We left our rather boring but tuned 08 WRX much faster than it started out but it was dying to get more power. While we were the first to tune the 08 WRX using an AP (not to mention first to tune an 08 WRX period with the Hydra) it was early enough in our development that we didn’t have an exhaust to install and do further tuning. Now we do and now was a good time to show off the HP results.
First off we left the WRX in Stage 1 tune. This was only with an ECU tune. We showed you the Cobb base map compared to our Tuned 93 octane map and the stock HP we found.
Before we get too much further, we needed to do a a few base run to get a good baseline since we last left the car. At this point we would be only running our maps we give out with our AccessPORT we sell. This would represent exactly what customers should expect to see on their own cars.
CATBACK Back to Back
After the base runs, we would be installing our catback exhaust first, then downpipes after that. Both would be initially ran with the same Stage 1 mapping, the after the downpipes were installed, our Stage 2 mapping would be installed.
To ensure accurate and consistent results were had, we made sure the runs were started at the same coolant temps each time, and same with air temps. But there is one huge flaw we found with the stock intake. I know everyone claims this is the best intake to have but I beg to differ! More on this later.
Onto the test…, well not quite. During our open house we did a custom tune on a Stage 2 WRX with our Stage 2 map. This car with a custom tune made 320ft-lbs and 230WHP. This was also on a very hot day. So we will see how this stacks up with our own results on our sedan.
Our first runs backed up our previous results (or pretty close) so it was time to throw on the Catback exhaust. With some gloves and with a little bit of prepping( removing a few unnecessary hangers) the system was swapped in about 10 minutes. Results were ok, and as expected almost 10WHP. That seems to hold true on pretty much all the Subaurs we have dynoed so far.
From there it was time to install the downpipes along with the catback. Again, we did this as quickly as we could and with thick gloves! About 15 minutes later, both front and read downpipes were installed and the car was idling. 15minutes is fast but we had prepred the downpipe and heat shield so it would come off much easier.
First run with a cold header was very surprising. Besides there being more HP the one thing that stuck out was how much boost the car started at. With the dyno holding 2000 as our launch RPM, we were seeing 12-13PSI of boost. This is compared to the 7psi the was seeing in Stage 1 form. Of course this better boost response made for more Torque and Power!
The additional boost and power shown here was with the same Stage 1 ECU tuning as the last 2 runs (Stage 1 run, and Catback run). The low end power is where this thing really rocks. The best part is this is a legal replacement downpipe and the car is still very mellow sounding. The catback exhaust did make some power, but more sound than power. The downpipes on the other hand make power with no sound change!
With these great gains, it was time to load out Stage 2 mapping and do a few more runs.
The blue line shows the power gained after the Stage 2 ECU tuning was done. Again even more, low end power and some more top end power. We are getting close to hitting STI stock Wheel HP levels, but with a lot more Torque! Yes we gained an additional 10WHP over the DP results but its getting obvious that top end is not this cars strength.
Comparing Stage 1 (stock car with tune) with Stage 2 (turboback installed and tune), Stage 2 nets an additional 40ft-lbs of peak torque and 20 peak WHP. With Stage 2 dialed it was time to do some intake test and tuning. At this point we already know that the new intake doesn’t replicate the stock MAF curve perfectly. We have been working on a PERRIN specific intake map for quite some time on the STI and it was time to put it to the test on the WRX.
Then if we compare Stock Vs. Stage 2 we really see a huge gain! For roughly $2000 in parts, you also can have these gains! For a few hundered more dollars you can add a few more poines as shown below.
Intake HP Results
Because there is ECU tuning required on this intake, this does add a variable to how much power the intake actually makes. Our goal was simple, make the Air Fuel Ratio match the last few runs on the Stage 2 map. With the MAF curve dialed and the Air Fuel Ratio dialed we felt comfortable (because we are not pulling a fast one changing other parameters) showing the results below. While the below results are legit, if we did this on a bone stock car you can expect significantly bigger gains. The intake system changes the MAF curve by making it read less air. This not only leans out the engine, but also add timing because of how the internal maps work. Its roughly .7AFR leaner. On a stock tune this is just fine as they are so detuned! We are bringing this up because we fell its important for customers to understand how and why its NOT ok to just throw on the intake on a car with any ECU tuing done. Oh and here are the results!
Yes the timing the car runs, and the Air Fuel Ratio is the same from run to run. Its not huge but add this to a few other small parts and its something you will notice. The intake does add some cool turbo sucking sounds along with some BOV sounds!
The first things people are going to say is,”Ya but what were the intake temps?”. The intake temps is what everyone claims is a huge issue with intakes. They are not just making this up but you have to understand why it normally is a problem, how it can be fixed, and why its not a problem on the 08 PERRIN intake.
If the temps go above a certain point, the ECU pulls timing, and bye bye power. Well everyone says their stock intake is the best at consistent temps, but I say NO, not on the 08 cars! What we found is the intake temps on the stock intake system started out cool, but after a few runs, the temps would climb, and climb and climb, and never cool off. It seems like the plastic, is ok at first, but over time gets heat soaked and never cools off and there is no way to cool it off quickly.
With our PERRIN intake on the 08 WRX being only a cold air intake, that puts the filter down in the fender well, the temps would be very close to ambient temps. During runs they were, but like the stock intake, they did go up during the runs(might have been because of the lack of fans blowing over the passenger side of the car) but not quite as much. The most important thing is how quickly it cooled back down. Within 30 seconds it was back to a normal temp (under 90F), were the stock plastic airbox would be holding 120 degrees and not drop at all. So what intake would you want on your car?
To help with the intakes causing a loss in power, we have taken it a step beyond making it a cold air intake. We have modded all of our newer maps so that when the intake air temps go up, the timing doesn’t get pulled. In stock form timing can be pulled as much as 3 degrees (which can mean 20ft-lbs or more of TQ loss). We have proven that changing this map doesn’t affect overall performance (except for the better) and provides more consistent runs, and overall more power! Another great benefit of the PERRIN custom maps!
One last test is Stage 3. Stage 3 is the same as Stage 2 but add a larger intercooler (either Top mounted or Front mounted). For this test we would throw on our PERRIN TMIC. With no tuning done the AFR’s got a little richer (should as its cooler denser air) and the power went up! Between the cooler charge the and less restrictive core, it gained some power. We did some further tuning for the Stage 3 setup, but we needed more time to do more testing. But below are the results .
The midrange power is pretty good, but notice one thing at 2000 RPM, the TQ is about 30ft-lbs more! This is because the core is allowing even more boost at launch. The extra PSI or 2 here and the cooler charge makes it a worthy mod. Don’t forget this is with no ECU tuning. After we did some playing we did get about 10-15ft lbs of torque and 10WHP more, but its needs more proving before that graph goes up.
That’s simple, Stage 2 with make about 100ft-lbs of torque and 40WHP over stock. You better hope Subaru build that tranny better than the 02 WRX!