: Is this an LT5



Maxb49
07-13-08, 09:46 PM
I read that the Northstar V8 was developed from the Corvette ZR-1's LT5 engine. If this is true, shouldn't some LT5 parts be used to enhance the performance of the Northstar?

CadillacSTS42005
07-13-08, 09:49 PM
not even close
the LT5 was a modified LT1
Pushrod vs DOHC
Optispark vs Coil Packs/later COP

the list could go on for days but no they arent even 2nd cousins twice removed...

Ranger
07-13-08, 10:04 PM
The Northstar was developed as what our old Guru used to call "clean paper". It was not a modified anything, but was designed from scratch.

Maxb49
07-13-08, 10:25 PM
Where did they get this from?


The "Northstar" V8, as it was then known, was an evolution of the Lotus-designed Chevrolet LT5 all-aluminum DOHC 32-valve V8 used in the Corvette ZR-1. Archrival Ford Motor Company was developing a similar engine at that time as well, and Ford's Modular engine would precede the Northstar into production with its introduction on the 1991 Lincoln Town Car. Both continue in production at 4.6 L of displacement.

CadillacSTS42005
07-14-08, 08:49 AM
dude
you got your info from wikipedia
notoriously unreliable....

Submariner409
07-14-08, 09:20 AM
Yeah, I went through the same fantasy 4 years ago. Lordy, lordy, if it were only true.........and if you read the qualifier in the Wiki statement, it says "as it was then known......"

I~LUV~Caddys8792
07-14-08, 10:36 AM
The LT-1 was developed after the LT-5, so they share pretty much nothing in common, aside from the 5.7L displacement.

And yes, the LT-5 was the only Quad Cam, 32 Valve 350 ever built.

CadillacSTS42005
07-14-08, 11:25 AM
i though theres an LT1 kit to make the LT1 into an LT5?!?!?
or maybe it was an LT3?!?
im not a chevy expert...

Zorb750
07-14-08, 02:52 PM
LT1 and LT4 are the same, except that the LT4 shipped with a more accurate knock sensor (worth 4-5HP on LT1) and different heads (can retrofit onto LT1). Northstar and LT5 were designed at the same time and share many many similarities, such as the starter being on the top, the DOHC design, the cam and oil pump drive mechanisms are identical, the two piece lower crankcase are the same, cylinder wall construction is the same, and lots more.

I've heard from numerous GM people who were in on either project that the Northstar and LT5 share some common engineering work on their bottom ends, which makes sense since development was started at about the same time and ran largely concurrently), however Lotus designed most of the top end of the LT5, while GM did the Northstar's. I have heard from some GM Powertrain people what there was no involvement, but not from nearly as many as who said there was common work.

Also, it should be noted that the LT5 is not a "350" engine by any sense of the word. Its cylinder bore centers, cylinder block oil passages, bore/stroke, head bolt locations, etc, are all different form the GM 350 engines (of any flavor - Chevrolet, Buick, Olds, Pontiac...). Additionally, its displacement is not 350 cubic inches (I did the math and came up with 346).

stngh8r
07-15-08, 02:24 PM
not even close
the LT5 was a modified LT1
Pushrod vs DOHC
Optispark vs Coil Packs/later COP

the list could go on for days but no they arent even 2nd cousins twice removed...

I believe you may be thinking of the LT4.

The 32 Valve Northstar engine, shares much of its design with the 32 valve DOHC LT5 Corvette ZR1 engine.

CadillacSTS42005
07-15-08, 02:26 PM
maybe there are some bolt ons on it would could use then...

Maxb49
07-15-08, 05:12 PM
I believe you may be thinking of the LT4.

The 32 Valve Northstar engine, shares much of its design with the 32 valve DOHC LT5 Corvette ZR1 engine.

Wow, so it was developed with the LT5...hmm, wonder if the cylinder heads would match up?

I~LUV~Caddys8792
07-15-08, 05:49 PM
It was NOT developed with the LT5. The LT-5 was designed in part by Lotus and built by Mercury Marine, it debuted in 1989 for the '90 ZR-1. The Northstar was designed by GM in roughly the same time frame exclusively for Cadillac, and it was designed from scratch to be a DOHC engine.

Jason, you were probably thinking of the LT-4 Conversion Kit. The LT-4 is a pushrod engine like the LT-1, but it had better flowing heads, a more aggressive camshaft and a better flowing intake. It was used only in the 1996 Corvette GS and made an additional 30hp (330) over the LT-1.

Submariner409
07-15-08, 06:50 PM
If, just IF, the "cylinder heads would match up" what would that get you ? Not to mention cam chain drive arrangement, front cover arrangement, actual cams, compression ratios, piston/valve interference, water pump drive, intake manifold/injector siting, PCV adapters, ignition coil arrangement, fuel rail modification, knock sensor, cam sensor, emissions program alteration.........

Piece of cake.

NHRATA01
07-15-08, 10:34 PM
They weren't developed together, but be sure that the things GM engineers learned on the LT5 project, they applied to the Northstar design. Open-deck, DOHC V8. The intake system is nowhere near as complex on the Northstar, and the cam drive more traditional. I'm sure there's plenty of other differences (no way will the heads come close to swapping). Just like they again took the learning from the Northstar, and applied it to the LS1's development.