Hi, I drive a 2004 G35 Coupe 6mt. I was wondering if cams are a good way to gain hp after I've done my bolt-ons.
If so, are they worth it?

 

Firstly I need to make sure you understand what changing cams actually does. Cam profiles determine where the engine will make peak horsepower/torque, when you shift the point upwards you trade low end power (-15 to -20 hp at low rpms) for high end power (+15 to +20 hp at redline).

If you're not going to build the rotating assembly to regularly run in the 7500 rpm range don't waste your money, the gain will definitely not be worth the cost and time for a cam swap.

Unless this is a TRACK CAR that spends it's life in the upper part of the rpm range you will likely need to offset the low end loss with different gears to compensate. Unless for some reason you NEED that 160mph top speed?

If this is a daily driver I wouldn't even consider a cam swap since the loss in low end power where the engine spends 99% of it's time will be significant.

If you are already boosted then the forced induction usually offsets the drop in low end power enough to justify the top end gain since it's a much more significant gain (~30ish whp peak).

Cams are a great option though when coupled with headers and a different intake plenum designed for maximum flow, there is a GREAT synergistic effect between those 3 parts but they ALL will cause you to lose significant low end power and trade it for high end power, at the end of the day it just depends on exactly what you're building this car for.

 

Thanks for all that info, I didn't actually know what cams did. What other options do I have for horsepower gains after bolt ons and a tune?

 

aside from forced induction

 

The list extends beyond just the engine assembly itself, once you have a plenum spacer (and lower intake if rev-up) airbox with quality filter, high flow catalytic converter, free flowing exhaust, then you can also look into losing rotating mass with lightened pulleys, lightweight flywheel, (not sure if a lightweight flex plate is even an option for the AT, sometimes problems arise from lack of rotating mass inertia), lightweight propeller shaft, overall weight reduction for the vehicle by removing "unnecessary" components like the spare tire and such.

A word of caution about lightweight flywheels however, when you remove weight from the rotating assembly you lose inertia, this inertia helps the vehicle launch from a dead stop because there is so much spinning weight behind the clutch that is quickly transferred into the transmission when you engage the clutch. A lightweight clutch requires you to slip the clutch (pretty severely on a full power launch) to keep from bogging the motor down due to this substantial decrease of inertia.

What you lose in initial engagement however you GAIN in faster revs throughout the rest of the process, stomping the pedal once you're already rolling down the road will feel much snappier with more power transmitted directly to the transmission since there isn't as much inertial barrier to overcome. If you're seriously thinking of going this route I STRONGLY suggest you find someone with a lightweight flywheel that will let you drive their vehicle a little, it feels MUCH different than the stock weight flywheel and might not be what you're looking for.

Personally I love mine and have always loved the FEEL of a lightweight flywheel but I've been driving them for years and it's completely instinctual for me to keep the gas pedal slightly depressed when shifting (because my engine practically drops to idle during a normal smooth shift otherwise) and to launch at about 3.5k rpms and slip the clutch for about half of first gear. Yes I have to replace clutches early but for me PERSONALLY the pros outweigh the cons. Its all a matter of building the car to suit YOU.

There are also MANY more aspects to "performance" beyond just how much power your car makes, suspension modifications with springs/struts or coilovers, sway bars, urethane bushings for critical launch components like the differential and subframe as well as all others for suspension and handling.

As important it is to go fast it's MORE IMPORTANT to be able to STOP FAST (for a public roadway vehicle) so make sure to upgrade your braking system as well depending on your needs and conditions. For most folks a quality set of slotted or drilled/slotted rotors and a proven set of brake pads is enough, for folks who want to engage in any track use or severe twisty roads and such would be well advised to upgrade calipers to a performance set that is proven to reduce brake fade (scariest condition you will EVER encounter from a normally operating vehicle).

Also, what good are all these performance upgrades if your car doesn't look clean inside and out, don't forget to give your interior leather and vinyl the love it deserves from quality cleaning/protecting products as well as exterior wax/cleaning on a regular basis, cosmetic upgrades like windows tinted to the maximum allowable tint for your area will protect the vehicle (and you) from UV damage as well as look better.

Lastly and MOST IMPORTANTLY.... tires.... tires.... tires.... there is no single component on a vehicle more important than your tires.... make sure you are properly aligned (or aligned for your driving style, personally I keep -2 camber front and -1.5 rear due to my driving style). Replace them BEFORE they are at the end of their life, check the date stamp on your tires and replace them if they are more than 5 years old. Use only quality rubber from known brands.

 

Also, if you really want to add power then you're going to have to reexamine your stance on forced induction. Do some research into the newer Vortech v3 kit, I've installed vortech superchargers on quite a few vehicles in the past (never done the G/Z though) and they are thorough, direct, complete kits with excellent instructions, proven gains, and very reliable on stock motors with low miles. Stick to your maintenance schedule and you're good to go for 60k miles in most situations before any components need to be rebuilt/replaced.

 

Thank you. I've looked into plenty of different forced induction options. I just really like the feel of my car N/A. I was looking at the HKS rotex supercharger.

 

Superchargers are relatively cheap and safe for the motor if properly tuned. They're just too noisy for my liking. Vortech is the most trusted brand.

 

Biggest problem with import cars and cams is there just aren't enough people buying them for street cars so the few companies who make them don't really design them with stop and go driving in mind. With a small block Chevy, its relatively easy to find a streetable cam that gives you nice gains without wiping out your low end torque.

 

Yeah no kidding, you can almost literally find a cam for ANY peak rpm for a small block.

 

as usual Cleric puts it all into perspective. On an NA car the gains will be smaller HP wise, but the responsiveness is much more rewarding (IMHO). and you have minimal worries about breaking the engine with a hiccup in fuel or timing due to excessive boost pressure.


my 03 6mwhp/t coupe is bolt ons to death, and even with a super rich a/f on a generic UpRev e-tune, put down 268rwhp/254tq the other day with 142k on the clock. I'm not going fully into the mods here, but I have just about everything except cams. I can tell you this, it feels like a lot more, and once I get the final e-tune I'll be very happy with the results.


My next step once the engine is tuned, is to re-gear the FD to something more aggressive to get into the powerband quicker. The G35 as a luxo-cruiser has a lazier power curve than say a 350z which is a "sports car" although they are interchangeable pieces.


I had considered cams for an all out build, but not sure I'll get there on this car. If I do however it will be with 11:1 pistons and a balanced rotating assembly to spin the motor higher. I LOVE to rev.

 

Are there no cams for low-end power for the VQ35DE platform?

 

Where do you want peak hp at?

 

5000RPM approximately.

 

One of the most informative posts I've seen on here.