# Pulley dia. vs. boost for VR6 (per Vortech 'charger type at peak RPM) - populating data table



## DHill (Jan 8, 2002)

Hey all,
I've searched new and archived threads plus the web to determine the various pulley diameters available and the corresponding boost for those pulleys (assuming stock crank pulley). I'm getting snippets of data from various threads but they are all conflicting. Some of this error is likely from V1/V2 vs. V9, etc. Also I think a lot of people are stating boost but not at peak RPM. Others say "30# injectors are fine" (for example) but they've never looked at the A/F ratio at peak boost so I can't tell what are the best recommended examples.
Ever since C2 changed their site this data is nowhere to be found.








Care to help me out? Give me the real data. Also, what injectors are you using with what chip? When I'm done I'll ask to put a screen shot of the list in the FAQ for everyone to use. Here's what I have so far. As you can see, I could use more data. Once I have enough I'll make some charts in Excel.
_*Data is (pulley dia. inches) - (avg. boost at peak RPM psi) - ('charger type) - (injectors lb./hr)*_
3.6 - 6.5 - V2 - ?
2.87 - 13 - ? - ?
2.5 - 15 - ? - ?
2.75 - 12 - V2 - 30 (7200 RPM)
3.125 - 11.5 - V2 - 30 (7000 RPM)
2.85 - 13.5 - V2 - 30 (7000 RPM)
3.125 - 10 - V2 - ? (6000 RPM)
3.2 - 6 - V9 - 30 (7000 RPM, non-intercooled)
2.7 - 8 - V9 - 30 (7000 RPM, non-intercooled)
2.25 - 11.5 - V9 - 30 (7000 RPM, non-intercooled)
2.87 - 14 - V1 - 30 (7000 RPM)
3.45 - 10 - V2 - ? (7200 RPM, 7.75" crank pulley on VF Stage IV)
2.5 - 10 - V9 - 36 (7000 RPM)
3.12 - 8.5 - V1 - ? (AMS kits)
26 tooth Cogged Pulley (48 tooth crank pulley) - 8.6 - V9 - 30 (6561 RPM) 

Thanks for your contributions so far. http://****************.com/smile/emthup.gif









Here are some charts uploaded on 11/26/2008
*V2 Data:*









*V9 Data:*








*V1, V2, and V9 Data all together:*









If this resolution sucks for you, try http://www.davionhill.blogspot.com and look at the Nov. 26 post.



_Modified by DHill at 10:18 PM 11-27-2008_


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## Nailbunny86 (Oct 18, 2005)

*Re: Pulley dia. vs. boost for VR6 (per Vortech 'charger type at peak RPM) - popul ... (DHill)*

i have a 2.75 pulley, 10-13 psi @ peak 7200 RPM V2 charger, #30 injec ,and the newest c2 software i have a small belt slip @ high RPM after 3rd gear


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## DHill (Jan 8, 2002)

*Re: Pulley dia. vs. boost for VR6 (Nailbunny86)*


_Quote, originally posted by *Nailbunny86* »_i have a 2.75 pulley, 10-13 psi @ peak 7200 RPM V2 charger, #30 injec ,and the newest c2 software i have a small belt slip @ high RPM after 3rd gear 

Thanks! I added this above, and split the difference of your 10-13 psi to 11.5. 
When I upload the list, I'll try to include some basic calculations for crank and charger pulley ratios plus expected boost, and data about charger efficiency from Vortech.
Keep it up. http://****************.com/smile/emthup.gif


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## leebro61 (Nov 7, 2001)

*Re: Pulley dia. vs. boost for VR6 (DHill)*

V2 Charger kit with some upgrades, ATP obd2 software with 30lb injectors, bone stock longblock, stock exhaust, etc....
3.125" Pulley (Original Vortech) - ~11-12psi
- When I dynoed the car, I did a quick digi cam video of the boost gauge. Here is a still frame from that video showing the maximum boost.








2.85" Pulley (ASP Racing) - ~13-14+psi
The boost figures are from my Autometer UltraLite boost gauge, measured from the stock 'nipple' on the brake booster vacuum line, at or near ~7000rpm. The gauge zeroed out perfectly but a $40 boost gauge is far from a precision instrument. The car made good power on the 3.125" Pulley and put down some impressive trap speeds on the 2.85" Pulley, making me think the gauge might not have been too far off.
Hope this helps...
Lee








Edit - Added some info




_Modified by leebro61 at 1:12 AM 1-6-2008_


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## newSWARTZ (May 10, 2003)

*Re: Pulley dia. vs. boost for VR6 (leebro61)*

ive got a v2 with the 3.12 pulley... 8-10psi at 6k rpms


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## slc92 (Feb 9, 2005)

*Re: Pulley dia. vs. boost for VR6 (leebro61)*

V9 Charger on a 12 valve VR6
3.2" pulley [email protected] 7Krpm
2.7" pulley [email protected] 7Krpm
2.25" pulley [email protected]
All numbers are non intercooled. 
Current setup is V9 charger, 2.25" pulley and VF single idler, 11.5psi @7K, stock compression, non intercooled, C2 #30 dizzy chip, #30 Bosch red top injectors. Air/Fuel is 11.0-11.5:1 up to 7k.


