924Board.org

[jcope]

Some of you might remember the "'87 924S Dies at Random" questions I had early in July. I solved the problem by putting in an ECU. I went against my best instincts and bought a used one from my mechanic. Based on some marks that were on the little tabs holding it closed, and based on the fact that the car feels faster now, I'm pretty sure there is a performance chip in it.

Have I done a bad thing to my car? Or did I score some extra power for free?

From what I've read, it seems like those chips just change the mixture. I'm not sure if there are any bad things about that as long as it doesn't burn too hot or knock. What do you think?

Also, I've found a pretty good book on Bosch fuel injection by HPBooks. I can't remember the author's name (if anyone cares, I'll get it), but it was just published in July this year. It isn't extremely technical, but it definitely covers more than the basics, and I didn't think it missed much. I'd definitely recommend it.

[-nick]

hi Jcope-
yeah, you've pretty much scored free hp. the chip will just change your timing advance in some key area where the factory could have but didn't, and it will change you a/f ratio in some key place also where it probably ran a little too rich or too lean before. however, some chips can make smog tests more difficult. but i doubt you'll have a problem. congrats

-nick

[klober23]

I have 1 1981 924 turbo...where can I get a performance chip? How else can I emprove horse power? Thanks fossil@wtp.net

[924RACR]

No chips for the 931 - it's not electronically fuel injected like the 924S. Review the Tech Section (link above) for info on how to get power. Simplest way, on a turbo, is to raise boost.

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Peter_in_AU]

grab a drink 'cause this might take a while.

we're all very lucky that there is no such thing as a "performance chip" for the 924/31. We don't have to put up with the stupid postings on other boards that start "I've just put a chip in my .... and it's gone from 200hp to 350hp".

Rewritten chips are the modern equivalent of snake oil and appeal to people who think that the laws of physics are actually a conspiracy to stop us getting everything we want for free.

Think about it for a moment:

An auto company (say Porsche) design a fairly high-output car (say a 944). They have their fairly large team of engineers spend a very large amount of time with the engineers, software designers and programmers who will design and write the software for the engine management system (Bosch). When they get it running they test and test and test and test. As a software designer I know that this would be a long and expensive task. If someone said the software cost $20 million I'd say that seems very cheap.

Anyway, the EMS software is designed so that the car will start in Canada in the dead of winter or in Australia at the height of summer, it will pass emission laws in California, it will give the engine a service life of at least 300,000km, it will tell the guy servicing it what's wrong with it and will give you it's rated horsepower over its service life without "tuning".

The way EMS software generally works is with multi-dimensional tables of numbers representing all the possible inputs (rpm, engine temp, air temp, throttle position, MAF reading, possibly country/state emission laws to adhere to, knock sensor input, crank angle position, atmospheric pressure etc etc) and the required action (set advance to x degrees and apply an x millisecond pulse to injector 3).

OK, so along comes some guy with an eprom (chip) reader who downloads the EMS program and tables on to his PC. Now all he's looking at are numbers but he can tell where all the tables are so that's something. He doesn't have the "human readable" program code because for some strange reason after spending millions of dollars Porsche and Bosch don't want to give it away. No problem, lets change a few of these numbers and see what happens .... won't start, OK change those back and change some others ... OK it starts and the injector duty cycle has increased, cool the mixture is richer I can run more boost without detonating the engine. Now, lets change some other numbers and see what happens......

This process goes on and on until eventually our hacker goes insane or whoever is paying him says "enough, just give me what you've got". They then burn a couple of hundred chips and go into marketing mode. The chips are bought by lots of people who also believe that having 14 big macs for lunch will not cause a weight problem as long as you wash them down with a bucket of diet coke.

One of the happy customers lives in California and he loves the way his car now feels quicker. Unfortunately he gets defected during a random smog test and fined heavily for illegal modifications. A Canadian customer who has worked long and hard to get the US dollars to buy his chip is less impressed when at the first sign of snow his car won't start because it floods itself. And there is the customer in the Sierras who is less than impressed when his engine detonates because the EMS seems to now be ignoring the signals from the atmospheric pressure sensor.

