Dispelling Some C5 Myths and Legends

Even though it’s barely two years old, the C5 has accumulated a fairly significant number of misconceptions about it’s specifications, responsiveness to modifications, and its future. Here are the facts on some of the most common C5 (and performance cars in general) stories.

The LS-1 is the same as older small blocks. Not true. The LS-1 is a completely new design, revised from the ground-up, and displaces 346 cubic inches (not 350). It shares no components except rod bearings with any earlier small blocks, including the LT4. The LS-1 will not swap into older chassis without substantial modifications. The good news the LS-1 is probably the best small block ever, with a stronger bottom end, better cooling and lubrication, and lighter weight than any previous production small block.

A computer chip is the secret to making LS-1 power. Not true. With the advent of OBD-II (On-Board Diagnostics, Gen. II), the Powertrain Control Module (PCM) has to monitor far more systems and parameters than ever before. To prevent tampering with this new system the C5’s PCM does not have a chip access port nor does it have any way of accessing the internal program parameters, such as fuel curves, ignition timing, and rev limiters. Without factory assistance, there is no way of modifying the C5’s computer for more performance. The good news is that it probably isn’t necessary. We run our 372 cubic inch motors with the stock PCM, and they idle well, pull hard, and make serious power, while remaining docile and emissions-legal. Don’t worry about the computer being the weak link in your performance strategy.

Bolt-on C5 superchargers are just around the corner. Not true. Unfortunately, the same computer that makes modifications so easy on a naturally aspirated LS-1 also makes it nearly impossible to run positive manifold pressure through the engine, such as in a boosted application. The problem is that the computer is almost too smart. When, for example, it sees too much air flowing through the mass air flow sensor (MAF) for a given engine speed (such as in a supercharged application), it will assume that there is something wrong with the car, trigger a trouble code, and revert to what is commonly called "limp-home mode" which means reduced engine power to prevent damage. Other sensors that make this a real problem include the manifold absolute pressure sensor (MAP), and the oxygen sensors (HO2S). The only way around it is with a custom computer. The good news Mallett Cars is working on a supercharger program to make a Vortech-supercharged C5 a reality. Stay tuned for more…

The LS-1 needs headers. Not true. In stock motors, the exhaust headers actually flow better than the engine’s heads, and adding headers will not add power (and may cost power from reduced exhaust scavenging and velocity). Like the computer, our 372 cubic inch LS-1 motors use stock headers and H-pipes, and work very well with them, and there certainly isn’t 30 horsepower hidden in there. The catalytic converters remain the biggest restriction in the C5’s exhaust system, to the tune of about 12 horsepower on an otherwise stock motor. There are several other points which are important to remember emissions controls are a reality—to comply with tightening standards, the double-wall headers and H-pipe should stay on the car (this promotes quick catalyst light-off). Also, a little back pressure in the exhaust is a good thing—the catalytic converters and mufflers provide enough so that the LS-1 has a strong low-end pull. Without a little back pressure, the car would not have the low-rpm torque it currently enjoys. The good news the money you wanted to spend on headers can now be spent where it will do some good.

The Z-51 suspension rides too harshly for daily driving. Probably not true. By now, there are almost 20,000 C5s on the road, and I’ll wager that most of them did not choose the Z-51 setup because of ride quality fears. Fear not, since the realities of suspension design are this in the past, heavy springs were used to not only control wheel movement, but also to compensate for chassis flex, which acted to reduce actual spring rates. With the C5’s ultra-stout frame and backbone powertrain, the chassis no longer has to endure the force of the engine’s power moving through it, and the suspension is more rigidly mounted. Softer springs can be used, because all they have to do now is control the wheels, not mask poor chassis design. This means that a good ride and exceptional handling are able to coexist on the same car. If you have concerns, by all means, drive a Z-51 before writing the check. But if you want the advice of the experts, choose the Z-51—I guarantee you won’t be disappointed. It makes the best foundation for real performance suspension improvements.