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## turbo mike (Dec 8, 2005)

*Re: Pulley dia. vs. boost for VR6 (slc92)*

V1 w/ 2.87" vortech pulley, i see 14psi(7k to redline) on my autometer gauge.

stock motor with schrick 268 cams, test pipe, magnaflow exhaust, c2 30# software
with a bad belt, c2 2.87" pulley and some slip, i pulled 286whp and 255wtq(ran lean), and had a real gauge connected, and saw a hair under 12psi - dyno sheet in my sig 
now with an inline pump, a good belt, and vortech pulley, im waiting to get back onto the dyno to try for closer to 300


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## DHill (Jan 8, 2002)

*Re: Pulley dia. vs. boost for VR6 (-THROTTLE-)*

Good stuff so far. Thanks to the community for sharing.


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## LSinLV (Nov 25, 2001)

*Re: Pulley dia. vs. boost for VR6 (DHill)*

VF STGIV VR6 12V uses a 3.47" s/c pulley with a 7.75" crank pulley on a V2....running at max impellor speed ~55K rpms and 10 psi @ 7,200 engine rpm's http://****************.com/smile/emthup.gif


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## DHill (Jan 8, 2002)

*Re: Pulley dia. vs. boost for VR6 (LSinLV)*

the list is growing....
I've seen a alot of people with 30# injectors but not many with meatier injectors... anyone?


_Modified by DHill at 11:19 AM 1-15-2008_


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## BIG DUB (Feb 13, 2001)

i have a c2 obd 2 12v vr6 chip w/out o2 sensors for #30 injectors and the #30 injectors and was wondering if i can use this set up with my vf stage 1 set up with v9 charger if i get a 2.25 pully or if i have to get the dizzy chip? Thanks


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## slc92 (Feb 9, 2005)

*Re: (BIG DUB)*

I answered this in an IM but dizzy means distributor, for VR6's that use one. You are fine w/ the C2 chip and #30 inj. That's good to ~280-300whp. Your issue will be spinning the V9 fast enough to move enough air to make that power. A 2.25" pulley will give you ~11.5psi but VF won't sell it to you. Try Vortech or getting one custom made. Deckmandubs has some kind of a cogged pulley system as well.


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## redskins98 (Oct 6, 2005)

*Re: (slc92)*

I run a AMS V1 charger,9 psi,and built 3.0,im still running AMS software,with stock injectors.The car runs lean at 6psi,right around 5000-5500 rpm's(yes i know it's the software,but it runs so smooth)
I have also ran C2 software,but for some reason,and after 3 chip's the car never ran right.
Next month,im going with megasquirt and 15 psi pulley,that will use #42 injectors,and good old BOOST JUICE


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## TheDeckMan (Sep 26, 2004)

*Re: (redskins98)*

26 tooth Cogged Pulley 30lb injectors - 8.6psi = 229.6whp @ 6561rpms @ EPL. Other mods are 2.9 Clone port-matched upper and lower, Port-matched cylinder head. 
V9 Charger
48 Tooth crank


_Modified by DeckManDubs at 10:38 AM 2-12-2008_


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## DHill (Jan 8, 2002)

*Re: (DeckManDubs)*

what are the diameters of the pullies for the last two posts? I guess for the cogged setup the number of teeth on the crank pulley are relevant too.
http://****************.com/smile/emthup.gif


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## TheDeckMan (Sep 26, 2004)

*Re: (DHill)*


_Quote, originally posted by *DHill* »_ I guess for the cogged setup the number of teeth on the crank pulley are relevant too.
http://****************.com/smile/emthup.gif


Crank, and charger added


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## BIG DUB (Feb 13, 2001)

thanks for the info again.. Also is the single or daul idler needed to prevent belt slip depending on pully size


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## Stahlberg (Apr 23, 2008)

*Re: (BIG DUB)*

up interested in this post and its numbers


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## DHill (Jan 8, 2002)

*Re: (Stahlberg)*

Yes sorry I promised that and have not delivered. I'll get it in a spreadsheet one of these days.


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## dirtyvr6dub (Feb 22, 2007)

what diameter pully do i need to run 6-8 psi on a v1 charger? i bought the kit with no pully and just wana keep it mild...


