Not mine but pretty cool..new lt5

[81DaytonaPaceCar]

Did some digging:

It should start with an X for MM Stilwater
last 4 are that days sequence, but the date derivative can't be right.
So should look something like this:

X911100015:
X = MM
9 = 1989
11 = November
10 = 10th
0015 = 15th LT5 assembled that day.

Repost......but the problem I have with this is why is the date stamped into the block? The production blocks had cast date codes...

[scholtmj]

Repost......but the problem I have with this is why is the date stamped into the block? The production blocks had cast date codes...

Ha, beat me to it!

Although I thought all the block numbers were stamped, not cast. The block on my ZR-1 is stamped I'll take some pictures once I get the motor out of the car.

[nascarnate326]

if that thing could talk.


Jeff the knowledge you have is amazing.

[Plantfoam]

And Phil makes a good reference that made me chuckle...back in the day, the OEMs would have several off-site skunk works developers working on some of their Secret Squirrel projects (Smokey Yunick immediately comes to mind), and when development concluded, they would make you destroy the item in some fashion, take a photograph of it, mail it to them, and scap the item (the OEMs didn't want to pay to have it shipped back to them and then scrap it themselves).

For engine blocks, you had to punch a hole in it.

I learned of this by hearing about life in a service department...There was a guy with a newer truck at the time (around a '96) that had a cold start knock at 20,000 miles. Warranty covered a new engine, and the old block had to be whacked and photographed. Since a certain someone already had a SBC with a legitimately bad rod knock, it could conveniently serve as the stunt double and wear the intake for a picture There you go...an almost new Vortec with a cold start knock(big whoop) in your garage.

[WMCCjames]

That has some uber collector value I'd imagine. 6 years ago I purchased 2 pewter ZR1 replica model engines for $150 a piece and sold them for $400 because they guy who had them didn't know what he had.

[sunsetmaro]

Awesome! LT5!

Cool engine. The Lt5 was gm's test engine to compare the power of a single cam vs Dohc technology. The LT5 and new LS1 was compaired side by side. The engines were placed in 2 cars ( can't remember either Camaros or vettes) Non of the GM officals knew which car had which motor. After the testing was complete, the LS1 was chosen. Hense why GM still have single cam engines producing big power. Cool history.

[scholtmj]

Cool engine. The Lt5 was gm's test engine to compare the power of a single cam vs Dohc technology. The LT5 and new LS1 was compaired side by side. The engines were placed in 2 cars ( can't remember either Camaros or vettes) Non of the GM officals knew which car had which motor. After the testing was complete, the LS1 was chosen. Hense why GM still have single cam engines producing big power. Cool history.

Interesting theory. You should read the book "The Heart of the Beast" and check your facts. The book has all the background information on why the LT5 was created, how it's development proceeded and speculates on why it was discontinued (OBDII compatibility, cost to produce, size/weight and the "not made here" stigma).

If the motor were just a "test" to compare the HP outputs of 4 cams vs. one, I doubt GM would have made 7000 motors.

There actually was a second generation LT5 created for the C5 that was suppose to have 475hp. Grahm Behan, an LT5 development engineer who now works for Lingenfelter, has the only two remaining block/head/intake assemblies left.

But yes, cool motor with a very cool history. The book is worth a read for any car guy.

[MP81]

According to Joe Spielman (known as "the man who saved the Corvette"), during a presentation he made at Kettering, it was due to the fact the extra power it made wasn't able to compensate for the added cost and weight of the extra components.

The LT5 is definitely a fascinating engine. I love it.

[scholtmj]

Let's see if I can copy/paste from one of my ZR-1 Registry news letters:

NextGenLT5.jpg

Shortly after seeing the biggest LT5 in a ZR-1 (441 Cubic Inch Monster!), we were treated to another amazing piece of machinery in the proposed replacement of the LT5, called the MY95 LT5. Automotive Engineer Graham Behan from Lingenfelter Performance Engineering (formerly of Lotus) brought with him a true jewel! He brought with him an item that was to be the replacement for the 405 hp LT5 and it was to be placed into the ZR-1 in 1995. This engine was one of 50 that were produced and assembled in England at Lotus, but before final completion of the project, it was determined that the LT5 was too tall to fit into the new corvette, the C5. Therefore the project was scrapped, and the majority of the motors were demolished. Two of these motors were shipped to the US and stored in a GM warehouse since 1993, and only recently were they discovered. Once discovered, calls were made to LPE to ask Graham Behan, one of the most instrumental members of the Lotus team, if he wished to have these motors before they were disposed of in ways we dare not speak!
To discuss this motor, Graham Behan and Gary Cline (formerly of Mercruiser) were in attendance to talk about the project and to display one of the engines itself!

