Myths

From 60DegreeV6.com

Contents 1 Thermostat 2 IAT Resistor Mod 3 Computers Tune Themselves 4 Electric Superchargers 5 Throttle Body 5.1 TPS-TEC 5.2 Throttle Body Heat Shield 5.3 Throttle Body Spacer 5.4 Throttle Body Coolant Bypass

Thermostat

I'm going to keep this short, because its a simple concept. For years people have been spreading the word that a 160 stat will cause problems. This is true, as it hurts gas milage and MAY cause the cylinder walls to wear faster due to less expansion. If your fan turn on times aren't matched, it can allow a cycle of 160 to 220 degrees back and forth, which will contract and expand the cylinders.

However, there is a myth in here as well. Open loop operation does not care if you have a 160, 180, or 195 degree stat. Closed loop is based on exhaust temp (O2 sensor working properly), coolant isn't below freezing (i have to look up the exact temp again...its really low though), and the time the car has been running.

IAT Resistor Mod

IAT stands for Intake Air Temperature. It is a simple thermistor that changes its resistance according to the temperature it is at. The idea beind this modification, is that by changing the resistance to that of a cooler interpreted reading, you will get more fuel. While it is true that you will dump more fuel...its false that this is a good idea. Running rich is bad for performance, so you are just wasting your time with adding more fuel in this fashion.

The stock computer already compensates fuel as it is, so trying to trick it into giving you more fuel is completely worthless. If you dump too much fuel, via switching to a colder resistance on the IAT while driving, you may even notice a puff of black smoke out the exhaust. Then, the O2 sensor will detect the overly rich mixture, and reduce the injector pulse width. This totally defeats the purpose or the IAT mod.

Computers Tune Themselves

"The MAF sensor will compensate for your mods".

No, it wont. It will accept mods, including boost a lot easier than a MAP sensor setup did, because the computers are programmed with the ability to read boost values and higher airflow through the MAF sensor. However, the computer is programmed with hard set tables for the MAF sensor inputs to be converted to g/sec of air. The problem with thinking that the computer will tune itself is that it really doesn't tune. It just adjusts to keep the engine running.

If you are lean, you will have knock, which the knock sensor will pick up and then the computer will retard your ignition timing. This isn't tuning your spark table, its killing your performance. Its not tuning your fuel tables, its catching up and trying to learn. However, all its really learning is that you have KR at x amount of air and need x amount more fuel. Tuning would be telling the computer what it needs to give the engine the right amount of fuel and then see what your ignition needs to be set at.

Stock setups aren't even perfect. This is why you can gain power from a tune on a stock motor (kinda obvious right?). If its not perfect or damn close on a stock motor, it can't have a chance when you start to mod. Stock 01 grand am had 5-8 degrees KR and LTFT (thats long term fuel trim, or the BLM for those that have messed with OBD1) of what was supposedly -2 to +5%. Funny thing happens when you start to adjust it though. It gets further off. It went from wanting 5% more fuel in some areas to wanting another 10%! How can that be? Perhaps the KR it was getting was making the fuel requirement less. How will it fix itself if its compensating fuel and spark when fuel was the main factor? Granted it still had KR but it went down as fuel was added, accelerator fuel added, and PE kick in vs TPS % reduced. If you don't understand that, ill put it simply. It wasn't tuned for stock in stock form.

If you are reading this, and happen to be thinking about a first mod, let me make a suggestion. Make sure you can tune your car, or have it tuned before you do anything. I'm not saying you are gonna blow your motor with a cold air intake. I'm saying you aren't going get the most out of it without the ability to tune.

Electric Superchargers

There are several different versions of this myth floating around.

Here is one view on why electricity and boost don't mix: Click Here!

While its not good on the charging system, and it won't produce any boost, these electric turbos can give you a small increase in power for a short period of time. Its proven on a dyno and at the track. So yes its a myth still because i still see it claimed to boost the motor, but its not a complete lie as there is a couple hp to be had. Obviously the size of the motor will matter as it would with selecting a REAL super or turbo charger.

Throttle Body

TPS-TEC

TPS, or the Throttle Position Sensor is the device that tells the computer how far the throttle plate is open. The major misconception with this device is that the car uses it for fuel delivery. The MAP (Manifold Air Pressure) or MAF (Mass Air Flow) actually have this job, not the TPS. The job of the TPS is for what is called Power Enrichment in the computer. At a programmed TPS %, the car will resort to a different set Air/Fuel ratio for the added demand on the motor.

The TPS-TEC is supposed to take the real TPS and tell the computer you are at a higher TPS%. This is all done through varying voltage, so the device itself most likely works. However, the real question is "what does it achieve". Well, it achieves what your foot achieves. You can think that your car is faster because instead of 70% throttle, it only takes 60% throttle to go into this Power Enrichment mode.

The other questionable advertising claim is its TPS% change. It claims that 70% throttle is all you need with this device...which is the exact same % that the stock computer is programmed for (at least on automatic 3.1 and 2.8 FWDs) to hit PE mode. It is uncertain if this means 70% of the stock 70%, or if its just the SAME % as stock.

