Just picked up the 2010 SI Sedan yesterday as my daily commuter. I also own an 07 335i (was piling on way too much mileage commuting 100+ miles a day to work), so clearly my performance tastes are a bit spoiled as that car is pure and simply a monster.
The SI, so far, is a total blast to drive, but I DEFINITELY feel the lack of power in the car. I don't really know why Honda doesn't increase the engine size to 2.2/3 l and squeeze out another 20-30 HP, because I feel like the car definitely needs it. I realize this is more of a bang for your buck car, but it still feels a little underpowered.
Aside from the 0-60 speed, I absolutely love everything about the car, especially the handling and fuel economy.
I've also heard that on the newer SI's, the standard intake/exhaust/headers doesn't really do much and in some cases actually decreases horsepower on certain revbands?
That leaves me scratching my head a bit, because I'm not about to drop the money for a turbo/SC only to shorten the life of the engine (I'm planning on driving this an easy 300k miles), so where should I turn for performance?
Best bang for the buck (besides FI) is to do an intake and reflash. It will give you good mid range gains where most of your driving is done. Some owners have reported as much as a 25 whp gain from 4.5-6K RPM's.
Remember, any increase in power - however minor - will decrease engine life. Engine wear is a function of compression and RPM's. Increasing either of those will put extra strain on the rings, sleeves, pistons, rods, etc. Even a simple intake allows for an increased amount of contaminants to enter the combustion chamber. It can affect the longevity of the cat, 02 sensors, and MAF/air temp sensors.
Not really. In some cases, you can lower backpressure too much and lose a significant amount of low end power. People who run a 3" no-name exhaust might suffer from this.
Most standard bolt-on's will give you a slight loss at the low end for better mid range/top end performance. You can expect a gain of 10-15 peak HP (maybe more) with I/H/E. Greddy, AEM/DC Sports, Apexi, and others have a good reputation with the Si.
Intake, Race Header (eliminates cat), exhaust and Reflash. I promise you, with that combination you'll be happy. I was in the same boat as you, really frustrated with the lack of power (I came from an automatic G35 Sedan) and I did these mods and night/day. Even my friend with a 350z drove it after the mods and told me that it felt like a different car. I mean, dont get me wrong, I still have the itch for something faster now but the relief you get from those mods in your quest for some "kick" is perfect.
Also learn from my mistake and since the reflash requires an aftermarket exhaust, go with a quiet one (Greddy SP2, Apexi WS, Greddy EVO, Tanabe RM) because although a loud exhaust is cool at first, it's obnoxious especially if this car is a "commuter" for you. I bought the Skunk2 and it makes me never want to take the SI on trips to Atlanta or anywhere else I go.
I'm jealous of the 335i, how is it? I was looking at a preowned coupe but the warranty sucked since the car had 49k on it and no offense but BMW's scare me out of warranty.
I have intake, header, stock exhaust and hondata reflash and put down 207whp and 165wtq. Up from 172whp and 134wtq. Night and day difference, especially for daily driving the car and midrange power.
Registered: 01/17/08
Posts: 69
Loc: Bloomington, IL
Originally Posted By: Design
Not really. In some cases, you can lower backpressure too much and lose a significant amount of low end power. People who run a 3" no-name exhaust might suffer from this.
Most standard bolt-on's will give you a slight loss at the low end for better mid range/top end performance. You can expect a gain of 10-15 peak HP (maybe more) with I/H/E. Greddy, AEM/DC Sports, Apexi, and others have a good reputation with the Si.
It's hard to take someone seriously when you claim lack of "backpressure" will hurt performance. Please do some research, backpressue is a myth spread around numerous internet forums. Exhaust velocity is about the only thing important in terms of performance increases. Sometimes a larger exhaust will slightly decrease exhaust velocity.
Not really. In some cases, you can lower backpressure too much and lose a significant amount of low end power. People who run a 3" no-name exhaust might suffer from this.
Most standard bolt-on's will give you a slight loss at the low end for better mid range/top end performance. You can expect a gain of 10-15 peak HP (maybe more) with I/H/E. Greddy, AEM/DC Sports, Apexi, and others have a good reputation with the Si.
