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article details
Author Jeff Palmer
Categories Project Cars, Civic
Create Date July 16, 2007 12:22
Last Update February 19, 2016 00:56
What's new with the TOV Project Si?

It's been awhile since our last published update on the Project Si. If you read our forums, then you probably already know about most of the refinements we've made to the car in the past few months, but in case you've missed those, here's a brief rundown of what we've done:

SSR Stainless Steel Race Header

Following two failures on the DC Sports racing header (both related to leaking flex pipe sections), we decided to see what some of the alternatives were, and maybe pick up a few horsepower in the process. It turns out that until somewhat recently there were very few off the shelf options for '06+ Sis. SSR (Six Sigma Racing) was one of the first that we came across, and having heard positive things about their RSX Type-S header (which is essentially the basis for the Si header), we ordered one up. At a retail price of $1150, it costs a pretty penny more than the DC Sports Race header, but in our dyno tests, this design develops a bit more torque and top-end power than the DC Sports header, plus it's available in stainless, and the craftsmanship is a notch or two higher in quality as well. Installation of the SSR header went fairly smoothly, but it helped that I was able to use Dynolab's lift. The length of these race headers makes installation/removal much more difficult if you only have access to jackstands. The job's not impossible, but I had quite a rough go at it when I had to replace the DC Sports race header the first time. An optional "test pipe" adapter allows you to bolt up the SSR directly to the stock exhaust system. It mated perfectly with our stainless steel DC Sports exhaust system.

Injen Cold Air Intake

Due to the timing of our project build-up (we took delivery of our Si 4 months before they went on sale), nearly everything we originally installed on the TOV Project Civic Si was a pre-production prototype, including the AEM cold air intake. This intake worked pretty well with our car, but no matter how we tuned the Hondata's fuel, ignition, and cam timing curves, there was always a bit of a stumble when ramping the throttle quickly from lower rpm ranges. A theory developed that the engine was receiving garbled signals from the mass-airflow sensor (most likely due to the different geometry of the non-stock intake), causing a momentary rich condition and subsequent throttle stumble. So with this in mind, we decided to check out a competing design from Injen, in hopes our WAG would be validated. Performance-wise there was no real discernable difference between the two intakes, though there seemed to be a bit of an improvement in the stumble-itis condition. The Injen and AEM designs look fairly similar, with a nearly identical bend profile (apparently dictated by the Si's labyrinthine engine bay), though my hopes of reusing AEM's patented Dryflow filter on the end of the Injen were quickly dashed. Visually, the Injen and AEM intakes look pretty similar, though Injen utilizes sections of pipe with varying diameters while AEM's pipe uses a constant diameter from tip to tail. The use of a narrower pipe profile on the Injen is intended to mimic the cross section of the stock intake where the MAF sensor is located, and this may account for the better low speed performance. The fact that the stumble was not completely eliminated indicates that there is another issue (probably the cams which may require more low speed tuning to avoid strange intake pulses that confuse the MAF).

Installation of the Injen intake called for some minor cutting of the left front fenderwell trim to be performed, something we'd rather not have to do. The AEM doesn't require this. This puts the Injen at some risk if you happen to be running larger wheel/tire packages (such as the 19" wheel/tire package that our car wore at SEMA). There seems to be plenty of clearance for our stock wheels and our 17x8 set of track wheels (with 235/40s). Some people have reported in our forums that they were able to complete the installation of the Injen without having to trim the fenderwell plastic, but it wasn't possible with our installation.


