Project Evo: GSC S1 Cam Review
Author: Ali Allage
Last Updated: 3/29/2007
One phrase can best describe the feeling of driving our Evo with these new cams, “holy mid range power!!” After the first pull, that look of shock was running down my face. I couldn’t believe that a set of cams made that much of a difference. But before we get into this review any further, I do feel a brief history about our older setup (before the S1 cams) will give everyone an understanding of what I’m comparing the S1 cams to.
Our Project Evo was running a set of HKS 272 intake and 272 exhaust cams with a set of Vishnu Cam Gears. This setup was matched with a Stock Valve Train, 10.5 hotside stock turbo, ported O2 housing, DC Sports Turbo Manifold, Vishnu Turbo Back Exhaust, XS Engineering Hard Pipe Intercooler Kit, Injen Intake w/ MAF, manual boost controller, and stock ECU. The car was tuned for 22psi (peak) on 93 octane and an additional map for 24-25psi on 100 octane. With this setup it felt like I needed to push the car towards the upper rpm band to get the most power out of it. It was a really nice setup and perfectly fine for driving at weekend track events. Driving the car on the street did get a little annoying because it needed to be pushed towards the upper rpm level to get it to move.
The following is our new setup: GSC S1 cams, Stock Cam Gears, Stock Valve Train, 10.5 hotside Stock Turbo, Ported O2 Housing, DC Sports Manifold, AMS Turbo Back Exhaust, AMS Front Mount Intercooler, AMS Intake w/ MAF, AMS Hard Pipe Intercooler Kit, AquaMist Water Injection Kit, manual boost controller, and stock ECU. AMS tuned the car and was able to provide us with two maps. The first map was for 21psi on 93 octane and the second map was for the water injection kit (27psi with 93 octane and Water Injection).
Now that we have a basis for what was on the car before and what is on the car now, the review can continue….
To be fair, the comparison was done WITHOUT WATER INJECTION. Since it wasn’t on the car before, there’s really no need to use it as a basis for this review. The decision was made to go with the 93 octane map with 21 pounds of boost and compare that to our older setup (93 octane with 22 pounds of boost). We put the car through a series of tests:
It was absolutely necessary to make sure the car was able to perform in each of these areas. $30,000 is a lot to spend on a car that sits in the garage only, so if this new setup was the right compromise for street and track use then we wanted to know for sure.
- Drove the car around the streets (city driving mostly)
- Put the car on the highway (all highway driving)
- Ran the car through a weekend at the track
About The Cams
First let’s get down to the specs:
|Brand Name ||Spec. ||Cam Duration ||Cam Lift |
|HKS ||Intake ||272 ||10.8mm |
|HKS ||Exhaust ||272 ||10.2mm |
|GSC S1 ||Intake ||268 ||10.5mm |
|GSC S1 ||Exhaust ||266 ||10.5mm |
**It’s important to note that both manufactures don’t require you to upgrade your valve trains in order to run either sets of cams.
As you can see looking at the initial specs HKS has a more aggressive Intake cam lift compared to GSC; however, the S1 cams have a more aggressive Exhaust lift. Also with the shorter cam duration, we now can see where the S1 is coming up with all this mid range power.
The street test was important for this review. We wanted to see what the differences were between the two setups when it came to idle conditions, cruising, etc. Right off the bat there is noticeable difference between both setups when the car is sitting at idle. The 272 HKS package had a more lopey idle versus the more subdued S1 package. To tell you the truth I do miss that “muscle car” feeling with the previous package but once I sat behind the wheel the sorrow was soon forgotten. Something as simple as driving the car around the city really showed the cams were different. Boost seemed to come on sooner and a little stronger then before. With the HKS setup I would start seeing some boost (around 4psi or so) right before I switched through to the next gear; however, with the S1’s boost came on earlier and held longer before the shift (closer to 8psi).
Highway impressions also showed signs of improvement. This was more apparent when entering the freeway in 3rd gear. As soon as there was a clearing on the exit, BOOM, full boost! To say the very least it freaked me out. Didn’t expect boost to come on that quick! Cruising on the highway felt the same as it did before. Only when overtaking another car did the rush of power come back. After that, it was like an addiction. I needed that rush again, time for the track.
Finally track weekend, time to really see what this new setup can do. The track used for this test was Summit Point Raceway (main track). My lap times before on this track were nothing special. Usually I would come in around 1.29 as the best for the weekend (full interior and ac, etc,). This time I wasn’t expecting that much improvement considering the weather was a little colder then the last time. Boy was I wrong. Getting some practice sessions done early in the morning, I really had some trouble fine tuning the boost to stay at or under 22psi on the 93 octane map (manual boost controller). Not wanting to risk an overboost situation I decided to just turn down the boost some more. With a little trial and error the boost stayed down to 19psi (consistently) with a slight overboost at 20 – 21psi. As the weather got warmer the boost stayed at 20psi peak. Once the car was finally setup, it was time to have some fun.
After the first two warm laps, I finally started to get on the gas. Turn 1 was approaching; I turned in, got on the gas, and….. “holy midrange power!!” (sorry had to say it again.). This thing was using its claws to pull itself out of every turn. I was in disbelief. Normally I would be in a lower gear going through some of the turns at Summit, put with all the mid range power, I decided to leave it in a higher gear. Turns were approached at 3700 rpm (roughly) and boost would come before the apex which allowed me to step on the gas more. The end result was a faster overall speed coming out of each turn. The other benefit was the amount times I didn’t have to shift, which shaved more time. In the end my best lap time came in at 1.26. Definitely much better then the last time. Call it better driving, but I would like to think that the new setup allowed me to reduce the amount of things that cost me more time before. The other thing to remember is the car was running less boost then it did before. This new package just seemed like it perfectly matched our setup and allowed me to get more useable power out of it.
In the quest for more horsepower, the one thing to remember is bigger numbers on paper, don’t necessarily equal the most horsepower or the fastest car. The one thing we learned with this review is if you match parts with the setup you currently have, a balance of power and drivability will occur. The S1’s for us was a perfect piece to our setup because it seemed to match with the stock turbo and all the other mods we had on the car. It ultimately gave us more useable horsepower/torque and more ammo to make that Z06 owner at the track feel less adequate.