Horsepower is all I need to be fast. Maybe, but only to a certain point. You’ve seen professional drag racers—they launch hard. Somehow, they’re managing to hook up hundreds, sometimes thousands, of horsepower and put it to the pavement. In the back of your mind, you probably know this is true—horsepower is nothing if you can’t hook it up. So why are there so many of you out there looking for 450 horsepower engines in your stock-suspension cars? All you’ll make is expensive tire smoke. Put a suspension and some real performance tires (not the run-flats) under your stock motor, and not only will it be faster in the corners, I’ll wager that it launches harder and you’ll go faster in the quarter mile (and stoplight) drags, too.

The next factory Corvette motor will be a 425+ horsepower Viper killer. Although GM is very good at hiding its secrets, I wouldn’t expect to see a huge increase in either displacement or horsepower from upcoming Corvette powerplants. The oft-rumored LS-6 motor will probably be a slightly revised version of the LS-1, with a different cam and cylinder heads. Most likely, it will provide the performance difference that, say, the LT4 provided over the LT1—more power, but only when you really work the car hard. How much will it cost? Who can say? But I certainly wouldn’t hold my breath waiting for the return of the $30,000 Corvette.

The C6 Corvette will be powered by a cold fusion reactor designed and built with technology stolen from the aliens who landed at Roswell. Yep, GM has acquired the wreckage. Expect this 600+mph supercar to hit the streets sometime after the turn of the century. You will need a suspension on this car.

If you’ve got anything to add, we welcome your questions, comments, and conspiratorial speculations. If you’re looking to make your car faster, give us a call—we’ll tell you how to do it without wasting your time or your money on parts that sound like a good idea, but are less than ideal in application. We’ve run as fast as 11.99 @ 117.38 mph on street tires through the catalytic converters in a 1998 C5, so the potential is definitely there. All you have to do is know the right people. The right people can be reached at:

 

Did not read the entire write up but the information on being able to tune parameters in the PCM is not correct. It's done through the OBD port with the correct devise like HP Tuners. Even the Tech 2 can do changes to the PCM when replacing a PCM based on the tranny and gear ratios using the TIS 2000 interface.

It seems to be a pretty good overview though.

 

No headers, no superchargers in the foreseeable future, computer is too smart. When was this written, 16 years ago?

Nice flashback post I guess. I don't think I was legally able to drive when this was written. The lsx platform has come a long, long way since this was written.

 

Would have been an easier read with more paragraphs/spacing, but still some interesting facts. Thanks for the post.

 

Article was written by Mallett back in 99... guess the technology hadn't caught up with the general public yet. That's why I found the article interesting...lol
and 12 HP by removing Cats! If it wasn't Mallett I'd probable have a hard time believing that one...

 

Thanks Jack... I'll edit it and try to fix that, I just copied and pasted it.

 

Yup about 16 years... Kinda Ironic coming from a guy that does some pretty nasty Supercharged vettes now huh?

 

Adding headers won't increase hp said no one ever. Except for this guy apparently

 

It was this guy.. Chuck Mallett

 

Is this the same mallet that put ls motors in those Pontiac solstice and Saturn skys?

 

mullet

 

When it comes to Mallet and Corvette, if we have to explain it then you wouldn't understand...as the saying goes. It also seems he took the article as a direct challenge to himself.

 

Yep. So for a guy who was so willing to talk so much smack back then makes you wonder what kind of smack he's selling now.

 

not sure if that was directed at me but my comment was a joke... the article is old and obviously some of the things he stated were proven wrong, the part about superchargers stood out to me the most... my car and many others here prove that one wrong... he's probably eating his own words now

 

Not yours...His reference to "this guy" seems to mean to me he doesn't fully understand Mallet Corvette history....

 

I was 13 when this article was written, so no I dont really know. But thats besides the point nearly everything in his article is wrong. Thats why I made the joke...

 

It wasn't wrong then... check out Mallett Corvettes today.
We all learn and grow with the technology... just you young guns were born in to it...
Someday you'll look back at what an low tech, powder puff car the modded C5 was....

 

depends whose powder puff modded c5 we are talking about... personally I don't like the direction things are going with electric cars and I think that is really where the future is headed, the government would love to have everyone driving one of those eventually... if it ever comes to that point in my lifetime then I guess it will be time for me to give up and move on

 

While I agree with your point about being born into technology vs learning it as it comes is easier. However, even then he was wrong about the headers. They scavenge better, thats part of how they make more power. Its physics.

 

I didn't say it Mallett did...