Upon removal of the AEM intake, we were a little surprised and disappointed to find evidence that the aluminum tubing was making contact with the chassis in one or two spots, to the point that a small hole had worn through the intake tubing in one of the bends. It's possible that the intake wasn't installed properly in the first place (when we got it, there weren't even installation instructions for our installer to follow), but we noticed that AEM's lower mounting bracket configuration seemed to make a little bit less sense than the mounting holes Injen picked for their design. When installed, the AEM's lower bracket had to make a LONG reach for a bolt hole in the chassis. Injen chose another bolt hole in the chassis, much closer to the intake, which logically reduces the leverage action that the AEM's longer bracket created (ie, the intake moves less with respect to engine position). Overall, the Injen intake is a nice design but one piece of the kit that didn't quite pass muster, and that's the elbow that attaches the intake tubing to the throttle body. AEM's design is much sturdier, made of stiff rubber. Injen's elbow is a much thinner material and we noticed after only a few dozen miles of driving that the elbow had twisted to a point of partial deformation. With as much as the motor moves around on its soft mounts, this can't be very good for performance. Fortunately for us, we had the better AEM piece, and it fit perfectly. The only other gotcha we had turned out to be a relatively minor one. Once we fitted the intake into place we attempted to attach the wiring harness for the mass-airflow sensor, but the machined plate on the intake interfered with the sheath of the harness, preventing it from "clicking" into place initially. By loosening the mounting screws for the MAF slightly, we were able to press hard enough on the wiring harness to click it into position. Then we resecured the mounting screws for the MAF.

Nitto NT-01 Tires

For our last track outing at the Streets of Willow, we had planned to run the car on the set of R-compound Avon tires that The Tire Rack had graciously provided for our project, but before we could even try them out, one of the tires corded heavily in the single day of testing performed by SCC. Shawn observed the entire day of testing and based upon the tests performed, he could see no reason why one tire would have disintegrated to the degree that it did, but the result was that we had to suddenly find some useful tires in a very limited timeframe. Fortunately we managed to score some used Toyo RA-1s from some of Shawn's racing buddies at Special Projects in Southern California, and even in their beat up condition, they delivered fantastic grip during our day at the Streets of Willow. That single track day was pretty much all the RA-1s had left in them, however, so to prepare for our most recent track day, we picked up a brand new set of track tires earlier this spring. RA-1s were the obvious choice but since we were actually paying for this set of tires, we decided to check out a much more affordable option - Nitto's NT-01. We were able to save nearly $150 by going with the Nittos.

The NT-01s turned out to be great tires. We beat the living snot out of them at Talladega Grand Prix, and then drove several hundred miles on them up to the Tail of the Dragon, where we resumed our campaign of merciless abuse. They passed with flying colors and delivered excellent grip, with less of the tramline effect we sometimes observed with the used RA-1s. Ultimate grip may not have been as high as the RA-1s at full operating temp, but the NT-01s never overheated or felt greasy, no matter what we threw at them. It is still too early to pass final judgement as we haven't figured out optimum pressures (whereas the RA-1s are very well understood), and the tires were run at full tread depth versus the RA-1s which were near slicks. Perhaps the best part of our experience with the NT-01s is that even after so many laps on the track and a good number of runs up and down the Tail of the Dragon, there appears to be quite a bit of treadlife left - something that the RA-1s are usually prized for. If only we had a set of them to put on the S2000 we took to Talladega that day...


We've been through several sets of stock brake pads, a few different aftermarket pads, and are now on our 3rd set of rotors. The first set of rotors was destroyed during our first track outing when we took our car to the Streets of Willow in bone stock form. The stock pads essentially vaporized to the backing plates and we managed to score up the rotors to a fair extent. The 2nd set of rotors lasted us through our next track outing and about 6 months of street driving. Immediately prior to Project Si's first encounter with the Tail of the Dragon, we put some Hawk HPS brakepads on the car. As seen in this video update from last year, we weren't 100% happy with them during their first outing at the Dragon. At the time we were thinking that they hadn't been fully bedded in yet, so we weren't ready to pass final judgement on them. Well, several months of street driving and another track day later, we've decided we're not that crazy about the Hawk HPS pads at all. For mildly aggressive street use, they seem fine, but for repeated stops from high speed (as required on Talladega Grand Prix), they just weren't up to the task. Since we had excellent results with a set of Carbotech PantherPlus pads at our 2nd outing at the Streets of Willow, we considered getting another set of track pads for Talladega Grand Prix. We knew Talladega Grand Prix was a short track, and we (incorrectly) assumed that it wouldn't be a very fast track, so we decided to see how the HPS pads would hold up there. As you will see in the video on the following page, that was a bad choice and while they didn't wear all that excessively, the excessive heat build up significantly changed their properties to the point where it felt like we had driftwood clamped to the calipers. The next set that goes on the car will be Axxis Ultimates - we've had great luck with these pads in the past - they deliver excellent performance under demanding conditions with a bit of extra dusting as a trade-off.

