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Old 04-30-2003, 03:00 AM   #1
supermarkus
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Lightbulb Perrin Short Ram Intake Road Dyno Results

Disclaimer: All of my dyno pulls were done on the same stretch of road, on the same afternoon, same temperature. Keep in mind that these plots each represent an N=1, so they may not be accurate nor precise. I did not want to risk my license to do lots of 3rd gear pulls in public, just to verify accuracy and precision. I'm also not clear on the actual accuracy of the Road Dyno option of the Delta Dash to begin with. Also, this was my very first attempt to Road Dyno this car, I'm now aware of the comparison option and will use it in the future, provided I can safely crank off some 3rd gear pulls without drawing State Trooper attention. YMMV

Exhaust Mods:
-Gutted up-pipe
-Scoobysport Downpipe
-Stromung FMP cat eliminator
-Prodrive BB

Here is a plot taken right after an engine reset via the DD diagnostic tool and Shiv's IAM "trick".


Here is it's associated info sheet


After turning around and driving back to the same stretch of road immediately after the pull, I tried to corroborate my first result.


Info sheet, imagine my surprise at this result.


Here is the real stunner, this run with a Perrin short ram intake was done about 2 hours before the above plots on the same road.


Info sheet, note the earlier torque peak with the Perrin intake.
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Old 04-30-2003, 03:10 AM   #2
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My preliminary take on these results is that the stock intake performs pretty well in comparison, but it appears to indeed be more restrictive than a short ram. Since I don't have engine management mapped to take advantage of the extra flow of the intake, I am probably not scratching the surface of it's potential benefits. I still haven't analyzed all of the datalogs to compare MAF, MAP, and such so I don't really know what effect the intake had yet. THESE ARE PRELIMINARY SPECULATIONS. Also, I wasn't able to observe EGTs since mine was damaged in the up-pipe modding process, a 2.2k ohm resistor is there right now. I'm going to bring along a passenger next time to monitor the EGTs on my GReddy gauge, it's better than nothing at this point. I may even try to rig up a Lab Jack to allow my Gauge to send info to my DD.
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Old 04-30-2003, 10:58 AM   #3
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It looks to me that your stretch of road is not flat or the wind was blowing. The DD Road Dyno is very sensitive to external factors that impede or aid your acceleration.

But the DD Road Dyno does have the ability to provide consistent, repeatable results that are useful for self comparison. It's not very useful for absolute horsepower comparisons between cars. But then, "real" dynos aren't that useful for comparisons between dynos.
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Old 04-30-2003, 02:03 PM   #4
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Was the run with the Perrin intake done in the direction of the first run or in the direction of the second run?
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Old 04-30-2003, 05:55 PM   #5
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All runs were done in the same direction on the same stretch of road, I would put the hazards on and wave people past until the road cleared, do the pull, then turn around and go back to the spot for the next pull. Whatever road inconsistencies, flatness etc. shouldn't matter in this experiment since all pulls were done on the same striaght, but no the stretch wasn't perfectly flat, there is a gradual dip and rise to it. I was on the Mukilteo Speedway going toward the 405 interchange between 99 and I5. I started my pull just after the Hwy 99 onramp ended and the road straightens out. So I guess I was sorta eastbound on 525(?). Thanks for the insight on the testing, this has been pretty fun so far. I just wish I could have sprung for engine management of some sort to go with the DD, I'm very curious about the XEDE now.
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Old 04-30-2003, 06:06 PM   #6
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Markus,

I'm a bit confused, is the second graph without the intake? Cause in the third graph, it seems that you lost power. Sorry if I missed anything, long day at school. I hate spanish class

Jason
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Old 04-30-2003, 06:12 PM   #7
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Well, if I knew how to read I guess I wouldn't have asked that question . The much earlier torque peak is interesting but there is so much jitter on the values through that whole range its hard to tell from just one run (although I fully understand why you only did a limited number). What is disconcerting is the variation between the first two runs since they were so close together in time. It would be nice to see some other values (like ignition advance) that correspond with these runs to get a better idea of what is going on. I really need to get a laptop and deltadash. I'd have way too much fun with it.
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Old 04-30-2003, 06:16 PM   #8
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There's still the wind gust theory to contend with. You're best off doing it on a perfectly calm day from the exact same spot, the exact same way.

I'm not even sure why you posted this. I now know the Perrin intake either gains ~4HP or loses ~20HP. I'm pretty sure you mean to imply the former. But those dyno results are so inconsistent I can only guess.

I'll stick with my stock intake for now.
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Old 04-30-2003, 07:07 PM   #9
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That was my conclusion too. I'll run the stock intake until someone makes a map that can take advantage of the extra flow.

