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Need help with 92 SuperNatural !!



Hi, folks! I'm a new member with a unique problem. Two years ago, I bought a 92 LT-5 Supernatural (all internal mods, no aero panels) with NO paperwork. (Yes, I'm a sucker!) Turns out this car, with Callaway written all over it, is NOT your average Vette or your average ZR-1. The original owner (anyone know Art Resnick?) had a Callaway "kit" put on it by Steve Moore Chevy in Boca Raton FL. (Reeves was out of biz for a while 89-93 and sold stock to Chevy for dealer installs - got this from Ed Prout, former Callaway engineer in '99 when I bought the car.) Unfortunately, this means that Callaway has no database info on it as a Callaway, but it's got the signs all over the car and it is a Monster!! Art even had it reworked to eke out another 75hp, from 475 to 550 (I haven't dynoed it). And it has been all the car that Art said it was (nope, I didn't buy it from Art and this isn't smoke he was blowing up my skirt to inflate the price!).
At any rate, I finally had to take it in for some work and asked the tech to decode it and see if he couldn't fix the high side (just running rough). Well, he found a vacuum connection undone and connnected it, and now I have NO high side. Without paperwork, I stand little hope of getting the monster side of the car back. If anyone out there can steer me in the right direction to get some info on basic SuperNatural specs/mods, I'd appreciate it.
This is an LT-5 with Watson Headers and a lot of TLC put into it. I'm working with Steve Klein in Tampa to get it back up to speed, but we need some basic info on numbers to expect out of the engine. Any help would be welcome.
I need to know what you mean by high side? Do you mean power mode? Are you talking about upper rpms? If something was done by a dealer I wonder if all that was done was just bolt ons I will have to find my old info from Callaway to see what they offered back then. I just need to get a better understand as to what the problem is before I would be able to help.

David Fulcher
I need to know what you mean by high side? Do you mean power mode? Are you talking about upper rpms? If something was done by a dealer I wonder if all that was done was just bolt ons I will have to find my old info from Callaway to see what they offered back then. I just need to get a better understand as to what the problem is before I would be able to help.

David Fulcher [/B][/QUOTE]

David, thanks much for your response; I appreciate it. Yes, I meant full power. It's just disappeared! I heard from Stan and Callaway that the norm-full power switch is unaffected by Callaway SuperNatural mods so it should still respond like GM factory. We'll go back at it with that in mind. When I took it in, it ran "a bit ragged" in full power; bogged down badly at low RPM, but OK at high RPM. Like it was running really rich (do they all?). Anyway, after being fixed, it's normal power and nothing else. Something's wrong. We'll check it out with the book.

And I think you're probably right again about bolt-ons, too. That would seem logical with a dealership doing the mods.

By the way, folks, I'm pleasantly surprised already at the reception on this site. I opted off the ZR-1 site after getting the "you ain't one of the clique and your car sucks" treatment. Thanks again, David, Stan and all!!

First of all, let me just say, regardless of whether or not you own a Callaway, a ZR-1, a solid axle, or a mid-year, they are all Corvettes, and that is the ONLY thing that matters.

From what I'm seeing here, the problem you're experiencing isn't specifically a Callaway related problem, but an LT5 problem. In particular, it doesn't sound like the secondaries are opening.

This can be due to several things, but first, let's establish a baseline of normal secondary operation. I don't know how your ECM is programmed in regards to the Callaway modifications, but on a stock ZR-1, with the power key turned to full power, the secondary port throttle system should come online around 2800 rpm. If I recall correctly, the 1st generation and 2nd generation LT5 engines maybe a little different in terms of the exact RPM the secondaries, open, but regardless, you should feel that usual kick in the seat around 2800 rpm.

The secondary port throttle plates operate on vacuum. There is a vacuum pump located in front of the coolant reserve tank on the passenger side engine compartment just under the headlight. This pump supplies vacuum to the secondaries. The vacuum system consists of a plethora of tiny hoses that are located under the plenum and connect to two secondary port throttle actuators which are located in the middle of the fuel rails. As vacuum increases, these actuators gradually open the secondary port throttle plates. The actuators do fail over time. They also have to be installed properly because if they aren't, the movement of the diaphragm arm is limited and the overall function of the actuator is decreased. Therefore the throttle plates will not open all the way.

