Dear Unregistered, the permission changes should be complete, if you notice any issues with your access on the site please let us know and we will check into it.
Hey Unregistered it seems that you haven't posted a message in our forums yet. Please join in on the fun and post a message!
Dear Unregistered,
We've noticed that you are not yet a member of our Cayman Insiders group. This group provides a number of additional value-add services via this website for a very low annual fee. You can find out more about this group here:
Insider Announcement
You can join the Cayman Insiders Group here:
Insider Enrollment Form
We hope to see you "Inside" soon!
Cayman ModificationsDiscuss modifications to your Cayman
Your Donation Will Be Used To Pay For our ever increasing bandwidth costs, our hosting Service, domain registration, software licensing fees, maintenance costs and product evaluations Only!
Please enter your donation amount above, and then click on the donate button below.
I have just started working on an article comparing the OEM pulley with the BBI and Mantis under-drive pulleys. One result surprised me, and I wanted to print it right away, since it could affect member’s decisions of which pulley to get.
Both UDP’s have essentially the same circumference (381mm and 383mm), and hence the same under-drive ratio. BBI pulley is black, Mantis pulley is silver:
The numbers quoted for Mantis is 20% under-drive, 16% for BBI. They are both the same size, and they are both telling the truth. I do not have the OEM pulley off yet, but expect it has a circumference of about 457mm. Rounded off, 382 is 16% smaller than 457, and 457 is 20% bigger than 382.
Concerns about belt length, alternator output, and power steering load might make you prefer a higher or lower under-drive ratio. There is actually not a choice – both are essentially the same.
__________________
....its even SAFETY YELLOW! What could be more practical???
Just for giggles, I measured my old, stock pulley. With an old measuring tape, I measured 454 mm circumference (measuring the same way you did). So, your estimate of 457 was pretty close.
BTW, that's the original Mantis pulley design (can tell by the two holder holes on one side). I wonder if they've changed the circumference on their current design....
I measured the weight between the stock and mantis. the mantis is heavier by 2.8oz. check out the article and remember to use the one man removal tool get one from Home Depot if you have to cost is around $0.12 Have fun.
I have just started working on an article comparing the OEM pulley with the BBI and Mantis under-drive pulleys. One result surprised me, and I wanted to print it right away, since it could affect member’s decisions of which pulley to get.
Both UDP’s have essentially the same circumference (381mm and 383mm), and hence the same under-drive ratio. BBI pulley is black, Mantis pulley is silver:
The numbers quoted for Mantis is 20% under-drive, 16% for BBI. They are both the same size, and they are both telling the truth. I do not have the OEM pulley off yet, but expect it has a circumference of about 457mm. Rounded off, 382 is 16% smaller than 457, and 457 is 20% bigger than 382.
Concerns about belt length, alternator output, and power steering load might make you prefer a higher or lower under-drive ratio. There is actually not a choice – both are essentially the same.
Excellent work!!!!!!
The new Mantis now has a six hole design just like the BBI
__________________
DISCLAIMER: I'm not an engineer, I just play one on the internet.
BBI Under-Drive Pulley | BBI Roll-Bar
BBI Brake cooling package | GT3 Lower control arms
GT3 Front Sway bar | Tarett Rear Sway bar
Tarett Drop links Front & Rear | Tarett Rear Toe arms
Quaife TBD | Nitto NT-01s | PASM Springs
Dynoed today after mantis pulley, 313WHP 276LBS/TQ!!!! I will post the dyno as soon as it is emailed to me. Also a video was taken but alot of the footage had errors so there was sound with no image I still have video of the car on the dyno though but it was the worst shot of the 3 pulls. The door was open on the final pull and that was the only one that recorded the image 8HP and 10LBS/TQ ADDED with the mantis pulley!!!
a clip from the dyno is on a video found on this forum: Cayman GT video
Ok so I am trying to update my sig but i guess the options have changed. My current mods are:
-APR Full Exhaust $2973
-APR software $800
-K&N drop in Filter $46
-IPD Plenum $995
-Mantis Sport Pulley $190
-GMP Spacers/Bolts $0
-BBS LMR 19" wheels $0
-MICHELIN PS2 19" tires $0
-Techart GTS CF wing $4700
-Techart Race Springs $500
-GT3 Grill $25
I had this info on my sig but no more
Plenum
The plenum is the piece that goes between the Cayman throttle body and the intake runners. The factory piece is a long black plastic tube with a divider down the middle. There are aftermarket replacements which are designed to allow the air to flow easier/faster into the engine and increase horsepower and torque.
__________________ Cayman GT
369BHP 325LBSTQ
313WHP 276WTRQ some people like the regular stock factory look, cool people modify the car.
Last edited by porsches4ed; 03-17-2008 at 07:19 AM.
Thanks for the post! Is any one of the two (MS and BBI) significatly heavier?
BBI is 386g, Mantis (old 2 hole) is 371g (1/2 ounce difference, old school). New 6 hole Mantis should be a little lighter (4 more holes!), but not really a lot of difference. May just be the weight of the paint BBI puts on.
__________________
....its even SAFETY YELLOW! What could be more practical???
get one from Home Depot if you have to cost is around $0.12 Have fun.
Just remeber MantisSport is the orginal one. I am sure both do the job. Lets enjoy our cars.
I still have video of the car on the dyno though but it was the worst shot of the 3 pulls. The door was open on the final pull and that was the only one that recorded the image 
