down Hondas on the road. The same people that bought those for the "great mileage" are now driving 12mpg SUV's... go figure... and don't even get me started about the minivans with the luggage on the roof
Anyway, even though the V864 was scrapped in favor of the HT4100 in 1982 (except in limos) the concept has been used in the Northstar engine for years now. This same technology is used to force open valves for air cooling of cylinders in the event of coolant loss.
The way that I am reading the current press is that the new V12 and V16 engine will run continuously on half of the cylinders and then activate the extra ones when called for.
- 01-16-03 12:21 AM #18
Thanks for the explanation.. This new idea sounds great.. So it wouldn't be so bad on gas.. Soughta like having turbo when you need it...
- 01-16-03 12:23 AM #19Cadillac Owners Connoisseur
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That's exactly what they're supposed to do, Yes there were some problems with the 8-6-4 but overall they worked. with new technology the concept will work better and be more trouble free. My brother had one of the old ones and had very good luck with it and bought a '90 DeVille based on his good luck with his 8-6-4. I'll admit some folks weren't as lucky with them but some folks don't have very good maintenance practices either!
- 01-16-03 12:43 AM #20
One of the things that I did to this car was to fabricate an override switch for the "variable displacement" system.
The system was programmed from the factory to only operate when the car was in high gear (3rd). This state was conveyed to the computer by means of a sensor mounted in the transmission. This was a simple 2 wire setup that supplied a ground signal when the transmission was in high gear. All I did was intercept one wire with a switch mounted on the dashboard. With this I could disable the system at any time forcing the engine to run on all 8 cylinders regardless of the situation.
I have to admit, it was a great thing to be staring at the fuel gauge on the interstate many miles from an exit and hit that sitch and watch the mileage sentinel jump from 20mpg to 32mpg instantly... whew!
- 01-16-03 08:19 AM #21
Nice modification!! I believe there should always be a switch like this on cars.. The switch would do just as yours did as well as changing the gear ratio and transmission shift points.
- 01-16-03 08:38 AM #22
Nice to see ya over here.
I gotta ask, if you REALLY liked the system, why put the switch in to disable it? And if you're running down the highway why would you have the system disabled?
Oh, about the comment you made about engines in '82 limos, back then most limos were built by coachbuilders even though the Caddy was still available. Unfortunately, most coachbuilders ended up stretching the base cars intead (cheaper) and they all had the HT4100. This unfortunately continued until the advent of the Cadillac Master Coachbuilder program which made it virtually impossible to stretch anything other than the commercial chassis cars.
- 01-16-03 09:37 AM #23Cadillac Owners Connoisseur
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Katshot said " Unfortunately, most coachbuilders ended up stretching the base cars intead (cheaper) and they all had the HT4100" And That's absolutly right! And I might add.....The 4100 was such a dismal failure that SOME Cadillac owners started defecting to other makes. If it got hot it was over, It had no power, It had lifter/cam Problems, It actually got to the point where Cadillac would replace the engine without a whimper (Even outside the regular warranty period) Mine (In my '85 Eldo) was replaced at 50,000 miles/ 5 years old without question due to a recurring overheating problem the they could never fix! It's too bad really 'cause my '85 was a wonderful car and I would probably still have it if not for all the engine problems!
- 01-16-03 01:11 PM #24
The main reason I hooked up the switch was for towing. Although with a full load the system rarely shut down cylinders, it would give a slight surge while coasting to a stop at the point where the transmission dropped down to 2nd gear. This created a somewhat unwelcome sensation with a 5000# trailer.
The only other thing that I would have changed is to leave out the 6 cylinder mode. Even though this was a transition mode, the unbalanced nature of it just gave me the mental willies It seems that Caddy is going this way now opting for a half # of cylinders shuttting down/starting up.
As for the limos, the only one that I have owned was a 1978 Fleetwood Formal which was factory built and came with the 425. That car had no shortage of power and could take a speed bump like nobodys business
- 01-17-03 09:43 AM #25
Yeah, you could call the 6cyl mode unbalanced alright!
We had Fleetwood formals for years and I loved 'em. It's a shame they dropped the rear radio/climate controls and the foot rests when they dropped those cars. Although I must admit, I hated working on them (rear controls).
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