With all the recent (over the last few months starting last fall) hooplah surrounding the idea that the 6637 is sucking in hot air from the engine compartment and is costing HP, I decided to compare the two. I've been running a 6637 for years, but recently got a good deal on a used AFE Stage II system so I've got the opportunity to do so.

For reference, with the 6637 my IAT temps were anywhere from 10-20 degrees warmer than ambient air temp. These temps were taken using AE from the stock IAT sensor. With the 6637, my sensor was located just under and behind the 6637 filter, zip tied to a bundle of wiring.

With the AFE II, the IAT sensor is located in a grommett on the metal shield, so it's taking it's readings from where the AFE fitler is pulling air. The AFE did give lower IAT results, but not much lower. It averaged 7-10 degrees above ambient over the last few days that I've been watching the live data.

This temp drop seems to be carried through to the MAT sensor as well, which is post IC in the intake spider. With the 6637, where the MAT was typically 8-10 degrees above ambient, the AFE II was more like 2-4 degrees above ambient. This was while running a pretty constant 5 psi of boost while cruising at 70 MPH down the highway, and the standard AFE II filter with a filter cover on it.

In one example that really amazed me, the overhead temp console read 25 degrees, IAT read 33 degrees, and MAT read 27 degrees. I couldn't believe that the air the engine was sucking in was actually that cold, so I pulled over, popped the hood and felt the intake. It was definately cold to the touch, while the rest of the engine compartment was up to full operating temp.

So I've come to the conclusion that the AFE II does provide marginally colder IAT's than the 6637 does. However, I have to wonder if the small temp drop, only around 10-15 degrees, is really providing any extra power or benefits. I know every little bit helps, but my EGT's didn't seem to change at all. Also, my mileage hasn't changed, max boost hasn't changed, spoolup hasn't changed, and the turbo noise seems to be about the same as well -- maybe just a touch quieter with the AFE II.

Is the AFE II worth the cost? That's up to you to decide. The only take I have is now that I have an AFE II in place, it's staying there. I do like the way they look.

 

Well for as much as the AFE II costs I could deal with the extra few degrees even if it is a HP or two drop. Though its nice to see a good comparision to see the difference between the two, rep rewarded for your research. Now only if we still had Gene here to do the graphs.

 

Good post, thanks for sharing.

 

Rep points given for the time, effort and data collection!

 

Sorry, computer says you're not worthy of any more rep points at this time. Someone else will have to do that. Do you have any summer data on your 6637? I'd be curious if the same temp difference holds true in summer time.

The only real difference with the AFE is a shield type set up right? If it's worth it, we could fab up a shield to help with blocking engine temps.

Thanks for the info provided so far.

 

Brandon (bdrummonds) and I should have that very item designed late spring or early summer. We'll post pictures and the template will be available to all for free.

 

ditto on the rep points, my question is does anyone have a similar comparison with the AIS and the 6637?

 

Too bad Gene's gone. This is his kind of thread...

 

You have perked my interest Chris, sounds like you and Brandon have something cooking that will look good with Pete's cover.

 

As you requested, taken September 2007 with a 6637: "A few examples, IAT/MAT: 115/104, 111/102, 117/111, 108/100, 120/106, 104/102. Ambient temp at this time was fluctuating between 88 and 90."

From this thread: https://www.ford-trucks.com/forums/6...ghlight=intake

I was thinking the same thing as I was writing the post. He'd love this kind of data. We'd have models and graphs to ponder over.

 

GREAT info JT! Nice to see the comparison! reps given for the time and effort!

 

Didn't Gene do this? At any rate, glad for the info Jeremy. We all know every bit helps, I believe you may note a bigger diff in the summer.

Again, I will predict that your IC is making the difference at speed with good airflow. I believe it can make a 25* diff at the intake look miniscule at the MAT. JMO. The turbo is going to make the most heat under boost. If you were to ask Gene, every * is critical. Thanks for the info. I am going to run the stock IC until I blow the ends off or find another reason to upgrade.

I am also curious about the DIY shield for the 6637. You guys gonna have that together sometime soon? I will say that on a dyno, unless it is a fresh air setup, it will not help without a bigtime fan for the IC.

 

Wow that spearco really works, if youre only pushing it past at 5psi and it cools below the intake temp almost at ambient!

 

Are you gaining enough from temps to overcome the difference in flow?

 

And the crowd goes silent......