Hi All,

Stumbled on this site while looking for something else and didn't dig too deep, so my apologies if this is covered elsewhere.

All the stories about this non-F body car beating that F-body car but it shouldn't have so that F-body must have really been a 5.0 not a 5.7 get me wanting to share.

GM/Chevy had at least 3 different computers and/or programming in the 5.0 TPI that all had the same part number and I can only assume a similar case for the 5.7L. Don't believe me? Look at the ignition lock problem. New part, same number, NOT A SUBSTITUTE.

The earliest 5.0 85 IROCs were UNGODLY quick and fast by the standards of the day, and would keep up with a lot of today's fast cars, IMO. These were all early production units that went to GM management types who qualified for company cars. Probably fewer than 200 or 300 cars, just guessing.

I sold one to a friend whose father worked for GM, and he got it after the plant manager put 5 or 6k miles on it. Only an Option 1 or 2 eligible buyer could get a PEV, as they called them. We took it out and timed it through a measured mile and put it's top speed over 150 on multiple occasions. It chewed up 85 and 86 Corvettes off the line and on the road, stayed with the occasional Porsche 911, and ran a few feet ahead of a 455 SD T/A that belonged to another friend at the local unsanctioned street races, until well over the statute of limitations may not have run out, your honor. By comparison, every other one I ever drove, including 5.7s, was somewhere between a dog and a PIG. I'm sure the Corvette issue plays into this in no small way.

Then the car started acting up. At idle, the engine rpm would surge and drop and occasionally stall, so my friend brought it in to the dealership, we couldn't find anything wrong in the limited computer diagnostic world of the 1980s, so after several service visits and elevations of the problem, someone from GM was brought in and he said to change the computer(you didn't just flash/reprog back then). The car was NEVER EVER THE SAME again. Lost all it's giddy-up off the line, lost a solid 15 mph on top, and lost to some other 5.0/TPIs by a lot, light to light. And those cars looked nowhere near as fast his used to be.

Fast forward a year or so, I have an 87 5.7, and another salesman at the dealership does, too. His won't keep up with mine, by a lot. Like 2 car lengths or more to 60. His gets sold and he gets another, and we do our usual light to light BS, and he's right there with me or slightly ahead.

So if you ever bump into an early production 85 IROC with a surging idle (not rough), ****** it up. And don't change the ECM, live with the restarts at red lights.

 

The 85 870 ecm was a piece of Crap !
Sounds like there is more to the story not a very good comparison, gear ratio, tuneup condition, engine wear . Neat street story

 

If a stock 85 IROC-Z EVER beat a Super Duty TA, something was wrong with the TA or the driver. I don't care if there was an IBM Blue Gen supercomputer running the Camaro - it didn't happen.

 

I never said stock, I said factory built, for GM management as product evaluation vehicles, which doesn't usually mean much, but they slowed these cars down several times during development because in the 80s nothing was allowed to go faster than the plastic fantastic sacred cow.

Look the numbers up: stop light racing, a stock 85 TPI IROC should be able to beat a stock a/c'ed SD in a street drag. They were nowhere near as quick as the non a/c cars. Those things needed a lot of road in front of them to get going. Then they kept going. They were faster than the 4 speeds because of the 3.08 rear end. Lived near 8 GM plants growing up, and had several acquaintences who had HO and SD 4 spds, and autos with air, and Formulas, too, that they inherited from parents or bought really used up and rusted out for stupid cheap. I know how fast they were. Even with 100k and an oil addiction. And let's not forget the 8 track stereo rear speakers and am radio front speaker sound system. And the wheel hop that kept you from putting it all to the pavement at the line. First time you put one sideways, you'll remember that for a long time. Especially if you're in the passenger seat.

