I'm looking to go down to a 3.4 pulley I'm wondering how much hp and boost I would gain. These are the supporting mods I'm going to do
180 or 195 t -stat (I live in wisconsin)
Colder spark plugs
Cold Air Intake
Headers
I already have exhaust work done
Please share your ideas because I don't want to harm my engine at all!

 

I've seen quite a few people recommend 1.9 rockers as well for a 3.4" pulley. As far as power and boost I really couldn't say as I'm not sure.

 

power depends on the tune. boost isnt the only thing that makes "power" you can have all the boost in the world but without having any ignition timing its useless. yes you will get a boost increase but idk how much it would be and honestly "boost amount" doesnt matter as everyone makes a little more or less depending on exhaust etc. headers will make the "boost" number go down because its not as restrictive but will make more power to do being able to tune more timing etc.

without a good tune for the parts they are almost useless. and if you drop the pulley you need a tune no matter what.

 

Here's my experience with a 3.4 pulley.

Had power log, ported rear manifold, ported s/c, autolite 104's, 180 tstat and PCM tune. Had 9 degrees of knock.

Ported the heads, had only 2* on a super hot day. So my advice is SCAN SCAN SCAN, don't wanna pop a piston.

 

I was told that if you are not going to retard the timing you do not need to go to a colder plug.
Find out for sure before making mods or else you could burn a valve or inversely you could
make engine sludge.

 

Wouldn't the ported s/c actually increase knock?

The scan advice is key and an Aeroforce gauge is probably a great place to start the build. The thing is, if you have to gauge and have done your build, as long as you have live data feed you are safe. If you find you have KR, you let off and go back to building more or uping a pulley size. Without, you'll never know if your pulley is too much and working against you.

 

Do all of your mods, scan for KR, tune, drop to a 3.6 pulley, tune, scan for KR.

If you can safely run a 3.6 with a decent amount of timing with ZERO KR, then feel free to drop to a 3.4 and tune.

There is no "set prerequisites" for safely running a 3.4 pulley. Only recommendations, and every car acts differently.

 

JuniorCar,

I had 10-11* with the stock blower.

DEI Monte SS 04,

It is very common to run colder plugs with these motors once you drop pulley sizes. And you never retard the timing unless you're running nitrous.

 

Jrcar, porting the SC will not make your Kr increase. a ported sc reduces restrictions in the SC/intake system. this lowers outlet temps. lower outlet temps reduce the chance and severity of a detonation that trigger Kr.

Like said most need some sort of valve train mod either rockers or cam on top of headers to safely run a 3.4. Honestly, plugs and tstat really are not "mods" I have never seen someone add a colder set of plugs or tstat and reduce Kr by any noticeable amount. Yes you should still do them, but dont think of them as a big help.