*UPDATE*

I have now tried one of these devices on a 91 Lumina Z34 using freescan to monitor the TPS that the computer sees. It appears that the TPS is the same as it would be stock until you hit 94% real TPS. It immediately jumps to 100. Thats 6% difference at near WOT anyway. What a complete waste of money, it doesn't even do what it advertises!

If you still insist this device gives you better throttle response, its time to have the ass-dyno recalibrated.

Throttle Body Heat Shield

I can't believe this was made, but it has been so I will now explain something AGAIN. As if the coolant bypass myth wasn't enough, we seem to have found our source for ignorance.

This heat shield mounts under the throttlebody, in an attempt to block the heat from the exhaust manifold crossover. However, we must first question the reasoning for such a device. What makes people think the TB is the source of evil and worthy to keep as cool as possible? I think it has more to do with the ease of install and production to make a quick buck than anything beneficial to the engine.

The air moving into the engine starts somewhere, and that place is USUALLY in the engine bay. Right there, you have warm air. At idle, that temp is going up because there is no circulation in the engine bay. Once you start moving, the engine bay gets fresh air, and starts to cool off. The throttlebody by then has also absorbed heat from the intake manifolds, who have got their heat from the heads and what is radiated from the block. I have to assume with the heat shield, you won't have the coolant lines going to it.

The smart thing to do is find a cooler source of air for the intake. For this, we look at a cold air intake. With this setup, your idle temps will increase still, but nothing like before because you only have the heat radiated through the fender well or the street or just stagnant air from wherever you mounted that bad boy. While driving, its instantly cool.

Now for the heatshield. What good does it do at idle? None. But we don't race at idle, and again I have to assume the everyday driver doesn't give a crap about his TB temp, or what it supposedly does for anything. So lets enter race mode. With the stock intake suckin up warm air, your TB is going to be warm to hot because the air going through it will not be a considerable temp difference to cool it off. That is right, the air moving through the TB will dictate its temp, not deflecting the directly radiated heat from the manifolds while ignoring the radiated heat off the bottom side of the hood, and the rest of the engine bay.

With the cold air intake, you will start to cool the throttlebody off as soon as you start racing. You will also be cooling the intake manifolds and the intake port of the head. The temp of the air however isn't going to be changed much because of its high velocity. Its the wind chill effect for your engine.

Now, of course, there will be SOME raise in temp, because it has to travel through the hot TB, hot plenum, hot lower intake, and the hot head. Given the surface area of each item, can you guess which has the least impact on the air temp? Thats right Einstein, the TB has the least effect.

So, what is the big deal with all these throttlebody mods? Its simple, people like cheap bolt ons, especially when they are new to cars and don't know that cheap and performance RARELY go together. Its easy for a company to make a profit on it, and making the product sound useful without lying is a cinch.

Throttle Body Spacer

Port injection

The TB spacer is meant to keep the throttlebody cooler, by seperating it from the manifold using a phenolic material instead of metal. The misconception is that by adding space behind the TB, you are going to get more torque.

The lowered temperature is fine, and is worthwhile (see TB coolant bypass), but the cost of a spacer and the remaining intake manifold temperature doesn't do a whole lot on its own. The performance myth with this device is that it allows more air in, or that it lengthens the runners, or anything else along these lines.

The torque curve is dependent on a lot of things, but for the TB related part, its actually not even related. The plenum, while connected to the runners, aren't part of the runner equation. You would have to lengthen the runners themselves to do anything. Actually, even this doesn't seem to work from testing on a 3100 with 1" spacers between the lower and upper intake. You would likely have to change the volume of the runners much more than just extending them will do.

Regardless, this has nothing to do with the plenum. The plenum volume is important to performance and the RPM range of the powerband, but the TB spacer isn't going to have any effect on this because its volume is minimal.

The only real value to a Throttle Body spacer is for a NOS setup. You can drill a hold in the spacer for a NOS injector. It is easier to work with a seperate piece for the nitrous injector, and it is easier to return the car to normal later.

TBI, Carb

Unlike the port injected manifolds, a spacer that goes under the carb or throttlebody will help out for performance. The extra space will help the air fuel mixture atomize, which will burn more efficiently. The myth part is for the port injected motors only.

Throttle Body Coolant Bypass

This isn't so much a myth, as it is exaggerated. The lines were put in by GM for cold climate conditions, which is said to cause ice to form on TB, which could cause a lot of problems, like a stuck open condition that can cause an accident. There have been no known reports of this happening, but there hasn't been any research either.

The idea behind removing it has nothing to do with the ice though, it is removed to keep the hotter coolant from heating up the TB. Cold air is good for a motor's performance, but the air moves so fast that the TB temp isn't really going to make a difference. Cooling the TB and Intake manifolds will help however.

The real gain from this mod is to eliminate one area that "can" leak, and if you tear the motor apart at all, those coolant lines can be a pain to remove when you want to remove the TB or the plenum. Because this is a really cheap modification, it is still recommeneded to remove the lines if you don't have to worry about ice forming on the intake (only because it would be bad to recommend something that could be potentially dangerous). Every little bit helps when cooling the intake, just don't think you will notice anything from it. Not only will you not notice anything, you won't get anything on a dyno because of it either (on its own).