Horespower Gain from just a tune??

[40oz]

thanks for the essay on how a MAF sensor works

The original debate was whether there were any additional gains to be had by adding an aftermarket CAI to a vehicle that ALREADY HAD A TUNE using the stock airbox.

Yes, and the dispute turned into "CAI's make a ton of power. My error codes are proof." Welcome to the internet, where thread discussions often don't follow the original topic :/

And you still need a tune to accomodate a new larger MAF tube even if you already had one for the stock airbox.

If you didn't need a primer on how a MAF sensor is used by the ECU, good for you

 

[grngt50]

Yes, and the dispute turned into "CAI's make a ton of power. My error codes are proof." Welcome to the internet, where thread discussions often don't follow the original topic :/

And you still need a tune to accomodate a new larger MAF tube even if you already had one for the stock airbox.

If you didn't need a primer on how a MAF sensor is used by the ECU, good for you

Sorry I thought this thread was pretty much toast

have at it, brother

 

[bradleyem]

Has anyone seen any numbers on how well the CDC shaker system flows? By the pics that I have seen, it seems as if the air tubes are pretty small, and they have some good bends in them too.....I like the look of the shaker, but I don't know if it would end up being a restriction or not

 

[Ken04]

holy crap, why don't people learn what they are talking about before arguing?

A different than factory MAF will require a tune because it returns different numbers than the factory MAF. A factory MAF installed into a larger tube requires a tune because the *sensor* is seeing a different rate of flow across the sensor than the factory system.

A MAF sensor measures airflow by measuring changes in the resistance of a wire. The wire changes resistance depending on the mass of air that passes over it. More air, less resistance; less air, more resistance. "More air" can mean either cooler, denser air or air travelling at a higher velocity. In a tube of known cross-section, this gives an accurate measurement of the mass of the air flowing down the tube. Since it can't actually measure the mass of all the air in the tube at a time, the system has to make certain assumtions about the tube the sensor is in.

When you install the factory MAF in a larger tube or when using an aftermarket MAF, the engine is still inhaling the same amount of air, but since the intake tube is bigger the air is travelling slower. Less air is flowing past the MAF sensor for a given throttle opening/engine load situation. The engine is actually getting the same amount of air it was getting before, but due to the larger diameter tube, it travels slower down the tube. The MAF sensor is reading low compared to the factory system under the same conditions. Since the engine is getting more air than the sensor would imply, the ECU ends up not giving enough gas, hence a lean condition.

This lean condition is NOT an indication of a CAI "working." It's an indication that you've increased the diameter of the MAF tube, causing the ECU to underestimate the air mass and deliver less gas than desired for efficient combustion.

Knowing that, it's no surprise that people who put the CAI systems to a scientific test see no gains. And it's obvious why a tune is necessary for a CAI that changes the MAF tube diameter. You might see power from the tune itself, but you'd see the same power from a tune on the factory system.

I don't know about anyone else, but your explanation was a big help to me. Thank you for your post.

 

[ski]

A different than factory MAF will require a tune because it returns different numbers than the factory MAF. A factory MAF installed into a larger tube requires a tune because the *sensor* is seeing a different rate of flow across the sensor than the factory system.

A MAF sensor measures airflow by measuring changes in the resistance of a wire. The wire changes resistance depending on the mass of air that passes over it. More air, less resistance; less air, more resistance. "More air" can mean either cooler, denser air or air travelling at a higher velocity. In a tube of known cross-section, this gives an accurate measurement of the mass of the air flowing down the tube. Since it can't actually measure the mass of all the air in the tube at a time, the system has to make certain assumtions about the tube the sensor is in.

When you install the factory MAF in a larger tube or when using an aftermarket MAF, the engine is still inhaling the same amount of air, but since the intake tube is bigger the air is travelling slower. Less air is flowing past the MAF sensor for a given throttle opening/engine load situation. The engine is actually getting the same amount of air it was getting before, but due to the larger diameter tube, it travels slower down the tube. The MAF sensor is reading low compared to the factory system under the same conditions. Since the engine is getting more air than the sensor would imply, the ECU ends up not giving enough gas, hence a lean condition.

