Thread: Pulley Drop Vs Higher Timing (Custom Tune)

Hi there! I bought an Overkill pcm last summer and was wondering what would be my best option for my future modifications (SSAC Headers and 3.6" MPS pulley)...I have a 04 CompG GTP with the following support mods

NGK Iridium IX Spark Plugs/Wires, CAI, 180 T-Stat, Overkill PCM

After looking at some threads on the forums, many claimed that increasing the timing of the pcm to 20* degrees and keeping the stock 3.8" pulley would be a better option than swapping to a 3.6" pulley and would actually make the car faster...

1) Would it be a better choice?
2) How would it affect KR? Gas mileage?
3) If I decide to do it, should I ask for a re-flash at the original seller (Overkill) or go get a custom tune?

Thanks for your precious time and advice.

Just want to make sure before I blow something up

headers 3.6 and timing, no pulley drop on stock exhaust.

Originally Posted by TheOtherNick

headers 3.6 and timing no pulley drop on stock exhaust.

Getting a 3.6 would mean getting a pulley drop...stock is 3.8 on last generation Grand Prix...

I said get headers....not stock exhaust and then drop.

Originally Posted by TheAce144

Getting a 3.6 would mean getting a pulley drop...stock is 3.8 on last generation Grand Prix...

Yeah he totally just posted that while I was typing this reply out.

Originally Posted by TheOtherNick

I said get headers....not stock exhaust and then drop.

So I get headers, a 3.6 MPS AND higher timing? Sorry you lost me

Get headers, the 3.6 and a custom in car tune with the highest timing you can run.

Originally Posted by TheOtherNick

Get headers, the 3.6 and a custom in car tune with the highest timing you can run.

Alright, thanks and sorry for the misunderstanding!

No problem.

This will be an expensive summer lol

x2 on the headers, you won't go much further with the pulley without them. it's a really delicate balance, basically you want both. keep in mind boost pressure isn't really what you're looking for, you want air flow, and you want to ignite the charge at the right time, not necessarily earlier. i would say start with the pulley and find what your timing should be, then put a bigger pulley on and adjust timing, and find what combo nets you the most power. keep in mind timing advance has to increase as engine speeds go higher, and small amounts of knock at higher rpms are like high knock at idle. don't be afraid to back out of the throttle if you see it

timing should decrease as engine load increases, you have it backwards.

the piston's moving faster at higher rpms, you have to spark it earlier the burn the mixture by TDC. advance at idle is like 4-6*, WOT is like 17-20*

advance at idle and cruising is WAY higher than WOT, by a very genrous margin.

why?

How exactly does the posi-trac rear end on a Plymouth work? It just does.




Load, cylinder temps, predetonation, fuel, mixture, cylinder pressure...

Originally Posted by FoSHO99

How exactly does the posi-trac rear end on a Plymouth work? It just does.

so i wasnt the only one watching joe dirt the other day then...

Originally Posted by Bio248

so i wasnt the only one watching joe dirt the other day then...

nope i was too... lol

plus i know we all know this but for the new guy the reason timing is so high while cruising is to get better mpgs... not so much for "performance" persay...

ok, your BOTH right.

Timing increases with engine speed AND with decrease in load.

HOWEVER, our boost goes up with rpm as well introducing another factor.

I find my timing drops a couple degrees from 3000-6000rpms or it will knock.