Track Day at Talladega Grand Prix

It's been a while since we had the Si out on a circuit, and after a few aborted attempts, we finally ended up renting a track all to ourselves for a day. While a full day of track time may seem like a lot, we wanted to make sure we got the most bang for our buck, so we brought along a few other cars to test as well. The Project Si, of course, acquitted itself quite well out there, but as mentioned above, the Hawk HPS brakepads were nowhere near up to the task of repeatedly hauling the car down from ~100mph. Even so, we managed to record pretty quick laptimes, easily besting the other factory stock cars (2000 Honda S2000, 2006 Honda Civic Si Coupe, 2007 Honda Civic Si Sedan, and 2007 Acura TL Type-S) that we had on hand by several seconds. While we were mostly focused on getting our track videography and photography completed, we still managed to put in a few cooking laps, with a best recorded time of 1:11.5. Not too bad considering our brake pads had basically turned to stone by that point. With suitable brakepads, we think we could have easily trimmed more time off. Overall balance of the car is very good - the grip afforded by the NT-01s out there allowed us to easily surpass 1.0G of cornering force - the only thing we would ask for would be a bit more rotation, but as it is, the car is extremely confidence inspiring to drive (apart from the brakes, which would quickly evaporate said confidence!). We're hoping to go back out to Little Talladega with better suited brake pads and maybe come home with a laptime in the 1:09 range.

Living the Rough Life

Considering the abuse the Project Si has seen and the fact that it's a very early pre-production prototype, it's held up quite well. There are a few chassis creaks here and there, but during our torturous track testing and, ahem, other testing, the car's jumped its fair share of curbs and seen a fair bit of airtime, so to speak. And considering the rather stiff calibrations of our Progress coilover suspension, the interior remains largely free of squeaks and rattles, though maybe we simply can't hear them over the sound of our rather loud race-oriented exhaust system.

As long as the Si's been out on the East coast, we've suspected that something wasn't quite right - while it runs fine, it's never felt quite as strong as it was when it was first assembled out in California. Two passes down a dragstrip last October (the track was so crowded we only got two runs in the car in 3 hours) revealed that our trap speeds were down by around 3mph compared to the times obtained during testing for the March 2006 cover story in Sport Compact Car. Considering the SCC testing was performed at much higher altitude and greater temps than our October testing, we were a little bit concerned with our trap speeds. But since we were testing on the (worn out) street tires that day, we figured the excessive amounts of wheelspin we encountered were the biggest problem. Plus, due to extreme delays at the track that night, we were only able to perform two runs that night AND the Hondata ECU program we were running that night was mistakenly set with a lower rev limit than our "final" tune had (8400 vs 8600 rpms). Later, during dyno testing of the SSR header, we confirmed the car had in fact suffered a reduction in power versus early tests by Shawn and SCC, so I proceeded to search for a cause. After adjusting the valves and doing a compression test, checking spark plugs, and oil level we found absolutely nothing wrong (well, the valves were out of adjustment, but correcting that did nothing for power though it did restore some lost midrange torque). Later, during our most recent track testing, we observed trace puffs of oil smoke on shifts, so maybe the early pre-production engine is just getting a little tired after all of our abuse.

What's Next for Project Si?

As the Project Si has been serving in more or less of a "daily driver" role for the past 9 months or so, we've had a bit of a chance to see what it's like to live with a car that's been tuned to such a degree. For the most part, the project car hasn't been bad at all as a daily driver. As a guy with a family, the one thing that I would like to have is an extra set of doors. As such, we're currently working on acquiring a 2007 Si Sedan. If we end up getting one, we'll apply much of what we learned on the coupe to this car, yet the target will be oriented a bit more towards suitability for daily driving. That means we'll be fitting a more compliant suspension, but we feel that we won't have to give up too much in terms of outright performance. Initially I'll install a progress swaybar on the rear and a camber kit up front. Later on I'll look at a set of HFP springs and shocks, or perhaps one of the other available options. I will also be installing on a set of Axxis Ultimate brake pads, the SSR Race header, a Hondata reflash, and possibly an intake. We'll see how it does with the header and reflash alone, first, though.
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