Graham and Gary delivered a fabulous presentation on this engine, showing multiple slides describing the technical wonders of this motor. Pistons were redesigned to be forged, have thinner rings: 1.1 mm on top ring, 1.2 mm on middle ring, 2.8 mm oil control ring, with all three moved higher towards the top of the piston. This would allow higher peak power (6500 rpm) due to reduced inertia, and fewer hydrocarbon emissions due to reduced crevice volume. The combustion chamber was tightened up to remove quench areas and to produce more power and decrease tendency towards detonation. Piston liners have the flame ring removed to match the combustion chambers to reduce detonation and hydrocarbons. Compression ratio was to be 11.25:1 on extreme tolerance models. Redline was to be 7500 rpm, and the duplex chains were retained. The heads were made by the Dunn company and the throttle was to be by wire (first one!). The throttle body is a 90 mm unit. The ignition system from the Northstar was adapted for this application.

Graham outlined the fact that the injector housings themselves are now eliminated, with this part of the engine how cast directly into the head itself. This allows for a much straighter path for the intake charge of air, and the use of eight fuel injectors instead of the sixteen injectors used on the LT5. Gone are the secondary butterflies in the heads, and a brand new variable cam timing system was developed by Lotus for use in the new LT5. This new technology was demonstrated in a video, which is very difficult to describe in print. A photo shows the tri-lobed cam profile and the specialized lifter system. If this looks familiar, it is because INA bearings bought the rights to this design and they produce the system used by Porsche on almost all Porsche engines and is called “Variocam”.

This engine was reported to produce in excess of 475-500 horsepower and roughly 475 lbs-ft of torque, with a redline similar to that of the current LT5. This is most definitely a stunning package with performance to match. It would easily pass all emissions requirements of current day and return phenomenal fuel economy.
Graham indicated that he intends on building up both of these motors, and placing one into a ZR-1 that was formerly John Lingenfelter’s, because this was one of John’s dreams for the motor. The other motor will be built up as well, and donated to the Corvette Museum for permanent display. Let’s all look forward to the completion of the build of these fabulous motors!

NextGenLT52.png

[1fstss]

this would be a fun motor to use...

[97z2801ss]

Great thread with great info guys!!! Wow I wish I had 8k right now id have an Lt5 z28

[Gottork]

Generally speaking, no, the OEMs don't go chasing parts, especially ones that are (from their perspective) technically obsolete...now if somebody smuggled out a new prototype LS motor and started showing it off (or worse, tried to sell it), oh yeah, the National Guard will be in your front yard.

And Phil makes a good reference that made me chuckle...back in the day, the OEMs would have several off-site skunk works developers working on some of their Secret Squirrel projects (Smokey Yunick immediately comes to mind), and when development concluded, they would make you destroy the item in some fashion, take a photograph of it, mail it to them, and scap the item (the OEMs didn't want to pay to have it shipped back to them and then scrap it themselves).

For engine blocks, you had to punch a hole in it.

For entire cars, you were required to cut them in half longitutdingly down the center of the car (generally speaking...sometimes you had to cut it cross-car as well). Smokey Yunick had to do such a task in 1964/65 on one of the first mid/rear-engine Corvette concepts, XP-819, except he skipped the "scrapping" step, and just stored the pieces in a corner of his garage after he chopped it in half.

The one-off prototype 327 aluminum block with aluminum heads was sold off sometime in the '70s to a guy in Florida to put in his race boat, but other than that, everything else remained forgotten for years until a Corvette collector was walking through the shop in the early 80s and spied it under a tarp. After some negotiation, he bought the pieces off Smokey and spent a couple of years reassembling/restoring it. It was shown a couple of times in the late 80s, and Muscle Car Review (I think) did a 4-page writeup on it in '89. It's currently "on-loan" from the current owner, and sits in the Corvette museum. So, no, they don't always go ape-sh!t over it...

http://www.corvettes.nl/gm_prototypes/xp819/index.html

I'll stop rambling now...

thanks for that answer Jeff

I love this site.. I learn soo much info on Fbody's.. Very interesting stuff on this motor, sounds like you're on to something jeff..

couldnt agree with you more larry..

[TrickyTransAm]

Keep in mind that if this is Indeed a "Display Piece" It may not have any internal parts, such as pistons, rings, rods, etc.
It's for display - not meant to run. So it may have a cracked prototype block, faulty rods etc. Why waste good parts when you can take junk out of the scrap bin sitting in the prototype shop. Sure it's neat to look at, but that's it. Paperweight.

When we scrapped our 94 ZR1 vette, every part on that car was destroyed piece by piece. It's a liability thing.

When we build display models, the parts going into them aren't 100%. So you may be buying a $8,000 hunk of junk here.
Sorry to burst the bubble... But there's a reason why this never should have made it to the publics hands.

Buyer beware anyway.

[scholtmj]

While on the subject of LT5s, a guy on the ZR-1 Net just dynoed his recent build.

427 cubic inch LT5, 703hp!

Valvetrain parts:
http://zr1.net/forum/showthread.php?t=13400
Assembled:
http://zr1.net/forum/showthread.php?t=13648