zzp downpipe and pcm question

[Josh Ehlert]

I will start by saying I have a 2001 grand prix gtp with a top swap, intake, 1.9 rockers, ported and polished heads, ls6 valve springs and retainers. Under full throttle I got around 4* of knock retard when the weather was warmer. Since it has gotten colder I really dont get any knock anymore. Either way, I have been waiting for speed-daddy to restock their headers for over a month now, and im sick of waiting. I can get headers in the spring or summer but I would like to get something in the mean time to hopefully kill the knock retard I have now. My car has a catback on it (i know, pointless) and still has the stock u-bend. I was looking at the 2.5 or 3 inch catless downpipe. Do you guys think that would kill my knock retard? Or are my expectations too high? Please dont tell me to wait and get headers, I know they are the smarter option and not that much more expensive. If they were in stock, I would buy them. Im not sure how far I wanna go with this car, I just want to get rid of my KR as of right now.

Also. I have an extra PCM that I think may have a tune on it. Is there a place (or person) I can send my pcm to and have them check it out? There doesnt seem to be anyone local to me that has experience with tuning.

Thank you for any help you guys can provide me with.

[blueguy]

here's my legit question.

how are you running a stock pulley...on a top swap...even with ported heads and rockers...with totally factory exhaust in tact before the catback...with no knock in the winter...but knock in the summer? That's bassackwards, the colder it gets the more prone to knock you are.

What are you using to scan the car?

Get headers ASAP.

I'd tell you to buy these awesome S&S headers but that's dumb money for WBody upgrades: GM 3800 w supercharger s s Headers Pontiac GTP 1997 03 USA Made | eBay

Buy them from Turbo Kits, Turbo Manifolds, Import Performance Products, SSAutochrome Inc.

And if you are in Wisconsin and can't find a tuner...then you need to search more because there are plenty of wbody people up there

[DOHCZ34]

the colder it gets the more prone to knock you are.

lol wut

[MoarkatsINmuhtrailer]

honestly, id say **** speedaddys/ssac's atm and just get a used set of SLP headers on the forums for around 300-350.

the pacesetter knock offs that nick posted...and even the real pacesetters have fitment issues and slipping of the y pipe unless welded.

[Josh Ehlert]

honestly, id say **** speedaddys/ssac's atm and just get a used set of SLP headers on the forums for around 300-350.

the pacesetter knock offs that nick posted...and even the real pacesetters have fitment issues and slipping of the y pipe unless welded.

I thought about that also, but like I said, Im not sure what I wanna do with this car at the moment, I just wanna make it as safe as possible for now. If I could get away with just a downpipe for now then I will.

[Josh Ehlert]

I thought the knock was supose to get worse in the winter also but that doesnt seem to be the case for me. I am using an aeroforce scan gauge to scan for knock. I posted in the wisconsin section that I was looking for a tuner and no one responded in the thread. There is also another looking for a tuner with no luck. Should I have more kr than I do? Is there something I should be checking for?

[MoarkatsINmuhtrailer]

nobody can tell you how much KR you "should" have...cuz honestly...you should have none.

i believe the ported heads are helping your cause right now but i wouldnt trust it for long. if anything, find a 4.0 pulley to put on.

[Josh Ehlert]

nobody can tell you how much KR you "should" have...cuz honestly...you should have none.

i believe the ported heads are helping your cause right now but i wouldnt trust it for long. if anything, find a 4.0 pulley to put on.

I understand no one can give me a definate answer on how much knock I should have but you guys have more experiance than I do and maybe spot an abnormality in my setup.

[DOHCZ34]

I sent you a PM.

[Slick2500]

If you can find a used cheep dp I would try for that for now. I think there are a few for sale in the for sale section.

[Slick2500]

I might be just guessing here but with a top swap on the stock pulley with ported heads and rockers should he even be seeing any kr at all?
What plugs are you running?
What tstat?
If you run without a cat make sure you leave the rear o2 in or else you might dump fuel.

[Josh Ehlert]

I might be just guessing here but with a top swap on the stock pulley with ported heads and rockers should he even be seeing any kr at all?
What plugs are you running?
What tstat?
If you run without a cat make sure you leave the rear o2 in or else you might dump fuel.

180 thermostat, autolite 104's