JRCivic1

Since I have an engineering background... I certainly helped, but I cannot take full credit for it. Motorvations will be producing this pulley for consumer consumption along with an exclusive "B" series Kraftwerks base kit utilizing the larger C38 series Rotrex supercharger for those with built engines wanting MORE power than the standard kit provides.

scottcraft

Hmmmm...... This is something that might be able to convince me to ditch air conditioning!

exgr

i finally clicked and view the video. top end is nice. can you post a dyno sheet with torque curve shown? sweet little ride.

JRCivic1

A new dyno session will be coming up soon... the last time on, the optical pick-up was fighting reflection from the crankshaft pulley, so we were losing tach signal before 7K. Motorvations will be verifying the engine performance with the new production pulley as soon as it is installed, so hopefully, we will get a clean dyno sheet then. The last time, I was pushed for time and had to bail out and catch a plane before it could be rectified.

There are some logical comparisons and deductions that can be made in the meantime. If you do the math, since the engine makes 539.5 HP @ 9300 rpm, this means that it makes 305 ft./lbs. Torque at the same 9300 rpm. Looking at the older graph, the torque curve is relatively flat from about 7000 to redline, so the torque should be hovering right around the 300 ft./lbs mark all along there. Since the graph shapes between the 539.5 HP and 505 HP dyno pulls look similar... you can deduce that the new torque curve will be similar in shape to the previous one... only 10 to 20 ft./lbs. higher at any given point.

I could re-pulley the supercharger and make the same power at a lower redline... which would in turn increase the torque numbers significantly... which would make most who focus on the "numbers" of the dyno sheet get excited with bigger numbers. Here's the thing: This car is right at the edge of adhesion in the real world from a roll in 3rd and 4th gears... on a hotter day with warmer pavement, the car sticks like glue on my P225/45ZR15 Toyo R888's. On a cooler day, combining the denser air for making a bit more power and the cooler pavement temps, the tires claw for traction... just barely dancing around at the top of each gear without having to pedal the car. So the way I see it... making MORE torque will only cause the car to break loose in 3rd and 4th... and then I will need some new device like traction control to solve the problem I have created by having too much power. Making power is easy... getting it to the ground is much more difficult... especially on the street. I want to make JUST enough usable power to make it easy to drive at the limit. I believe I have that now.

CX-Adam

It'd be cool to see the stress/strain plots from the FEA but I'd imagine Motovations wouldn't want to share them.

What's the pulley made of and what's the grade? Will it be heat treated or peened? The radius at the base of the hex is huge but that makes sense as it experience peak torsion loads.

What were you going for in the design? Lower inertia? No fear with the undamped pulley, crank, and (assumed) lightweight flywheel? This thing is going to rev to the moon instantly.

JRCivic1

The new production pulley is lighter than the one currently on the car. The new pulley is made of 6061-T6 aluminum. I haven't seen the FEA either... as for worrying about the weight, in my case, EVERYTHING is so light anyway... a few more ounces lost can't make a significant difference in the likelihood of an oil pump failure from the pulley change. Time will tell. They have not mentioned to me if any additional heat treating or peening would be done... I highly doubt that either would be applied but I could be wrong. It's just a crank pulley... let's not go too overboard.

chill85

Sweeeeeeeeet!!!

ReMiNiScEnCe

Looking forward to Motorvation's next batch of pulley kits. I'm on the queue to get some! They certainly are gorgeous.

exgr

If you guys want to build a batch of say 100 pieces I should be able to do it via. a forging to make it stronger and cheaper (vs. billet machining) and also greatly reduce machine time. hit me up if you want to look into this...

i wonder what this setup will do on my "stock" block b16a that makes 190 whp... hmm.

hondatech8798

iTrader: (2)

What kind of rpm are u turning this motor too? I'd imagine with the amount of light weight stuff and that cylinder head u must be turning 10,000 + or are u still keeping it lower and safer for longevity?

JRCivic1

Redline is set at 9300... which is still high, but I wanted to keep the torque number artificially low and use the longer power band.

DA BOSS

iTrader: (1)

I think that based on your motor build it laughs at 9300. As long as the blower is happy at its RPM peak I think you're good.

JRCivic1

All went well Friday on the dyno for testing the prototype/production big boost pulley. Although it was a little warmer than the last time the car was strapped down, power stayed in the game at 519 HP and 301 Torque. Tach signal worked flawlessly this go around, so I will get that dyno sheet posted for you all to enjoy on Monday. Motorvations likes the way the pulley fits and works... so they have signed off on it and the go ahead will be given to the machine shop on Monday as well. So, all those who are waiting for the "big boost C38 crank pulleys"... get ready, they are only a few weeks away.

CX-Adam

Updates?

JRCivic1

I took the machinist that saved this project for a ride in the car this afternoon... he and his old Bridgeport lathe whittled out that prototype crank pulley after the original machinist that was recommended to me gave up and quit on the project. He is a die hard Corvette guy... and he now has a new appreciation for these little "rice burners". He said he truly didn't expect for it to feel anywhere near as fast as it did. I made him a believer... and it put an immense smile on my face at the same time. WIN WIN !!!

CX-Adam

DA BOSS

iTrader: (1)

I need to borrow the car for the weekend for a little "get-together" here in Puerto Rico at Salinas Dragway.

effin

iTrader: (1)

Man I really enjoy this build so much! I have a simple question...... Can you post a video doing a pull man? It doesn't need to be a fancy go pro vid or any of that crap. You have such an awesome setup and I can bet that everyone is waiting on the same freaking thing..... A video of a pull to really hear and see this beast open up. We've seen dyno vids..... and dyno sheets alongside numbers...... Your setup is rather rare and looking at Kraftwerks rotrex s2000s, 8th & 9th Si's is cool but.....

Sorry if I'm coming off as a dick. I just keeping checking back at this thread in hopes of a simple "doing a pull so we can see" with a cheap old *** phone or something all the way to 9300rpm......

GEN2 LS

iTrader: (3)

hit it right on the money, every time this thread gets bumped to the top, I hope to click here and see a meat machine hooking jaws down the highway, but I never do. Give the masses what they want JRcivic stop teasing.

Bitch Puddin'

post some vids OP, car sounds awesome.

JRCivic1

I walked into the office at Motorvations today and saw this on the couch !!! It looks to me like those people waiting on their new MVM C38 big boost pulley to make their kits work are about to be VERY HAPPY !!!

Still working on the videos gang... hopefully soon I will have something for you.

scottcraft

Those pulleys look very nice!

JRCivic1

I agree... I think the production version turned out really nice. I am still trying to convince them to give me one since they used mine to create the new product from... I am still rocking a pre-production pulley.

I am going this Saturday to get the car out scottcraft... and I fully intend to get the GoPro mounted and FINALLY get you guys some video... you have all been so very patient. Now I am going to have to figure out how to use the GoPro software to "produce" the video... you guys may have to help this old low tech guy out with that !!! LOL

Chance EG

Such a beautiful, perfect powerband.

I really wish this was possible to do and retain AC.

scottcraft

Awesome! Can't wait to see it in action!