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67Sally
10-04-2005, 10:47 PM
Can someone tell me the basic difference from Gen I, Gen II, Gen III, and Gen IV.

W.

MarkM66
10-05-2005, 08:33 AM
I'll start it. Not sure how much you're wanting to know though.

Gen I was the first small block chevy. Cubic inch started at 265, and went to 400 though the years.

Gen II was the LT1 and LT4. No rear distributor. Not sure on all the cubic inch sizes. Not to be confused with the Gen I LT-1.

Gen III. Started as the LS1. And I'll stop there, not real knowlegable off hand. :D

Gen IV. ?

67Sally
10-05-2005, 08:46 PM
Thanks for the start Mark. The basics is all I am looking for right now.

And the questions continue..........
Is the the new ZO6 engine an LS-7? is it considered a Gen IV? Is there such a thing as a Gen IV?

W.

Musclerodz
10-05-2005, 11:13 PM
There is actually two versions of what you are calling Gen I. There is a 2 piece rear main seal block and a 1 piece rear main seal. In '88 they also went to roller camshaft setup.

Mike

sinned
10-05-2005, 11:37 PM
The new Z06 is an LS7 and is a gen IV as is the LS2.

MarkM66
10-06-2005, 10:57 AM
There is actually two versions of what you are calling Gen I. There is a 2 piece rear main seal block and a 1 piece rear main seal. In '88 they also went to roller camshaft setup.

Mike

Yep. I'm running a later model block in my Nova. If you want a roller, and a T56 it's the way to go.

67Sally
10-06-2005, 08:51 PM
Thanks for the infor guys. Some more basics please.

What makes the LS7 and LS2 different from the other the other LS engines.

I am assuming that there are LS1's, LS3's, LS4's, LS5's, LS6's.....are there? and is this what people are talking about when they say LSx?

Thanks,
W.

Musclerodz
10-06-2005, 10:23 PM
LS2 is very similiar to LS1, the LS7 is kind of a breed of its own. LSx refers to any of the LS based engines including truck engines starting from 99 and up with the 5.3 and 6.0 engines.

Mike

Musclerodz
10-06-2005, 10:25 PM
Oh and I forgot to mention that when talking LSx motors, it does not refer to the older LS5, LS6, and LS7 big block motors, only the new ones.

Mike

sinned
10-06-2005, 10:40 PM
Actually "all" of the other LS engines are not LS engines, they just get that nomenclature as it easily understood as genIII engines. The only LS engines are the 5.7 LS1, the 5.7 LS2, and the Z06 LS7. "All" the other genIII engines (the 4.8, 5.3, iron 5.7, and the 6.0) are just genIII engines.

The LS2 is very similar to the LS1, some head modifications and oiling issues resolved but the LS7 is a truly unique piece of automotive genius, do a google on Z06/LS7.
__________________

Stuart Adams
10-07-2005, 09:29 AM
Wow, can they (GM) make it any more confusing.... :willy:

67Sally
10-07-2005, 09:34 PM
Wow, can they (GM) make it any more confusing.... :willy:

:yes: That's why I need help.......all I know about is the FE and the mod motors (and not very much).
W.

sinned
10-07-2005, 10:49 PM
Wow, can they (GM) make it any more confusing.... :willy:
Actually, we as enthusiasts make it complicated. GM has no problem differentiating between them. Every engine has a very specific code assigned to it and in the everyday world those are the acronyms used to describe what engine we are working on. In the after market world and on the Internet/magazines is where the confusion comes in.

Diognes56
10-11-2005, 06:17 PM
Some good info on GenI vs LT1/LT4 vs LS1: http://www.hpsalvage.com/lt1.htm

Great article on GenIII LS1 vs GenIV LS2: Popular Hot Rodding (http://www.popularhotrodding.com/enginemasters/articles/chevrolet/smallblock/0405em_ls2/index.html)

Another III vs IV: Hotrod (http://www.hotrod.com/techarticles/engine/113_0503_ls2/index.html)

Another III vs IV: Car Craft (http://www.carcraft.com/techarticles/116_0609_ls1/)

David

Diognes56
10-11-2005, 06:50 PM
Also interesting (http://smallblock.gmblogs.com/pdfs/Americas_Favorite_Engines_sm.pdf) : shows the original 265 smallblock against the LS2.

From article Zero to 90 Million in 50 Years Flat! (http://smallblock.gmblogs.com/archives/2004/10/zero_to_90_mill_1.html) (though edited for length)

Since 1955, General Motors has produced about 90 million small-block -based engines for passenger car, light truck, marine, industrial, crate and racing applications. If you laid all 90 million small-blocks end-to-end, you’d have over 30,000 miles of potent V-8 at your disposal.

Here are some critical milestones in the history of the GM small-block:

1955: Small-block V-8 introduced in 1955 Chevrolets.

1957: Larger bore increased displacement to 283 cubic inches; Ramjet mechanical fuel injection was introduced, bringing horsepower to 283 – one horsepower for every cubic inch.

1967: The 350 cubic inch engine debuts in the Camaro SS as a 295 horsepower version.

1970: 400-cubic-inch small-block is offered – the largest-displacement small-block built.

1982: Fuel injection reintroduced with the cross-fire injection system on Corvette and the redesigned Camaro Z28.

1985: Tuned port fuel injection replaces cross-fire injection, ushering in the modern era of electronically controlled, port-injected engines.

1986: block changed to accept new single-piece rear main seal.

1987: Hydraulic roller lifters introduced.

1989: The H.O. 350 “crate engine” is developed, offering a ready-built performance engine from the factory. It would revolutionize the way hot rodders approach engine building.

1992: LT1 engine in the Corvette introduces Gen II small block design, which features reverse-flow cooling, revised cylinder head design, and crank-triggered optical distributor.

1996: Vortec V-8 engines introduced in trucks, featuring cylinder heads with swirl-inducing combustion chamber design to increase power and torque.

1997: Gen III 5.7-liter LS1 small-block introduced with all-new Corvette, featuring all-new deep-skirt block casting with six-bolt mains; redesigned cylinder heads with symmetrical ports and combustion chambers; and coil-near-plug ignition system.

1999: Gen III-based Vortec V-8 engines introduced in GM trucks; displacements include 4.8 liters, 5.3 liters and 6.0 liters.

2005: Gen IV small-block introduced 50 years after the original.

Fifty years, four generations and over 90 million copies.