LT5 Durability, how are they holding up after 16 to 21 years?

[93Rubie]

I just finished reading my (new to me) copy of The Heart of the Beast by Anthony Young. Awesome book. Like Dave McLellan's book Corvette From the Inside, it left me with more questions than I had before I started reading the book. That being said, to all ZR-1 owners or former owners, how is the LT5 engine holding up as it is at least 16 to 21 years old. I mean yes, the engine mechanically is extremely durable I learned that. How are things like oil leaks, seals, gaskets, etc...holding up? Are the valve springs still good at 20 years old?

Also, I understand some LT5 parts are hard to find but not impossible, that being said, I would assume owning a LT5 could potentially be an expensive proposition?

By the way, I'll take a 93 ZR-1 in Ruby Red please...hahaha...maybe someday. Although, I did see one very nice 92 that had a Marc H. 485 package on it for about 20K in VERY nice shape.

To Hib Halverson, if you read this, did you ever get those Z07 springs and bars on your ZR-1? If you did, how does it handle now?

P.S. I'd like to see the new C6 ZR1 try to beat the C4 ZR-1's 24hr+ endurance record using a production crate engine and mostly stock car like the C4 did. I doubt it could. Nothing against the C6 ZR1 but for me it seems that it never had (has) the same fanfare, legacy, reputation, and enthusiasm as what seemed to be present when the C4 ZR-1 came out. (I was like 3 in 1990 so I'll have to let the history books be my guide on this.) I've seen a couple C6 ZR1's but never a C4 ZR-1.

 

[xfirez51]

Let me suggest you go to zr1.net for your answers.

 

[Hib Halverson]

(snip)

To Hib Halverson, if you read this, did you ever get those Z07 springs and bars on your ZR-1? If you did, how does it handle now?

Haven't yet. I haven't found a rear spring yet.

Once I get those springs and bars on, the car will handle better but may ride a little more harsh.

 

[93Rubie]

Haven't yet. I haven't found a rear spring yet.

Once I get those springs and bars on, the car will handle better but may ride a little more harsh.

Sounds good. I've began an informal search for Z07 parts myself. Auto-x gets addicting, granted base suspension w/FX3 is still faster than I am. I think in SCCA B-Stock the C4 has a LOT of speed potential. My most recent auto-x was only my 4th but I was only about 3.5sec. behind the B Stock leader. He was on street tires as was I. Lots of S2000's and Boxster's in B Stock. I could tell where I was losing speed, but I'm still learning. All things being equal at 19 years old my 93 C4 is still a VERY FAST sports car.

Thank you to xfirez51, I did indeed find my answers there. Do ask why I did not think of that, I don't know. Came to the conclusion nothing worse than any other C4, mostly typically dumb stuff like oil sender leaks, pan, cooler lines, etc..., just if a internal engine failure occurred (unlikely) it WILL be more expensive than a L98 or LT1/LT4. Then again if one can afford the price of admission one should be able to afford the upkeep.

 

[xfirez51]

Rubie,

The LT-5 is incredibly durable. Witness the 24hr Endurance records. In Heart of the Beast,
you'll learn about some of the torture testing. If the motor breaks, it will be because you meant to do that. Marc Haibeck recently did a freshening up of a 200k motor and found that the liners rings were still in good condition. The bottom end is an anvil. With the motor a non-issue, the other ZR-1
problems are C4 issues.

 

[93Rubie]

Yeah for real, 200hrs for the 90-92 engines peak torque to peak HP, 400 for the 93-95. I learned the other day that the Nissan GT-R engine is dynoed and this includes a 10 minute redline run....:eyerole Granted the GT-R is a pretty fast car but not fast and DURABLE.

 

[JT ZR-Won]

After 22yrs and 44,7xx miles later, my Dad's LT-5 can still balance a nickle on it's side on idle

Jay

 

[xfirez51]

One other thing about the LT-5 is how receptive it is to mods and increasing horsepower. With just the addition of headers, and DIY porting of the plenum and injector housings, you can go from 375cwhp(factory rating) to a 400rwhp motor.These things just LOVE to breathe.

 

[Hib Halverson]

One other thing about the LT-5 is how receptive it is to mods and increasing horsepower. With just the addition of headers, and DIY porting of the plenum and injector housings, you can go from 375cwhp(factory rating) to a 400rwhp motor.These things just LOVE to breathe.

It is true that the LT5 responds quite well to airflow modifications, but 400 at the wheels with only headers and DIY porting, unless the engine is already making a very "optimistic" 375-hp, is unrealistic.

