Vortech crank pulley question

tunedin302 · Aug 2, 2006

I have a SC trim right now and would like to switch to an 8-rib setup , as well as, spin it a bit faster (~ 8psi).
I have a 3.33 and 6.87 crank out of the box that Vortech says puts down 5-6psi (and I know psi is based on engine mods too)

1) Anybody know pulley configuration to go with for about 8psi?
2) Didn't vortech used to make an 8" crank pulley? I don't see it advertised anymore.
3) If I went with an 8" crank, do I need to change the water pump pulley too?

Thanks,
Matt

Blk91stang · Aug 2, 2006

a 6.87 crank SHOULD give you 8psi no problem. I'm running only a 2.87 Supercharger pulley and see 10psi with an intake, ported heads, stock cam and full exhaust. If you go on vortechs website there is a supercharger impeller speed calculator. type in for a 2.87" pulley, 6 inch crank. Than do your setup u want and see if you come close to the same speed. I make 10psi at 6,000rpms to give you an idea.

Also a powerpipe will help as I have one and it gave me about 2 psi more. I'm still running 6 rib with no belt slip. Constant 10psi all the time and everytime I bring it to 6,000rpms.

donsbad68 · Aug 2, 2006

^ Good info

FullAuto · Aug 2, 2006

donsbad68 said:
^ Good info

Nice sig Don. Maybe we should meet.

Rick 91GT · Aug 2, 2006

If your worried about the warranty the only pulley you can adjust is the lower or it will break the little mark on the blower pulley. I like the keep the head unit pulley as large as I can since the Vortechs and Paxtons have issues with belt slippage when the pulley gets to small.

ASP www.aspracing.com sells a 8 rib 8" lower, alum with the underdrive crank ASP810800

tunedin302 · Aug 2, 2006

Rick 91GT said:
If your worried about the warranty the only pulley you can adjust is the lower or it will break the little mark on the blower pulley. I like the keep the head unit pulley as large as I can since the Vortechs and Paxtons have issues with belt slippage when the pulley gets to small.

ASP www.aspracing.com sells a 8 rib 8" lower, alum with the underdrive crank ASP810800

Thanks Rick ... long time no hear. Good to see you around again. How's your engine building schedule look for early next year?

tunedin302 · Aug 2, 2006

Blk91stang said:
a 6.87 crank SHOULD give you 8psi no problem. I'm running only a 2.87 Supercharger pulley and see 10psi with an intake, ported heads, stock cam and full exhaust. If you go on vortechs website there is a supercharger impeller speed calculator. type in for a 2.87" pulley, 6 inch crank. Than do your setup u want and see if you come close to the same speed. I make 10psi at 6,000rpms to give you an idea.

Also a powerpipe will help as I have one and it gave me about 2 psi more. I'm still running 6 rib with no belt slip. Constant 10psi all the time and everytime I bring it to 6,000rpms.

Thanks for the info

Blk91stang · Aug 2, 2006

tunedin302 said:
Thanks for the info

Yep, I took a guess when I did my pulley. Luckily had no problems and made the boost I was looking for.

BTW- A 8" crank pulley will put you right at the MAX efficient impeller speed @ 6000rpm. I would go with the 6.87" crank pulley from Vortech which will put you 500rpm less impeller speed than the setup I have. If all my calculations are correct, your gonna see some serious ****! (aka about 8psi).

Rick, shame on you for recommending a pulley that will plant the guy in his seat so hard his heart stops.

Impeller speed link - http://www.vortechsuperchargers.com/support/impspeedv-1.html

Max Speeds for Head Units - http://www.vortechsuperchargers.com/products/units/performance.html

Rick 91GT · Aug 3, 2006

You would have a heart attack if I told you how much over the max impeller speed guys spin the race blowers was figuring 5800 motor rpm, 3.33 blower, 8" crank a lil over 48,000 impeller. You may pick up 3-4 pounds with that pulley.

We had a 7.xx" pulley years ago that ASP made but they do not offer it anymore, I think we ran a 2.87 or a 3.12" blower pulley on the A-trim, spun to 5800rpm saw 10psi with the AFM power pipe.

tunedin - I haven't went anywhere just been busy. Schedule is light for beginning of next year so far, but I am pretty busy right now. If were talking DART based again it is best to get it in early, the block lead time can vary greatly....

Blk91stang · Aug 3, 2006

Rick,

So just to pick your brain a little, have you been able to get more cfm from exceeding vortech's recommendations for maximum efficient impeller speed? I would understand if they rate them lower than their capable of to reduce the amount of phone calls about how their blower impeller landed somewhere in Africa. From an engineering standpoint, products like these are usually built with a 150% - 200% safety factor.

Sorry for going off topic, thought this question might interest others in the topic.

Rick 91GT said:
You would have a heart attack if I told you how much over the max impeller speed guys spin the race blowers was figuring 5800 motor rpm, 3.33 blower, 8" crank a lil over 48,000 impeller. You may pick up 3-4 pounds with that pulley.

We had a 7.xx" pulley years ago that ASP made but they do not offer it anymore, I think we ran a 2.87 or a 3.12" blower pulley on the A-trim, spun to 5800rpm saw 10psi with the AFM power pipe.

tunedin - I haven't went anywhere just been busy. Schedule is light for beginning of next year so far, but I am pretty busy right now. If were talking DART based again it is best to get it in early, the block lead time can vary greatly....

tunedin302 · Aug 3, 2006

Blk91stang said:
BTW- A 8" crank pulley will put you right at the MAX efficient impeller speed @ 6000rpm. I would go with the 6.87" crank pulley from Vortech which will put you 500rpm less impeller speed than the setup I have. If all my calculations are correct, your gonna see some serious ****! (aka about 8psi).

