an upgraded pcm will advance your timing which can "lean" out your fuel mixture add that to a boosted motor and its gunna go boom because it will most likely run to lean and thats not a good thing. If you are going to get a turbo kit dont worry about an upgraded pcm, and If you do want to tune it more get a stand alone unit so that things can be set up correctly.

 

i need to post pics of my turbo ... just cant wait!!!

 

I can't wait until my AFX Race PCM gets here. It'll be about another 3 weeks!.

 

If u add a turbo system and have to much power for the stock internals, do you only have to rebuild the bottom end of your engine (pistons, cylinders, etc.) or do u have to also upgrade the top end of the engine?

One more question: What's the benefit of having a forged crankshaft and what does it change on the performance?

 

forged crankshafts will be lighter and stronger than a cast one. This wont "give" you any more power but it also wont take as much power to turn a lighter crankshaft thus giving back power. Like lifting a bag of rocks vs lifting a bag of feathers you arnt any stronger but you dont have to work as hard to lift the feathers. The topend should be fine as long as you arnt going to rev it to the sky "breaking valve train components"

 

I don't know anyone that actually bothered to install a forged crankshaft in their Neon. I've never even seen one offered. Hardly like comparing rocks and feathers... more like rocks vs. shiny rocks since forged parts aren't inherently lighter, just stronger (let's not get into metallurgy here...). Lightening the crankshaft is totally different usually only done for balancing. The Neon's stock crankshaft was actually very well designed and from the start and only weighs 33 pounds. Weight only matters once it is moved from the center of rotation, and the crank simply isn't that big around for a few pounds to make a difference anyways.

Len's test setup for Chill Factory was pushing 500 HP on the stock head (and stock intake manifold, stock PCM, stock crankshaft, stock tranny), including the stock valvetrain - just bored 0.020" over and 8.5:1 forged pistons and rods. The upgraded DOHC valvetrain really isn't that much though. You can (and should) start tuning your turbo at lower boost pressures on stock internals until you start nearing the 225 HP point. Just because a turbo says it's capable of 400 HP doesn't mean you'll actually get there, and definitely doesn't mean you have to be there...

And yes, mixing a turbo setup with an aftermarket PCM is bad because of the timing advance. Timing doesn't lean out crap. Lean and rich have to do with number of oxygen molecules compared to number of fuel molecules. Neither cares when they get lit, because the mixture doesn't change becuase of it. What they do care about is pressure and temperature. Octane is the rating a fuel gets based on when it spontaneously combusts, resulting in a massive rapid pressure spike (preignition) as opposed the the slow burn of normal compression. Or worse, detonation after spark. Higher octane numbers (higher percentage of octane compared to heptane) are more resistant to spontaneous combustion. With a turbo, the incoming air is already warmer and under pressure. So when the intake valve closes and the piston starts moving up, the mixture is that much closer to the magic pressure point. So the spark needs to happen earlier (retarded) to prevent that from happening, or a higher octane fuel needs to be used.

 

kind of what I was tryin to say....thanks radar....

 

I called Howell to check on my Race Computer a few days ago and they said forged crankshafts will give you more power. Forged crankshafts will also be stronger and more effective when using Nitrous.

 

Gary also says that short tube runners make more power than long-tube runners, despite the hundreds of dynos showing differently. He also claims to have a 350 HP naturally aspirated 2.4L neon... that only manages to run mid-14's at the track... at sea level...

I like Gary, he's a nice guy. But he comes up with some off the wall stuff every now and then. Doesn't stop me from buying the products he sells, but a forged crankshaft is not on any of my wishlists...

 

It's funny that u say that b/c I was reading a magazine featuring Howell and some other car tuners recently. Howell had their SRT-4 and they claimed a lot of horsepower and the magazine said they thought the SRT-4 would be a lot faster for the amount of hp they stated. They also use to claim that the computer/PCMs created more power than they did but, later they lowered the claimed hp increase. They're cool though. I believe what they just told me.[X(]