So finally GM acknowledges the LT5 as one of theirs.

[XfireZ51]

http://www.autoguide.com/auto-news/2017/08/top-7-coolest-engines-in-the-gm-heritage-center.html

[ZR1North]

Excellent! I saw the LT5 while visiting the Heritage Centre a couple of years ago.


On an unrelated note, I did a rare thing (for me) last weekend and took the ZR-1 to a show where there were about 125 cars. My car was the only ZR-1, and I was quite surprised with high number of people that came by and hung there for a while. Also surprising was the number of people that had some basic knowledge of the story of the LT5. The windshield was another point of conversation - "what's with the windshield and that cutout at the bottom?" People were fascinated with that aspect of the car too.

[RussMcB]

Did they deny it in the past? :confused:

[USAF Retired]

Did they deny it in the past? :confused:

Lets just say they never totally said it was theirs. Why? Who knows for sure.

[XfireZ51]

Did they deny it in the past? :confused:

Russ,

There had been a story of people entering GM Powertrain HQ where there was a display of the GM Engines. The LT5 was not included.

[ssrszz4]

Probably better if they didn't claim it makes it more one off more unique.

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[Paul Workman]

Sooner or later, the truth comes to the surface... Long Live The KING!

[rush91]

So was or is the LT5, never accepted by GM? By that I mean, they didn't do the bulk of design OR building them. So are they looked at as a bastard step son? Part of the family....but not really? If so that is a shame. Name me an engine this unique, that talks the talk, and is that bulletproof if maintained....

[Blue Flame Restorations]

Read Heart of The beast. GMM was involved for sure.

[Kevin]

GM never really liked to claim the lt5 or the zr-1 for many years. "It wasn't made here" syndrome. It's nice to see they're coming around. I was shocked to find a plaque with the zr-1 on it in the corvette racing tent at carlise a few years ago

[USAF Retired]

GM never really liked to claim the lt5 or the zr-1 for many years. "It wasn't made here" syndrome.

Why?

[rush91]

Why?
I maybe wrong, isn't the LT5 the only engine before or since that was ever outsourced by GM? I could see that as a reason...

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[XfireZ51]

I maybe wrong, isn't the LT5 the only engine before or since that was ever outsourced by GM? I could see that as a reason...

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It is the reason. NIH was a major contributor to GM going under during the 200$ "recession".

[Kevin]

Why?

because the lt5 was designed mostly by lotus and built by meccruiser

[USAF Retired]

because the lt5 was designed mostly by lotus and built by meccruiser

I understand but why did GM out source the LT5? Why didn't GM or Chevy build the LT5 in Michigan or wherever they were building GM motors for other Chevy cars like the Camaro, Firebird, Monte Carlo, etc?

[Kevin]

I understand but why did GM out source the LT5? Why didn't GM or Chevy build the LT5 in Michigan or wherever they were building GM motors for other Chevy cars like the Camaro, Firebird, Monte Carlo, etc?

because they didn't know how to build a high rpm 4 cam engine. they wanted to try and slap 4 cam heads on an l98 and that didn't work.

[BigJohn]

because they didn't know how to build a high rpm 4 cam engine. they wanted to try and slap 4 cam heads on an l98 and that didn't work.

They had four cam race engines in the 1960's!

[efnfast]

I also understand there would be too few of them for GM to set up shop.
Plus, who knew aluminum engines better than Mercruiser.

[Paul Workman]

I understand but why did GM out source the LT5? Why didn't GM or Chevy build the LT5 in Michigan or wherever they were building GM motors for other Chevy cars like the Camaro, Firebird, Monte Carlo, etc?

(Source: Heart of the Beast) Small volume project: From the beginning the project was seen as a limited edition and the cost for GM Powertrain to tool up and develop and conduct the training, made sense to out-source the project.

MM was very successful building all-aluminum engines that were designed to run for extended periods at WOT. Initially, MM already had the manufacturing technical advances unique to precision manufacturing of aluminum engines as well as the trained personnel with the expertise to build these special motors to the extreme tolerances these motors would demand - already in place,. It was a good fit...and the "REST IS HISTORY".

An important footnote to the LT5 was the DOHC V8 developed by Oldsmobile which appeared as the Northstar in the Cadillac and variants of it continued to the Aurora as the L47 V8s.

These 4-cam, DOHV motors were expensive to build and expensive to implement on a large scale. As result, GM reverted back to the cheaper and much improved OHV motors, (thanks to the development and lessons learned from the LT5) for all of their gasoline V8 vehicle applications.

[Riviera]

Mike and I took our Z to a Corvette car show in Whitby, Ontario last Saturday. Surprisingly, another Z showed up but it was in really rough shape. We were able to park our car sideways so you had a good view of the LT5 as you walked up to it. We had a lot of admirers and talked to a lot of other Vette owners about the car. None of them had ever seen the LT5 before or the ZR-1 for that matter.

[5ABI VT]

(Source: Heart of the Beast) Small volume project: From the beginning the project was seen as a limited edition and the cost for GM Powertrain to tool up and develop and conduct the training, made sense to out-source the project.