Blk91 - are you saying I should go with a 6.87" crank and a 3.33" headunit pulley? The vortech packing list says that it comes with a 6" crank pulley but I am not sure if that means 6.87 (just rounded down).

Rick91 - I'll definately be in touch and thanks for the info.

Rick 91GT · Aug 3, 2006

tunedin302 said:
Blk91 - are you saying I should go with a 6.87" crank and a 3.33" headunit pulley? The vortech packing list says that it comes with a 6" crank pulley but I am not sure if that means 6.87 (just rounded down).

Rick91 - I'll definately be in touch and thanks for the info.

I thought you already had the 6.87" pulley, you most likely have the stock 6" pulley, by increasing it you should gain about 2lbs. I have a stock S-trim lower at home I can measure this afternoon.

iwearpro · Aug 3, 2006

Rick 91GT said:
I thought you already had the 6.87" pulley, you most likely have the stock 6" pulley, by increasing it you should gain about 2lbs. I have a stock S-trim lower at home I can measure this afternoon.

Hello,I have a sc trim as well and it DOES come with a 6" pulley....I just upgraded to the 7" (6.87") pulley from asp racing and I see about 8 or so psi at 6000rpm.... I dont think Im seeing any belt slip and the car runs really awesome....The sc trim comes with a 3 year warranty and the second you take off the stock 3.33 pulley it voids the warranty and I wouldnt touch it..

Do the 7" pulley from asp racing,it underdrives the acc's and is super light aluminum...I love mine and the car runs great...

Brian

Blk91stang · Aug 3, 2006

iwearpro said:
Hello,I have a sc trim as well and it DOES come with a 6" pulley....I just upgraded to the 7" (6.87") pulley from asp racing and I see about 8 or so psi at 6000rpm.... I dont think Im seeing any belt slip and the car runs really awesome....The sc trim comes with a 3 year warranty and the second you take off the stock 3.33 pulley it voids the warranty and I wouldnt touch it..

Do the 7" pulley from asp racing,it underdrives the acc's and is super light aluminum...I love mine and the car runs great...

Brian

Do you have a powerpipe and what mass air meter are you running?

Blk91stang · Aug 3, 2006

tunedin302 said:
Blk91 - are you saying I should go with a 6.87" crank and a 3.33" headunit pulley? The vortech packing list says that it comes with a 6" crank pulley but I am not sure if that means 6.87 (just rounded down).

Rick91 - I'll definately be in touch and thanks for the info.

Considering your looking for 8psi, I would go with the 6.87" crank or 7" crank from ASP if you can get it. I'm just going by the fact i'm making 10psi @ 6,000 so a similar impeller speed to my setup should get you very very close. There are other factors like inlet restriction and such. I'm running a 80mm Pro-M and a UPR powerpipe. This will help the blower create more cfm. If you want more you can always change the supercharger pulley to max it out. I changed mine 4 months after I got the charger. Yes I voided the warrenty, but the thing has been on for 3 years now so I doesnt matter anyways. These Vortechs are stout!!

donsbad68 · Aug 3, 2006

FullAuto said:
Nice sig Don. Maybe we should meet.

Sure, sounds fine to me. Bring a car down to SMP sometime! We are there every saturday. But I think I'm in like 9th in the points

getusummm · Aug 3, 2006

I have a question for BLK91. You say you changed to a powerpipe and picked up 2psi? Was this the only mod done at the time? Am I reading this correctly? If so, then actually wouldnt your powerpipe be adding a resriction to the system?

Blk91stang · Aug 3, 2006

getusummm said:
I have a question for BLK91. You say you changed to a powerpipe and picked up 2psi? Was this the only mod done at the time? Am I reading this correctly? If so, then actually wouldnt your powerpipe be adding a resriction to the system?

I can't back that up at all. . Heres a little story which might help a little bit.

Stock motor and stock pullied supercharger = 4psi

Stock motor and 2.87" pullied supercharger, C&L meter, PVC home made 3" powerpipe = 5psi

New heads, intake, TB, UPR powerpipe 4", 80mm Pro-M = 10psi

I gained 5psi adding the last bit without touching the pulley since the last time. I gotta assume the powerpipe helped out a good amount and is DEFIANTLY worth the money. If you plan on ordering a Mass air meter for a certain calibration, might as well do it once and get it calibrated for a Powerpipe and never worry about it again. I paid $99 for mine.

getusummm · Aug 4, 2006

Blk, I had the exact opposite effect when I added my new TW heads. I went from 10lbs with E7 heads to 5 running the TW. This usally indicated less restriction and better flow. I changed to the 7" or 8"(not home right now to check) crank pulley along with a smaller top pulley to get back to 10lbs. Where is your boost gauge hooked up?
I am not raggin on your setup by the way, just trying to learn.

Blk91stang · Aug 4, 2006

getusummm said:
Blk, I had the exact opposite effect when I added my new TW heads. I went from 10lbs with E7 heads to 5 running the TW. This usally indicated less restriction and better flow. I changed to the 7" or 8"(not home right now to check) crank pulley along with a smaller top pulley to get back to 10lbs. Where is your boost gauge hooked up?
I am not raggin on your setup by the way, just trying to learn.

My boost guage is T'd off the vacuum tree but I forget which one it is. I didnt have a good test being I changed so many things BUT I never did touch the pulley. Just the fact I went from 5 to 10 psi before and after without touching the pulley showed there had to be a good amount of restriction before the supercharger.

Don't worry, I was expecting my boost to drop also being I opened up the whole intake track. I allmost shat when he told me he saw 10psi. I never thought once u were knockin my setup, I fully admit I never saw a 2psi increase from a powerpipe alone, just an educated guess!

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