Just bought 1991 ZR-1, how do I drive it???

[zr-1chad]

I know, it sounds like a funny, and/or stupid question. I've owned countless Corvettes in the past, along with many other classic pieces of GM iron, but obviously the LT-5 is a very different beast. It just seems to love high RPM's (obviously). Should I be driving it in the higher RPM range (above 3500) most of the time, or should I just treat it like any other V-8 engine, and drive it normally? I drop it into 6th gear on the freeway, and obviously it's almost useless. Seems like it really lugs the engine, and I don't like doing that. What is a good max RPM to hit on hard acceleration, etc.

It almost sounds like I want to beat the car, and that's really not the case. I had looked at one last year, and the seller seemed very knowledgable about these engines, and told me they were designed to spin 11k. Obviously, I wouldn't consider doing that at all, but I am curious about what it can really do.

The car is amazing. 39k original miles, Med. Quasar Blue metallic, looks showroom new, has a chip (unknown specs), and flowmasters. I am absolutely in love with the car. No rattles, squeaks, or abnormal noises.

Any advice for the new ZR-1 owner is appreciated!

Thanks!
Chad

[xlr8nflorida]

There really is no right or wrong way to drive a ZR-1. If you drive it easy though, you definitely want to get on it here and there because the LT-5 is known for Carbon deposits.

You have to be moving pretty good for 6th gear 70+ or it will lug, so you usually stay in 5th or you can stay in 6th for fuel economy etc... should add some speed so you don't lug. You also want to drive it aggressively to exercise the secondaries as well.

If your injectors are stock, you really want to find ethanol free gas if at all possible as the ethanol can ruin the injectors over time.

You don't want to over rev the engine. The guy who said 11k is clueless. Also if you take it redline all the time, its hard on the accessories, water pump etc. Many take it to 7200 all the time and beat the snot out of it. It's designed to be driven aggressively and the LT-5 is bullet proof. Also don't take it to the bank but on some cars, the analog RPM gauge seems to sometimes be off a few hundreds.

We all have different driving styles, my Z is pretty fast and my roads are somewhat limited so I drive in the high RPMS but am not redlining alot. In the first few gears, I have traction problems as it is.

Many feel the harder, the LT-5 is driven, the better it performs.

I like to wind up 3rd and 4th gear which is not as hard on the drivetrain.

Bottom line - you can drive this car hard but like any car, if you hammer the redline, speed shift, do alot of burnouts etc, eventually it takes its toll on the car and repairs will be in order. (more on rear, tranny then the LT-5)

The LT-5 is rock solid built for 200,000 miles.

Make sure before you start winding it out that you have good coils, injectors, wires, plugs, waterpump, fresh oil, fresh coolant (green only - no dexcool) etc.

Also, many people may disagree but I let my car get up to temp before I start getting on it. The LT-5 takes awhile to warm everything up on account of the 12 quarts of oil etc. I drive my car easy probably the first 15 minutes and let all the fluids and mechanical parts up to temperature.

Keeping the secondaries clean is important which is why you like to kick it in that 3000- 3,500 range. Also most people don't realize but that is not the only way to exercise the secondaries. For example if you are on a long cruise say 500 miles and for 100 miles you just want to chill, drive slow and clean the secondaries. You can push the pedal to the floor then let it back up 90% but not all the way 100%. If you keep the pedal down that small amount, the secondaries will be getting cleaned the entire time until you lift your foot off. If you lift your foot off, you need to do the procedure over again.

But of course, the more fun method is to just hammer it along, and enjoy all the gears on your trip!!!

You will love the ZR-1 and soon have what is known as Perma-Grin!

Welcome to the Brother Hood

[zr-1chad]

Thanks for the advice. I have let it warm up completely before getting on it. And I don't get on it that often at all. When I've driven it on the freeway, it just seemed to really be in a sweet spot at about 3k. The previous owner claims the injectors were replaced a few years ago.

I'm still learning about the secondaries. I'm assuming everything works fine, as it's not lacking power. I do get a little bit of a ping on when I open it up at higher engine speeds. It's running on Chevron supreme. Maybe this is normal? I had a LS2 GTO, and that car pinged all the damn time on acceleration.

In all reality, I do baby the car. It's in such nice shape. Came with extra parts that apparently the original owner bought when the car was new. New in the box radiator, starter, waterpump, misc interior trim. Etc. The car is really just exceptionally nice and clean. I feel I got an excellent deal on it at $17k. The only issues are the A/C needs charging, and the radio isn't working.

Not sure what chip is in it. Although I do know that that the power key does nothing now. It's always in full power.

Thanks again, keep the advice coming.

[xlr8nflorida]

It's not like its going blow up if you don't let it warm up but it makes me feel better to warm everything up to operating temps. That is great if the injectors were replaced. There is an entire graph of when the secondaries open up and its triggered by many things, one of which is temp. At the 3,000-3,500 range is where it feels like a turbo or a kick in the pants, that is where if you "get on it" the car is going take off fast. If you are a new owner or have a new passenger, they should be like OH ****, when you floor it. If not, you may have secondary issues.

You should not have pinging. The LT-5 does make different sounds then a regular engine. Are you sure its pinging? The computer will adjust timing if need be or should be anyway. Try a different gas station and only run 93/94. As a good measure since the car is new to you, inspect serpentine and hoses.

You got an excellent deal and all those extra parts are nice to have on hand.

The bose radios are always an issue over time. The guy you want to talk to is Dr. Don http://www.doctordons.com/

He has fixed 4 bose radios or me. It's $150 to fix CD player and he also can fix amps and other parts of the system depending on your issue. He can have the radio back in 1 week time. He can also make it play CD-R's or put a plug on it for Ipod etc but that is extra $$.

