Demise of the LT5 Engine

[Rob]

Ummmmm....I'm not afraid to quote anything. So what if they put out gobs of torque. Click on the links I provided to the pages here on the site and compare the performance numbers. I'm sorry, but I don't agree with Reeves Callaway that the ZR-1 was an "oversized pig". Compared to the Z06, yes it is, but that's comparing apples to oranges (just like comparing the LT5 engine to a Callaway Twin Turbo engine). If you're comparing the ZR-1 to a Callaway Twin Turbo, I don't see any reason to call the ZR-1 an "oversized pig" anymore so than the Callaway TT.

And one last comment on Mr. Callaway's quote....assuming that quote was accurate and he did say it, he wasn't saying it when he was running to the bank with ZR-1 owners' checks in hand.

 

[USA ZR1]

And one last comment on Mr. Callaway's quote....assuming that quote was accurate and he did say it, he wasn't saying it when he was running to the bank with ZR-1 owners' checks in hand. [/B]

Reeves said it,Rob. The interview with John Nelson at Vette magazine was taped. If you could have read the glowing praise on Callaway's website about the ZR-1,those comments will come as a shock. Sorta destroys what little credibility Reeves Callaway had with ZR-1 owners. Makes you want to hold your nose when doing business with them.

 

[Vettelt193]

ZR1's and Callaways are very comparable cars. If you take 1990 as an example you have two cars, same chassis, same tranny, just about everything is the same, with the exception of the engines... one turbo, the other LT5... what does this mean? Callaway Corvettes as a factory option didn't come with a whole lot of boost... As I understand it, Callaway wanted the engine super reliable... Sure you can tell me the LT5 can be built up too, and you can also point out the numbers... I have seen callaways run... seen them run against Vipers, ZR1's... etc. Callway TT's, in the real world, are amazing cars... They are super fast... The stock numbers don't really show it... Just like the stock numbers don't show how good the LT4 is... I think the LT5 is an over complex engine, Don't get me wrong, I love the ZR1 as much as any corvette.. I love them even more because of the high tech brute force they come with... What it comes down to in the end is simplicity usually wins... and it did with the C5... it also wins when a turbo buick outruns your ZR1...

This whole debate reminds me of a C5 versus NSX shootout in one of the major car mags... The writer of the article said something like... what are you going to do when you are driving your NSX and a Corvette, which costs half as much, whips your butt? are you gonna shout out the window when he drives by explaining how your high tech engine makes more HP per liter than his? The guy in his Corvette with the low tech V8 isn't going to care it is low tech, he just cares he whipped the butt of a car that costs twice as much!

 

[Rob]

Actually, this whole thread reminds me of an article in 1992 that compared the Viper to the ZR-1. One of the comments made by the author in comparing the Viper's engine to the LT5 was that the LT5 made it's horsepower using high tech trickery. The Viper's engine makes its horsepower using simplicity - plain old cubes.

 

[ArtZR1991]

I agree with KR, and would only expand Clint's observations about the "not invented here" syndrome to include the basic "mind set" envelope of the target group that the Corvette is supposed to represent. The LT5 was not perceived (unfortunately) by GM to be a "Corvette" first (as was the high performance small block), and was not developed. Remember that we are talking about an engine that in less than 10 years went from paper to discontinuance. The small block has been refined for near 50 years. Clint is essentially correct... It is the positioning of the Corvette that makes the LT5 an oxymoron, not the LT5 by itself.

As far as the "keep it simple" idea, that is far to complex an issue to discuss here, because we are talking about too many issues such a materials science, rather than number of parts, or parts cost (remember, cost is a Corvette issue, not a Ferrari issue). Cost is a relative thing. If you think the LSx in production form can match the LT5, then go after the record. Also look at the great endurance races in the world, and look at the basic engine layouts. What? Endurance not an issue? Of course it is, that is a big part of the reason for the existance of the LT5.

There is no need to fight about it. Corvette's decision to make an engine (and a very, very good one) that fit their marketing goals (LSx) is perfectly appropriate. But it has no effect what so ever on the worthines of the LT5.

Final note: I think Reeves will regret those comments attributed to him about the ZR1. They ignore too many realities, such as the implication his cars were not "over weight pigs" (weighed less than the ZR1, and/or could match the ZR1 at what it was designed to do.) If so, let him go get the record. Otherwise, I think the only way most Corvette enthusiasts (even justifiably proud Calloway owners) will forgive those comments is to consider them as out of context, or temporary insanity.

Well, no, this is the final point. Most of tyhe packaging issues related to the LT5 do indeed relate to GM's 4.4" bore to bore dimension, which cost quite a bit of efficiency, raw horespower, and packaging problems. After all, the Northstar, which has single handedly led the rebirth of Cadillac, is not an especially large engine.

