GM phasing out MercuryMarine on the LT5?

[Brett]

Disuscussing the ZR-1 on the board here, I've picked up a few comments here and there about this, and would like to hear more about it.

I've heard that GM didn't like the control MM had over making the engines. So did GM start making the LT5 in the later years? I've also heard that the earlier '90 LT5's supposedly had the best build quality.

Can anyone elaborate on these statements?



Brett

 

[Aaron71771]

MM Made all the LT5's. They did an excellent job.

 

[Rob]

I'm not aware that GM had any issues with Mercury Marine building the LT5 Engines.

The reason why Mercury Marine was chosen to build the LT5 was because they had plenty of experience building low volume, aluminum engines unlike GM which is used to building millions of engines on an enormous assembly line.

If I'm not mistaken, the last LT5 engine built (for 1994-1995 ZR-1 production) came off the Mercury Marine assembly line in November of 1993. Mercury Marine built all of the LT5 engines for all 1990-1995 ZR-1s.

What I have heard several times is that some folks higher up in GM Powertrain were not pleased with the fact that Corvette Engineering went outside GM to engineer and build the engine. Instead, they went to Lotus and Mercury Marine without trying to have the engine developed in-house. Supposedly, that was one of the reasons why the LT5/ZR-1 project was killed, but I'm not sure we'll ever know for sure.

 

[Vettelt193]

I agree with the higher ups at GM not liking the LT5 because it was an out of house project. It was a smack in the face for them because it basically said they were not good enough to make the engine for the super Corvette.... the best car in the GM lineup. I think this really killed the ZR1 because it made competition between the GM powertrain team Vs. the LT5. This lead to the LT1, and a value that made the ZR1 seem overpriced.

 

[Lee74C3]

I'm not sure about the politics of choosing Mercury Marine but I do recall discussion on phasing out the ZR1.

Primarily, it was related to improvements in the LT1 and LT4 that offered performance capabilities very, very close to the ZR1 at a fraction of the cost.

Too that point, I recall a little race I had in a 6-Speed Z28 Camaro where I just killed the ZR1. He was a liitle slow out of the hole and smoked the tires just a little too much. In the flying mile he caught up and passed me due to more horsepower and ECM speed limitations due to differences in tires.

Back on track... it just became too hard to rationalize the purchase price of a ZR1 vs. LT1/LT4.

Oh, but what a car... truly "King Of The Hill" then and still now! I just have not warmed up to the C5's as much as I still like a C4. The C4's still have more "ooh - aah" value to me.

 

[Rogue]

Well, if you guys can remember, the ZR-1 was almost TWICE the price of an LT1! The performance difference wasn't big enough and for the most part, the ZR-1 gave its owners bragging rights & exclusivity and little more. The market bore this out because Chevrolet had a hell of a time trying to sell the ZR-1's. I remember seeing them with big discounts sometime in the middle of its production life. The bottom line was GM was loosing money on the ZR-1's!

Chevy's formula today, with the LS1 & LS6 engined 'Vettes is more successful because the modest price difference between the ordinary C5's and the Z06's is in proportion to the Z06's advantage in acceleration and exclusivity. In other words, the price difference can easily be justified.

When you're trying to sell a car that is twice the price of another, the performance had better be 100% better (or close). That just wasn't the case with the ZR-1 when compared to its LT-1 powered brother.

 

[phrogs]

it was the LT1 that nail the last one to the coffin thats why they increased to 405 just to have that little bit more HP
but its ok with me I am happy with my ZR-1
Its just a sweet car and I did have a Z06 and its still the only C-5 I will ever own.
johnny

 

[Rob]

Personally, I still think that GM shot themselves in the foot by not marketing the ZR-1 appropriately.

If you really stop and think about it: compare the amount of advertising and marketing that you remember seeing in the magazines for the ZR-1 to the amount of advertising you have seen in the magazines since the C5 debuted in 1997. In almost every single mainstream automotive magazine since 1997, there has been at least 1 ad for the C5.

ZR-1 production was at a pinnacle in 1990, then decreased in 1991 and when the LT1 hit in 1992, ZR-1 production took another major hit. After that, it was downhill from there.