This lean condition is NOT an indication of a CAI "working." It's an indication that you've increased the diameter of the MAF tube, causing the ECU to underestimate the air mass and deliver less gas than desired for efficient combustion.

Knowing that, it's no surprise that people who put the CAI systems to a scientific test see no gains. And it's obvious why a tune is necessary for a CAI that changes the MAF tube diameter. You might see power from the tune itself, but you'd see the same power from a tune on the factory system.

Excellent write up! That's one of the best, if not the best, explanation I've read regarding why a CAI with a larger than stock MAF diameter requires an aftermarket tune.

However, I have a question and a comment on your last paragraph.
(1) Does the "CAI system" in your 1st statement refer to a "tune required"(larger than stock MAF diameter) CAI installed with an aftermarket tune, a "tune required" CAI installed with the stock tune, or a "tuneless"(same as stock MAF diameter) CAI installed with a stock tune?
(2) I may be misinterpreting your last statement, but it appears that your implying that a tune and a CAI with a larger than stock MAF diameter produces the same amount of power as a tune and the stock air intake. If that is what you're saying, then I disagree. The former produces more power than the latter. This fact has been proven numerous times in dyno graphs posted on various forums, and also in the "Cold Score" article in Mustang 5.0

 

[40oz]

Excellent write up! That's one of the best, if not the best, explanation I've read regarding why a CAI with a larger than stock MAF diameter requires an aftermarket tune.

However, I have a question and a comment on your last paragraph.
(1) Does the "CAI system" in your 1st statement refer to a "tune required"(larger than stock MAF diameter) CAI installed with an aftermarket tune, a "tune required" CAI installed with the stock tune, or a "tuneless"(same as stock MAF diameter) CAI installed with a stock tune?
(2) I may be misinterpreting your last statement, but it appears that your implying that a tune and a CAI with a larger than stock MAF diameter produces the same amount of power as a tune and the stock air intake. If that is what you're saying, then I disagree. The former produces more power than the latter. This fact has been proven numerous times in dyno graphs posted on various forums, and also in the "Cold Score" article in Mustang 5.0

Thanks!

My point was mostly that unless the stock intake piping is a real choke on the system, you wouldn't see much for gains. I don't know how much of a choke the factory system is.

So, 1) I was thinking of a CAI and tune. 2) It's probably not fair to say a CAI nets zero gain. Just not the 25 hp gains a magazine article would claim. A tune nets power with the stock system, down to the paper filter. Anyone who gets an aftermarket CAI and tune should see benefits over the factory tune and filter.

Are those benefits related to the piping, the filter, or the tune being more aggressive for higher octane gas? A combination of factors? It's kind of tough to eliminate all the variables so we could say for sure. But it might be reasonable to suggest that real world testing by people without a horse in the race would indicate a CAI doesn't show much benefit at the track, comparing tuned stock to tuned modded. But other mods could very well change the equation. The more power you are making the more gains you see from little changes, changes that would be invisible to an otherwise stock system.

The "Cold Score" article in Mustang 5.0 makes the case for aftermarket CAI's. But one test system, from MMR, replaced just the filter and MAF and saw a 12 hp bump with a tune. Swap in their tube, and get another 3 hp after tuning. It's pretty clearly not the intake tube making all the power there.

The Mac system did pretty much the same thing, replacing only the filter and MAF tube on the end of the factory tubing. 14.4 hp gain according to the article if you compare tuned stock to re-tuned with CAI.

The K&N intake pipe showed 11 hp gains comparing tuned to tuned, but appeared to put the factory MAF into a tube the same diameter as stock.

Among all tested systems, they showed anywhere from 8-18 hp gains comparing tuned stock to tuned with CAI. There seemed little benefit to a whole new intake pipe vs. a factory pipe with a new air filter and MAF tube. Kind of proves the CAI tubing is mostly cosmetic and not really beneficial. But the easiest way to mount a cone filter is to buy a CAI

 

[ski]

Thanks!

