Working with the 2011 Kia Optima has been a harrowing experience. During our baseline pulls at the dyno, the car experience massive heat soak from the first run to the last despite how much time we allowed it to sit. Lo and behold we find out that the owner of the car (and many other owners out there as the reports on the forums show) was led to believe that it was a-ok to run 87 octane in a 9.5:1 Compression, Twin Scroll Turbocharged, Direct Injected vehicle. While we won't try to battle in that debate on this post (because some people simply can't be convinced that, in the real world, direct injection isn't a magic carpet ride to no-detonation-land), we acknowledge that the baseline pulls had some amount of timing pulled due to heat soak and the lower octane fuel. That being said, we are confident that the low end closed loop area of the early dyno pulls was accurate without any retarding of spark by the computer until around 5200RPM.
Additionally we'll venture a guess that this car probably isn't the strongest one to roll off of the boat. I wish it were, I wish it were like our STi that we ran the same day as the Kia that thrashed down 280hp on nothing but an intake, but it's not. With the Subaru's we see a lot of variation from car to car. Like 30hp differences between identical model stock cars. Either way, we're comparing one car to itself, and despite the fact that it only made 251whp at peak, doesn't make the gains any less.
Needless to say, the gains from one mod to the next on this car are impressive. Down low at 2700RPM we knocked down 30 HORSEPOWER from the highest baseline pull to the fully modified pulls. Up top, even if you bias the original baseline results by 15-25hp (although intercooler inefficiency and heat soak are a fact of life for real world comparisons), we're making 50whp at the top end (Nearly 75 if you take a direct comparison). And seriously, if you interpolate the baseline graph given the later curves of the modified pulls, it might be pulling 15hp worth of timing, but we're being kind. Either way, there are a few more things to discuss before you get to see pictures:
1. Intake comparisons were taken with the stock AND Nameless Performance intake receiving a K&N filter that flows 628CFM (~30% more than the actual breathing capacity of the _modified_ turbocharged engine). No comparisons were taken to account for power gains netted in the filter itself. This is important because from what we can tell, most of the high end gains from induction tract improvements are filter related. That being said, I think we knocked it out at retaining and building great low end power with our pipe design.
2. We did not have the ability to test every product on the car independent of others. Because of this, we chose to leave the following items on the car at all times for our most recent day of runs: TurboBack Exhaust, Charge Pipe w/ Synchronic BOV. The Synchronic on its own in a single gear pull environment would make little difference other than those found from a leaking BOV, but with the electronic actuated boost controller, the ECU would quickly chase that out of the equation. The Turboback Exhaust was something we really couldn't justify testing one piece at a time given the extensive number of pulls required to test other items. I'll say this much – in the past I've tested a lot of exhausts on the dyno, and a lot of exhaust components. On boosted cars, dyno tested gains may indicate that the downpipe makes 15hp, midpipe makes 14 and the catback makes 12 when each are added independently to an otherwise stock system. However, as you remove restriction, you will reach a point of diminishing returns. For that reason, I would highly suggest that anyone on a budget pick one or two exhaust mods, and do them and spend the rest of their budget on the other elements in the system rather than sinking all of your money into a balls-out TurboBack exhausts without remedying the heat soak or other power robbing issues with the car.
Ok so with that out of the way, lets look at the plots:
First off, we'll take a look at a plot showing four configurations on a horsepower graph. From lowest to highest power output, we have:
1. Baseline Pull, essentially stock, 87 octane fuel.
2. Nameless TurboBack Exhaust, Charge Pipe w/ Synchronic BOV, Stock Intercooler, Stock Intake Piping, K&N Filter
3. Nameless TurboBack Exhaust, Charge Pipe w/ Synchronic BOV, Stock Intercooler, NP Intake, K&N Filter
4. Nameless TurboBack Exhaust, Charge Pipe w/ Synchronic BOV, NP Intercooler, NP Intake, K&N Filter
Three cursor points have been illustrated here: one showing a 29hp peak low end gain from baseline to fully modified at 2700 RPM, the next showing a ~20hp gain across the low end from stock to fully modified. That second point also shows a 5hp gain from the intake pipe alone (with the K&N filter taken out of the equation by being part of the baseline). The third cursor (from the left) shows a 42 horsepower gain over the stock baseline at 4700RPM. At about 5200RPM, the system is well heat soaked and starts pulling advance, effectively flatlining until 6000RPM. In our opinion, anything past this point on the stock dyno graph needs to have some biasing added in – meaning we need to assume that without heat soak (wait, but it DID heat soak....so what!? we're giving it the benefit of the doubt) it would have continued on a similar to the other graphs above it show, still fairly flat, but increasing nonetheless. so lets draw a line to fill in that trough in the baseline pull. Might be 15hp, but lets say it's 20 for good measure. Our final cursor shows a 70whp gain at 5950RPM, we'll bias that down to a 50whp gain.
So why give the crappy intercooler the benefit of the doubt? I'll tell ya why – because there is NO WAY to emulate the flow of air over an intercooler at speed on the dyno as you would expect to see on the street (well, without cooling fans big enough to circulate air at the Sears Tower).
But here's the rub: The fans we use on the dyno can't cool our intercooler as well as ambient air at speed either. We saw approx. 18 degree boost air temperature drops between the dyno and the street on the same day of this testing. I'll let you do the math to see how much additional power that is.
One more area of the graph to focus in on is the midrange horsepower gains from the use of our intake pipe over the convoluted factory unit:
These two graphs show that the intake piping alone makes up for 5-11 low end to midrange wheel horsepower without even evaluating the difference of impact in the 628CFM K&N Filter vs. a stock unit. As a note, competitors conical filters flow roughly the same ~600CFM, but they're pulling hot engine air. What'd I say about heat soak?
Finally a sneak peak of the torque graph – we made 55 ftlb over stock there as well. You'll see a little hiccup in the graph on the full FMIC pull, and it's consequent is visible on the horsepower graphs as well. However, it wasn't there on any of the other pulls, but I chose the peak hp pull for each session to keep my numbers consistent and non-biased. I'll be discussing the torque curves in depth after I get some sleep. 23 hours of work is enough for one day.
And to those of you who waited patiently for this, I really do appreciate your patience. I know it's been four days since we were at the Dyno, but it's been a spectacularly busy four days.
Good times,
Jason Griffith – Engineering Director, Nameless Performance, Inc.