ZR1 v. C5

[UvetteIrace]

Hi gang -

New to the forum here, and before actually signing on board, I've read many of the inputs people have, and truly amazed at the high level of knowledge about cars and Corvettes. Most importantly, the responses to the comments and questions have been so amenable compelling me to join.

Now that im ready to purchase my first Corvette, I would like to do it right b/c this maybe the only time. I have boiled the corvette I want into two - the ZR1 or the C5 (more than likely a 2003). In either case, the price will be somewhat the same, but obviously the ZR1 will be a used car. Since I dont have the finance for both, I must choose one of the two.

My question is about the ZR1. If the ZR1 is accepted by the Corvette world and the non-corvette world as the best Corvette (King of the Hill), why is the engine based on OHC, when (and please correct me if I'm wrong) the Corvette is the "torchbearer" for the "push-rod OHV engines". To my understanding there is or has been a big debate on which engine type is a better: Overhead valves or Overhead cams. The former offers torque and HP (displacment), whereas the latter offers mostly HP (rpms). Is that right?

Why did the corvette people decide to put an OHC engine in making the 'best Corvette ever'. And why does the corvette world accept the ZR1 as the best corvette, YES IT IS A GREAT CAR, but a denial in the debate over the superiority of the push-rod OHV against the OHC?

WHAT REASONING(S) ABOUT CORVETTES AM I MISSING?

 

[ZR-1 Fanatic]

We are fortunate and blessed to own both a ZR-1 and a C5, and either would make a great car for you. Some other questions that may affect your decision are:

Daily driver?
Is gas mileage an issue?
Auto or 6 speed transmission?
Do you anticipate driving with the top off regularly? (I'm assuming you would buy a C5 coupe)
Is luggage space an issue?
Is rarity factor an issue?

For a daily driver the C5 is a better choice, IMO. It gets way better mileage (the current averages on both cars are 15 mpg for the ZR-1 and 21+ for the C5). The C5 has LOTS of luggage space; we take it shopping for groceries and never run out of room, and we have 3 teenage boys! The C5 chassis is much stiffer than the C4, and taking the top off the C5 makes no difference in the ride. Take the top off a C4 and it feels like it's going to come apart, especially at speeds below 50. The ZR-1 will outrun the C5, but not by a whole lot until you get seriously into triple digit speeds (not that we would ever do anything illegal...

Having said that, I drive the ZR-1 everyday to work unless there's precipitation in the forecast, and if we had to divest our collection it would be the last one to go (although Liz may argue that). As you point out, it is the only Corvette to ever have an OHC engine with 4 valves per cylinder. It makes a sound like no other V8, and makes the radio obsolete. It has a personality that the C5 doesn't, and it's hard to describe except to say that it just feels more like a race car. There were only 6939 made, and unfortunately there have been several hundred totaled. They will be sought after in the future and, IMO, the price will rise over time from current ridiculously low levels.

The best way to find out what YOU want is to drive both; that will probably make up your mind.

BTW, there are many who argue that the Z06 is the best Vette yet, and I'm sure they'll chime in here.

 

[Rob]

Good topic and questions!

I think that the reason why the ZR-1 is known as the "Best Corvette ever" or whatever the slogan may be is because, for it's day, the technology was pretty advanced and the performance pushed the Corvette into the competitive territory of European exotics that cost twice as much as the MSRP of a ZR-1.

That technology and that performance commanded respect throughout the automotive community. However, as technology has progressed, the whole concept of the LT5 engine literally lit a fire under the rear-ends of GM Powertrain to encourage them to find a way of making the pushrod motor just as powerful, and efficient as the LT5 was, but at a much less cost in terms of development, production and mass/weight. For more background information, I would highly suggest running through this thread:

http://corvetteactioncenter.com/forums/showthread.php?s=&threadid=14104

 

[JT ZR-Won]

I think Barry said it perfectly. They only way to find out is to drive both. I also agree that if it is a daily driver I would probably chose a C5 simply for the increase in comfort level. The ZR-1 does have a very unique sound like none other and performs amazingly for a car that's been out for 13 years.

You might want to check out a book by Anthony Young called, "The Heart of the Beast." It will explain a lot of unanswered questions concerning the idea behind the making of the ZR-1.

The good news is that you're in a "win-win" situation. Good luck in your choice.

Jay

 

[UvetteIrace]

Hey Thanks for your response : For minute there I thought i was not welcome in this very welcoming forum.