To get 400 at the wheels SAE-corrected, you first need an engine which is in good condition. You need to port the heads, the housings and the port exits in the plenum and the port work needs to be done by someone with LT5 porting experience. A DIY with no LT5 knowledge and a yen to burn up some abrasives may or may not do the right porting tasks. The cam timing, also, needs to be properly set. There was a big variation in cam timing (and a commensurate variation in power output) because of the procedures and tools used at Stillwater and you're never going to know whether the cam timing is optimal until you either do it or have it done. You also need a low restriction exhaust system. Lastly, you need some good calibration work. Do all that and you'll make 400-420 SAE at the wheels.

 

[xfirez51]

Hib,

I appreciate your writing and your sense of history re: the LT5 and ZR-1 programs. However it's not correct to suggest that a 5.7L LT5 with headers, and top end porting won't make 400rwhp.
I'll post my SAE corrected dyno sheet next. Also, look at what Haibeck is now claiming for a stock block LT5 with porting of top end and heads, but stock cams. 450rwhp. I'll also post my latest dyno sheet of stock block ported top end, GVD heads and larger intake/ stock exhaust cam setup.
~435rwhp. There's more from the FBI crowd in Chicagoland where that came from. Science marches on.

P.S. When we checked, the cam timing was off at the time the motor made ~400rwhp.

 

[xfirez51]

Ported Top End, Watson 1 7/8" headers, Magnaflow cat back, stock cams and heads. Second dyno is Ported Top End/GVD heads, stock block, Watson headers, DynoMax Ultraflow w z06 flapper, larger intake/stock exhaust cams, my own tuning.

 

[Hib Halverson]

The first set of dyno results does not demonstrate 400 at the wheels from an engine with DIY porting and headers. You're close, but you only made 398 from an engine with DIY porting, headers AND a low-restriction exhaust. That exhaust makes a huge difference–about 10-12 horses at that power level. In my opinion, your earlier claim (ie: 400rwhp from a 350 with only DIY porting and headers) is not substantiated.

The second set of dyno results is for an 350 with ported plenum, housings and heads, aftermarket cams, custom tuning, headers and an aftermarket exhaust but, at 434 at the wheels SAE, I'd say you've left some performance on the table somewhere.

Back a few years, I extensively tested a 95 with a 350 modified with an Automasters Street Skinner performance enhancement package (ported heads, housings, partiallly ported plenum and reset cams) along with a little of extra work on my part in a few areas and calibration by Ron Zimmer. It made 410-413 at the wheels SAE-corrected over three passes on a Dynojet. The engine had stock cams, stock exhaust manifolds, cats and custom-built Flowmaster exhaust system and, after the dyno runs, it passed a California style exhaust emissions test.

Your second set of numbers are only up about 20 horses on my 413, but you, also, have headers and cams. I would expect more of a bump in the power and torque from those mods.

I think your dyno test info is quite revealing and it shows that stock displacement LT5s respond no better or no worse to modifications than any other modern GM V8 engine.

 

[SnakeDr]

I just finished reading my (new to me) copy of The Heart of the Beast by Anthony Young. Awesome book. Like Dave McLellan's book Corvette From the Inside, it left me with more questions than I had before I started reading the book. That being said, to all ZR-1 owners or former owners, how is the LT5 engine holding up as it is at least 16 to 21 years old. I mean yes, the engine mechanically is extremely durable I learned that. How are things like oil leaks, seals, gaskets, etc...holding up? Are the valve springs still good at 20 years old?

Also, I understand some LT5 parts are hard to find but not impossible, that being said, I would assume owning a LT5 could potentially be an expensive proposition?

By the way, I'll take a 93 ZR-1 in Ruby Red please...hahaha...maybe someday. Although, I did see one very nice 92 that had a Marc H. 485 package on it for about 20K in VERY nice shape.

To Hib Halverson, if you read this, did you ever get those Z07 springs and bars on your ZR-1? If you did, how does it handle now?

P.S. I'd like to see the new C6 ZR1 try to beat the C4 ZR-1's 24hr+ endurance record using a production crate engine and mostly stock car like the C4 did. I doubt it could. Nothing against the C6 ZR1 but for me it seems that it never had (has) the same fanfare, legacy, reputation, and enthusiasm as what seemed to be present when the C4 ZR-1 came out. (I was like 3 in 1990 so I'll have to let the history books be my guide on this.) I've seen a couple C6 ZR1's but never C4 ZR-1.

You were 3 years old when the ZR1 came out?

You never seen a C4 ZR1? Wow...

C4 ZR1 or C4 Callaway Corvette was my dream car. Now it's the C6 Z06/ZR1. However, before I move onto a C5/C6...I want to experience and own a C4 ZR1 and right now they are pretty cheap. Besides, the C4 ZR1 is the "Original King of the Hill"

Are you down with the King ?

