How to Choose Your Cam.. Duration, Overlap and more.

Choosing performance cams can often seem like a difficult task for many, considering the many variables that can apply to any one camshaft profile or application. I’ve seen too many cars with the wrong cam profile struggle on the dyno or even worse make their owners struggle with just driving.

Before choosing a cam however, don’t forget to remember what you are choosing the cam for; drag racing? road racing? any daily driver usage?

 

Let’s begin by tackling each term and what it means.

What is valve lift?

How far the cam opens the valves, when increasing lift you increase the length the valve opens, which will produce positive gains in airflow. Be careful when selecting your cam, as too much lift may cause valve float as you will see many manufacturers list recommendations for upgraded springs, retainers or guides.

What is duration?

The amount of time that a valve is open, regardless of intake or exhaust and measured in degrees of crankshaft rotation for that period. What does this mean to you? It tells you what the cam’s potential is within a specific rpm range. Shorter duration cams provide low end torque, while longer duration cams allow for more top end flow.

For all the SOHC ninjas :)

What is overlap?

The amount of time that both exhaust and intake valves are open in any one cylinder at the same time. Usually this is close to Top Dead Center as the piston stroke begins down the bore and the exhaust valves must stay open until the piston pushed the gases out.

 

What is timing?

Enthusiasts most commonly mistake this term “timing” to ignition timing when it comes to valvetrain events. Trust me, this happens way too often to make any sense.

What is camshaft timing? It’s what you can adjust when you have an adjustible cam gear, that will allow you to alter the timing events.

When you advance the camshaft timing, you are making the intake valve open sooner which will give you more low end torque. As always, when advancing or retarding the camshaft timing you must be conscious of the safety window in piston-valve clearance as to avoid a “catastrophic” event.

Retarding the camshaft timing will delay the intake closing and keeps the intake valve open for longer. This is one of the oldest tricks in the book for turbo Eclipses, Talons and Lasers in the mid-90s by selecting just one exhaust cam and retarding it to -5.

EPSON DSC picture

By retarding the one exhaust cam you could sacrifice idle quality for some terrific top end by holding the intake valve open to move the overlap higher in the powerband.

This is a shot of my old 1999 Mitsubishi Eclipse Spyder, before AWD conversion, retarded negative -5 on the exhaust cam and putting down 395 to the wheels @ 22 psi on 91 octane, extremely reliable.

Of course in today’s age of variable valve timing in everything, many of these older tricks are not needed to generate huge amounts of power without sacrificing idle and start response. In the mid 90s however, you weren’t doing that unless you had a turbo VTEC motor, which had it’s own set of problems in that era.

Increasing the duration is increasing the amount of time the valve is open, therefore helping the engine effectively fill the cylinders and produce power. Many camshaft profiles maximize flow by opening the exhaust cam extremely early in the cycle, increasing exhaust output and increasing the exhaust valve fully open when the exhaust stroke begins. During the power stroke, the burning fuel has used about 80 percent of its available force on the piston by the time the crank has turned 90 degrees.

The bottom half of the power stroke actually provides very little in terms of engine power, and it can be better used to help exhaust the combustion chamber so that there is more efficient cylinder filling on the intake stroke.

Meanwhile a more aggressive profile with higher lift velocities will shorten the duration which will help power, but narrow the powerband.

What is LSA?

Lobe separation angle is the number of degrees between the centerlines of the intake and exhaust lobes on any one cam. The lower the LSA, the more overlap you create while increasing the separation decreases overlap.

Remember to avoid the most common mistake, and that’s going with the most aggressive cam available only because “It sounds so badass” An overly aggressive long duration cam may sound cool at idle, but will give you a very top heavy and small window of power in the rpm range.

Add to that equation the idle, emissions and starting issues, and you can quickly see how a mistake in cam selection can ruin your enjoyment with your car. Which isn’t the point… right?

In the end, choosing a cam that’s right for you is a big part of your performance equation. If you have any more questions, feel free to shoot me an email or post below! As always, if in doubt ask your nearby tuner in your area!

Happy shopping!