It will be interesting to see just how much farther the pushrod technology can go. It has fit GM's scheme perfectly, has given the LS1 cars a feared reputation on the street, and fit the cost and packaging issues of the Corvette. Does that ultimately make it the better technology? I think not. But then it doesn't have to be... All it has to so is what GM "paid" for it to do, and that it did gloriously. In fact the original small block is the hot rodder's engine of all time, bar none, forget it, no argument. That's why it is the "standard" whan it comes to privateer weekend racing. It even had it's effect on us when we built my (now retired) Cobra as a full time bracket racer 20 years ago. see http://www.cobra65.org/hardcore99.htm.
You'll love it! By the car was quite a champion at tracks in the mid west, mainly Ohio, in the late '80's. (But don't tell anyone I have a Cobra with a Bow Tie in it! Actually, I like to point out that it only has one Ford part and one GM part in it, and neither of them move. The Ford part is the 9" axle housing (gears are aftermarket Moser, as NHRA required), and the GM part is the block, chosen for one reason only, the selection of aftermarket parts available to hang on it. Even today, it is 50% or more of the total market.)

 

[Edmond]

It seems like a bunch of the import guys are always talking about their DOHC engines and how their engines put out more HP per liter.

How/why is that so?

Comparing a NA LT5 to a TT Callaway just isn't a fair comparison. Any blown car versus a NA would be a useless comparison. Comparing Vette's against each other is just treason. I think it was Chairman Mao who said, "Comrades do not fight one another." Let me know if I'm wrong.

We're all in the Corvette ship here, so we're all in it together.

I believe that a factor in the demise of the LT5 was that GM wanted a car that owners could work on themselves. They (GM) probably got a lot of feedback from owners who couldn't work on the complex engine. Could that be a valid theory???

 

[inferno-vette]

I believe that a factor in the demise of the LT5 was that GM wanted a car that owners could work on themselves. They (GM) probably got a lot of feedback from owners who couldn't work on the complex engine. Could that be a valid theory??? [/B]

Well I don't think so, the DOHC Cobras have been around for ~6 years and, for what I see it isn't very hard to work on'em. I think that GM discontinued the LT5 because of costs of production. Remember that a ZR1 costed more in 1990 than a Z06 costs now.
Paul

 

[90 Corvette ZR-1]

What it comes down to in the end is simplicity usually wins... and it did with the C5... it also wins when a turbo buick outruns your ZR1...

A stock Turbo buick will see nothing but tail lights agaisnt a ZR-1. So will the C5. Of course this is stock for stock. Now mod vs stock it will be different and I hope it would be that way. But Mod for mod we are back at square one.

 

[rkreigh]

the LT5 still is a superior piece of engineering compared to the LSx. I love the twin turbo callaways, but many owners had bad experience with early IHI turbo failures, broken rods, overboosting, etc... I know one gent who went through 4 sets of turbos and was told "don't come back" the realiability of the LT5 was far better IMHO. as for being complex, BS. the DOHC design is very simple in comparison to even your basic 5 valve AUDI or Ferrari engine. yes, any DOHC engine is more complex than a pushrod engine. but the LT5 is no more complex than the Northstar or Auroro, Cobra engine ect...

just an observation, how many race engines continue to rely on pushrod tech in F1??? zero.

the next advancement will be computer controlled valves and elimination of the cam itself. BMW already has a fully variable intake, and Mercedes is working on some very innovative valve control tech. that will be pretty cool.

Clint and Rob are spot on, the NIH and marketing considerations killed the LT5. I am amazed that merc marine could actually get costs even at 30K volume to 2k. I would buy 5 of em!!!

the ZR1 isn't the fastest car on earth, and no it won't beat my turbo buick in the 1/4 mile either, or a hot rod small block chevy either, but not too many of those cars will do sustained WOT over 180 ALL DAY.

endurance racing is still where the ZR1 excells. Most races I run are a bit longer than a 1/4 mile. given time, I will get by....

 

[FrankUrbinati]

A stock Turbo buick will see nothing but tail lights agaisnt a ZR-1. So will the C5. Of course this is stock for stock. Now mod vs stock it will be different and I hope it would be that way. But Mod for mod we are back at square one.

Your kidding me right ??

 

[90 Corvette ZR-1]

about which part?

 

[FrankUrbinati]

The first sentence.

 

[90 Corvette ZR-1]

high 12's stock for a ZR-1 low 14 high 13's for a Turbo Buick stock. last time I checked a 12 sec ET beats a 13 sec et

 

[Vettelt193]

Alright, I will say just a bit more... all corvettes are great... I love ZR1's... heck I love C4's in general, they are my personal favorite generation...