 

[93Rubie]

I am down with the king.

I am only 24 so yes I was 3.

When I do see a C4 ZR1 for the first time, I'll probably freak out, big time.

I've seen maybe 3 or 4 C6 ZR1's and 2 other 93 40th like mine. One auto, one stick.

 

[SnakeDr]

I am down with the king.

I am only 24 so yes I was 3.

When I do see a C4 ZR1 for the first time, I'll probably freak out, big time.

I've seen maybe 3 or 4 C6 ZR1's and 2 other 93 40th like mine. One auto, one stick.

That's scary...because it make me a old man. I have seen a few C6 ZR1s. I have seen a many C4 ZR1s over the years, there is two or more around by me.

I remember seeing the first Ruby Red Corvette and it was the Summer of 1992 at Berkley Heights, NJ.

 

[4CAM LT5]

After 22yrs and 44,7xx miles later, my Dad's LT-5 can still balance a nickle on it's side on idle

Jay

I totally agree with Jay. Can do the same with my '91 ZR-1. Probably the most fun-to-drive Corvettes I have ever had...or driven...!!

 

[SnakeDr]

I totally agree with Jay. Can do the same with my '91 ZR-1. Probably the most fun-to-drive Corvettes I have ever had...or driven...!!

Still thinking about making a brief pit stop on a C4 ZR1. Probably go for a 93 to 94, IF I can get my hands on one.

 

[4CAM LT5]

Still thinking about making a brief pit stop on a C4 ZR1. Probably go for a 93 to 94, IF I can get my hands on one.

You'll be glad you did it...

 

[Tojh245]

I just finished reading my (new to me) copy of The Heart of the Beast by Anthony Young. Awesome book. Like Dave McLellan's book Corvette From the Inside, it left me with more questions than I had before I started reading the book. That being said, to all ZR-1 owners or former owners, how is the LT5 engine holding up as it is at least 16 to 21 years old. I mean yes, the engine mechanically is extremely durable I learned that. How are things like oil leaks, seals, gaskets, etc...holding up? Are the valve springs still good at 20 years old?

Also, I understand some LT5 parts are hard to find but not impossible, that being said, I would assume owning a LT5 could potentially be an expensive proposition?

By the way, I'll take a 93 ZR-1 in Ruby Red please...hahaha...maybe someday. Although, I did see one very nice 92 that had a Marc H. 485 package on it for about 20K in VERY nice shape.

To Hib Halverson, if you read this, did you ever get those Z07 springs and bars on your ZR-1? If you did, how does it handle now?

P.S. I'd like to see the new C6 ZR1 try to beat the C4 ZR-1's 24hr+ endurance record using a production crate engine and mostly stock car like the C4 did. I doubt it could. Nothing against the C6 ZR1 but for me it seems that it never had (has) the same fanfare, legacy, reputation, and enthusiasm as what seemed to be present when the C4 ZR-1 came out. (I was like 3 in 1990 so I'll have to let the history books be my guide on this.) I've seen a couple C6 ZR1's but never a C4 ZR-1.

Well I have one, you're welcome to come see it. I have a couple of problems with mine, the flywheel is one, which I've found, the other is a kind of dieseling sound when I accelerate. A good mechanic said it may be a timing issue, I hope so.. but no one works on them.. at least the dealerships. Outside of that I've got 40k miles on it , interior near perfect.. would appreciate any input..

 

[rkreigh]

Well I have one, you're welcome to come see it. I have a couple of problems with mine, the flywheel is one, which I've found, the other is a kind of dieseling sound when I accelerate. A good mechanic said it may be a timing issue, I hope so.. but no one works on them.. at least the dealerships. Outside of that I've got 40k miles on it , interior near perfect.. would appreciate any input..

Marc Haibeck and Pete are in your back yard. Any good mechanic can replace the flywheel. We can get very good deals on Fizanza alum flywheels. The "diesel" sound you are talking about is likely from the flywheel causing gear rattle.

At high loads and low rpms you can get a kack kack kack rattle. Unfortunately with the lightweight flywheel the car DOES get more noisey with that type of rattle at idle and low speeds.

Stock dual mass are also available but pricey.

As for my old Lingenfelter Special Vehicle (LSV) the 390 has just over 101k miles on her. Near as I can tell the car was build at 18k miles so I have 83k miles on the LPE build. Still puts down over 500 at the tires, and a smile on my face.

The LT5 is one of the most reliable high performance engines out there as long as you don't floor it dead cold otfl