Due to age and heat, the secondary port vacuum hose system under the plenum can crack causing small vacuum leaks. Along with this, the vacuum pump is prone to failure due to its location. It is prone to water damage over time. Once water gets inside, the pump shorts out. If you have a well sealed secondary vacuum system and the pump is burned out, the engine can still produce enough vacuum to power the secondaries. Normal operation will continue and no engine codes will be set. This isn't always the case though.

One of the simple things that you can do is test the pump and vacuum system to see if it's functioning normally. To do this, get in the car and turn the ignition on, but don't start the car. You should hear the pump turn on and prime the system. If there are major leaks in the system, the pump will run constantly...it will not shut off (which can lead to eventual pump failure). The pump should run for about 5-10 seconds to prime the system and shut off. You may...every minute or two hear it click on and off. This is normal. If it clicks on several times within a minute, you may have small leaks within the vacuum hose system under the plenum.

If you're not sure that the pump is functioning properly, with the key left in the on position, go over to the passenger side engine compartment. Near the oil filter you will see a small vacuum hose with a "juncture". One end leads to the pump in the front, the other goes under the plenum. Unplug the hose being careful NOT to bend it. There is a platic hose connector inside that can break off and if that happens, you have to replace the entire hose system. It's not easy to pull the two hoses off sometimes, but it can be done. As soon as you do, the pump should kick on and run constantly until you connect both ends in. If it doesn't, the pump is probably burned out and you'll need a new one.

If you have access to a vacuum pump, you can connect the pump to the other end of the hose leading under the plenum and manually try to open the secondaries.

I can't recall the exact Hg needed to open the secondaries, but it's buried in my service manual somewhere.

Regardless, these are simple steps that a knowledgeable Corvette mechanic should be able to do for you.

I'm not saying your secondary port throttle vacuum system is the cause, but it is a possibility that should be checked. Be aware that if you need to have one of the actuators replaced, replace BOTH of them and make sure they are installed correctly. If they are installed backwards (which it is well known that some LT5 engines came from the factory with actuators installed backwards), they will not function properly.

I hope some of this helps in some way. Good luck and definitely keep us posted!!!
Rob has done a good job passing on a few things to look at, the vaccumn pump is a common falure they will also brake at the vaccumn line fitting. Another possibility is that the throttle plates could begummed up keeping the secondary plates from opening I have seen this on cars with a lot of local driving a lot of short trips. Also you have not stated how many miles are on your car you could also be dealing with a plug or wire again a lot of short trips and locial driving can do a job on the plugs and a bad plug or wire may not seem to be a problem at high rpms compaired to low rpms. You have a few thing to look at but I'm sure if you are able to find someone near you that is trust worthy you will be able to find the problem but don't forget got to check the simple stuff first, spark plugs, fuel filter and MAP sensor hose.

David Fulcher
ths92zr1cal said:
(Reeves was out of biz for a while 89-93 and sold stock to Chevy for dealer installs - got this from Ed Prout, former Callaway engineer in '99 when I bought the car.)

Hi - Welcome to the forum... I'm new here too! But know most of these guys from the other Corvette forum that David eluded to where the ZR1 guys get cranky when we talk about Callaway's. Anyway, I don't know the answer to your specific problem but am puzzled by the statement quoted above. Those years were major in terms of Callaway actually being into producing tuner Corvettes. They made the TT's from 87-91 and then started SuperNatural production in '92. How could anyone say Reeve's was out of business and farmed out parts to dealers? No way. He's such a control freak he'd NEVER to that even if it was advantagous to him in some way. I think someone is blowing smoke. You should try to dig up more history on your car if you are concerned about it's authenticity as a Callaway. Basically, if it wasn't converted in Old Lyme, CT it's probably not a legit car. Not to say that someone couldn't have finagled all the parts necessary to build it though.
Re: Re: Need help with 92 SuperNatural !!