MM was very successful building all-aluminum engines that were designed to run for extended periods at WOT. Initially, MM already had the manufacturing technical advances unique to precision manufacturing of aluminum engines as well as the trained personnel with the expertise to build these special motors to the extreme tolerances these motors would demand - already in place,. It was a good fit...and the "REST IS HISTORY".

An important footnote to the LT5 was the DOHC V8 developed by Oldsmobile which appeared as the Northstar in the Cadillac and variants of it continued to the Aurora as the L47 V8s.

These 4-cam, DOHV motors were expensive to build and expensive to implement on a large scale. As result, GM reverted back to the cheaper and much improved OHV motors, (thanks to the development and lessons learned from the LT5) for all of their gasoline V8 vehicle applications.

Their biggest mistake with the Northstar DOhc motors was lack of knowledge and they all had head gasket faliures because of their attempt at Dex-cool coolant. My parents had 2 Aurors and they still are the smoothest engines Ive ever had. I wish GM used Bigger displacement Northstars in the c5 and onwards because then i would be interested in having one !

[Crusin]

The LT5 engine cost as much as the car when ordering but was well worth the money as it made the ZR-1 special at the time. Love the sound as it whines out and still enjoy driving it today.

[XfireZ51]

The LT5 engine cost as much as the car when ordering but was well worth the money as it made the ZR-1 special at the time. Love the sound as it whines out and still enjoy driving it today.

I really love the sound of the motor as it winds out. It has a turbine like whine to it.

[Crusin]

That's the sound XfireZ51, let the good times roll.

[XfireZ51]

That's the sound XfireZ51, let the good times roll.

And the BWAaaaa as u open the throttle reminds me of an old QuadraJet.

[Paul Workman]

I really love the sound of the motor as it winds out. It has a turbine like whine to it.

Have a good friend of mine that was begging to drive my 90 Z. He has a friend that owns a Mustang of some sort, and he had experienced a wild ride (yeah, right) in it the weekend before and wanted to compare.

After this went on a while, I finally gave in.:rolleyes:

We lined up on a straight country blacktop, free of traffic and driveways and he hit it from a rolling start. We accelerated smartly - turbine smooth - up to 5000 rpm and then he shifted into second!? I watched as he ran through second, again only as far as 5k (there abouts), and he shifted again. Third gear up to around 4k before letting off.

"That's pretty good!" he says. But, I gave him pause cuz I was apparently rolling my eyes and shaking my head. He asked what was wrong, so I told him that he short shifted, even before the torque peaked. He says he was going by the sound, and it sounded like it was winding out "pretty good."

Uh, huh... Well, we switched drivers and shot that stretch of blacktop again. Only this time I kept the hammer down to the shift light (7100 rpm) in the first 3 gears! Mind you he is an ex-cop, but the wide eyes and slack jawed expression said it all! (AND, I didn't have to hear about that Mustang anymore after that!) :dancing

[lfalzarano]

Nothing like shifting at 7000 RPM's!


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[Crusin]

Paul Workman! you are one mean shifter, (lol) I bet his jaws did drop shifting at 7.000 RPMs in all 3 gears. In all the time I have had the Z, have to admit I have never tried it. Perhaps I shall someday. Cheers!

[Paul Workman]

Paul Workman! you are one mean shifter, (lol) I bet his jaws did drop shifting at 7.000 RPMs in all 3 gears. In all the time I have had the Z, have to admit I have never tried it. Perhaps I shall someday. Cheers!

Little of what we took for gospel re: the small block Chevys applies to the characteristics of the DOHC LT5. And, mine is fully ported which unleashes the beast's full potential. Had to have Marc reset the rev limit to 7600 to keep from pinching the motor off before crossing the 1/4 mile finish line!

It makes over 430 rwhp and still retains the stock cams and TB (508ish at the crank) - further testimony to what GM left on the table when the LT5 program was halted prematurely. Purrs like a stocker w/o a hint of what lies under the hood! :D

https://www.youtube.com/watch?v=y1YFa8ruh8A

https://www.youtube.com/watch?v=y1YFa8ruh8A

Dave McLellan once said the LT5 should be run up to 7000 often, and the motor will thank you for it!:cheers:

And, of course NO example of what the LT5 potential is would be complete w/o Pete Polatsidis' incredible NA, stock-bottom ZR-1...

https://www.youtube.com/watch?v=SFNFOhGGlR4

[bb62]

Just a note on how "ownership" of the engine was viewed. GM is (especially at that time) a huge company. Each of the respective organizations had their own culture in some ways. Certainly GM Corporate and the Chevrolet organization as a whole felt ownership of the LT5 and the Corvette as a whole. The NIH syndrome would only really apply to GM POWERTRAIN as their involvement was more limited. Even more so, the Powertrain organization is typically divided into different groups - Powertrain planning, Base Engine design, Engine-as-installed design, calibration, & manufacturing. Only the base engine design and manufacturing departments would not have been involved directly (though they had an oversight role).