What is a chip and what does it do?

[RedRagTop]

We were discussing pros/cons of (hyper)chips on another thread so I thought I would start one here to see what would come up.
Some claim all a chip does is to turn on your fans earlier at a lower temp. Is this true? Is that the ONLY reason for installing one for $200? I can't believe that.
I have one in mine and am happy with the performance but cannot say how much if any of that is attributable to the chip. I have never driven a stock C4 to compare.
What is a chip and what does (CAN) it do?

 

[Dave C. '04 Z06]

The reason people say it just turns on the fans is because if your engine is almost stock, then there is not much that can be done to improve upon the stock programming as far as air and fuel, and ignition timing, are concerned. So basically it will just turn you fans on earlier to keep the engine cooler. (the factory was tied by the federal regulations for emissions, and the car has less emissions when it's hotter.)

If you have internal engine mods like higher flowing heads or a different camshaft, or even some headers, then performance tuning can enhance performance via the air/fuel and ignition timing.

-Dave C.

PS: actually, it's arguable that keeping the engine cooler actually increases performance. Most race cars are run hotter because the engine makes more power when hotter (if the block and heads are hotter, the less heat that is removed from the combustion process through them). The common street car theory is that the air moving through the intake to the engine gets heated, which causes it to expand thus allowing less air into the chamber. But if you actually calculate how much the air temp can rise in the few milliseconds it takes to get from the air filter to cylinder at WOT at high rpm, you start to figure that there isn't that much horsepower loss there due to expansion.

 

[Vettelt193]

One thing to look at as well is the year of the car. The older your car is, the less powerful the computer is. So, an older C4 will have a computer that does much less than a newer C4. This means a chip (or new programming) will do much less in an older C4 than a newer one.

 

[rrubel]

Dave, there must be SOME quick exchange of heat going on between the intake and cylinder because otherwise nobody would use an intercooler. Air passes through one very quickly, and they're proven to lower the charge temperature significantly.

I have read in several performance books that every 10-degree lowering of the intake charge adds one horsepower. Not a lot, but it's measureable.

[RICHR]

 

[Dave C. '04 Z06]

Well, there is ALOT of difference between an intercooler and your intake tract. The intercooler is like a radiator, and the air gets divided between the runners in it, so you have a relatively small portion of air going through a rather large heat sink. So there is MUCH more surface contact than a regular intake tract, plus much more efficient cooling fins.

Your intake path on a regular engine is just a basically a pipe, so the whole volume of air flows through it with only a small portion of it actually touching the sides, which doesn't add very much heat in a short amount of time.

If you want to test this, then take out your radiator and just put a pipe in there in place of it. I bet your car overheats.

I imagine if you flowed the air through an "inter-heater", or a radiator with extremely hot air or water blowing through it to heat it, it would heat up your intake charge much more quickly than your regular intake path too.

The other thing is that a cooler intake charge CERTAINLY makes more power. But what I am saying is that having your block run at 170' or 215' isn't going to make that much difference in the temperature of your intake charge (at WOT, high RPMS). All it will do is lower your combustion efficiency. Yes, this will allow you to increase your timing by a degree if you're running lousy gas, but the net result is the same.

I would say the only real gain I see by letting the car run cooler is increased accessory life, and the AC might operate better because the condenser is attached to the radiator, so that could be cooler.

-Dave C.

Also, I'm not saying there is NO exchange. I would guess there is on the order of 2 or 3 degrees change from the air filter to the intake valve at WOT. But that's not worth $200 to me, which is what the original question was about.

 

[vader86]

Its supposed to advance timing curves and thats supposed to give you HP, however many have track results and dyno's that either had no gain, or very small gains in hp.

I think the best benefit is allowing the engine to run cooler by turning the fans on earlier in conjunction with a 160 tstat. Having the lower temp stat, and the fans keeping the car cool, allows you to advance the base timing higher. This will give results.

Most of those who say the Hypertech made a world of difference have no real results to prove it.

