Some more:

Stock Alternator Pully> 5.8oz
Stock Water Pump Pully> 10.9oz
Stock Timing Ring> 5.5oz
Stock Water/Alt Rear Crank Pully> 11oz
Stock A/C Front Pully> 1lb 2oz
Stock Crank Hub> 15.6oz

Total Stock Crank Pulley - Hub & Nuts/Bolts> 2.156lbs

Total All Stock Pulleys - Hub & Nuts/Bolts> 3.2lbs

Total All Stock Pulleys + Hub - Nuts/Bolts> 4.175lbs

Total All Stock Pulleys/Hub/Nuts & Bolts> 4.345lbs

Goal...
 

Ok, the goal is to reduce all this by at least 50% or 2+lbs, improve throttle response and gain 8-10hp with no underdriving...

After this set I might do one with 10-15% underdriving of the water-pump and alternator for about a 12hp gain...

The sprung vs. unsprung weight argument has been carried out elsewhere in this forum, more than once. Using SEARCH will find a post by Mr Wiggles showing closer to 2:1

Do you install all this stuff yourself or do you have a shop do it? I was curious as to how long it takes you to do some of these mod installs.

I do all my own installs and the time it takes depends on the task at hand...

Just to clarify... the unortodox ultra s pulleys for the rx-8 are lightened..the only pulley that is underdrived is the crank pulley..they dont' underdrive their accessory pulleys. this was good news to me b/c i didn't wan to purchase and underdrive pulleys for the same reason Cortc is designing his own pulleys. Great work by the way. Keep it up.

teh ultra ss pulleys are all underdrived by the way (i wouldn't go for these myself)

Well if they run a stock diameter on the accessory pulleys and then machine the crank hub to under drive they are in affect under driving the complete system... The set I am developing (They are already in the machining process...) do not under drive at all, they rely on the maximum weight reduction to free-up hp... We have designed three crank pulley styles, one combines both pulleys into one and does not under drive. (The stock crank pulley is a two piece design one pulley fits into the other then bolts with the crank trigger to the crank hub... One pulley drives the water-pump and the alternator and the outside one drives the a/c compressor...

The other pulley design separates the two like on the stock setup so you can remove the a/c drive pulley entirely to free up even more hp when you do not want to run the a/c... (Auto-X or Racing...). There are two versions of this design, one that does not under drive and one that under drives about 20%...

The first sets will be with the combined pulleys...

This project has been the most time and resource intensive and represents quite an investment, developing well engineered custom parts for cars is not as easy as one might think…

Are you going to make these custom pulleys available for sale?

just curious as to how the progress was coming along.

yes cortc.. sell them we will all buy them.. I have been looking for just this.

Keep it up ..

:)

P.S. All my Peeps in Fla made it out ok. :)

thew: Made it out just fine, thanks... I will have the first set next week...

P.S. I will be offering the titanium lugs soon as a group buy...

Once I get done with the prototype get it installed and tested, and everything goes well then yes, I may offer them up for sale...

If ya need a beta tester on SoFla let me know :D

I'm interested in a set so I can bypass the AC for Auto-X days too.

Well ill buy them too, im in south fla also, im not as crazy as genom by passing AC, but ill just take lighter ones.

Jesus cortc, that's great news! Is there a possibility for someone outside the US to get in the group buy?! I mean, seiously, I'll pay more if I have to! :)

They will be available to everyone, even internationally...

Not to rush ya cortc, but do u have an Est Time of Completion? and a rough ball park on price?
Living in VA and doing a lot of road trips soutward...light weight is the prefered route...gotta have that A/C!

Did you still plan on performing a before/after dyno run?

Really nice to hear it! Please count me in and let me know when you decide to sell them!

Is the installation of the pulleys a hard thing to do? just asking because I don't do my own installs... and I'd like to know if its an expensive procedure...

Could someone explain to me what is "underdriving"? Thanks!

CORTC... I love reading about the mods you are doing to your 8... even though half the time I don't understand the engineering cincepts. Please keep sharing!

p.s. I am interested in buying the lug nuts and pulleys.

Eh. Underdrive is when you reduce the size of the pulleys so that not as much power is delivered... you under drive them. It causes them to work less, but delivers more power to other parts of the car.

Ok, to answer the questions:

The production ones should be ready about October 30th...

Pricing will be competitive, example: Pulleys only U$325.00-375.00...

I will do a before and after dyno run, depending on the option I am expecting 8-12hp... (With just the pulleys about 8 and a few ft/lbs...)

It should be a DIY for most, on a scale from 1-10 in difficulty it is a 4/5...

Like robertdot said, under drive pulleys reduce the RPMs at witch the accessories are driven therefore reducing parasitic loss and freeing up hp... Weight reduction does the same thing. The first set will not be under driven just lightened; I will then come out with a under drive crank pulley with a 20% reduction...

With the A/C off you can get a little extra, even though under full throttle its automatically turned off, or with the A/C drive belt off... The two piece crank pulley that will come out later is so that you can further remove weight and free up even more...

The lugs bolts will be going up soon as a group buy, just waiting for final approval from Omicron...

The prototype is being machined...:)

pulleys
 

hey good work!
so when you say underdrive do you mean the pulley is bigger or smaller in diameter , i am guessing bigger. so 20 percent bigger of overall diameter of the crank pulley. i just never really knew when they said underdrive thanks inadvance
chuck

RX8MAN04: Thanks, and acually it would be smaller...