Regardless of the fact that the 1993-1995 LT5 engines jumped up to 405 hp, it wasn't enough of an increase to compensate for the gradual weight gain that the ZR-1 underwent. The ZR-1 was around 300 lbs heavier than the baseline LT1 so the gap in performance between the LT1 and ZR-1 closed dramatically. Once the LT1 debuted and GM decided to cease any further development and production of the LT5 engine in Nov. of 1993, the final nail in the ZR-1's coffin was driven in.

The ZR-1 was almost a stillborn by the time it left the womb in 1990. It got decent reviews/publicity when it debuted (in production form), but other than a couple ads that I'm aware of in 1990, GM never bothered to market the ZR-1 like they are doing with the C5.

I honestly think that regardless of the birth of the LT1/LT4 - had GM continued development of the ZR-1/LT5 model and made more of an effort to market the car and improve, not only it's performance, but it's appearance as well, we would have seen a much longer life span for the ZR-1.

The top four reasons why the ZR-1 met an untimely death:

1. Poor marketing
2. Lack of enough physical distinction from the base Corvette model lineup
3. Lack of engine development to keep it ahead of the LT1 in performance
4. Impending emissions regulations necessitating a redesign of the engine
   [/list=1]
   
   Yes, the LT5 was expensive to build and the 450-475hp that we've heard mentioned that was planned for the 3rd generation LT5 engine would have been the max. output in that configuration without making a major investment in cash to redesign the engine, however notice that the Z06 has been in production now for 3 years going on 4 years and we have been hearing very strong rumors that the Z06 nameplate will return late 2005 as a 2006 (?) with a much more powerful engine than the baseline model.
   
   Had the ZR-1 been lead down the same path of development, I think we would have it seen it last longer than the 6 years it was in production.
   
   This is all just my own personal opinon so take it for what it's worth.

 

[Brett]

I agree with you Rob, except for #2.

One of the reasons I love the ZR-1 so much is because it is so unique. I find it a fascinating car with a very interesting history. The LT5 is truly one of a kind.

The ZR-1 was more different from the base vehicle than the ZO6 is from its counterpart. Wider stance, different tires, wheels, badging, but the main thing is the LT5.

With the ZO6, the LS6 is just a slightly modified LS1, and it has some performance modifications here and there, but it isn't really different , if you know what I mean. The ZR-1 really had its own guts that no car has shared since.

I guess from an outward appearance, the ZR-1 does look similar to the base 'vette though, which is how most people see them. So I guess you are right. But for anyone that knows anything about the car, the ZR-1 was definitely more unique.

As for poor advertising, I was only 9 when the ZR-1 first came out, but I remember being super hyped up about it. But that could be because I come from a Corvette family, so I guess I can't say how the vehicle appeared to the general public.

I've read (I think it was on this forum, in fact) that the LT5 design was just too heavy compared the push-rod design, and the extra weight basically nullified the extra horsepower when they were trying to design the next generation engine for the next generation Corvette, so they ended it. Plus it was an expensive project to boot.



Brett

 

[Aaron71771]

I came from a 92 LT1 and moved into a 91 LT5. Anyone who thinks that the 300HP LT1 is compariable to the 375hp LT5 is smoking something. There is a huge difference between the way these two engines drive. Between the sound, the 7000RPM redline and the pull after 3500 RPM the LT5 is definetly a world apart. If GM thinks they were able to get LT5 like performance for less, they are mistaken.

The LT5's could have been produced for a much cheaper cost had they been produced in mass.

 

[Rob]

I came from a 92 LT1 and moved into a 91 LT5. Anyone who thinks that the 300HP LT1 is compariable to the 375hp LT5 is smoking something. There is a huge difference between the way these two engines drive. Between the sound, the 7000RPM redline and the pull after 3500 RPM the LT5 is definetly a world apart. If GM thinks they were able to get LT5 like performance for less, they are mistaken.

The LT5's could have been produced for a much cheaper cost had they been produced in mass.

It depends upon what numbers you're comparing. If you're comparing engine output between the LT1 and and LT5 - yes - they are a world apart.

If you're comparing overall performance on the road - which is really what matters, then that "world apart" just became a small gap.