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Everybody was KUNG FU FIGHTIN!!!!

stockspyder:

The words Mitsubishi Evolution and Jackie Chan go hand in hand, if you have watched any of his movies and many of the car scenes.

Reblogged from Bob’s Your Uncle, this fresh set of Jackie Chan modifications that are custom tailored for the Evo IV and V. Enjoy!

Originally posted on BobsYrUncle:

Firesports by Jackie Chan? I knew he was into cars like the Evo IV and V from some posts I’ve seen a long time ago but never knew he was into design and making parts. WOW Jackie Chan! Nice to see there’s real car enthusiasts that are into the scene and supporting it. http://img399.imageshack.us/img399/8421/42513978sq.jpg

http://img399.imageshack.us/img399/3585/42513989ei.jpghttp://img399.imageshack.us/img399/7429/42513954jf.jpghttp://img399.imageshack.us/img399/5991/42514070cw.jpghttp://img399.imageshack.us/img399/7840/42514069sl.jpghttp://img381.imageshack.us/img381/7053/42514084jd.jpg

Here’s the man himself in one of his Evo

http://img381.imageshack.us/img381/6352/42513938zq.jpg

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SRT-4 Civic? Say it isn’t so……

Civics are funny cars.

Most will garner negative responses from people, the occasional “ricer” or other obligatory insult, usually uttered by those ignorant of Honda’s rich racing tradition or what Honda has done for automotive enthusiasts for the last 2 decades.

But they are also some of the coolest machines on the road ( well, at least for me ) and I for one love Hondas for their cheap price, light weight and an excellent choice of modifications.

So it’s not everyday when I see a motor swap in a Civic that makes me scratch my head. And that’s what makes this Civic so special?

Yes, that’s a SRT-4 engine stuffed into a EG!! I can hear Honda fan boys gasping in shock all across the world!

If you can get over the obvious Honda – Dodge hate, it’s clear to see why this is a cool choice. Cool gimmicks such as oil squirters, oversized diameter valves and seats, exhaust valves made of Inconel and a larger displacement are all great upgrades over the usual GSR or K series swap.

440hp / 424 ft lbs of tq from one unique swap.

Happy boosting!

Project Fit – Hondata’s New Flashpro

Well, it’s been a long time waiting for our 2008 Project Fit Sport, and with dreams of turbo whooshes, we’ve finally received our Hondata FlashPro. Our FlashPro is part number FP-FIT-US-120001, (yep number one baby!) and after our supporting turbo mods, we are ready to install the FlashPro and start tuning!

Newest changes to the FlashPro as it pertains to our Honda Fit are :

  • Added support for the 2012 Civic Si, 2013 ILX, 2007-2008 Fit.
  • [Traction Control] Firmware 6
  • FlashPro firmware updated to version 47
  • [Civic Si / Type R] Added learned fuel trim under closed loop parameters

After flashing the unit, we are ready for install and setup of the most basic parameters. I will outline a few of the settings we’ll be adjusting. As this Fit is still a daily driver, we’ll be aiming to retain it’s factory emissions and gas mileage without disrupting how the car drives or feels on the road.

To do this, we’ll be looking at tuning the Fit in closed loop mode while referencing the “closed loop target lambda” table in the FlashPro.

This controls the target lambda (air/fuel ratio) when the vehicle is running in closed loop. A combination of tables is used the set the target lambda, based on temperature and load.

Next up : Trying to squeeze as much power and torque from the engine stock as possible, before slapping on our turbo kit and going for broke.

Happy tuning!

Case Studies : Apexi Super AFC Wiring Diagram : How to install a AFC.

While the age of the piggyback computer is slowly coming to an end, many enthusiasts would be remiss to overlook the benefits of adding a piggyback such as the Super AFC to their vehicle for tuning flexibility.

So people have been asking for diagrams and sending questions regarding the APEXi SAFC unit. I have included a scanned image displaying the wiring diagram and how to install steps below :

And here are a few links to previous Case Studies where we install the AFC and tune it.

Installing SAFC into a MKIV Supra

Installing SAFC into a Dodge SRT-4

Tuning SAFC – How to tune your car for dummies

Happy tuning!