My point on the Callaway Vs. ZR1 debate comes down to where you are going to put your money... you can develop a high tech engine that creates a solid amound of HP, or you can turbo a more simple engine... what it comes down to, and I am not talking stock - stock comparisons here... mildly modified cars (how many C4 owners out there have done nothing to their cars??)... The callaway comes out on top... The ZR1 guys talk about endurance etc... Callaway has run endurance races, during a time chevy didn't want to... How about the sledgehammer?... My whole point to the turbo buick comment is that turbocharging is a better deal when it comes to making power... In my opinion, more and more cars will be turbo/supercharged in the future... why? it makes more economical sense... I this is where chevy is headed with the corvette in the future as well... If you want to make a ton of horsepower, but keep the car good on gas and emissions, natural is not the way to go... Engines are made so much better today as well... They can be easily built to handle turbo/super applications, and handle it while keeping the car as reliable as it ever was... I see a future of smaller engines and bigger blowers due to the economics on everything.

 

[FrankUrbinati]

90 ZR1. Keep on checking and reading all you want. You can grab your stock ZR1. I will get a guy with a stock Buick Turbo. Bring your Title. And take a cab home.

 

[Vettelt193]

a completely stock buick turbo Vs. a completely stock ZR1:

the ZR1 would destroy the buick, end of story

throw a grand at both cars, whole different story.

 

[FrankUrbinati]

Just a little high octane in that stock Buick and your door's come off.

 

[Rob]

Instead of everyone *****ing back and forth, bury the hatchets and backup your performance claims with some data:

1986 Buick Grand National

********************************
Year: 1987
Powertrain Layout: Front Engine / RWD
Make: Buick
Base Price" $29, 900
Model: Regal Grand National GNX
Production: 547

Engine: Twin Turbo V6
Weight: 1588 kg / 3501 lbs
Valvetrain: OHV
Length: Not Available
Displacement: 3785 cc / 231.0 cu in
Width: Not Available
Power: 205.8 kw / 276.0 bhp @ 4400 rpm
Torque: 515.21 nm / 380.0 ft lbs @ 2600 rpm
Wheelbase: 2746 mm / 108.1 in
Bhp / Liter: 72.92 bhp per litre

Transmission Type: 4 Speed Automatic Turbo Hydromatic

Final Drive Ratio: 3:42:1 Rear

Performance:
Top Speed: 228.5 kph / 142.0 mph
0 - 60 mph: 5.4 Secs
0 - quarter mile: 13.42 Secs
0 - 100 mph: 11.7 Secs
Lateral Acceleration: 0.92g
EPA City/Hwy: 15/23


What the Critics Say:
"The GNX is an ax-wielding barbarian laying waste to everything in it's path"
"Rockets to 60 mph in 4.7 seconds and squirts through the quarter-mile in 13.5 seconds at 102 mph"
(Tony Assenza) Car & Driver, May 1987: Buick GNX

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"This (GNX) is no batamweight, over-motored car. It's a hefty 3,500 pound family sedan. ANd on this cold, blustery day, five very large men-give or take a pound, 1,082 pounds of them-fill up every inch of it's livable interior space. What the hell-a stand-on-it run is in order. In less than 20 seconds-20 seconds!-fuel shutoff valve kicks in signifying the ride is over. That's impressive."

(Dutch Mandel) Autoweek, February 16, 1987: Speedway Born

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"More than a straight-line rocket sled, the GNX is a suspension tuned to hug the corners like a Grand Prix car."

(Paul Garson) Car Craft, September 1987: The Ultimate American Muscle Machine

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"For you who remember the spine-snapping GTOs, Road Runners, 4-4-2s and Shelbys of 20 years ago and think they'll never be equalled in this era of desmogged Wimpmobiles, they have. And passed. By the Buick GNX."
"And they came up with a 300 hp stroker that looks like Darth Vader's Staff Car. One that, unlike the GTOs and Road Runners, doesn't pitch and yaw when when you ask for a smoking burnout. It goes straight. And goes. And goes."

(Scott Heimer, Auto Editor) Philadelphia Daily News: Ride On!

 

[Vettelt193]

Rob just loves numbers...

Show me in the numbers where a stock L98 automatic takes every LT1, LT5, and LS1 car off the line that it has run against... You haven't felt frustration until you pull up to the line in a C5 and get dusted off the line by a 1990 auto.... I can't imagine how the guy in the ZR1 felt... takes almost the whole length of track to pass it by too (at least the ZR1 did much better at getting by him than I did).

 

[Rob]

Yes, I do love numbers. I'd rather see someone take the time to post some documented/published numbers rather than bantering back and forth about who's car is quicker based upon hearsay. If you have dyno numbers and dragstrip time sheets, great.....post them and list whatever modifications you've done to the car, otherwise, lets all back off on the arguing as it doesn't accomplish anything.