# Instant Test: Cold Side Charge Pipe Flow

A discussion yesterday around the airflow performance potential of the cold side charge pipe prompted conducting a test of this part.

## Background:

During a discussion about the cold side charge pipe somebody mentioned that Neuspeed had stated that the stock GTI charge pipe was as good as the design could get. They forwarded me a screenshot of the conversation.

With my curiosity piqued I contacted Neuspeed to find out more detail about how they had arrived at this conclusion.

The next day I received a reply, confirming what the other owner had been told; the stock GTI hard pipe is as good as the part can be.

## The Setup:

I’ve not conducted a flow test exclusively with the cold side charge pipe and the reply from Neuspeed made me curious to see if the statement was true, that the stock part performs as well as any part for that location there could perform.

I have a stock set of pipes in the garage as well as a set of eBay charge pipes that I’ve not yet installed.  (I’m using the Revo charge pipes).  From a casual look at the shapes it appears that there could be some difference, even if small.

Fortunately this would be a relatively easy test to set up and I just needed to roll the GTI back in the garage a few feet to access the flow bench.

## The Test:

For the test each cold side charge pipe would be attached to the stock intercooler outlet hose, which has a bell mouth inserted into the open end to help deliver air smoothly into the parts.

The other end is attached to the flow bench adapter using the stock rubber hose, and a silicone hose with the eBay pipe, as the eBay hard pipe is longer in length than the stock plastic pipe.

Both parts were tested for airflow at a test depression of 28″ of H2O.

## Results:

The stock GTI charge pipe flowed 436 CFM and the eBay charge pipe flowed 450 CFM.  These results are shown on the chart:

## Conclusion:

The eBay charge pipe allows approximately 3% more airflow versus the stock GTI charge pipe at the test pressure.  The claim that the stock GTI cold side charge pipe performs as well as is possible is not validated by this test.

### 12 thoughts on “Instant Test: Cold Side Charge Pipe Flow”

1. Thanks again for all your time and effort bringing real numbers to the discussion.
I do have to say that a 3% increase doesn’t really disqualify Neuspeed’s claim.
3% +/- on any measurement usually falls “within the noise.”
And at prices from $175 to$350 I think anyone with a realistic budget would give this upgrade a pass.
I certainly wouldn’t remove it if it was already on the car.

1. I do not agree that a 3% increase in performance qualifies saying that there is no performance difference between the two parts If I were buying 450 pounds of gold and I was given 436 pounds I wouldn’t be satisfied that the amount I received was within the noise.

Measurement margin of error during this test was less than +/- 2 CFM.

The cost of the eBay charge pipe kit, hot and cold side was \$160.

I try and stay out of the “is it worth it” area of questions.

1. Haha, yeah it’s not the best I’ve ever come up with.

Point being that the measurement was accurate to less than <0.5% of the values and the difference in performance was > 3%, that’s not a performance difference I would consider being within noise.

2. Funny how NEuspeed claims there’s 0 improvement on the charge pipes and that they wont make a part because there’s no improvement to be made…. Jump over to the Turbo muffler delete…. which actually has 0 performance improvements… Neuspeed makes one of those…. hmmm….

1. Neuspeed told me “it’s simply not worth the time and effort to design, engineer, and manufacture at scale for a 3% gain in airflow.”

Producing a turbo muffler delete to include as part of the charge pipe kit does not make sense if what they communicated to me was true.

3. Did Mishimoto send their intercooler pipes too? They do sell replacement piping for both sides of the intercooler.

4. I understand your point but it doesn’t appear that either of these is a bottleneck.
What I’m asking is: if either charge pipe is attached to the best flowing intercooler (267 CFM by your measurement) can there be a measurable difference if both charge pipes flow rates far exceed that measurement?
I am not asking as some sort of “gotcha,” I really don’t know. My knowledge of fluid dynamics is pretty basic.

1. There’s a cumulative effect happening. Every part adds some resistance to the air making its way to the engine. If the intercooler is attached to the charge pipes the airflow through the system will decrease. In the case of the 267 CFM IC, once the charge pipe is attached the airflow would go lower than 267 CFM.