small block generations

[LMN8R]

What are the different generations of small block Chevy engines? The LS-1, most places, is referred to as a Generation IV, but I count 3:

1. The original one used in vettes up until '91
2. The LT-1/LT-4
3. The LS-1/LS-6

Is the other one the LT-5?

They're killing me.

 

[Rob]

The LT1/LT4 is known as the Gen II Small Block

The LS1/LS6 is known as the Gen III Small Block

The LT1/LT4 engine was redesigned in comparison to the L98 engine. If I'm not mistaken, it was drastically redesigned. The LS1/LS6 was drastically redesigned in comparison to the LT1/LT4 small block engine.

The LT5 is it's own separate engine and shares nothing in common with the Gen II or Gen III small blocks other than bore spacing and I believe, a rear main seal. That's it.

 

[LMN8R]

That's what I thought...

Thanks, Rob. That has been my understanding for some time. Unfortunately for me and my obsessive/compulsive tendencies, some people talk about the LS-X engines being fourth generations. Glad to hear that that is not the case. Protects my sanity for another day or so...

-Greg

 

[Rob]

According to retired Corvette Chief Engineer, Dave McLellan, in his book....that is not the case.

 

[LMN8R]

Well, okay then.

Yeah, I read the brief exerpt of the book available previously in the forums. I'm gonna buy the book. Seems pretty cool, and it is consistent with what we've been talking about.

Ahhh.

 

[Edmond]

What exactly classifies an engine as a small block?

I know the 350 is a small block, but I read some magazine articles about a 427 small block these days. I thought the 427's and 454's were big blocks.

Someone help me out here.

 

[RalleyRed]

The 427 sb, is just a 350 punched out to 427ci

Same as the 454 being punched out to 468ci

I'm not positive how they do it, but I suspect boring and stoking.

I'm sure someone will be along shortly to tell us exactly how it's done.

Rick

 

[LMN8R]

Yeah, they use a new crank and bore it out. Most commonly, it seems to me, this is done by Lingenfelter. Just looking around at their site casually, it doesn't say what they use for cylinder liners, etc. I'd bet doing this kind of work on an aluminum block is a nighmare.

The Corvette site by Chevrolet shows a comparison between the C5R and the LS-X engine, and they are using the exact same block for 427 CID as well.

Kind of a shame we're still at 345.

Does the 'Vette share the block with any of the GM trucks, H2, etc?

-Greg

 

[Edmond]

So GM could probably quite easily punch that 350 out to 427 huh? And why don't they offer that as a RPO?

I know they'd have to beef up the rest of the car to handle the extra power, but people would pay. Instead, people are paying Lingenfelter, Mallet, etc... to do something that GM could be doing...

 

[LMN8R]

Yeah, and a couple of other things come to mind for feeble reasons that GM won't crank out the good stuff:

1. Liability
2. The Lingenfelter cars, etc, even when tested by C&D had to be MUCH more expensive in order to have significant advantages over the Z06. Some of the competitor's cars in the issue were tens of thousands of dollars more expensive than the vettes, but only marginally faster.
3. Longevity: I hear the cylinder walls in the new SB 427 are paper thin. Combine that with high compression, turbo/supercharger, and presumably a different cooling system and I'm not sure how long the engine is going to last. Certainly not as long as the current 350.
4. Least importantly (and to me, not at all important): fuel efficiency.

The majority of these, as I said, are feeble reasons not to make an explosive vette in my mind. One of the problems is they're trying to make a specialty car for the masses, and the masses, on so many levels, love the current car. You and I are in complete agreement, however, and I really do wish they'd make it an RPO. Charge $25,000 for the option if they want to. Make it a principle thing to shred the competition.

Oh, well.

 

[Edmond]

Hey, they did it with the ZR1 in some of those respects. Sure, it was still a 350, but it had much more power than the L98 and LT1 engines that were offered at the time.

Even if they threw a supercharger in there, Lingenfelter does it for:

$8399 for the supercharger, new hood for clearance and installation.

$395 for a LPE high flow intake system.

I got those figures out of the April Car & Driver.

 

[LMN8R]

Yep. Again, we're in agreement. Maybe they're just stubborn.