The Power Programmer for the 94-96 guys is probably worth the money (barely), but not the chips.

 

[Vettelt193]

in conjunction with Dave C.'s post.... You will get a better temp. drop in the intake by bypassing the coolant going into it and the throttle body than any drop in engine temperature a chip could provide.

 

[WhalePirot]

beware perceived 'gains'

The chip is the brains of the ECM. I believe ECM stands for Engine Control and Management. The rest of the ECM is supporting circuitry.

They control more and more as ECM capabilities and speeds evolved (increased). The '84 and early '85s had a separate thermal witch to activate the cooling fan, which was incorporated into the newer ECMs. The ECM knew the water temperature already, but only the improved capabilites allowed the ECM to take over.

The chip also contains data tables. They are multi-dimensional and quite complex. The ECM uses bvariou sensors to 'see'; things like hrotle position, manifold air temperature and pressure, depsending upon which system it uses to calculate the amount of intake air, knock sensing, oxygen content in the exhaust, etc. All of this goes into the ECM's dictates for ignition timing and fuel pulsing, for proper mixture and the amount of spark advance needed.

As engines are modified, all of this may change. The more radical changes exceed the ECM's capaility to adjust from standard factory spec. Every engine, even 'identical' ones vary. They also change as they age, hence the variability based upon real data.

The factory spec allows for differences based upon fuels used and such, and are not optimized for YOUR CAR. You can have a custom chip (PROM) made if you only use better fuels or demand more than the 'average' driver. There is room for more performance in the programming. Most mail order chips only change WOT settings; some change fan ON speeds.

REAL data table modification should be left to experienced RPOM guys, kinda like changing the BIOS in your computer. It can have nasty effects on how things work, or not.

There's been a lot written about engine temperatures and intake air temp and I won't further hijack this thread by expressing my views. (search)

Just be wary of perceived gains without real data to back them up. I am lucky to work closely with a long-time Corvette mechanic who knows what works and what only delivers perceived, wishful gains. He has installed most everything at one owner or another's behest and has learned. He has saved me hundreds of dollars while helping deliver astounding power to my car.

mike

 

[Edmond]

I think this would be a good topic for moderator Jeff to chime in on. He burned a chip for me last fall and in addition to having a cooler engine, I can feel an improvement in acceleration.

 

[RedRagTop]

Mike! Please elaborate on the findings of your mechanic friend (what works/what doesn't) as we would be happy to get a professional opinion on this matter. Good post!

 

[Dave C. '04 Z06]

Yea, let's get someone who's made money selling performance chips to alot of you guys to give us an opinion on it. :eyerole

I wonder what he's gonna say? Let's take a poll:

1. All you guys have really wasted your money.
2. Sure, they'll improve your horsepower. They have much better spark and fuel curves than Chevrolet's curves have for your otherwise stock motor, even though they spent hundreds of hours of IR&D time to get them right.

The fact is, maybe on a minivan that's designed as a family cruiser to run on 87 or lower octane fuel, you can get better performance from a chip. But on a Corvette, you're not going to find but maybe, and I say MAYBE, 5hp or so. And 5hp is nothing. Chevrolet tuned these things for performance already, that's why they REQUIRE 91 or better octane fuel. And they spent many hours to make them right.

But, everyone has thier own opinion. So I do what I do, you do what you do. And we're all happy.

-Dave C.

 

[rrubel]

Dave, older C4's require 87 and no better. Also, Chevy has to worry about CAFE, emissions, and time:benefit ratios. Most of us don't (well, emissions to a certain point, but there's more leeway). I'm certainly willing to sacrifice 2-3 MPG for better performance (ex: replacing rear end), but GM as a company can't afford to lower its CAFE rating.

That's one reason why everyone's switched to 5w30 motor oil - 1/2 MPG better economy means nothing to us, but spread that over 10 million cars sold...
[RICHR]

 

[SPANISHVETTS]

Yea, let's get someone who's made money selling performance chips to alot of you guys to give us an opinion on it.

