Given the "variable valve timing" nature of our engines, after market cams won't change the timing of the valves too much, especially the cams meant for "Street use". After market cams are usually used to open the intake and exhaust valve more than the stock cam opens the valves, or just keeps them open for a longer duration. Opening the valves more/longer allows the engine to inhale more air at higher RPMs. However, due to the valves opening MORE they will start opening sooner, and start closing later (the valves will be open for a longer duration); thus the valve timing WILL be effected with ANY performance cam. If you get too aggressive with the valve timing/duration, the car will idle like crap (e.g. ever listen to a race car idle? It's not even close to "smooth"), and taking off from a dead stop becomes more challenging, especially if you have a lightened fly wheel.

Also, when it comes to upgrading cams you want to upgrade your valve springs. The larger you open your valves the longer it takes to close them. With the stock valve springs and a performance cam, you can end up with "floating valves" in the higher RPM band. "Floating valves" is very bad, because the piston can impact the valve and send it through your hood. Stronger valve springs help the valves close faster, and there by increasing the RPM at which the valves will start "floating" and as a result increasing the head's red line.

Which, depending on the engine, means the red line will now be limited by the "bottom end" (crank, rods, pistons, and bearings).

so on and so forth...

There are few cars out there in which 1 N/A upgrade will result in 33% more power. However, of the cars I can think of that this applies to, all of them are classics.

 

Pistons do not change the displacement, that is a function of the engine size (as dictated by bore and stroke). Pistons can change the compression ratio though which can change the ability of the motor to handle power or make power depending on what you want (ie. raise or lower the ratio).

 

So if i found/make a piston that is 5mm taller than the stock piston, my displacement isn't going to change???

Sorry, but all those classes in math tell me differently. Since the pistons mentioned are for the EVO X, without knowing the exact dimensions, you can't say whether they will or will not change displacement. Using logic, the GTS has a compression ratio of 10.5:1 while the EVO X has 9.0:1. If those bad boys do fit in the lancer, it would most definitely change the displacement.

 

No since the evo is a 2.0 L car and the old GTS was a 2.0 L but they had different compression ratios. Part of this is probably a difference in stroke but pistons are not a good way to change displacement. A 5 mm taller piston would be insane, I would suspect that you'd have clearance issues in that exact situation.

 

It was just an example. But the same would be true opposite direction. Its an option for someone that really knows what there doing. I wouldn't bother messing around with that stuff. I'd just slap a turbo on it and be done with it. And the bore is the same for both, so you could put the evo ones in as long as the connection rod fits.

 

No. It would change the compression ratio not the displacement. (Bore x stroke) x number of cylinders = displacement. The piston wrist pin remains in the same place in both pistons just the compression height changes. Same volume just how much its squeezed changes. Now increasing diameter of the piston will increase displacement.

 

lets put numbers in this time...(I am completely making these numbers up)

stock:
stroke = 86mm
bore = 86mm
total volume of 1 cylinder = pi*r^2*h = 499.55 cubic centimeters
total engine volume = 1998.2 cubic centimeters, or 1.998L

change the piston so that it is 3mm shorter in height...aka the distance between the pin and the top of the piston head.
stroke = 89mm
bore = 86mm
total volume of 1 cylinder = pi*r^2*h = 516.98 cubic centimeters
total engine volume = 2067.92 cubic centimeters, or 2.068L

You can't argue with math.

Compression would change too, but minimally.

 

I'm pretty sure you're missing something there.

 

Yeah, it makes sence if the piston doesn't move. Your missing something.....

 

I'm just not sure on all the terminology, but if all u change is the height of the piston, you will definitely alter the displacement.

 

No. The piston travel remains the same. In your earlier post, your equation would increase displacement, IF.... the increase in stroke was in the rod/crank. Piston compression height is not stroke.

 

An easy to understand page about displacement http://www.car-videos.net/whatis/displacement.asp

Just those pistons alone are pointless for the lancer unless you are going turbo. Lowering the compression on N/A cars will lower your HP in most cases. Having lower compression WITH turbo however, is good. It allows you to run more boost (Along with other upgraded internals - rods, cams, valve springs, etc). You cant just get pistons then try and run 20psi

I have no idea how the JUN kit would really effect the performance of N/A lancers, although keep in mind that all the Evo X parts are designed for turbo.

 

That is my entire goal, i could careless about an N/A build. I want to build a stronger engine for a turbo set up. Ive got the money to play hard ( thank you iraq deployments) and could care less about the warranty. I wanna try to get some closer on this and maybe spark some new ideas for our 4B11.

 

If you have a lot of money, why not buy a Ralliart or an Evo and save yourself the headache of turboing an NA car? If you want to do it though your best bet is to get lower compression pistons (anywhere from 8.X:1 to 9.X:1 depending on what you'll be doing), stronger rods and maybe upgrade the valvetrain.

 

To be completly honest i thought about it, and im doing it for two reasons. One i love my car, yea i should have waited for an Evo X or the RalliArt but i didnt. And two id really like to do this for the sake of tuning. Not to mention insurance for either of those cars was going to rape me....

As for my plans, im not looking for insane power numbers, but just something streetable.