Not sure what pulley size to get

[camopaint0707]

Ok so the car is a 1999 GTP with a Gen V M90 on it. VS cam with springs/retainers. Headers, downpipe, 180 thermostat, cone air filter, northstar throttle body, 2 step colder plus. I've heard conflicting thoughts about if I should get a 3.4 or 3.25 pulley. Remember the blower is a Gen V

[darkhorizon]

altitude? 3.2 if you are up in the air.

[camopaint0707]

Altitude? 1200ish 3.2 without an intercooler?

[dmahlikGT]

A 1.8in pulley lol. Id say start with a 3.4 then work your way down.

[DanPrixGTP]

Start with a 3.4.

You have a scan tool?

[camopaint0707]

I assume you mean for knock?

[Explicit_Spade]

Get a full size intercooler and run a 2.8.

[Max Cook]

Id definitelly start with a 3.4 as others have said. Im currently running a 3.25" on my setup and I have an IC over you. I can run a 3.1 but its pushing it. I imagine you wont do better than a 3.3" depending on tune.

[dsmuts]

I'm on a 3.4 right now and running lean because i'm in need of a tune. But I have a bigger cam and ported heads.

[camopaint0707]

Well I would get it tuned properly for whatever size pulley I put on it. Just not sure which one with the gen v blower and which if the car could handle a 3.25

[dsmuts]

just get a 3.25 and a 3.4 and see how it handles it.

[camopaint0707]

I suppose I could do that. I would need to different tunes though for that if I wanted to swap in and out.

[dsmuts]

Just use the one that works.

[camopaint0707]

I'm sure both would work.

[dsmuts]

Maybe not. If you get a lot of KR on the 3.25 then just run the 3.4

[camopaint0707]

well a 3.4 on a gen v is like a 3.2 on a gen III right?

[dsmuts]

That's what I hear but have no info confirming nor denying that.

[dbextreme]

As long as you have a way to scan get several pulleys. They are cheap, people are always putting them up for sale. I have a 3.4 with an Intense custom "canned" tune on my Gen III with mods in my sig and I see 0 KR. My plan is to start collecting pulleys from a 3.0 - 3.3 and start dropping until I see KR then I'll go the next size up. Every car is different and where you live plays a part to.

As for both pulleys "working". They will, but with each .1 pulley drop you gain ~7.5HP. Each degree of KR kills ~5hp sooooooooo.. for example...

3.4 pulley base line.
3.3 pulley 0 KR = +7.5hp
3.2 pulley 2*KR = -2.5hp from a 3.3 but 5hp over baseline AND possible damage... so you are getting more power from a pulley one size larger and being safe when it comes to KR, win win

Hope this makes sense, it's just tinkering with YOUR car to see what it likes best.

And as for the "pros vs cons" of a Gen V over a Gen III don't come into play until you drop below a 3.0 pulley anyway I believe. Now if you are intercooled, then that's a whole new world..

my $.02 so take it with a grain of salt. I could be off my rocker, I'm learning as I go... lol

[camopaint0707]

Problem is that zzp's modular pullies go from 3.4 to 3.25

[dsmuts]

Intense is the same bolt pattern as zzp for the pulleys.