[dgarrett]

Alot of people are saying the 93 - 99 year N* are better than the 2000 to 2004 engines, why is this? Simply basing it on the block, bottom end, and the top end/heads ( excluding the ignition and fuel injection) which is better for performace purposes?

Thanks!

 

[I~LUV~Caddys8792]

I hear they had a lot of kinks in the 93-94 motors...
But that's to be expected of anything in its first few years.

 

[jadcock]

Lots of differences in the engines...small, but differences nonetheless.

The 1993-1994 engines had a two-piece intake manifold and generated 270 hp and 295 hp for the LD8 and L37 versions respectively. I believe the 93-95 engines are also speed density controlled, but I could be wrong on that.

In 1996, they switched to a composite intake manifold that increased the horsepower to the common 275/300 that we reference today. The '96+ engines have MAF sensors. Sometime in the 1996 timeframe, they upgraded the seal at the case-half joint making that leak much more uncommon. In addition, sometime near the 1996 timeframe, they upgraded the valve springs on the LD8 engine. Historically, the L37 had stiffer valve springs, but sometime during 1996, Cadillac started using the L37 valve springs on both engines.

If I had my druthers, I believe I'd take a 2000+ design. It's optimized for regular fuel, and they lose the spark plug wires in favor of a coil-on-plug ignition system. But I can't say anything bad about my 1997 example. I haven't had a single engine problem with it...haven't even had to remove a cam cover. The only things that've been replaced are a A/C compressor bearing, an alternator, and water pump (and the plug wires after the fuel rail recall).

If you want to talk strict numbers, I believe 1995 is theoretically the "best" one...it has the upgraded composite intake manifold and doesn't have a MAF sensor that I recall...so in theory, it might make 1-2 hp over a 1996 or later engine due to SLIGHTLY less restriction in the intake from the MAF sensor. But in essence, all FWD Northstar engines use the same block and internals, performance-wise.

 

[dgarrett]

Thanks for the reply.

Do the 2000+ cylinder heads have bigger intake valves? I think they are around 1.43" OD. Also I think the ports are different too.

 

[jadcock]

The ports may have changed. The compression ratio is slightly lower on a 2000+ engine (10.0:1 vs. 10.3:1) to help accomodate the 87 octane fuel optimization. The combustion chamber is also slightly different...perhaps larger or a different shape. I don't know of a change in the valve sizes.

 

[dgarrett]

FYI... I purchased a shop manual for a 95 and it states the intake valve is 1.3" and the exhaust is 1.14". I measured on a 2002 head the intake to be 1.425 and the exhaust is 1.10". I have a 96 4.0L head and they are completely different than the 2002 4.6L head. The intake ports on the 2002 look far superior. I thought the only difference between the same vintage 4.0L and 4.6L heads was the valve size was slightly lager in the 4.6L but the castings were the same other wise.

I read some where (another internet take it for what is it worth source) that the 2004 engine, which dimensionally is the same as a 2001, puts out 320 hp. Does any one know what the true HP ratings of these engines are?

Darrin

 

[JSMeloche]

FYI... I purchased a shop manual for a 95 and it states the intake valve is 1.3" and the exhaust is 1.14". I measured on a 2002 head the intake to be 1.425 and the exhaust is 1.10". I have a 96 4.0L head and they are completely different than the 2002 4.6L head. The intake ports on the 2002 look far superior. I thought the only difference between the same vintage 4.0L and 4.6L heads was the valve size was slightly lager in the 4.6L but the castings were the same other wise.

I read some where (another internet take it for what is it worth source) that the 2004 engine, which dimensionally is the same as a 2001, puts out 320 hp. Does any one know what the true HP ratings of these engines are?

Darrin

2004 have VVT: Variable Valve Timing. I think the camshaft is dynamicaly adjusting to provide higher lift / duration during certain engine load. Its basically the same principle has the V-tec hondas but with less rice

 

[caddydaddy]

But only the RWD Northstars have VVT. The FWD Deville engines are still 275 or 300 HP.

 

[jadcock]

Also keep in mind that under the new SAE testing procedures, the L37 engine (which used to be marketed as 300 hp), really only puts out about 292 hp (at 6300 rpm). Torque has also "fallen" from 295 to 288 lb*ft (at 4500 rpm). The LD8, under the new SAE testing procedures, generates the same 275 hp (at 6000 rpm) and 295 lb*ft (at 4400 rpm).

Here's the PDF file from GM Powertrain:

http://media.gm.com/us/powertrain/en/product_services/Spec Sheets/Premium V/2006 PremiumV (LD8).pdf

It's correct that REAR WHEEL DRIVE version has VVT and 320 hp. The FWD engines are still (relatively) the same as they've always been.

 

[Tommy Deville]

as long as it runs who cares

 

[caddydaddy]

My weedwacker engine runs, but I could care less about that!

 

[MrEr1c]

i thought i read somewhere that the later n* engines (2000+ maybe?) had forged pistons or something in the engine that made it stronger...

EDIT:

ok i found on http://en.wikipedia.org/wiki/Cadillac_Northstar_engine that is says the northstar uses forged aluminum pistons but it does not specify which year(s).

 

[caddydaddy]

I think it was in 2003? that it used a forged crankshaft.