 

Project SC : 2JZGTE ECU Wiring into SC300 Guide

To prep the SC for the GTE swap, I’ve sourced a MT GTE ECU and a Aristo ( JDM 2JZGTE ) engine harness. For those doing this swap into a SC300, the wiring is a lot easier than the typical S-Chassis wiring in that many of the vehicle’s functions and wires are the same.

Given the similarities between the SC300 and the MKIV Supra, this is really no surprise, however you will need to lengthen and extend the third plug or body plug as well as rewire.

This body plug disconnects from the sc300 along the firewall, next to the ABS module and near the windshield.

Upon splicing open this harness, you will notice many similarities with your Aristo harness.  The large connector on this harness connects to the SC300 body plug and also the small plug that leads to the ECU.

For ease of wiring installation, we are eliminating the following wires (Traction Control D17,  Pressure sender ( Dummy Light ) D10, and Transmission Shift indicator D1)

Use the following pinout and match the corresponding colors accordingly.

courtesy of clublexus.com. not my pic

The Aristo harness and ecu plugs :

For a pin by pin how to, refer to this chart here :

Now with your engine harness properly wired, you may now remove your old SC300 harness and install your GTE ECU and plug it in. Next up, we start yanking weight in preparation of motor swap, as well as installing a new Cometic head gasket, ARP head studs and selecting our turbo setup.

Happy boosting!

Project SC : A New Beginning… Or is it?

I have to admit that moving from the nimble and athletic S14 chassis to a heavy pig like the  Z30 ( or Soarer if you are in Japan ), hasn’t been an easy transition for me.

It’s taken some time, but the comfort of the SC300 and overall finish make for an excellent street car and comfortable cruiser. However the issue of curb weight / power to the wheels is still undeniably present, but nothing a 2JZGTE swap won’t fix.

First however, I’ve got to ditch the belt driven fan assembly, because…. well…. it’s stupid. Not only does it constantly spin and create a drag on the rotating assembly, but its freakishly huge and bulky, taking away precious engine compartment space.

Upgrading to a slimline fan assembly

We’ll be using a Mishimoto fan shroud, and 2 12 inch dual speed fans for A/C connectivity ( California is hot! ) as well as a fan controller for maximum reliability.

This will be replacing this honking huge piece of crap.

For a fan controller, I personally love the Derale lineup of controllers which feature a safety bypass, dual speed control as well as your choice of probes and temp senders.

For this install, I have opted for the push in style of connector for ease of install. Why? well the 2JZGTE is a very high temp motor, and given the turbocharged nature of this motor cooling is of the utmost importance, especially on a daily driver.

However a true 3 core radiator is not in stock currently from Mishimoto or Fluidyne, two of my favorite radiator companies. So for the meantime, we’ll be rocking this push in style sender until our permanent radiator arrives.

This install is berry berry easy sir.

First we crack the 12mm nuts on the fan assembly, while keeping the tensioner tight on the belt itself. There are 4 10 mm bolts that hold the shroud in place, you may or may not need to remove your factory battery to remove the shroud.

Once these have been loosened, then undo the tension by turning the belt tensioner clockwise. Slip the accessory belt over the pulley and then proceed to carefully remove your factory fan and shroud.

Install of the new assembly is very straightforward, outside of a fabricated driver side mount.

After wiring in the ground to the Derale relay, we start up the SC and get it to operating temps very quickly. The slimline fan not only makes the engine bay look more clean and organized, but gives me at least 5 more inches to move and wiggle when the GTE motor is ready to go in.

I also ditched my Stern ST7’s for another set of Stern wheels, this time in 19 inch and ST11. With 19×8.5 in front and a 25 offset with 19×9.5 in rear with a 30 offset gives me a good stance and is cheap enough so that I won’t cry when a rim bends due to California highways.

Not really looking to change much more of the looks about the car until after my motor swap is completed. Lots of work on that front so I’ll be busy no doubt there.

First however, I’ve got to prep the wiring for the GTE swap, which means lots of wires and a lot of cursing. Fun.

Next up : Wiring up the 2JZ engine harness and combining with the SC300 body plug for a true plug and play installation.

Happy boosting!