And yes, i was thinking about a daily driver, and the dimensions of the C5 are more suitable for daily driving compared to the C4 (as my research goes on). Is the leg room in the C5 truly more wider than the C4 b/c they moved the transmission to the back?? If they did, why does the back have so much room as well?

In any event, I am really crossed between Calling Rick Daniels right now and request a new C5 from the factory ( and I want to do the NCM thing to make it special), and this really "drop dead gorgeous" 1991 White ZR1 with low miles (16k) for a price of 26k. Im thinking i could low ball him to 20k or even 22k which i can pay out right in cash.

The only thing is Im the type who hates hand-me downs. I have to be the first in, howver, thsi ZR1 is really beautiful

 

[Rob]

You're more than welcome here. You don't have to be an owner to be a member here.

There is A LOT more leg room in the C5, however, if you really love the ZR-1, take it for a test drive and test drive a C5. They are two completely different Corvettes from the ground up. See which one pulls at your heart strings more. Whichever one it is, is the Corvette for you.

I love the C5....but for obvious reasons, I'm quite partial to "The Corvette From Hell"

 

[UvetteIrace]

hey rob thanks for the exciting links for me to check out . . . and yes I read somewhere (i think a mag called " Corvette Magazine" about the logistics concerning the production aspects of a powerful OHC engine - thats why both the ZR1 and the Nissan 300z are gone of the do-do bird. Thank goodness though, that the ZR1 came out the best from that catagory.

JT-ZR-won::s YOU HAVE A GREAT ZR1 i think you know exactly what i feel when I see that ZR1 that caught my eye.

:cool :crazy :love

 

[Vettelt193]

You may just want to do a C4 Vs. C5 comparison first... then look at the benefits of the ZR1... My Dad has a '98 Pace Car, and when I drive it, it feels more like a cruising, easy going (but fast) 'vette. When I drive my C4, it feels more like I want it to... very race car like... The lack of leg room and tight interior actually makes it feel more sporty, and better to me... but, for my father, It is a chore just to get in and out of my car. It isn't that much fun owning a car that is difficult to use, so one of the things to look at before even considering a ZR1 is the way the car feels to you. After all, you will probably only push the limits of the car 5% of the time, it is the other 95% (normal driving) that matters.... If you want the cruiser feel: C5, race car feel:C4/ZR1

 

[secondchance]

Hi, UvetteIrace, welcome to the forum.
To answer your question, in my opinion, OHV 's advantages are simplicity, lightweight and relatively inexpensive to manufacture and repair. As far as torque is concerned, I think it is more of a function of displacement, all things being equal (I know I¡¯m over simplifying here).
Actually, its weakness is, for high rpm hp, one has to sacrifice low rpm torque (remember old built up muscle cars running on the verge of stalling at idle?) and vice a versa. Reason for this, is for high rpm, intake and exhaust valve openings have to be large as possible and stay open as long as possible for maximum amount of air/fuel mixture delivery. However, at low rpm same large opening results in relatively slow intake velocity creating poor vaporization and end result is loss of low rpm torque. Smaller valve area solves low-end torque but restricts high rpm horsepower. The same issue applies to OHC engine also. However, Lotus side stepped this trade off by resorting to utilizing one set of intake and exhaust at low rpm (smaller area = high speed intake at low rpm) and using all 4 valves at 2500 rpm and up (max area for high rpm fuel delivery). Some modern engines from Honda and BMW uses variable valve timing to keep valves open longer to address the same issue.
Another advantage of OHC is reduced reciprocating mass due to using spinning of camshaft to operate valves directly as opposed to single camshaft in the V and using rods to operate valves. Incase of 4 valve V8, you end up with 2 camshafts per bank, 4 camshafts total.
Independent of above comments, any motor, OHC or OHV, careful manufacturing is also crucial to high rpm and long term durability, especially when running at high rpm for long periods of time. In this respect, LT-5 was manufactured with unusually high level of care. Also, its split block design with lower block acting as a girder for the crankshaft minimizes crankshaft wobble, again resulting in high rpm capability and durability.
Frankly, apart from motors, I think C5 is superior to C4 in terms of structural integrity and handling. As far as motor is concerned, despite LS6 posting similar numbers for hp and torque, anyone who understands engineering will pick LT-5 for its logical, superior engineering. ¨ù drag racing is one thing but 24 hour endurance run will separate a good engine and a great engine.
This does not mean you should go for a ZR-1. However, since you asked, I thought I would share my understanding in this subject.
My 91 ZR-1 and now 94 was and is my daily driver.
BTW, I don't understand how to fill out the survey.
Hi, Vettelt93, somehow I knew you would join in on this one.

