6 rib crankshaft pulley for SC project

[ezzzzzzz]

 

It has been over two years in the making but I'm moving closer to a finished LD28/P90A supercharged L6. The plenum is in the works at a local metalsmith. It will bolt up to Justin Olson's intake flange. The Laminova water/air aftercooler is finished and will sandwich between the plenum and M62 SC. That brings me to the crankshaft pulley. I labored for a cost effective means to procure a pulley without machining one. What I came up with should fit the bill. The stock two pulley damper will be machined out slightly to provide a uniform smooth inner bore and drilled in a six bolt pattern to fit a cylinder shaped plug (it then goes to damper doctor for an overhaul). That plug will sit flush with the surface of the outer pulley and have a protruding step to provide a hub for centering the 6-rib pulley. I'm using a reworked GM 24500426 power steering pump steel pulley. The center shaft sleeve was pressed out and then I pressed the whole center section flat in my press. It needs to be chocked in the lathe and turned to open the center uniformly and drilled to bolt to the damper. Another thin spacer will sandwich the pulley to provide reinforcement. It measures 17.125 around the ribs. The SC is 8.75 giving a 1.957:1 ratio. I think that should provide about 8psi boost. This has been a long expensive exercise in frustration. I'm thinking I'll have to push the engine back 1" and down about .5" to provide clearnce for the SC belt/pulley to fan and account for the .75" additional height of the LD28 block (note the V07 casting number in the engine photo).

[SHO-Z]

From my calc sheet your set up will give you about 5.5 psi of boost. In a perfect world you will get about 35% hp gain. For 8 psi of boost you will need about 2.19 ratio. I was looking at http://www.rpmoutlet.com/lightaspm1.htm for the lower pulley my project. I was going to use a M62 out of a SLK Mercedes. But the project has been sitting on a bench for years.

 

Good luck on the project.

Edited November 2, 2010 by SHO-Z

[ezzzzzzz]

From my calc sheet your set up will give you about 5.5 psi of boost. In a perfect world you will get about 35% hp gain. For 8 psi of boost you will need about 2.19 ratio. I was looking at http://www.rpmoutlet.com/lightaspm1.htm for the lower pulley my project. I was going to use a M62 out of a SLK Mercedes. But the project has been sitting on a bench for years.

 

Good luck on the project.

 

Thanks. I found my way to your supercharger boost calculation post. I came up with approximately 5.9 psi of boost with my pulleys. I'll start with this lower boost and see how the engine performs. Compared to the 2.4 N/A with a 272 Crane cam this 2.8 should be a lot more interesting. Upgrading to a larger crank pulley would not be a difficult task if it is warranted. A reliable spirited vehicle is all I want to achieve. Trying to beat every vehicle at every stoplight ended years ago.

L28 SC.bmp

[yellowoctupus]

I fabbed up an intake for a direct mount SC a few years ago, but never finished that project...make sure you wrap or ceramic coat those headers, the heat will soak into your intake like CRAZY!! BTW, I like your innercooler. That was one of the things I couldn't figure out where to put. (I had my SC mounted vertically, and didn't have room the way I made the manifold to fit an innercooler in there.)

Edited November 11, 2010 by yellowoctupus

[ezzzzzzz]

A full length metal\composite shield will be installed to deflect radiant heat. I personally do not like header wrap. My header is an old school Janspeed S\S 6-2-1 so a coating is out of the question too. The header in the photo is just a spare piece lying around for mock-up. Some sort of air duct will likely be incorporated to feed cool air into the intake\exhaust area. The inspection covers are louvered. The hood has a Nissan competition hood scoop and the hood has two rows of louvers to vent out heat.