I don't have to have a reason to post the info. I made enough disclaimers about it being YMMV situation, non-scientific, and low N. Until I get the sample size up, all this really does is show how much the ECU can adjust to make power.

Jason, you're reading it right. In my quick and dirty experiment the stock intake system holds its own pretty well. But let me reiterate, this means virtually nothing until I can take at least 10 pulls under the same set of conditions to confirm the results. If anything this whole post is just eye candy. But I thought you guys might be interested in seeing some preliminary testing. If you aren't, just say so and I'll delete it.

I'm not sure about the wind gusting, it was pretty sunny and calm last sunday when I was testing, it got windy in the afternoon though. I don't know if I can find a place where I won't have to contend with wind. I 'll just need to rattle off a bunch of runs in quick succession so I can accurately compare them.

Last edited by supermarkus; 04-30-2003 at 07:15 PM.
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Old 04-30-2003, 07:14 PM   #10
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Quote:
Originally posted by MojoHand

I'm not even sure why you posted this. I now know the Perrin intake either gains ~4HP or loses ~20HP. I'm pretty sure you mean to imply the former. But those dyno results are so inconsistent I can only guess.
That's actually not what the graphs should show, they should show that the stock and Perrin intakes show roughly the same power output under similar conditions. I don't have a graph that shows a 20 hp loss with the Perrin, I'm confused... did they come through all jumbled up?
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Old 04-30-2003, 07:16 PM   #11
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I have this Turbo Magazine right next to me and basically they had a whole WRX theme in that mag. They tested the Apexi air filter on a stock WRX. Baseline was 162.6 hp and 162.5 tq. Now when they added the Apexi air filter, they got 164.4 hp and 166.6 tq. Not bad gains. While the perrin is a "foam filter" the apex is more like the K&N mesh type filter. Either way I dont regret having the perrin in my car. Looks nice, sounds nice, and its said that your gonna need a intake when you get some big power mods.

Jason
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Old 04-30-2003, 07:47 PM   #12
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No, it was I who got jumbled up. Your results don't show a 40hp loss. But they do show that your mumbers aren't to be trusted (if you got a 20HP discrepency between runs).
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Old 04-30-2003, 08:02 PM   #13
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Quote:
Originally posted by MojoHand
No, it was I who got jumbled up. Your results don't show a 40hp loss. But they do show that your mumbers aren't to be trusted (if you got a 20HP discrepency between runs).
He didn't get a 20hp discrepancy.

The first run was done immediately after an ECU reset, which resets all the ignition advance multipliers in the ecu's ignition timing maps. That makes the car slower...

The second run was done after giving the ecu a chance to build those multipliers back up. That makes the car faster.

The only thing the first graph is good for is to compare it to the second graph, to determine how much command the ECU has over ignition advance, and how much more power a "learned" ecu gives over a freshly reset ecu.

The only thing the third graph is good for is to compare it to the second graph, to determine the differences between the stock intake and the Perrin intake.

Nice job Markus! Quality post!
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Old 04-30-2003, 08:07 PM   #14
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Yeah I'm really kicking myself now, I wish I had ignition advance and knock numbers for those runs. I literally did the base run, drove to exit 181, went back, turned around to go east bound and did the run again, something like 10 minutes between the pulls.
My theory is that the IAS trick that Shiv suggested was not enough to build an set of lookup tables in the short time I had to get into position. I did the DD reset, which killed all my learned timing, and on my way to the test site I did the IAS trick. Then after my first pull, graph 1, I the ECU was able to establish knock limits under the Road Dyno conditions. That's probably where the extra hp came in the second pull. That or the the Road Dyno really is terrible for precision. Has anyone here been able to establish AT LEAST some sort of feeling for the precision of the Road Dyno? I'm not so much concerned with the accuracy right now.
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Old 05-01-2003, 11:35 AM   #15
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I'm also interested in how you worked out the weight of the car?

My trick has been to take it to the local waste recycling center and ask them nicely to provide me with the weight print out and not charge me. (I'm not dumping anything)

The DD road dyno is very sensitive to the weight of the car, try it. Change the weight a little and see the HP differences.

With the correct weight and a good stretch of road the DD road dyno does turn out very similar numbers to a full dyno.

Mick
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Old 05-01-2003, 11:47 AM   #16
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There's no mystery, being my first time using the DD software, I used whatever settings were provided in the 1.36 software. Like I said earlier, I'm not interested in accuracy right now, which is what vehicle weight would impact. I'm going to continue using their settings to try and establish a feel for the precision of the software, after that, I'll worry about the accuracy by comparing it to some sort of AWD dyno. But that's down the road a bit, time is tight right now.
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