Pully question?

[Roots25]

Whats up, just starting to modify my cobra, looking into a set of pullies. This car is my daily driver, but i also drag and autocross it for this summer, so im looking for performance but also reliability. I dont mind the whine, so help me get a set up, thanks, running accufab tb, and bbk cold air, slp headers, x pipe and loudmouth2

thanks

 

[SSSNAKE03]

2.93 Upper pulley, 4lb lower pulley, All Idlers...and a tune :thumbsup:

 

[CobraBob]

2.93 and 4 lb. lower is a good choice. If you don't want to mess with the lower, consider a 2.90 upper only. Depends on how much power you're wanting to make. To be honest (with an unported blower) a 2.90 upper only will get you in the neighborhood of 455-465rwhp with the other mods you have, depending on your tune. I made 457rwhp with the 2.90 and that was with the stock headers. You'll also see moderate boost increases (12-13 lbs.) with less heat soak. You can then always add the 4 lb. lower later, especially if you port your blower. You might also consider adding a larger heat exchanger (Gords or LFP). IMO it is a very wise investment. Heat robs power! And don't forget the suspension mods. Click on the Red Pill below.

 

[Silver95]

2.93 and 4 lb. lower is a good choice. If you don't want to mess with the lower, consider a 2.90 upper only. Depends on how much power you're wanting to make. To be honest (with an unported blower) a 2.90 upper only will get you in the neighborhood of 455-465rwhp with the other mods you have, depending on your tune. I made 457rwhp with the 2.90 and that was with the stock headers. You'll also see moderate boost increases (12-13 lbs.) with less heat soak. You can then always add the 4 lb. lower later, especially if you port your blower. You might also consider adding a larger heat exchanger (Gords or LFP). IMO it is a very wise investment. Heat robs power! And don't forget the suspension mods. Click on the Red Pill below.

Hey, newb here, what is the purpose of the LOWER pullie? What exaclty does it doo, and also *when should one consider putting one on, and what other mods woud you recommend before slapping the lower pullie?

 

[CobraBob]

The lower does the same as the upper -- increases boost which increases power and torque. A smaller upper pulley (increases boost) and tend to produce belt slip which causes a loss in power at the upper rpms. A larger lower crank pulley increases boost without increasing (potentially) belt slippage. Which is why a 2.93 upper with a 4 lb. lower is popular. You can use the search feature for additional info.

Some also just install a 6 lb. lower and keep the stock upper. Without a ported blower you want to keep your boost to al maximum of 15 lbs. of boost after which inefficiencies enter in with diminishing returns and increased heat. And heat with these motors robs you of power. A 2.93 upper (only) is a popular mod. When you port the blower you can go a couple of additional pounds of boost. So installing a larger lower can be done now, later or not at all. Just remember that it is TOTAL BOOST you're shooting for. Any combination of upper, lower, or upper/lower can get you basically that same goal. Hope this helps. Oh, and one reason why some people prefer only changing the upper is because changing the lower is more difficult and time consuming.

 

[Roots25]

Pullies

OK, well what does the stock blower push, 10psi?
Im looking to push 14-15 lbs right now. Will be porting the blower over the winter, so this is just for the rest of the summer. I should go with a 2.93 upper and a 4 lb lower. Running a tuner already so i wont need that. What are good pully namebrands? thanks guys

 

[Steve@TF]

i have a 2.80 pulley and was experiencing majory belt slippage, and eventually torn belt. ive since moved to a much tighter belt. i also am currently running Diablo's "pulley tune". should i add a lower pulley to my 2.80? or is this pulley too small to begin with? :shrug:

 

[Snake Pliskin]

No problems with my combo.You will need the aux. idler and the right size belt to eliminate belt slip.

 

[CobraBob]

OK, well what does the stock blower push, 10psi?
Im looking to push 14-15 lbs right now. Will be porting the blower over the winter, so this is just for the rest of the summer. I should go with a 2.93 upper and a 4 lb lower. Running a tuner already so i wont need that. What are good pully namebrands? thanks guys

Here are four pulley brands I can recommend. There are others.

Billetflow (upper)
Metco (lower)
South Florida Pulley (upper)
Reichard Racing (upper)

 

[Roots25]

Is the blower pully the upper, crank pully the lower, and what do idlers do for you? THANKS

 

[rsnyder]

Stay with the 2.80 upper, and add a 100mm Metco idler. That's what I run, and I have ZERO belt slip issues......but with a stock clutch, you will have major CLUTCH slip issues. Then get a good tune. Before I got my custom tune, I ran the Diablo pully tune, but after the custom tune went in......Big difference (well, at least enough to feel by seat of the pants). Then I had it dynoed after the custom tune. 455 / 475 with Steeda cai, Magnaflow cb, 2,80 pulley and custom tune. Messing around with the lower is a waste of time for now. Wait till you port the blower and add more mods.

 

[FireRed04Vert]

OK, well what does the stock blower push, 10psi?

Actually, it will usually only flash to 10 psi. It actually produces about 8 to 8.5 psi. Nice cool mornings can get you a tad more.

 

[Quik Z06]

Good info... Sorry for the hi-jack but I have a question, maybe it can help others too. I had the 2.8 upper but we just ordered a 2.9 or 2.93 I'll have to call and find out for sure, but we just installed my Steg Stg 4 ported blower last night and switched the 2.8 back to stock and left the 4# Billy @ MSX said it ran way better that way than with the 2.8 upper. Im wondering should I install the 2.9 when it comes in possibly friday or wait for my MAF, BAP and injectors. Im pretty sure with the 2.9 and 4# I'd be pretty close to maxing out the injectors, I know im already maxing out the MAF (according to my SCT Tuner) The car seems to still pull pretty good with the stock upper (obviosuly because of the port) so im not in a real hurry so Id rather be safe what do you guys think? Thanks