Let's take a look. From:

http://corvetteactioncenter.com/specs/c4/zr1/zr1perf.html

http://corvetteactioncenter.com/specs/c4/1992/1992.html

Average ZR-1 Performance Numbers - 1992 (Motor Trend and Road and Track)

Horsepower: 375 hp @ 6,000 rpm
Torque: 370 ft lbs @ 4,800 rpm

0-60: 5.25 seconds
1/4 Mile: 13.65 @ 106 mph
Top Speed: NA (although average Top Speed for 1990-1995 ZR-1s tested is right around 176 mph)
Lateral G: 0.91

Average LT1 Performance Numbers - 1992 (as reported by Car and Driver)

Horsepower: 300 hp @ 5,000 rpm
Torque: 330 ft lbs @ 4,000 rpm

0-60: 5.0 seconds
1/4 Mile: 13.6@ 104 mph
Top Speed: 157 mph
Lateral G: 0.89

The main differences we see here are top speed. In all other categories they are nearly identical.

Base price of an LT1 coupe in 1992 was just under $34,000. RPO ZR-1 in 1992 came in at $31,683 - almost double the price of an LT1.

So basically for the cost of 2 1992 LT1s you got:

1. a limited production car that doesn't look much different than the base model that cost 1/2 the price,

2. a beautiful looking engine with fantastic engineering and great output numbers to boot - something that most people won't see and appreciate unless the car is stopped with the hood open and,

3. a great sounding engine like no other

4. other than top speed (how many of us really take our Vettes over 150 mph on public roads...), overall performance that was almost identical to the base model LT1.

This is just a guess on my part, but people who spend $65,000+ on a car, probably want something that is going to be more unique than something that looks almost identical, performs almost the same and costs 1/2 the price.

Output numbers are great to look at - and they are impressive, but they become much more impressive if the overall package is impressive.

Put a 1992 LT5 engine into a 1978 Cadillac Fleetwood and those output numbers don't look too impressive given what that engine has to move. Wedge that LT5 under the hood of a Pontiac Fiero, and suddenly, those output numbers are much more impressive because that engine now only has to move 1/4 of the Cadillac.

The performance numbers (that which, in my own personal opinion, is more important than horsepower and redline RPM numbers) of the Fiero would be a hell of a lot better than the Cadillac.

In summary, yes, the LT5 engine is impressive when looking at design, technology, output and sound characteristics, but the performance numbers and overall appearance of the car when compared to the 1992+ LT1, could not justify the price.

In my opinion, it's the look and performance that sells a car first over engine output, design/technology and sound.

Just my two cents.

 

[Gorgon]

If you remember the early 90s weren't a good time for GM financially. I am pretty sure the marketing budget for Corvette was pretty small considering they almost killed a project a couple times. C4 lasted 12 years and you bet when C5 was coming out that GM was going to let everyone know. The car was originally supposed to be released as a '93 MY car. It makes sence that GM would spend more money marketing the C5 than they would the ZR1.

Leon

 

[Vettelt193]

I think the problem with the ZR1 was balance.... I am not talking weight balance or the actual balance of the car here.... i am talking the balance of reliability Vs. Power. It is great that the ZR1 is capable of going 24 hours straight at full throttle.... LT1 and LT4 engines would be hard pressed to complete that, much less live to race another day. But, who owns a street car and runs races for 24 hours with it? I would rather have an engine that has a bit more power for the dollar than one that can run like that.... Just my personal preference.... For the money spent on the LT5, GM probably could have had a less reliable engine that had 500-600 HP, but reliable enough to drive every day on the street.

 

[Aaron71771]

Rob, the numbers you post do seem to indicate a negligible difference between these two fine engines. I can tell you first hand tho, from the driver's perspective the performace is much different. Having driven both for extended periods of time I can safely say that the LT5 is a much better performer over the LT1 then what some magazine tests show.

*conspiricy theory*
Perhaps in an effort to kill the LT5 the GM people sent doggy ZR-1's out for test drives to help kill the program, thinking that people could not justify the $35K markup over the base LT1 for a few mph more in the 1/4 pass.