If you have 91 and its always on then you must have a chip. You can take the ECM out in 3 minutes after you unplug battery. Undo the screws on bottom and inspect the chip, it will say: SGC/Haibeck/Corvette Consultants/ DRM etc. Also a good time to make sure your clutch master has enough fluid in it as these ZF-6 trannys are not cheap to fix.

The car is fast as is and for most of us we have modded even more. It's not a rice grinder where you need to beat it to be fast. It's fast already and then when you get on it 100% its really fast. Each person is different, I have 1 friend who went through 3 transmissions on his LT-1. He would rev it to 5,000 cold, do a burn out in reverse and then leave tire marks leaving the parking lot while hitting rev limiter. That is how he liked to drive. He also hit the rev limiter probably 30-50 times a day. That being said the LT-1 never blew up. I find that type of behavior very abusive and not my style at all.

I think the tranny is rated to 450 hp or more if I'm not mistaken so unless you are sloppy shifting, missing shifts or power shifting alot, you should be fine.

Don't be afraid to drive the car hard though - as Dave M - the engineer of the C4 ZR-1 said, the LT-5 loves it!

There are guys on this forum that absolutely punish the car at the strip and race track in endurance races and there are no issues. That is why the LT-5 engine set the 24 hour endurance records in the world and internationally - the motor is that good!!

I have other Corvettes that I don't care about as much. As I get older though, I tend to be driving them easier and easier.

My C5 is boring compared to my C4 - 345 HP LS1 engine is dull, so I just lug around in 6th gear.

[Kevin]

drive it like you stole it. 6th on the highway is largely useless unless you've got gears in it. as you said these things love to rev, and i do mean love. I make it a point to run mine to redline at least once per drive. after attending a talk by mark haibeck, you'll know him well soon, the zr-1 just has tip in knock and there's not much you can do about that.

congrds on the car, you'll love it

[zr-1chad]

Maybe I do have secondary issues. The power seems smooth all the way through. No real kick in the *** at 3500. What do I check?

[xlr8nflorida]

Originally Posted by zr-1chad

Maybe I do have secondary issues. The power seems smooth all the way through. No real kick in the *** at 3500. What do I check?

It's smooth, its not like a big turbo lag. Let's put it this way, if you were about to race someone, you want to be in that 3-4k range which is the sweet spot. When you floor it, the car will respond, make a ton of noise and start pulling like a freight train.

The car should do low 4's to mid 4.5s in 0-60 and do a quarter mile in high 12's. I believe stock gears can get you around 60 mph in first gear or a quick shift to 2nd for 60. Does that sound about right?

If the secondaries don't work you only get like 245 on valet. You should be able to tell if you are getting 245 or 375 by the seat of the pants feeling.

[tomtom72]

and welcome to our asylum!

I'm sure in the Tech section sticky by Dynomite has a guide to doing trouble shooting the secondary system.

A quick check for vacuum integrity in the system is to use a mity-vac hand pump at the vac line that goes from the pump under the right headlight, and routes under the plenum by the alternator. At / near the alternator there is a connection point that you can unplug. At that point you apply vacuum to the side of the line that goes under the plenum. If it holds at least 8" usually the system is okay up to the control solenoid, check valve & tank. If while the line is disconned you turn the ing key to "on", and you should hear the vac pump run and if you plug the pump end of the line with your finger the pump should shut down after pulling a vacuum. The next check would be for the actual pull off canisters on the 2* linkage, Secondary Actuators they're called. On the drivers side, under the ECM & it's bracket, there is a MAP sensor. Pull the vac line off and apply vacuum there and if it holds then the left side actuator is holding vacuum. I want to say that the vacuum line in between the runner groups for #4 and #6 cyls can be used to check the right side actuator....but I think my memory is incorrect on this. We should have a diagram for the vacuum lines in the secondary system here in the "solutions" sticky. Use that and not my senile memory!


Tom

[Paul Workman]

A couple things come to mind...

1) According to Marc Haibeck (one of THEE professional ZR-1 gurus), the factory fueling is a "bit fat" for normal driving. This is part of the answer to the occational comment about carbon. However, since you have a modded chip, that may be behind you. In any case. at least one or two 7k blasts per outing will keep things relatively clean and the LT5 will love you for it!

2) You might want to measure the resistance of your injectors when the engine is warm/hot. I too had injectors recently installed in my car when I bought it. Yeah, turns out they were NOS, and simply replaced with the same stock injectors that had issues with alcohol in the fuel. (More on how to do that later)

3) You won't get much of a "kick" feel when the secondaries come on; I used to feel a little bump, sometimes, but usually the transition is pretty seamless. And, the secondaries are controlled by several load demand situations; not just rpm. Any time throttle is more than (about) 75%, regardless of rpm, the secondaries come on and stay on until throttle drops below about 10%. (Punching it and then backing off to cruise control will result in the secondaries remaining open as you cruise, which will serve to clean the secondary intake valve that gets pretty carboned up, if not "excercised" some.)

4) Go WOT and if it pulls like a freight train to 7k, the secondaries are working. However, if it suddenly falls on its face around 5500 or so at WOT, it could be the "accordion" snorkel between the air cleaner and the intake is collapsing. Easy fixes: Mark Haibeck has some little wire hoops that fit inside the snorkle and keep it from collapsing at WOT. Or, and what is perhaps preferable, some fab up an aluminum sleeve that fits inside of the shorkle. (Theoretically, air flow is smoothed over the surface of the tube.)

5) The LT5 responds very well to some simple DIY mods, e.g., top end P&P will buy an extra 30 hp or so.

Gotta run. Welcome to the Brotherhood! Your gonna love the ZR-1

P.

[sammy]

he lives in california home of junk 91 oct fuel .so no 93-94 unless you cut it with 100 oct unleaded