I have only a limited knowlegde on cams in general so.......

When EVO cams were first being installed everyone was matching 264/264 or goin 272/272 now it seems most are settling with 264/272 MiX.

Some1 care to fill me in on why this is or is not the better choice?

 

I don't want to sell your post but what's bothering me is if one side is more agressive does it not ware the vavle train un-evenly.

I will say this 264 idle good
264/272 idle not so good
272/27 also idle not so good.

I think the 264 if you sticking with the stock turbo on a street car.

Eric

 

Here is some background info gleened from the Evo manual.
I believe someone asked about the stock cams in another thread.

The intake cam: opens valve 17deg BTDC; closes 59deg ABDC.
That is a duration of 256 degrees.
The exhaust cam: opens 57deg. BBDC, closes 15deg. ATDC.
That is a duration of 252 degrees.
This also gives you 32deg. overlap ( the time both valves are open ).

Going to a 264 cam on the intake isn't that much of a stretch from stock. Just 8 degs.
I assume there is more lift involved; this is where the big gain would come in.
The farther you push the valve open, the easier the air path gets.

Going from 252 to 272 on the exhaust is a bit more- 20degs.
But the longer the valve stays open, the more exhaust you can push out.
Also I assume there is more lift.

Also the overlap increases. If we assume the cam durations are centered over the old ones,
then the overlap goes to 46degs.
I believe this why you hear engines idling kinda lumpy with cams.

I will be looking to put in a 264/264 combo.
I want some more power, but not mad power.

 

My idle was fine when I had my 264/272 setup. Now that I have the special AMS race cams, my idle's gone to hell.

 

an evo local to me installed the hks cams 272 / 272 .. idles fine .. alot of power increase .. this is prolly the setup i will be going with

 

Don't forget there may be changes in how quickly a valve opens vs OEM too. Aftermarket may leave a bigger overlap, but it's the ramp up that matters as well.

 

when you guys say idle bad do you mean like...it feels like the cars gona die or like the whole car is shake or what?
cant really undersatnad your term of bad idle

 

I had this question as well. I posted a link to some info from AMS that I found useful. Its the second to last post to the bottom of this page in Shiv's forum here:

https://www.evolutionm.net/forums/sh...3&pagenumber=1

 

I run 264 intake and 272 exhaust side in my eclipse gsx and the idle is fine.

 

272/272 idles like a race car, and stalls frequently. i have thr 264 mix and you really have to be listening to hear the difference in idle, but it is there.

 

http://www.automotosports.com/cam_test.asp

that was the study 954DRGSR was referring to
very informative

 

I will probably get 264/264 cams.

Do we need to get HKS adjustable cam gears to go with the 264 cams?

 

you don't need to go with the cam gears although it would be a plus. a lot of people are running these cams and te 272's with out adj. cam gears and they are fine. however, you might be able to squize a little more hp with the adj. gears providing you have a good tuner which can use them right.

 

ditto, i dont run adjustable gears and i dont plan to, just the stock gears with the 264/264 is fine for me.

 

Going with Tomei 264/264. They have higher lift than the HKS cams.