 

[Rob]

*conspiricy theory*
Perhaps in an effort to kill the LT5 the GM people sent doggy ZR-1's out for test drives to help kill the program, thinking that people could not justify the $35K markup over the base LT1 for a few mph more in the 1/4 pass.

That's an interesting way of looking at it. I honestly think that as soon as the LT5/ZR-1 project went into production in 1990, GM's internal support for the car started to disintegrate. The support floor underneath it, literally dropped. By support - I mean marketing it and trying to actually promote the world-class technology and sell it.

Why? Who knows, but my unprofessional guess is there were a few key members of GM Powertrain who became extremely insulted at the fact that Corvette Engineering went "outside the fold" for the LT5 and that combined with the fact that due to changing CAFE standards, the engine would have had to be completely re-engineered down the road, they couldn't (or wouldn't) justify the cost of doing that.

In looking at the production numbers, in 1990, the production numbers for the ZR-1 are the highest - due to all the hype generated. In 1991 - they settled down into reality but the baseline L98 comes out of the bag wearing the ZR-1's rounded rear bumper and oval tail-lamps - thus removing more distinction between the two models. In 1992, the LT1 debuts raising the performance bar closer to the ZR-1. ZR-1 production takes a major nose-dive.

Where were all the magazine advertisements promoting the 24 Hour Endurance Records that the ZR-1 broke?

It's unfortunate, but in my opinion, the ZR-1 no sooner hit production in 1990 when GM sealed the car's fate.

 

[bbw]

*conspiricy theory*
Perhaps in an effort to kill the LT5 the GM people sent doggy ZR-1's out for test drives to help kill the program, thinking that people could not justify the $35K markup over the base LT1 for a few mph more in the 1/4 pass.

That theory is interesting. Does anyone have a ZR-1 whose car has been timed in the 60 and 1/4? Are the numbers similar to what Rob posted?

 

[Rob]

That theory is interesting. Does anyone have a ZR-1 whose car has been timed in the 60 and 1/4? Are the numbers similar to what Rob posted?

I haven't track tested mine but I have driven a couple LT1s as well as a 1996 LT4 Collector's Edition coupe.

The LT1s are pretty stout but you can definitely feel their limited breathing capacity as compared to the ZR-1.

The LT4s are even more stout and in all honesty, I can say that by seat of the pants feel, 0-60 the LT4 was damn near comparable to my ZR-1 (which is completely stock). The one thing I noticed again, is that by about 5,000 rpm, the LT4 starts running out of steam where as the ZR-1 is still pulling like a locomotive.

I had to shift earlier in the LT1/LT4 than I do in the ZR-1.

Again, unfortunately, this is all seat of the pants feel with no supporting numbers.

 

[Brett]

5.25 seconds for a 0-60 time?

From the numbers I have seen, it seems like most ZR-1's can do it in around 4.6 seconds.



Brett

 

[Rob]

5.25 seconds for a 0-60 time?

From the numbers I have seen, it seems like most ZR-1's can do it in around 4.6 seconds.

Brett

Yep. I agree. That is slow for a 0-60 on a ZR-1. That figure came from averaging 5.6 and 4.9 0-60 times for a 1992 ZR-1 published in the link I have on the first page.

The average 0-60 time for 1990-1995 ZR-1s as published is: 4.88 sec

 

[Aaron71771]

Regarding 0-60 times, on the street using my *ahem* Gtech-pro I have gotten anywhere from 5.35 to 4.76 when doing 0-60mph tests. This is with my 91 ZR-1 running an aftermarket exhaust and chip, and at operating temp (93C) using street tires at 35psi. Launching at 2100RPM and shifting somewhere around 6500-7000RPM. Properly set up on a track and with more launching expirence, I could probably get a 4.5 or less 0-60mph time.

With a wearing clutch I don't do a lot of launch practicing in hopes of getting a good 0-60mph time. Maybe with a new clutch and a track that was not 3 hours away I could learn to drive this thing

Looking at the links Rob gave, the difference between the engines after 100mph is pretty clear, even in the worse running ZR-1 magazine tests. By 150 mph the cars are ten seconds apart, that is about 100 cars... pretty significant.