5.7" OD Crank Pulley - Focaljet

**2.0TooSlow** · 07-03-2006, 09:06 AM

I need some help with belt selection. More specifically, what sizes I need to order.

Question Part A (belt sizes):
5.7" OD Pulley with Stock Vortech Pulley (2.87" I believe)
5.7" OD Pulley with Smaller Vortech Pulley (2.62" I believe)

Question Part B:
Boost levels with the OD crank pulley with:
Stock Vortech Pullley?
2.62 Vortech Pulley?

Thanks!

**2.0TooSlow** · 07-04-2006, 02:04 PM

Bump.

**CFM Focus** · 07-05-2006, 12:49 AM

A 102" belt might work for both pulley sizes. Some brands come in slightly longer/shorter sizes only. The pulley will increase boost by 2-3psi with either pulley.

**j20000** · 07-14-2006, 11:22 AM

I used it with a JRSC....and using the 5.7" pulley with the JRSC/BBK gave me a total of about 12psi. Thats a 2.5" sc pulley. So I would figure around 11-12psi.

**Ray** · 07-16-2006, 09:53 PM

i see around 12psi with the 2.62 vortech pulley and the cfm 5.7" pulley. (dyno has a boost pickup - i can post the boost vs rpm if needed)

i forget which belt length i'm using - i think it's 101.5" napa gold (gatorback, same thing)

**2.0TooSlow** · 07-17-2006, 09:52 AM

Quote:

Originally Posted by demonfire

(dyno has a boost pickup - i can post the boost vs rpm if needed)

While not needed, that would be awesome if you don't mind. Thanks!

**Ray** · 07-17-2006, 10:50 AM

sure thing. i'll have to wait till i get home.

**2.0TooSlow** · 07-17-2006, 07:49 PM

Make it home yet by any chance?

**Ray** · 07-18-2006, 08:34 AM

yeah i did but the online database didn't have my boost reference saved, just my AFR, power, torque, speed, and engine speed.

basically it's like this - boost builds linearly with engine speed until after like 6000 when it goes up even more, almost logarythmically.

**CFM Focus** · 07-18-2006, 11:31 PM

Here's my BOOST vs. RPM with a 5.9" crank and 2.2" blower pulley:

2500 - 1.8psi
3000 - 3.0psi
3500 - 4.7psi
4000 - 6.2psi
4500 - 7.9psi
5000 - 10.5psi
5500 - 12.7psi
6000 - 15.5psi
6500 - 19.8psi
7000 - 22.6psi

Belt slips a bit right before 7k. It should be around 24.5 psi.

**pocus** · 07-19-2006, 12:10 AM

What was the math equation to figure out blower rpms again?

**DigitalGT** · 07-19-2006, 10:11 PM

Quote:

Originally Posted by pocus

What was the math equation to figure out blower rpms again?

You have to figure out the perimeter of both pulleys first.

The equation 2 x Pi x R gives you the perimeter. So for a 5.7" diameter pulley you would input: 2 x 3.14 x 2.85 = 17.90"

The pulley turns at the same speed as the engine so at 7000 RPM the 5.7" pulley moves 125300 inches of belt per minute. Thats 10441 feet of belt per minute. Just shy of 2 miles.....pretty fast huh?

Using a 2.62" blower pulley you plug in the numbers again and come up with a pulley perimeter of 8.23" Now taking the 125300 inches per minute belt speed and dividing by the pulley perimeter of 8.23" you get 15225 RPM blower pulley speed at 7000 rpm engine speed. Now just multiply the blower pulley speed by whatever the gear ratio of the blower is (if any).

Of course you can also just divide the engine pulley perimeter by the blower pulley perimeter and then multiply by engine RPM.

That being said, anyone know what the stock SVTF pulley diameter is?

**CFM Focus** · 07-19-2006, 10:47 PM

The formula for the Vortech used on the Focus kit is:

crank pulley / blower pulley x 3.60 x engine rpm = impeller speed

Quote:

Originally Posted by DigitalGT

That being said, anyone know what the stock SVTF pulley diameter is?

It is approximately 5.2"

**2.0TooSlow** · 07-19-2006, 11:04 PM

So with a stock crank pulley and a 2.62" blower pulley how much boost should I be seeing at 7500?

**CFM Focus** · 07-19-2006, 11:33 PM

I'm going to have to charge you for that...

53587RPM

**2.0TooSlow** · 07-19-2006, 11:58 PM

Quote:

Originally Posted by CFM Focus

I'm going to have to charge you for that...

53587RPM

The entire reason I asked is because I don't know how impeller speed relates to boost PSI LOL!

**CFM Focus** · 07-20-2006, 12:21 AM

Opppss for some reason I thought I read "how much RPM" instead of "how much boost". Must be tired...

To answer your question, there are too many variables to answer that correctly. A wild guess would be around 13-15psi.

