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XT6 Dyno Cobb CAI vs JC Sports Intake Results


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#1 Myxalplyx

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Posted 03 January 2005 - 04:16 PM

Hey guys,

Did 5 runs earlier today testing out how the Cobb intake faired against some of the old dyno tests of the JC Sports intake. I have to say, things did not go so well. :? I dunno if it's just a fact of my car slowly dying, the intake just not doing as well or the header I had custom made taking it's toll big time. I do know after that header was installed, I lost a ton of low end torque but I kept it. Even still, the JC Sports intake was tested with the header as well. The two intakes were tested on the same car which is a 1989 2.7ltr XT6 (FWD/Autotranny). The JC Sports intake is no longer on the FWD XT6. It was put on my AWD XT6.

Here are some quick pics of the intakes before posting the results. This is the JC Sports intake--->
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Here's a picture of the Cobb (PRM filter) air intake I have now on the FWD XT6-->
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I did a total of 5 dyno runs today. My goal today was to aim for a 13.0:1 air/fuel ratio. All over the internet, I'm always reading that this is the optimum air/fuel ratio for naturally aspirated cars when it comes to making the most hp. My first run I had a 13.5:1 air fuel ratio. I adjusted the fuel pressure via a AEM fuel pressure regulator (fpr). The second run I had a 12.9-13.0:1 air/fuel ratio. Perfect! However, it appeared I had lost just a tad of hp/torque according to the computer at the dyno shop. :?: The 3rd run I dialed back the fuel pressure regulator shooting for a 13.25:1 air/fuel ratio across the board. It seemed to have gained a tiny bit of hp/torque. So I then adjusted the car for a 13.5:1 (which is what I came in with) and let the car cool off. After this, I ran the car two more times and I had to leave to pick the wifey up. *She had to take off work today and go shopping didn't she? :roll: *

I'm using run #4 for comparison to one of my JC Sports intake runs. Run #4 was after letting the car cool off. All runs with my automatics are done from the bottom of 1st gear to the top of 3rd gear. I only show 3rd gear to avoid confusion by some not familar with dynos.

In the end, I have LESS hp and torque than I did previously. *sigh* During high rpms, the dyno graph appears to be wiggly at some points. I have seen this trend before when I had my cams installed. I had to richen the air/fuel ratio all the way to 12.0:1 air/fuel ratio and add timing to make the wiggly lines smoother. Perhaps I'll adjust fuel to 12.0-12.5:1 tomorrow. That's turbo fuel richness though. I'm using 93 octane gas.


This graph is of a horsepower comparison between my XT6 with the JC Sports intake vs the Cobb CAI intake. The JC Sports intake peaked at 112hp while the Cobb CAI was only able to muster 108hp.
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This graph is of the torque comparison between my XT6 with the JC Sports intake vs the Cobb CAI intake. The JC Sports intake peaked at 125lb-ft of torque while the Cobb Cai was only able to make 115lb-ft. *Note* this isn't a true JC Sport or Cobb intake for the XT6 because there aren't any. I just scrapped some extra parts together to make them work.
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I'm trying to figure out if I want to go back tomorrow to see what happens if I adjust the air/fuel ratio to in the 12.0:1 or 12.5:1 areas. I'm thinking about it. In the meantime, this is all I have for now.

#2 MorganM

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Posted 03 January 2005 - 04:30 PM

As much as I love reading dyno comparisons I dunno if its really a fair comparison based on the drastic exhuast change.

Still good to be reading XT6 dyno charts :drunk:

.... reading more close.....

did you change intakes there and run these both on the same exhuast??? or is it just a comparison from previouse runs to your current runs?

#3 Myxalplyx

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Posted 03 January 2005 - 04:53 PM

did you change intakes there and run these both on the same exhuast??? or is it just a comparison from previouse runs to your current runs?

It's just a comparison to previous runs vs the current ones. The graph you see is the JC Sports intake with the exhaust work already done. Believe it or not, the hp drop was just as dramatic before when I had a ProECM powerchip installed with a 2.25" exhaust (1st cat back) vs the 2.5" exhaust I have now. I just made the graph up below so you can compare up so you can tell. I just picked a random point on the graph so you can see the difference between the ProECM powerchip/2.25" exhaust/JC Sports intake run vs 2.5" exhaust/No chip/JC Sports intake vs 2.5" exhaust/Cobb CAI intake *today*. 112hp - 106hp - 98hp at the point I chose is the difference. Be careful what you do. This car is for testing things anyways. The AWD model is the one things will be done 'right'.

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