If you are ever tempted to buy a "performance chip" do the following:

1. Ask yourself how some guy in a garage somewhere can discover secrets about an engine that were totally missed by the engineers who actually designed that engine from the ground up.

2. Ask to see the independant dyno test results. Actually confirm the tests. Remember, a blown engine will really stuff up your day.

3. Ask yourself "at a time when horsepower sells cars, why would a company produce an engine that would not produce as much power as possible within the constraints of laws and fuel efficiency?".

4. Ask yourself why you bought a car made by a company that so obviously knows nothing about making cars.

5. Send me an email, I've got this old bridge and an opera house that I'm not using any more which I could let you have really cheap

[-nick]

i have to say Peter, i respectfully disagree. not to say that there aren't alot of chip manufacturers who prematurely release products. if you look at a reputable company like Huntley Racing (or equivalent) you'll see that chips can and do enhance normally aspirated cars. no, you're not going to get a 50% horsepower increase, but i have no problem believing the maps can be altered to give you the 15 or so horses that are advertised for a 944.

some of these aftermarket tuners are just as bright as factory designers. take a look at RUF. noone will argue that they don't know what they're doing.

if you consider that out 924's can gain a couple horses just by advancing the distributor timing, let alone having a fuel injection map to play with, then this becomes even more believable. why didn't Porsche do this for the 924 in 1977? mostly emission and fuel consumption reasons. will my advanced ignition cause me to get less mileage out of my engine? doubtful.

you mention that Porsche would have done it if it were worth doing. then why didn't they put a better cam in our cars? everyone knows that will give our 2.0L's a healthy power increase. sure gas mileage suffers, but big deal if this is truly a horsepower crazed market.

then there are chips for turbocharged cars. you can turn the boost up safely if you consider your timing and fuel mixture. which is what chips do. amazing increases come out of 951 chips. why didn't the fatory do it? again just emissions and fuel economy. for the market of the car noone was willing to deal with V-12 like fuel consumption (some people are however, just look at 930's).

if the factory had all the right answers there would be no aftermarket performance market at all. there will always be those looking to get 600hp from 2.0L's where the engines last for 2 passes down a dragstrip, but increases from stock can safely be had and chips are one way to do this.

this is just an alternate view. i know a number of 951 ownwers who have had really bad luck with chips from certain manufacturers. at the same time many other owners are pulling well over 300hp to the rear wheels with the aid of a chip. i wouldn't say that they don't work.

regards,
-nick

[Peter_in_AU]

Nick,

I wasn't trying to say that is not possible to remap a chip sucessfully although it did sound a bit like that.

Given enough time and money anything is possible. It's just that unless you have unlimited resources or factory assistance then you can never be sure that any changes you make to maps will not have an evil side effect.

Companies like RUF work very closely with the factory and have the resources to fully test their products.

I am totally sceptical about the benefit of "performance chips" probably because I have never seen any independant verification of the benefits. If someone would show me before and after dyno graphs where the only thing that changed was the chip then I might think differently.

Given that an hour of dyno time costs less than $100 plus Operator cost I can't see why companies selling performance products do not include graphs with every product

[Peter_in_AU]

OK, I found one at Autothority for the 996



It's not a genuine graph as produced by a dyno but it looks reasonable.

According to Autothority the graph shows a 16hp increase. The downside is that you have to get above 6000rpm to get that increase oh and it costs $695 unless you have a model year 2000 or later 996 in which case the 16 horses are a very reasonable $2500.

[-nick]

hi Peter,

sure, whether the couple of ponies is worth the $$$ you have to put out is a whole other discussion

i'm just going on what alot people have told me about chips. to most it's worth it. it's much easier to replace a chip than put on a header.

regards,
-nick