It's hard to take someone seriously when you claim lack of "backpressure" will hurt performance. Please do some research, backpressue is a myth spread around numerous internet forums. Exhaust velocity is about the only thing important in terms of performance increases. Sometimes a larger exhaust will slightly decrease exhaust velocity.
LOL, you misread my post. What many people forget is that at low rpm's there is a relationship between backpressure, pipe diameter/length, and the rate of combustion. In addition to pipe diameter/length, exhaust velocity is affected by the initial resistance (backpressure) against low rpm "pulses." A small amount of backpressure actually helps to maintain the exhaust pulse throughout the entire length of the piping. Hence, if there's no resistance (however small that might be), the pulse quickly dissipates and the scavenger effect is lost.
So I think the point you're trying to make is that backpressure kills top end performance, which I agree with. But since most of us bought the Si for daily use, we sacrifice a bit at the top end to have better drivability throughout the powerband.
I'm certainly not an expert in this area, but several engineers much smarter than all of us once explained this concept to me. Take it for what it's worth.
Hmm...not sure why the Si was your first choice as a commuter, but either way it would probably be best to just leave it stock. As mentioned with the intake, it will just contaminate your oil faster and since you put so many miles on it, I'd imagine that you'd want to stretch out your OCI's as much as possible. In that case, an intake would not be a smart idea. Instead, I'd put that mod money towards the 335. DCI's and a tune of some sort should make for an awesome treat as a weekend cruiser
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1994 Ford Mustang Cobra 2003 Honda Civic Si
The I/H/E are the basic mods for this car. Intakes: A problem with the makeup of our air induction system is that the MAF sensor operates off the air diversion method. Meaning, there are vanes that channel the air as it passes over the MAF. That posed a problem for most aftermarket intakes because the standard norm of intake construction, didn’t take the vanes into account when designing. That led to a lot of AFR issues, bogging, sluggishness and other things. It took a young man by the name of “X” to design an intake using the MAF housing that produced relatively good numbers. Now, many companies are taking these vanes into account. While, they now see the potential, some of these intakes still have issues. That’s where Flashpro come in. This tuning solution can virtually fix the problems that came from these intakes as well as other things from a list of components. Header There are 6 Cat less Race Headers, 2 Short Headers and 1 Race header with High flow Cat. The choice to make is do you want to go cat less (Most power), High flow Cat (Mild Power), Short Header w/ stock cat (Least Power). As an alibi for the short header, you can couple that with a Random Technology High Flow Cat. I urge you to stay within your states emission laws (If you have none, go race header), due to the fact that you drive a civic and now you are on the radar (Unless you’re a cop or some sort of law enforcement). Exhaust Never go with a cheap, no name exhaust. They have no R&D behind them, the craftsmanship is subpar and you may end up going back to stock, or upgrading to something worthy. In any case, you wasted cash. Also, if you stay NA, there is no need for super wide piping. That reason has been explain in a previous post. Now the only thing you should do is find one that complies with your state’s Exhaust decibel standards. Forced induction Turbocharger. There is no substitute for the kind of power and torque you can achieve from a good turbo setup. There are multiple options that you can choose from. And each option will net you a specific amount of power. So far, of the reptiable companies, the lowest I’ve seen is 300 HP from a greddy on stock internals exhaust and intake. Supercharging is much easier and sometimes more cost effective. This is for the guys who want the reliability and aren’t really into tinkering almost everyday. While you sacrifice some of the torque you may gain to turn the blower, there, are advancements and breakthroughs almost daily to add to the functionality of supercharging. While both has its pros and cons, the K20Z3 is a stout and tough motor. It can withstand a lot of abuse. Tuning. Flashpro is the catchall for at home tuners. It’s easy to learn and unlocks so many options. Once installed and tunrd, your car will seem brandnew. Cobb Accessport is good also, but one thing Cobb lacks is thorough support for forced induction applications. While both of these are great tools for your cars drivability, there is no replacement for a good dyno tune.
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