90Callaway said:

How could anyone say Reeve's was out of business and farmed out parts to dealers? No way. He's such a control freak he'd NEVER to that even if it was advantagous to him in some way. I think someone is blowing smoke.

All I can tell you is that Ed Prout, who was Chief Engineer at Callaway in 1999, when I bought the car, told me that in a phone conversation about the car's history. (The dates may be off a bit, based on my fading memory.) I too was skeptical, as you are; so I called Callaway and asked them to run the VIN. And you'll be interested to know that Wayne McCurdy, current Engineer with Callaway, is researching the car right now, based on the same story. Whatever it is, the car's a real monster and unique as they come; just wish I could get to the bottom of this interesting case. Thanks for your interest.
Trying to clear up a few things

Hi Guys,

I hope no one mines me jumping here for a minute. The person 92ZRLCAL is referring to is Bill Prout.

Callaway has never closed there door ever since opening in Olde Lyme, CT. As to "farming out work". I cannot see that either. I was very close to them during those years and I never heard that thought mentioned. In fact, they had Barry who owed the Supernatural ZR1 Twin Turbo bring his car in for a simple oil sump pump installation that he could have done by a good GM tech. 90 Callaway is right, Reeve just would not do something like this.

It is possible that the CHIEF performance Package which was sold by Callaway for the ZR1 (about 40hp+ increase) could have been install by an outside group as Reeve sold this without installation. A few good pics of the engine close up to the headers will show if this was the case. This package was almost all "bolt on" except for the "flywheel" change over.

This would have qualified a ZR1 as a Callaway car.
Hope this helps..................

Wayne is a nice guy to work with - you'll get a straight answer from him one way or another on the originality of the car.

Stan is correct - Bill Prout would have been the contact at Callaway, although he left about 2 years ago to take a position with Rolls Royce; he is still active in running racing schools in the Northeast as well. Bill was the Sales and Marketing Manager at Callaway. Bill was great - he drove me between New York City and Old Lyme a number of times while they were working on my car.

By the way, Callaway's East Coast Dealer is Manhattan Motorsports, located on 11th Ave and 28th Street if you're looking for a C12.

If the motor was a true Callaway Conversion, there would be records at Old Lyme; I believe all conversions were performed at the facility.

The CHIEF package, however, is more or less a few bolt-on's (expensive at $4500+), which included the following: Callaway EPROM, Headers/Cat-Back Exhaust, Single-Mass Flywheel & Centerforce Clutch, and a K&N filter. The CHIEF package could be bought and installed locally. A Callaway Serial Number was not offered with just the CHIEF package, therefore, it would most likely not classify the car as a SuperNatural.

A few subtle items that Callaway added to their cars to help as identifiers are the "Callaway SuperNatural 475/490" stickers on either side of the rear hatch glass window, as well as "Callaway Corvette" emblems on the front and rear of the car.

sounds like someone just bought the package and had it installed elsewhere, You can still buy a 450 upgrade from them and have installed elsewhere, the upgrade from the 400 to 450 is just a head, intake and exhaust swap without going into the motor itself. without the VIN from Callaway , you'll have a hard time selling it as such, as anybody that buys one , calls them first to verify what was actually done. Sounds like and awesome car non the less. I guess the question would be at what point would a car become a SuperNatural, lower end work, top end, . If it's just a head and exhaust swap I don't think it wold truly qualify as a SuperNatural car or would all the work have to be performed at Callaway itself. Seems like it would as they would not know what could have been done to it. I would see if Callaway could certify it and record it as such. might require that the car be brought to them for them to go over it, but it's worth a shot. Since Reeves is very careful about who buys Callaway parts from them it could be that whoever bought all the emblems had a Supernatural car and sold them to someone else. when you call down there they won't even sell you the windshield banner if you car is not in their database or the emblems for the front and back. what about contacting the dealer who installed the kit, they must have paperwork on what was installed, labor time, cost etc.

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