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## SUPERCHARGED-JETTA (Aug 7, 2001)

*Re: (dirtyvr6dub)*

Boost will be a little different depending on intercooler size along with your piping. Belt slippage and other factors can determine optimum performance. I have had pretty good luck with my set up and i am thinking on going up a few more psi


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## slc92 (Feb 9, 2005)

*Re: (SUPERCHARGED-JETTA)*


_Quote, originally posted by *SUPERCHARGED-JETTA* »_Boost will be a little different depending on intercooler size along with your piping. Belt slippage and other factors can determine optimum performance. I have had pretty good luck with my set up and i am thinking on going up a few more psi









Good luck with it. VW1320 and myself have both bailed on the SC







I sold mine but I think he still has his. I ran a solid 12 with a simple V9 setup so I'm happy. 
My V9 crapped out after only 6500 miles so I figured if it couldn't take the abuse then I might as well move on.


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## Stahlberg (Apr 23, 2008)

*Re: (slc92)*

I have:
95 vr6 motor
vortech v9 2.5 C2 pulley 10psi at 7000rpm
36# Injectors
C2 Software with 4" Maf Housing
2.9 Intake Manifold
2.9L motor
262 autotechs
Custom Headers with 3inch exhaust and highflow cat
Walbrow 255lph Fuel Pump
Stage 2 Snow Performance Water Methonal Kit
AC SAI EGR Delete
10# Flywheel
Peloquin
I have to get it dynoed still waiting for the new motor to break in. Curious as to what numbers you guys think I might see.


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## DHill (Jan 8, 2002)

*Re: (Stahlberg)*

So I am adding the charts to the original post. Overwhelming majority uses C2 software and 30# injectors, and most of these numbers are assumed around 7000 RPM. I am missing some data for injector types.
I made the plots and looking at them they might appear like no brainers, but this thread should be helpful to anyone building their own setup. 
I fit a linear trendline to the data and added +/- 2 psi error bars. My justification for that is that these values are all assumed to be at 7000 RPM but it could scatter a bit. The error bars are only to help you ballpark your setup. 
Check out the differences between V2 and V9 in terms of available boost.


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## turbo mike (Dec 8, 2005)

*Re: (DHill)*

big difference in a v9 and v1/2 unit. ill have more to post up eventually, once i get some things changed.


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## FourSeasonTuning.com (Jan 12, 2005)

*Re: (dirtyvr6dub)*

3.12 pulley was used on the AMS V1 kits for 8.5 psi.
Edit as advertised in the AMS flyer.


_Modified by FourSeasonTuning.com at 8:15 PM 11-28-2008_


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## DHill (Jan 8, 2002)

*Re: (FourSeasonTuning.com)*


_Quote, originally posted by *FourSeasonTuning.com* »_3.12 pulley was used on the AMS V1 kits for 8.5 psi.

That would give the V1 a much sharper slope than the V2 and V9, apparently making the V1 very sensitive to pulley diameter.
Any more data to add? 
If this were statistically possible, it would be interesting to collect a full list of mods and WHP at peak rpm and throw all of that data in.


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## FourSeasonTuning.com (Jan 12, 2005)

*Re: (DHill)*

Here is a copy of the AMS flyer . Next year I could provide some data with the V1 and the 3.12 pulley (still piecing together a kit).


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## leebro61 (Nov 7, 2001)

*Re: (FourSeasonTuning.com)*

The AMS "kit" that was supposed to make 8.5psi really made 10-11psi (11.5 on my setup as posted above). The v1 and v2 blowers should be identical as far as boost vs pulley size. I say this because at the time, the only 7 rib pulley that vortech made was the 3.125" pulley that we all ran on our v1 and v2's (and was included in the AMS/Eurotech and later C2 kits). The AMS kit might have made 8.5 psi if either a) your belt was slipping or b) you were letting off at 6000.


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## DHill (Jan 8, 2002)

*Re: (leebro61)*


_Quote, originally posted by *leebro61* »_The AMS "kit" that was supposed to make 8.5psi really made 10-11psi (11.5 on my setup as posted above). The v1 and v2 blowers should be identical as far as boost vs pulley size. I say this because at the time, the only 7 rib pulley that vortech made was the 3.125" pulley that we all ran on our v1 and v2's (and was included in the AMS/Eurotech and later C2 kits). The AMS kit might have made 8.5 psi if either a) your belt was slipping or b) you were letting off at 6000. 

Perhaps AMS quoted the "average" boost over the power band to get that number?


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## leebro61 (Nov 7, 2001)

*Re: (DHill)*


_Quote, originally posted by *DHill* »_
Perhaps AMS quoted the "average" boost over the power band to get that number? 