 

[UvetteIrace]

oops :duh sorry about my survey/poll, when i started i wasn't really sure how it functioned . . . but basically: I wanted to know from people whether they thought OHV gives Power or Speed, or Power and Speed, and is it effectively efficient (in operation - less mechanical breakdown, I understand that the push-rod have many intricate moving parts, ehnce more prone to breakdowns), and the same question and answers for the OHC.

In any event thanks for your inputs (secondchance + vettelt193) . . . thats an interesting aspect you pointed out concerning the issue of compactness with the ZR1. It would truly feel like your ina fighter jet, and certianly have the speed for it.

I also like the instrumentation of the ZR1's, it truly looks like a cock-pit of an F-16 tomcat.

Secondchance, thanks for that in depth anaysis (basically an education) in the complex system of automotive engines - im truly learning everyday. An yes I do want a daily driver, and it sems that the C5 has been designed and built to address that situation. From the many articles I have read about Corvettes is space/leg room . . . but vettelt193 has offered a new insight for me regarding the tight feel.

thanks again ;worship

 

[USA ZR1]

I guess it depends how tall you are when discussing the "tightness" of a C4 interior. I'm 5'8" and my ZR-1 has tons of room for me. The lower door sills on a C5 allow easier entry but I like the seats and seating position of a ZR-1 better. Different strokes,,,,
Barry,15mpg average??? Your right foot needs to go on a diet.
Sheesh,my modified car gets that in town and easily knocks down 25+mpg on the road,,with 4.09 cogs.

 

[Adam Boca]

You asked about a couple questions about leg room and trunk space. Below you will see a comparo I just did here at the NCM. I know the pics are not that great, but an idea of floor space, trunk space, and engine. Enjoy!

Here is a C4 floor with a 12' Ruler. It almost got hung up.

Here is the C5 floor with the same ruler.

Here is the C4 Floor with a 15 inch ruler. The pictures do not show it to well, but here the ruler did not touch the floor board.

The C5 Floor, as you can tell, the C5 does have more floor room due to the tranny being moved to the rear.

Here is trunk area on the C4.

Here is the trunk of the C5.

ENGINES!

C4 LT5

C5 LS1

I will comment more on my opinion when I get home shortly.

 

[ZR-1 Fanatic]

IBarry,15mpg average??? Your right foot needs to go on a diet.
Sheesh,my modified car gets that in town and easily knocks down 25+mpg on the road,,with 4.09 cogs.

Cruising on the freeway at 80 I can get mid 20's for mileage, but around town let's just say I do my best to inhibit carbon build-up in the intake....

 

[Jeffvette]

I use my Zr-1 for daily driving, hasn't given me any fits or problems, then again it's gotten to be fiesty in doingthe 368 conversion

I've driven a few C5's and to me it seemed like I was riding in a Caddilac and the driving response felt liek a Caddy Granted it was quick, but everything was to plush. The C4 on the other hand, has a cockpit feel to it, it gives you feedback on the road, the handling is still awesome.

The choice for me was a ZR-1 as I have dreamed of owning one since I had gotten a ride in oe when I was 13. Took me 10 years to get one, but I got it.

 

[ZROne]

Well, the reasoning you are missing is that GM is in the business of selling cars as cheaply as it can. The corporation touted the LT-5 engine as an engineering tour de force (which it was), the people loved it - and the press drooled over it.... and GM canned it because it became too expensive to manufacture (since it was outsourced).

They took the lessons there and made the Northstar.

The people who like to claim the pushrod smallblock is the height of technology are the same ones who would like you to buy Suburban's because they are cheap to make and cost a mint to buy.

Basically - the LS1/LS6 are fine engines. Probably worthy of much praise. However they are not that sophisticated; and tend to blow up when subjected to lots of stress over a period of time; but for what they are made for - cheap power and easy to replace parts - they shine. The LT-5 route is not cheap to produce or fix.

As for the daily driver debate - I've had a C5 convertible, two ZR1's and a C3 (still have the C3 and my latest ZR1 <g>).

The C5 is flat out much more comfortable than the ZR1 will be. That should be pretty evident to those who drive both. The C5 is a very good daily driver and commuter car. It even gets good gas mileage (my ZR1's get about 15MPG at best).

