after market cams /stock internals=what?

[Revolution]

Well after reading through 3 to 4 threads with an over abundence of post one question kept poping up , but nobody ever seemed to answer.

This is not going to turn into a web and hks bashing .

There are a few questions that I would like answered ,and maybe some of you members out their can lend a helping hand.

When upgrading you'r cams do you have to also upgrade you'r lifteres ,retainers,springs, valves??

Or can you run all those peices stock ??

ok how about what specs are the stock cams??

Idle ,ok ive heard stories about idle quality and how some are chopy while others arent , but what about fuel consumption??

When upgrading you'r cams it's like changing the way you'r car breaths and farts , to a more agressive pace , does this directly cause you'r mpg to drop??

 

[Morphius]

First, let me say that I've not upgraded cams on my DSM, but have on a v8.

Originally posted by Revolution
When upgrading you'r cams do you have to also upgrade you'r lifteres ,retainers,springs, valves??

Or can you run all those peices stock ??

The rockers? No. There are no replacments, but also note in general, roller rockers are usually reused.

Lifters? Again, no. There are no replacements except for the later gen version of the same lifters.

Retainers/springs? In general, typically no. But I don't know the lift limits on the DSM springs. If you run some radical grinds with cam lobes that are abrupt, you'll need stiffer springs to keep the rockers from floating. And at the same time you'll need to be sure you don't hit a coil bind situation. (ie spring is totally compressed and "solid" in a sense)

Valves? Depends on the particular grind of cam. If the lift characterisics are such that the valves are severely limiting the flow through the head, then yes. I can't speak to the traits of the DSM with aftermarket cams. Most likely you won't need to for a good street/track grind. Of course, you increase the efficiency by going larger. It can only help.

Originally posted by Revolution
ok how about what specs are the stock cams??

Sorry, can't help you there. I'm sure someone on here has degreed a stock cam and can speak to this.

Originally posted by Revolution
Idle ,ok ive heard stories about idle quality and how some are chopy while others arent , but what about fuel consumption??

When upgrading you'r cams it's like changing the way you'r car breaths and farts , to a more agressive pace , does this directly cause you'r mpg to drop??

Choppy idle? This comes from decreasing the lope separtion angle (LSA). (ie the amount the intake and exhaust valve overlap) A stock vehicle will have a LSA of 114 vs a real choppy idle would have a LSA 109.

Fuel economy? Again, someone with DSM cam experience would have to speak to this. In a case of a V8, it depends on the amount of lift and lobe separation angles. Usually, with a increase in performance you are increaseing the efficiency of the engine. More usable power at the same load and in the end you tax the engine less while driving it. I've had an aftermarket cam on a 454 significantly increase the performance while still bumping the MPG up.

 

[paul s]

I have used hks cams on stock valvetrain for few years now and no problems at all, just last year I purchased matching Hks springs and oversize valves, if you get the cams it will "wake the car up" a lot..

 

[Revolution]

Well im glad when answers are direct and informative . thanx to morphius (sorry about the matrix joke) and paul-s .

well if this is the case senario I guess 272's will be finding a way into my car soon .

I was pm'ed by some guy who I will leave namelss about why I cared about my gas milege if im trying to build a fast car.

So this is my response to him .

It's not about throwing money away , it's about finding the right specific mods that will work, and not hinder the daily drive routine but instead make it more enjoyable (peppy) in other words .

But me well I would rather peppy on a prozac binge.

So if hks 272's all around can only better my cars performance and not hinder it's gas or internals then that my friend would be a good mod.