My point was mostly that unless the stock intake piping is a real choke on the system, you wouldn't see much for gains. I don't know how much of a choke the factory system is.

So, 1) I was thinking of a CAI and tune. 2) It's probably not fair to say a CAI nets zero gain. Just not the 25 hp gains a magazine article would claim. A tune nets power with the stock system, down to the paper filter. Anyone who gets an aftermarket CAI and tune should see benefits over the factory tune and filter.

Are those benefits related to the piping, the filter, or the tune being more aggressive for higher octane gas? A combination of factors? It's kind of tough to eliminate all the variables so we could say for sure. But it might be reasonable to suggest that real world testing by people without a horse in the race would indicate a CAI doesn't show much benefit at the track, comparing tuned stock to tuned modded. But other mods could very well change the equation. The more power you are making the more gains you see from little changes, changes that would be invisible to an otherwise stock system.

The "Cold Score" article in Mustang 5.0 makes the case for aftermarket CAI's. But one test system, from MMR, replaced just the filter and MAF and saw a 12 hp bump with a tune. Swap in their tube, and get another 3 hp after tuning. It's pretty clearly not the intake tube making all the power there.

The Mac system did pretty much the same thing, replacing only the filter and MAF tube on the end of the factory tubing. 14.4 hp gain according to the article if you compare tuned stock to re-tuned with CAI.

The K&N intake pipe showed 11 hp gains comparing tuned to tuned, but appeared to put the factory MAF into a tube the same diameter as stock.

Among all tested systems, they showed anywhere from 8-18 hp gains comparing tuned stock to tuned with CAI. There seemed little benefit to a whole new intake pipe vs. a factory pipe with a new air filter and MAF tube. Kind of proves the CAI tubing is mostly cosmetic and not really beneficial. But the easiest way to mount a cone filter is to buy a CAI

You're welcome.

If the term "stock intake piping" in your 1st statement refers to only the factory air system's inlet tubing sans the air box/MAF housing/filter, then I believe it's safe to say that it's not that much of a bottleneck. A gain of only 3 hp when using MMR's inlet tubing in place of the factory inlet tubing in the Cold Score article attests to that. However, even a small power gain can make the difference between winning and losing a race. And some owners like the CAI tubing for the "bling".
But if "stock intake piping" is referring to the entire factory air intake system, then the Cold Score numbers attest that it's a definite bottleneck.

I agree that the way the Cold Score article depicts the power numbers is somewhat misleading. I remember having to read it twice when it was initially published to get the facts straight.

An aftermarket CAI and tune should show benefits not only over the factory air system and factory tune, but also over the factory air system with a modified tune.
In the Cold Score article the power numbers of the factory air system with a modified tune consistently fall short of any of the tuned CAI's numbers. That's because the CAI's larger MAF housing flows a greater volume of air per unit time than the the factory air system's MAF housing, and this makes it necessary for the CAI to have an aftermarket tune that feeds more gas per unit time than the factory intake system's modified tune in order to prevent a dangerously lean A/F ratio. And more gas + more air per unit time = more power(8-18 more hp per Cold Score).
Hence, the combination of the CAI and a tune working together is what accounts for most of power increase. Add more timing for more power with higher octane gas, and 25 hp becomes attainable as shown in Cold Score and on dyno graphs in various forums.

 

[Sandman33]

Wow! this info may just save me from spending $600-$700 bucks! I jst assumed a cai was about the first mod you should do b/c of the relatively low cost and gain in hp.

Seriously, I have put CAI kits on a dozen cars. They don't do anything except hurt your hp on hot days. Cold days they may get a little more hp but nothing noticeable.

I just spent $40 and bought a K&N drop in unit for my factory airbox.

 

[essyweb]

That makes sense, I think I'll just stick with the tune, not waste my money on a CAI.