I hope nobody is taking a shot a Jeff. While Jeff has never burnt a chip for me I have followed the results of his work in other threads. He ain´t doing this for the money. At best it is a break-even for the service he is giving us.

If you are running a stock SBC then the factory chip will serve you ok. As soon as you start changing things you need to get a chip burnt for your mods. WhenFrankie built my current motor he spent as much time re-burning chips as he did porting the heads. I am still 1 burn away from the perfect chip, thanks to the waterless coolant it takes me 20 min. to get into closed loop so on short runs my gas mileage is pre ´68,(9 MPG), as soon as she goes into closed loop she leans out and does 29 MPG at 80 MPH.

No ¨off the shelf¨ chip is worth the money. When you are ready and your motor is ready, get a custom chip burnt by someone who will re-burn it a few times after the data comes in.

 

[Eagle85C4]

I have not taken my car to the track, nor do I plan to. I have not had my car on the dyno, nor do I intend to.

But I can tell you that there is a definate change in the operation of my 85 when I introduced the hypertech chip. Again, it accelerates faster, runs smoother and appears to get better mileage.

So for the naysayers although you may not have had any results with the Hypertech chip in YOUR car, I did and still do with mine. So you cannot say the chip does nothing.

There are many like myself that are not intrested in a fire breathing gas station to gas station corvette that cannot be enjoyed versus a bit more performance that can make a sunday afternoon cruise with your lady much more preferable.

 

[hott85]

I purchased my first chip from Formato's Faster Proms in Tampa. My Vette idled smoother, accelerated harder, ran faster and got better gas mileage.

I'm having additional mods done to my Vette and have already purchased a replacement chip from Faster Proms.

For me it works - incredibily so! Money well spent and I'll continue to purchase replacement chips should I have additional mods done to my Vette - it's a no brainer for Vettes that have been modified!

By the way, these are customized chips made according to the modifications to my Vette - no off the shelf stuff!

 

[WhalePirot]

elaborate on the findings of your mechanic

I have a short, partial list, but I am quite reluctant to nay-say any products, lest I invoke the wrath of members?

Many Vette owners seek improvements or distinction for our 4-wheeled passion. This makes us vulnerable to marketing hype and not wishing to feel taken, we perceive improvement and vociferously defend, in the face of questions.

SpanishVettes said what I have said all along. You mod your engine enough; you need a custom chip. Perhaps some shop can burn a new chip that gets within the ECM's range for fine tuning; perhaps not. EVERY ENGINE is different!

I drove a very rich running car for years; unable to find a great chip guy. When I went to the guy with the best reputation, he improved it, but needed much more time to get it right than either of us had. The richness fouled my CAT and soiled my car's rear. I had slightly tweaked heads, with larger valves, headers and a mild cam; hardly a radical change, but enough to exceed the '84 ECM's 'tweek' range.

as much time re-burning chips as porting the heads I agree, totally, from my experience. My chip took hundreds of hours, as no dyno was available and well over a grand. I was not charged for all the time the two guys spent on my car, and they started with a chip that was fairly close! The results amaze anyone who knows something about engines; especially those ECM controlled. Other experts claimed that this 406 would never idle proberly nor pass California SMOG. It idles with a smile-evoking lope and passed SMOG with ease. It lights the 315's at ease; as any Vette I own, should.

I am glad Eagle is happy with his chip and his car. Such is the bottom line, right? My car delivers driveability and face stretching performance while appearing like a stock '84. I can, and do pass gas stations. Our wishes and cars are somewhat different, which is GREAT.

My summary? Know what you want from your car and ask the best professionals you can find. I listen to how they say it as well as what they say. Minimize the mix and match ideas, meaning use ONE approach. For example, some tuners increase fuel pressure with small injectors. Others use factory pressure and size the injectors based on expected horsepower. Both may work equally well, but a combination will not. The engne is a system and must be engineered as such.