**pocus** · 07-20-2006, 02:41 AM

is the ratio of a procharger the same as that of the vortech or s it different.

**CFM Focus** · 07-20-2006, 03:04 AM

99.9% sure it is different. I'm sure if you call them they'll be glad to tell you what it is.

**pocus** · 07-20-2006, 04:24 AM

so insted of the 3.60 i would change that out with whatever the correct ratio would be and that would give me my total blower rpm. correct?

**Ray** · 07-20-2006, 08:28 AM

With the 5.7" pulley you're looking at a 7.9% change in impeller speed (and accessory speed).

**CFM Focus** · 07-20-2006, 10:32 AM

Quote:

Originally Posted by pocus

so insted of the 3.60 i would change that out with whatever the correct ratio would be and that would give me my total blower rpm. correct?

Correct.

**adn_zx3** · 07-22-2006, 12:28 AM

how much boost Ill see with a 2.25 blower pulley and the stock crank pulley?

**CFM Focus** · 07-22-2006, 12:39 AM

Quote:

Originally Posted by adn_zx3

how much boost Ill see with a 2.25 blower pulley and the stock crank pulley?

What size pulley do you have now and how much boost are you seeing?

07-03-2006, 09:06 AM	#1
2.0TooSlow TEAM Member Join Date: Mar 2006 Posts: 160	5.7" OD Crank Pulley I need some help with belt selection. More specifically, what sizes I need to order. Question Part A (belt sizes): 5.7" OD Pulley with Stock Vortech Pulley (2.87" I believe) 5.7" OD Pulley with Smaller Vortech Pulley (2.62" I believe) Question Part B: Boost levels with the OD crank pulley with: Stock Vortech Pullley? 2.62 Vortech Pulley? Thanks!

07-04-2006, 02:04 PM	#2
2.0TooSlow TEAM Member Join Date: Mar 2006 Posts: 160	Re: 5.7" OD Crank Pulley Bump.

07-05-2006, 12:49 AM	#3
CFM Focus Premier Sponsor Join Date: Jun 2002 Location: www.c-f-m.com Posts: 1,506	Re: 5.7" OD Crank Pulley A 102" belt might work for both pulley sizes. Some brands come in slightly longer/shorter sizes only. The pulley will increase boost by 2-3psi with either pulley. __________________ Central Florida Motorsports, Inc. - Since 1996 sales@c-f-m.com / NEW! Online Customer Service - Live Chat / 407.339.9211 / Subscribe to CFM Forum We match ALL advertised prices on products we carry! Our Latest Products / SVT Focus Parts Video of our 12 second Vortech Supercharged 1/4 mile Focus / Specs / Timeslip / Dyno .:Focus Showoff:. Picture and Video Gallery

07-16-2006, 09:53 PM	#5
Ray Driver > Car Join Date: Jul 2002 Location: CT Posts: 26,774	Re: 5.7" OD Crank Pulley i see around 12psi with the 2.62 vortech pulley and the cfm 5.7" pulley. (dyno has a boost pickup - i can post the boost vs rpm if needed) i forget which belt length i'm using - i think it's 101.5" napa gold (gatorback, same thing) __________________ Cable Ties. Is there anything they can't fix? Driver > Car - in memory of GaryK *Roadtrippin.org* \| CART

07-17-2006, 10:50 AM	#7
Ray Driver > Car Join Date: Jul 2002 Location: CT Posts: 26,774	Re: 5.7" OD Crank Pulley sure thing. i'll have to wait till i get home. __________________ Cable Ties. Is there anything they can't fix? Driver > Car - in memory of GaryK *Roadtrippin.org* \| CART

07-17-2006, 07:49 PM	#8
2.0TooSlow TEAM Member Join Date: Mar 2006 Posts: 160	Re: 5.7" OD Crank Pulley Make it home yet by any chance?

07-18-2006, 08:34 AM	#9
Ray Driver > Car Join Date: Jul 2002 Location: CT Posts: 26,774	Re: 5.7" OD Crank Pulley yeah i did but the online database didn't have my boost reference saved, just my AFR, power, torque, speed, and engine speed. basically it's like this - boost builds linearly with engine speed until after like 6000 when it goes up even more, almost logarythmically. __________________ Cable Ties. Is there anything they can't fix? Driver > Car - in memory of GaryK *Roadtrippin.org* \| CART

07-18-2006, 11:31 PM	#10
CFM Focus Premier Sponsor Join Date: Jun 2002 Location: www.c-f-m.com Posts: 1,506	Re: 5.7" OD Crank Pulley Here's my BOOST vs. RPM with a 5.9" crank and 2.2" blower pulley: 2500 - 1.8psi 3000 - 3.0psi 3500 - 4.7psi 4000 - 6.2psi 4500 - 7.9psi 5000 - 10.5psi 5500 - 12.7psi 6000 - 15.5psi 6500 - 19.8psi 7000 - 22.6psi Belt slips a bit right before 7k. It should be around 24.5 psi. __________________ Central Florida Motorsports, Inc. - Since 1996 sales@c-f-m.com / NEW! Online Customer Service - Live Chat / 407.339.9211 / Subscribe to CFM Forum We match ALL advertised prices on products we carry! Our Latest Products / SVT Focus Parts Video of our 12 second Vortech Supercharged 1/4 mile Focus / Specs / Timeslip / Dyno .:Focus Showoff:. Picture and Video Gallery

