Background:
Intake power gains, or the lack thereof, is a regular theme when questions are posed about the “best intake”.
The responses are fairly uniform:
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The responses are so consistent that sometimes when people ask about intakes they preface the question by stating they “know” that intakes don’t make any power:
I was curious to find out if intakes in fact do not produce any power gains.
Test Procedure:
Two intakes for the Mk7 GTI are subject to this “intake power gains” test. One is the stock intake, the other an Eventuri aftermarket model.
The GTI is set up with the entire stock intake, with no modifications.
Note: I am aware that modifications can be made to the stock airbox.
Note: The turbo inlet elbow is not being tested. Both intakes were tested using an aftermarket turbo inlet pipe/elbow (TIP).
No other changes are made to the car other than the intakes. The Eventuri intake is connected to the stock accordion hose.
The GTI is operating with a Shuenk IS38+ turbocharger and custom EQT ECU tune. Data is recorded during full-throttle acceleration in third gear. The GTI is accelerated from an engine speed of around 2000 rpm until approximately 6300 rpm. A minimum of ten (10) data points are logged using each intake.
Measurements during the period of acceleration are input to the Virtual Dyno application to estimate Wheel Horsepower.
The peak wheel horsepower value is averaged and compared between the two sessions.
Test Results:
The outside air temperature during both test sessions was 79 degrees Fahrenheit.
Data recorded using each intake is shown in the boxplot:
The absence of an overlap of the interquartile ranges indicates there is likely to be a statistically significant difference in the mean horsepower values.
The peak wheel horsepower values are analyzed using a t-Test:
The t-Test confirms that the Null hypothesis, no difference in the mean power output, should be rejected.
The mean difference is 7.8 whp. The median whp difference is 6.5 whp.
Conclusion:
A test using a stock Mk7 GTI intake and an aftermarket Eventuri intake was performed to assess the accuracy of claims that “intakes don’t make power”.
On an IS38 equipped GTI generating approximately 360 whp an aftermarket intake helped the engine to produce approximately 7 wheel horsepower more than using the stock GTI intake.
Claims that “intakes don’t make power” are not supported by the results of this test.
Hello Jeff,
nice test. The intakes do not generate any additional power is not true. OEM we have 4 HP in Germany and tuned, depending on the stage, we can measure up to 12HP on dyno. WHP it is a little less each time.
The completely modified OEM airbox achieves approx. 8 HP.
However, most people will hardly notice this when driving.
Non-tuned, the engine control unit allows a maximum of 5% more power (tolerance) after conversions and adaptations. It doesn’t matter what else has changed. Tuned can achieve significantly more in the context of tuning.
We have achieved the best result several times OEM or tuned with the VW-R 600 and a large hose.
Best regards
Thanks for doing this. To me a reasonable hypothesis (for those of us without knowledge and resiurces to test) is to assume there is some gain if the setup flows better without increasing air temp. Whether or not the gain is obvious to the owner or a mod priority will vary by owner.
Your test puts good context on the level of gains ar a higher than stock, if they occur for a specific intake. Great stuff!
Thanks!
Intake data/tests always have intrigued me. What I’ve always wanted to do is a dyno run with 1) stock intake 2) no intake/straight turbo and 3) aftermarket intake. I can’t ever see how 3 can be greater than 2 but can be greater than 1 w/r to power.
First off I just found your website today and just ordered a now, after reading your statistics, subpar intercooler lol (ARM FMIC) and stumbled on this article. I have to say this is absolutely hilarious. I cannot tell you how many posts I’ve seen about CAI being useless on this car over the years and yet, if t-test is functioning correctly on your end, it would seem they are in fact incorrect lol. 7whp is 7whp. I would be willing to bet though that the removal of the snow-catch from the air box and a drop in high flow filter as you hinted at in your first note, would offer the same if not a degree over or under.
Either way, good read Jeff and thank you for this absolute library of information for my car that you have compiled over the years. There no telling how much money and frustration you have saved people.
Thank you.
It would be interesting to see the diff between the stock intake and your best full intake configuration in terms of performance. Considering, that it is believed (among the mk7 forums) that the elbow is the most restricting part of the intake system, I would expect > + 10-15hp in total gains
It would be interesting to see the total gains of the best full intake configuration
Hi,
You should make a disclaimer that your motor has an aftermarket bottom end.
What relevance does that have to this post about intakes?