LT1 Engines
 

What makes an LT1 an LT1? I mean the LT1 has been out since around 1970 in various versions, so with all the different versions made what designates it as an LT1? Do a search on the LT1 an no site goes into detail as to why its called LT1.:mad: Its just frustrating.:mad2:

Guess it's what they decided to call it "again". I had Special edition "96 Vette with LT4, and regular vette's that year had LT1's...GM Recycles the names.

LT1 is just an RPO (Regular Production Option) code. GM is good at taking RPO codes and have their marketing team put the code to work. Z28, ZR2, Z71, etc. just to name a couple. None of the LT1s produced since its first use have any direct relations, other than the code itself. Each LT1 has been VERY different.

The first "LT1" was a Gen 1 small block 350. 11.0:1 compression, 4bbl carb and solid lifters. Things changed for 71 and 72 with a compression drop. Note, its the only LT1 that was marked with a hyphen between the LT and the 1 (LT-1).

The second "LT1" was a Gen 2 small block. 5.7 (350ci). Reverse flow cooling of the engine (head first then block), 2 or 4 bolt mains, Optispark distributor ignition, sequential fuel injection. 260-300hp. B body got iron block and heads, Camaro and Vette Aluminum heads, iron block.

The third "LT1" is a Gen 5 small block. 6.2 (376ci). Direct injection, 11.5:1 compression, VVT, AFM, wet and dry sump capability. 460-465hp. All aluminum construction. Six bolt mains.

All said and done, there are three things the three of them share in common. 4.400" bore centers, something all Chevy small blocks have had since 1955, cam in block pushrod valvetrain, and the LT1 designation.

Why call it LT1 again? Why not? Corvette got the Stingray designation because they felt it was the best design since the C2 and C3 Corvette, and worthy of the Stingray name. LT-1 was used in both Camaro and Corvette in 1970-1972. We now have LT4 and LT5 as well. A bunch of other codes have been recycled too. L99 was the Gen 5 Camaro SS A6 RPO code, and L99 was the code for the 4.3 LT1 based V8 and the 262 V8 from the late 70's. LS6 was revived from the 454 Chevelle to be used on 2000-2004 Corvette Z06. LS-3 was used on a 402 big block. L83, the 5.3 V8 in the trucks was used for the L83 Crossfire engine. LS9 was an old truck small block.

Nothing really "special" about the '96 LT4

In 1996
All Corvettes with the 6-speed manual transmission got the LT4
All Corvettes with the automatic transmission got the LT1

The LT4 was just a factory hopped up version.
Different heads, intake, roller rockers, and higher compression.

And as iPODFAN11 notes below, they were just RPO option code names, same as GM has always done.

Yep, GM has always reused option code name after enough years have passed.

The new ZR1 Corvette has the new LT5 engine in it.

The C4 Corvette ZR1 also used an engine with the LT5 RPO Code.
But it was a completely different double overhead cam engine.

Just RPO code names.
Just as the Z/28 and ZR1 names are also RPO option code names.

Thank you for that history lesson.:cool:

Lt4 might not have been special in a vette. But get one in a camaro from factory was. With the orange block on that. Lt4 z28 with low miles is worth a few bucks now.

IPODFAN11 has effectively ended this thread. I could not have said it better myself, and I was more than a little bit involved in some of that history.

Please share.:drool:

From 2001 - 2004 I was the Director of Product Portfolio Planning for GM Powertrain. The department that assigned engine and transmission RPO codes reported to me.

And?......:drool:

Not a whole lot more to it. Setting RPO codes is boring as hell. Engineering would develop new variants of whatever engine or transmission, Engineering Specs would suggest the RPO code. Planning would confirm that the new variant was different enough from existing variants to warrant a new (or re-cycled) RPO code and then set up the RPO in the portfolio system. Then Planning and Powertrain Engineering worked with vehicle teams and their engineering to get the applications approved.

This is usually done several years before you see it on the lot.

:faint:

Thanks, still cool to a non Chevy guy.

I guessing here but he may be talking about the C4 Collector Edition with the LT4 Motor

http://www.jagpromotions.com/forsale...te/c4/507a.jpg