07-19-2006, 12:10 AM	#11
pocus Senior TEAM Member Join Date: Sep 2002 Location: Janesville WI Posts: 1,317	Re: 5.7" OD Crank Pulley What was the math equation to figure out blower rpms again? __________________ 358whp and 335TQ-23psi-93oct. New E85 build in progress.

07-19-2006, 11:04 PM	#14
2.0TooSlow TEAM Member Join Date: Mar 2006 Posts: 160	Re: 5.7" OD Crank Pulley So with a stock crank pulley and a 2.62" blower pulley how much boost should I be seeing at 7500?

07-19-2006, 11:33 PM	#15
CFM Focus Premier Sponsor Join Date: Jun 2002 Location: www.c-f-m.com Posts: 1,506	Re: 5.7" OD Crank Pulley I'm going to have to charge you for that... 53587RPM __________________ Central Florida Motorsports, Inc. - Since 1996 sales@c-f-m.com / NEW! Online Customer Service - Live Chat / 407.339.9211 / Subscribe to CFM Forum We match ALL advertised prices on products we carry! Our Latest Products / SVT Focus Parts Video of our 12 second Vortech Supercharged 1/4 mile Focus / Specs / Timeslip / Dyno .:Focus Showoff:. Picture and Video Gallery

07-20-2006, 12:21 AM	#17
CFM Focus Premier Sponsor Join Date: Jun 2002 Location: www.c-f-m.com Posts: 1,506	Re: 5.7" OD Crank Pulley Opppss for some reason I thought I read "how much RPM" instead of "how much boost". Must be tired... To answer your question, there are too many variables to answer that correctly. A wild guess would be around 13-15psi. __________________ Central Florida Motorsports, Inc. - Since 1996 sales@c-f-m.com / NEW! Online Customer Service - Live Chat / 407.339.9211 / Subscribe to CFM Forum We match ALL advertised prices on products we carry! Our Latest Products / SVT Focus Parts Video of our 12 second Vortech Supercharged 1/4 mile Focus / Specs / Timeslip / Dyno .:Focus Showoff:. Picture and Video Gallery

07-20-2006, 02:41 AM	#18
pocus Senior TEAM Member Join Date: Sep 2002 Location: Janesville WI Posts: 1,317	Re: 5.7" OD Crank Pulley is the ratio of a procharger the same as that of the vortech or s it different. __________________ 358whp and 335TQ-23psi-93oct. New E85 build in progress.

07-20-2006, 03:04 AM	#19
CFM Focus Premier Sponsor Join Date: Jun 2002 Location: www.c-f-m.com Posts: 1,506	Re: 5.7" OD Crank Pulley 99.9% sure it is different. I'm sure if you call them they'll be glad to tell you what it is. __________________ Central Florida Motorsports, Inc. - Since 1996 sales@c-f-m.com / NEW! Online Customer Service - Live Chat / 407.339.9211 / Subscribe to CFM Forum We match ALL advertised prices on products we carry! Our Latest Products / SVT Focus Parts Video of our 12 second Vortech Supercharged 1/4 mile Focus / Specs / Timeslip / Dyno .:Focus Showoff:. Picture and Video Gallery

07-20-2006, 04:24 AM	#20
pocus Senior TEAM Member Join Date: Sep 2002 Location: Janesville WI Posts: 1,317	Re: 5.7" OD Crank Pulley so insted of the 3.60 i would change that out with whatever the correct ratio would be and that would give me my total blower rpm. correct? __________________ 358whp and 335TQ-23psi-93oct. New E85 build in progress.

07-20-2006, 08:28 AM	#21
Ray Driver > Car Join Date: Jul 2002 Location: CT Posts: 26,774	Re: 5.7" OD Crank Pulley With the 5.7" pulley you're looking at a 7.9% change in impeller speed (and accessory speed). __________________ Cable Ties. Is there anything they can't fix? Driver > Car - in memory of GaryK *Roadtrippin.org* \| CART

07-22-2006, 12:28 AM	#23
adn_zx3 TEAM Member Join Date: Nov 2005 Posts: 215	Re: 5.7" OD Crank Pulley how much boost Ill see with a 2.25 blower pulley and the stock crank pulley? __________________ OBX turbo manifold , T3 garett, P&P head , stg 3 intake crower cam , crower valves springs and retainers, Borlas exhaust, sct X-cal 2 , snow performance kit.