: Why didn't Cadillac make a larger displacement Northstar?



coati
02-05-08, 02:31 AM
This may have been brought up somewhere in the forums but why is it that Cadillac never created a larger displacement version of the Northstar engine ie., 5.6L or greater after all these years?:confused:

I would definitely liked to have seen it.

Lord Cadillac
02-05-08, 02:38 AM
They were working on a new Northstar codenamed Ultra but it's been cancelled. There are some discussions in this forum about it...

coati
02-05-08, 02:45 AM
I didn't realize that the Ultra was a larger displacement Northstar.
It's a shame it was cancelled.:(

codewize
02-05-08, 09:52 AM
You know I never really thought about that. That would be cool wouldn't it. like a 400CID Northstar. Sweet

Lord Cadillac
02-05-08, 10:30 AM
I'm actually not quite sure the Ultra was larger.. It was the only other Northstar that I knew of, however.

Ranger
02-05-08, 06:09 PM
Displacement = fuel. With all the talk oil & gas prices, I would think they want as much power as they can get from small displacement while maintaining as high a fuel mileage as possible. The Northstar does that pretty well.

Edahall
02-05-08, 07:13 PM
The Northstar is already physically very large. I don't know how much larger they could go and still stuff it in a Cadillac engine bay. The 4.6 Northstar is already physically larger than a Chevy 350 5.7L push rod engine.

eldorado1
02-05-08, 07:40 PM
The Northstar is already physically very large. I don't know how much larger they could go and still stuff it in a Cadillac engine bay. The 4.6 Northstar is already physically larger than a Chevy 350 5.7L push rod engine.

The size difference is completely due to the DOHC heads. Compare a 4.0L and 4.6L northstar and you'll see no difference physically. The "ultra" UV8 base engine was supposed to be a 4.7L

But the short answer is they did - there was a rumor the UV8 would be pushed to 6.0L to compete with mercedes' latest. These engines (now scrapped) would have been 380hp(4.7L) to 550hp (6.0L) naturally aspirated. That's right - more HP than the supercharged northstar.

dkozloski
02-06-08, 02:35 AM
There is no way the bore size could be increased with the existing casting line and machine tools. The cylinders are already siamesed. The tooling could not be stretched to increase the bore center to center distance. It would require a complete engine and tooling redesign. A stroke increase is possible and the only alternative.

eldorado1
02-06-08, 06:07 PM
When the 3.4 TDC came out in 91, what they did was slap DOHC heads on a pushrod 3.4L V6 block. Had to install a dummy cam and geared distributor plug to drive the oil pump. (It was DIS, so no distributor to get in the way of the heads) I don't see why something similar could be done with a LSx block and redesigned N* heads.

Po Pimp
02-07-08, 12:40 AM
Dkozloski, hit the nail on the head.

AJxtcman
02-08-08, 12:20 AM
When the 3.4 TDC came out in 91, what they did was slap DOHC heads on a pushrod 3.4L V6 block. Had to install a dummy cam and geared distributor plug to drive the oil pump. (It was DIS, so no distributor to get in the way of the heads) I don't see why something similar could be done with a LSx block and redesigned N* heads.

The 3.4L X motor is not a 3.1L with DOHCs. Think about it please. HTF would you lube the over head cams? The block is a lot different. I guess it is still a 60 block.

Why would you want to use a LSX block?

AJxtcman
02-08-08, 12:31 AM
There is no way the bore size could be increased with the existing casting line and machine tools. The cylinders are already siamesed. The tooling could not be stretched to increase the bore center to center distance. It would require a complete engine and tooling redesign. A stroke increase is possible and the only alternative.
If you want to spend the money you can go out to a 4" bore.
YOU WILL NOT GET ANY MORE POWER FROM THE ENGINE!!!!

stoveguyy
02-09-08, 11:03 PM
they designed the NS back around 1990. It was destined for a FWD setup and i think GM figured 300hp was all the trans and platform could handle. remember the lexus ls400 was 4.0 too and now it has grown to 4.6L. its hard to find a OHC V8 in a sedan over 5 litres. i'm talking mercedes and bmw here, not a 1996 impala SS. that was the target for caddy back than. throwing a turbo or supercharger on a small displacement motor is a good way to have additional power on tap and still get good mileage. like the STS-V. the cts-v is old school cubic inches.

NHRATA01
02-10-08, 09:11 PM
The 3.4L X motor is not a 3.1L with DOHCs. Think about it please. HTF would you lube the over head cams? The block is a lot different. I guess it is still a 60 block.

Why would you want to use a LSX block?

The 3.4 is indeed a DOHC version of the 3.1. In fact, it even uses the original in-block cam to drive the 4 overhead cams via a cog'd belt.

Its kind of a sad story, that motor was slated to be offered in 275hp tune (which is what it made in the development stages) but hydramatic couldn't build a transmission to hold the power or handle the revs, so it was detuned to 210-215hp.

Destroyer
02-12-08, 09:46 PM
The Northstar is already physically very large. I don't know how much larger they could go and still stuff it in a Cadillac engine bay. The 4.6 Northstar is already physically larger than a Chevy 350 5.7L push rod engine.
Exterior dimensions have NOTHING to do with cubic inches. A 260 Chevy V8 and a Chevy 400 for instance are exactly the same physical size but different bores.

Ur7x
02-13-08, 02:38 PM
Exterior dimensions have NOTHING to do with cubic inches. A 260 Chevy V8 and a Chevy 400 for instance are exactly the same physical size but different bores.

I think you are missing his point. The N*s is pretty much maxed out in the bore department with siamese cylinders and all... To make a bigger bore you would need to change the bore spacing yielding an even longer block.

To go the other way.. more stroke The counter weights are already really close to the piston bottoms so you would need a "Tall deck" version... but the DOHC nature of this motor already make this motor "uber" tall. Hood lines etc make this motor already a tough package fit.

It was posted before, to consider this motor you have to go back to 1992. This motor was going into FWD cars ONLY... There were zero plans for new RWD cars at GM. And there is only so much room between the front wheels. As well the Allante, new Eldo and Seville had kinda low long hoods. A VERY nice design then and now... So the engine couldn't be too tall.

The final nail in the coffin... GM's FWD trannys have never been known for strength 300hp/300 ft-lb it about all you want to push through them.

So the 300 4.6 was a perfect balance of "fit" "power" and "effiency".