I have driven both the C5 and my old 1990 ZR1 around the country once (each). The C5 was by far the easiest to just fly around and not feel tired or cramped. A very good cruiser.

The 1990 ZR1 was more fun ... and it wasn't too bad around the country, but it's no C5 in terms of comfort. My 1994 ZR1 was actually pretty close in terms of comfort - but it's not anymore <lol>.

The next Vette I get will be a C5 Pace Car most likely (mostly because they will be dirt cheap soon and I don't want to beat the hell out of my ZR1 on these crappy Dallas roads [and Texan drivers]).

sirhC

 

[UvetteIrace]

ZROne : thanks for sharing your road experiences between the two Vette types.
Hey Adam - I appreciate the comparsion photos, it clarified some thoughts for me about the sizes of the two.

But i thought that the OVC engine was easier to manufacture than the OHV (b/c it has so many parts). So the advanced technology of the LT-5 is not simply based on OHC, but many other contributors are involved in its making as well, right? Its' not just another OHC engine like the ones Japan or Germany produces. Or are OHC engines in general are better than OHV engines b/c it is harder to manufacture, and it is harder to maunfacture b/c it is far more superior in technology to build?

Now my new question is " If I wanted to build from scratch a new car ( just the way Delorean did it, but not for mass production, just for myself), would I be better off manufacturing an engine based on OHC or would i be better off with OHV (V-8 or higher), if I wanted high performances without any sacrifices - Power, Speed, and efficiency/durability.

Or perhaps one can achieve it all in both types of engine, it just matters what new contributing factor(s) one adds to it.

 

[secondchance]

If I may, let me clarify a few other things. First of all there are 2 types of OHC engines: single OHC and dual OHC. Single OHC can be designed to actuate 2 valves per head or 4 valves perhead. Dual overhead cam setup typically uses one for intake side and one for the exhaust side. OHC set up typically has more components then OHV due to camshafts and drive mechanism needed to run these cams. Also, typically more expensive to manufacture and assemble.
If you want mass production and lower cost, OHV is a cost effective way to go. If you want a motor that produces low end torque AND high end hp and the cost is immaterial, DOHC V8 or V12 is the way to go. Look at Lamboroghinis, Ferraries and Aston Martins.
I totally agree with ZRone's comment that one of the primary reason Chevrolet went to OHV for LS1/LS6 was due to lower cost of OHV. To be fair, another reason was due to relatively lower weight of OHV.
True difference of these to types of design shows up not on the drag strip where engine only needs to perform for 12-14 seconds but in an endurance race lasting hours.
Remember in 1990, Chevrolet set the endurance record w/ stock ZR-1: 24hours @ 175.??? mph. That record was broken last year by VW purpose built prototype. I doubt tha LS6 could achieve the same.
BTW, nothing wrong with Japanese OHC engines, typical displacement is too small for torque and hp. Germans are starting a hp war. Audi RS6(?) produces 450hp and some top of the line Mercedes are producing 400+ hp and 516 lb.ft of torque albeit with help of supercharger.

 

[Remo]

C5 Common Sense

UvetteIrace,

In your case I would recommend a new C5 for the following reasons:

1. It's an all around more comfortable car.
2. It's performance is excellant.
3. If you're worried about the max performance thing - then get a Z06.
4. You don't have to worry about what the previous owner(s) did to the car.
5. The new C5 will have a warrenty.

Regards - Remo

 

[A26B]

There have been some outstanding and frankly unbiased opinions rendered here and I'm very proud of my bretheren for that. You all are a class act.

For my input: I wrestled with the same questions last June and ended up buying a 94 ZR-1. Why: I wanted something unique and exotic. You can't get that in a new C5. It's a kick talking to others who never heard of a ZR-1. I feel that way even more so now! Absolutely no regrets for my decision.

Comfort?? My wife is a real sport but was aprehensive about riding in a Vette, especially on road trips. She drives a Cadillac STS daily. We made the Eureka Springs, AR event from Oklahoma City and when we arrived she commented that she was definitely and plesantly surprised at how comfortable it was.

Decision is really, do you want to be unique and exotic or somewhat ordinary & common?

Good Luck in you choice. As it was once said "Choose wisely Grashopper!"

 

[Remo]

Unbiased Indeed

Jerry,

I agree that we were doing well about being unbiased - untill you ended your message with:
"do you want to be unique and exotic or somewhat ordinary and common".

Just an observation from an ordinary and common guy.

Regards - Remo