I think you are putting too much faith in them, especially considering the "tune" that came with the kit. They probably didn't want to scare people with a 10-11psi kit (which would have been radical back then) and they probably wanted to use the only available 7 rib pulley vortech offered


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## DHill (Jan 8, 2002)

*Re: (leebro61)*


_Quote, originally posted by *leebro61* »_
I think you are putting too much faith in them, especially considering the "tune" that came with the kit. They probably didn't want to scare people with a 10-11psi kit (which would have been radical back then) and they probably wanted to use the only available 7 rib pulley vortech offered









If that's the case then it makes the slope match more closely to the other chargers.


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## corpsman-up! (Apr 21, 2007)

*Re: (DHill)*

where are you guys getting the smaller 2.25 pulley's? are they all custom made?


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## 2PointGoGoGo (Sep 11, 2005)

*Re: (corpsman-up!)*

So I have a vf engineering 2.62 pulley here at work. based on the v9 graphs I would assume it's a 9psi pulley. I currently run the vf stage 2 kit mk3 so I'll be try this thing to see what I actually have here. downside is I am still waiting on some parts from a few companies


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## gticarlos2003 (Jan 19, 2005)

*Re: (leebro61)*

hey leebro61 i have the same kit and i have a couple questions so i pm'd you


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## gticarlos2003 (Jan 19, 2005)

*Re: (FourSeasonTuning.com)*

i pm'd you too fourseasontuning


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## lotar_6 (Jan 16, 2004)

*Re: (gticarlos2003)*

I'm curious about a few things. impeller RPM being the focus... what is the diameter of the stock VR crank pulley? Same on dizzy/coil/24v engines? And I'd like to get an equation to calculate the RPM's of the impeller based on the pulley diameters if anybody has one. I'm assuming everybody that posted up boost levels so far on this thread is using a stock crank pulley. Nobody's said anything to the contrary. 
Also, isn't the impeller trim very important to the boost levels produced regardless of pulley size? I'd imagine a T-trim V1 would produce way more boost on the same pulley than an S-trim V1! Even the V9 has various trim levels to choose from...
I did find this spreadsheet online w/ a quick google search to calculate impeller speeds... LINK Can anybody confirm if this is 'accurate' and can be modified for the VR data?


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## turbo mike (Dec 8, 2005)

*Re: (lotar_6)*

i THINK vortech has a calculator on their website for the info youre looking to obtain.


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## lotar_6 (Jan 16, 2004)

*Re: (-THROTTLE-)*

yup... found it... LINK
I sure hope our crank pulley is 7" or less in diameter! A 3.2" pulley on a 7" crank pulley makes 55,125 RPM impeller speed at 7,000 crank RPM.
any insight to impeller trim and how it affects this data collection??


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## DHill (Jan 8, 2002)

*Re: (lotar_6)*

Someone earlier indicated a 7.75" crank pulley. Using your link, 7.75" crank pulley with 3.2" SC pulley makes about 50,100 RPM at 6000 engine RPM. 
Perhaps another way to go about that data is to then correlate charger RPM with boost.



_Modified by DHill at 9:37 AM 12-28-2008_


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## Nailbunny86 (Oct 18, 2005)

*Re: Pulley dia. vs. boost for VR6 (per Vortech 'charger type at peak RPM) - popul ... (DHill)*

third on the list 2.5-15psi-v1/v2-7200 RPM #42s and C2 chip 350 HP


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## turbo mike (Dec 8, 2005)

*Re: Pulley dia. vs. boost for VR6 (Nailbunny86)*

experience any belt slip? where did your hp#'s come from?


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## lotar_6 (Jan 16, 2004)

*Re: (lotar_6)*


_Quote, originally posted by *lotar_6* »_Also, isn't the impeller trim very important to the boost levels produced regardless of pulley size? I'd imagine a T-trim V1 would produce way more boost on the same pulley than an S-trim V1! Even the V9 has various trim levels to choose from...

sooo.... nobody has any insight about the trim levels on the various chargers? I think the variance seen in the data collected for pulley sizes on the 'supposedly' same charger model could be explained by this. I just don't think the data is working the way the op intended. 
Also, the stock crank pulley on my AAA is 6 & 5/8 inches. This makes a huge difference in calculating the impeller speed! The calculator on the Vortech site has different step-up calculations for the V1 & V2... very handy!


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## vr6milz (Mar 29, 2011)

im bringing this one back from the dead...

what you guys think the power im going to make with a v9, 2.7" pulley and c2 #30 software and red top injectors?


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## vampvr (Apr 13, 2010)

hi guys, i want to know if i need to change my serpentine belt if i change the pulley from 3.2" to a 2.25" on a V9 charger, i also want to know how much power would be the gain, im running with genesis 415cc fuel injectors, GIAC software, high flow cat and magnaflow exhaust, thanks.


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