- I found Monza exhaust noisy w/o perceived flow improvement.
- I found a 52 mm BBK to flow plenty of air to my 550hp, 406, even breathing hot, post-radiator air. Colder air is more dense and would likely increase power.
- I found wrapping headers delivers much better power. My headers did not crystallize and fall apart.
- I found very FEW totally honest, experienced Vette shops.
- I found little or no change from pulley size changes.
- I found (in CAC) that a popular air filter made no difference in a lab test.
- I found the TBI could NOT be modified to flow like the old Smokey Yunick manifold it was emulating.
- I found custom chip demands much time and $$$ to get the most from my engine. My hat's off to Jeff and the great comments on his work.
- Finally, I was told the license plate cold air rammer, the MAF screen cut, an MSD and the TB bypass are probably not going to deliver too much.

These last three are very popular with CACers and I expect to be flamed. Weigh for yourself, with your God-given common sense what my 'guy' said. The air flows through the TB at a very high speed. How much can it be warmed up in those 3 or so inches?

How much more airflow does no MAF screen allow? Look at the cross sectional area freed. Weigh that against the easy damage to this expensive part and decide for yourself.

The engine only uses as much spark as it needs to fire the plug. The HEI delivers plenty in a normally aspirated engine. MSD means Multiple Spark Discharge; the HEI doesn't. The burns in my cylinders are fine with the HEI. Less than optimal ignition components and/or mixture issues might be covered up.

It's your car and your money. I truly hope you enjoy it as you intended. Part of that joy for me is working on things. I wasted some dough, but learned, too. It serves no one to blast another for sharing their lessons.

I'll wave, even if YOU don't.
mike

 

[RedRagTop]

Thanks, Mike.

 

[Dave C. '04 Z06]

more stuff...

rrubel:

It's true the factory has to adhere to the CAFE standards for emissions and such, but there are no such rules for WOT, only "cruise" mode. So they are free to let her scream. Which they do, because the car is more reliable when running at peak efficiency. (too rich, then ring wash...too lean, things melt..too much timing, detonation ...too little timing, exhaust system heats up and melts the catalyst)....and also, the Corvette is thier performance flagship so believe it or not they do take a little pride in that I believe.

Also, I tend to forget about L98's and the cross-fire engines and only think of LT-1's and the Flash-based PCM's when thinking of C4's, however I believe the main reason you could run lower octane fuel in the L98's was because they were lower compression (9.5:1 or less depending on year). Not because their timing was unecessarily retarded.

Like I said, though...I believe you could possibly get 5 horsepower or so from tweaking the timing and fuel, but 5 horsepower isn't going to make a difference in a stop light race, and cruising around will be no different. So it's hardly worth the money.

So to answer the original question, because it can only add 5 horsepower or so, that's why people say it only switches on the fans earlier. Because that's really the only benefit (if it is at all).

Once you go into the engine, or even just add decent headers and such, then a PCM re-program is necessary to correct for the change in volumetric efficiency of the engine to get the full potential.

But I still stand by my thought that on an otherwise stock engine, you aren't going to do much better than Chevrolet did re-doing the PCM. There is no magic 20 horsepower waiting to be unleashed.

-Dave C.

 

[Dave C. '04 Z06]

Oh yea...one other thing...

Here is a tried and true horsepower estimation:

for a ~3400lb car to travel to 100MPH in the 1/4 mile, it takes approximately 300 flywheel horesepower (providing everything else is in order)

For every 1MPH incease over that, it takes approximate 10 Horsepower.

So you can see how useless 5HP is if it only makes a car go 1/2MPH faster after a 1/4 mile.

Obviously all those 5's add up if you do enough stuff....but ...well, I don't know... that's just a FYI.

-Dave C.

 

[RedRagTop]

Dave; I don't have headers but only free-flow (flowmasters) exaust so can I assume my computer already learned the difference or is this why I have a chip or what? K&N fiter and lid too.