And of course the rest of the story of this particular car is he only kept it until it had 12,000 miles on it, because in a little over 6000 miles owning the car, it: broke an axle shaft and had to have the rear end replaced due to the incidental damage (warranty); had to have the transmission replaced shortly after that(warranty); had to have another rear end installed because the new one locked up(warranty); wouldn't hold alignment, turned out it bent(yes it had t-tops); developed the obligatory oil leak at the rear main(warranty); had cooling problems every time the temp outside went over 80; blew up the serpentine belt and destroyed the hood(warranty); and finally, went from driving like a car with 400 hp to a car with 200 hp when the computer got swapped out(warranty). He traded it in and the new owner had an electrical fire three or four months later(GM said nice knowin ya, good luck with that). That car was JUNK. But it was REALLY REALLY REALLY fast junk until he swapped the computer out.

My point is all these people thinking someone's car doesn't really have the engine they say it does need to understand how EXTREMELY inconsistent GM was in the mid 80s. I drove 50 or 60 of these things for more than a minute or two each between 1985 and 1989, some of 'em would light it up off the line, chirp it 1-2 1nd 2-3. Others wouldn't break it loose on ice, 5.0 and 5.7 alike. This one ripped 'em loose and went sideways on the 1-2 if you didn't back off at the shift, overheated, and bent, and would've killed every stock one I ever drove. Others needed a tree to bend them. Even with the 350. So it is possible that an RX-7 or a Mustang GT beat a particular 5.7 TPI with "nothing wrong with it."

 

An interesting story. And I believe it to be true. I'm not sure if it was the earliest TPI engines were tuned for faster performance by GM programmers (aka car guys) before being tuned to a more standardized baseline later. (Reliability, emissions, fuel economy, who knows) Or if it was just that the early models were tweaked in other ways by the racing division and sold to people high up in the company. Think about when the 427 came out in 1966 in the Corvettes. They were 450 HP for a month or so. Then they became 425 HP. Same engine.

My parents ordered a 1985 Corvette brand new back in the day. It was ordered as early as you could do for the model year. Black Z51. Manual transmission. Every option ordered except for two tone paint. Dad ordered it with a 3.31 axle ratio even though the only available ratio for a 1985 manual Corvette was 3.07 And the car showed up with the 3.31.....He ordered it with sport seats in leather. That was available, but never advertised. Back then when you ordered a new Vette, you got base seats in cloth or leather or sport seats in cloth. That car was the only 1985 Vette I've ever seen with sport seats in leather. The Corvette Black Book lists it as an option. But there are no number of sold figures available for sport seats in leather. Dad ordered it with an aluminum driveshaft and sure enough, it came with it. There were a few other minor things. A few suspension pieces. If you're wondering how he did this, Vette Vues magazine posted a bunch of RPO codes in mid 1984 that weren't on the Corvette order form at the dealership. You had to know the codes to get them.

The car was delayed for several weeks before finally being delivered. My parents had told the GM dealer to phone them when it arrived. They didn't want some junior sales staff driving the car around town. So when the delivery date arrived, we got the call and went and drove it off the car delivery truck at the dealer with the rest of the new cars......But the odometer had 52 kms on it. What's going on here? After some calls to upper GM levels and supplying VIN number and details, the story was that GM's racing division had been using the car for testing before leaving the factory.

Fast forward a few months. The car was in the shop for something. So the sales manager gave my parents his 85 demo Corvette as a loaner and said he would bring the car to our house when it was finished. The loaner Corvette was nowhere near the same to drive. And the sales manager when returning our car said the same thing. I don't know what you ordered, but this Corvette is a rocket.

I have no way of proving that anything happened on purpose at the factory to warrant it being any different speed wise. But if I put myself in the testing department's shoes and you're looking at then brand new TPI technology, why wouldn't you take the Vette that is black as night, Z51, manual trans, shorter axle, this car was ordered with poly bushings? Who ordered this thing?! Hey let's take this car out around the track and fiddle with the chip programming.

 

Neat story & definitely interesting for a third gen owner, but I'm not buying it. Having owned or still owning the majority of the cars on your list above, I can clearly say, without reservation that ANY 73-74 SD car with or without A/C cannot be touched by an 85 Tuned Port IROC.