Diameter of crankshaft pulley?

[jones83]

Does anyone know what the O.D. of a 1992 NSX crankshaft pulley is? I can't seem to find the info. Thanks!

 

[greenberet]

Here you go: http://www.nsxprime.com/forum/showt...lancer/page2?p=1324951&viewfull=1#post1324951

Manual transmission NSXs use the same crankshaft pulley regardless of model year. The dimensions of the OEM pulley are noted in Ken Sampson's drawing. Good luck with whatever you're doing!

 

[jones83]

Thanks Greenberet! If I am reading this right then this is the dimensions for an ATI pulley. OD is 6.780". Is the OEM crank pulley the same OD?

 

[greenberet]

Yes, that's the blueprint for an ATI crankshaft pulley that was designed to drive an eight rib supercharger belt on the side of the pulley that's closer to the wheel well. The drawing mentions OEM next to some of the dimensions, though. For example, it lists the overall thickness as 3.175 and OEM as being 3.125.

To double check the dimensions, I just dug out the spare OEM five speed crankshaft pulley I bought in 2009. That's built to drive two belts: a four rib belt on the side closer to the engine block and a five rib belt on the side closer to the wheel well. The section that drives the four rib belt has a slightly larger diameter than the section that drives the five rib belt. Measuring with my vernier caliper, the largest outer diameter on the side facing the engine block is 150.5mm. The largest outer diameter on the side facing the wheel well is 145.5mm. Those are the outer diameters of the lips surrounding the belt drive areas of the pulley. The belt drive area on the engine block side has an outer diameter of about 145.7mm and the belt drive area on the wheel well side has an outer diameter of about 141.7mm (the lip on the engine block side is slightly higher than the lip on the wheel well side).

I measure the overall width of the OEM five speed pulley as 66.1mm. For whatever reason, some of my measurements don't agree with what's listed as OEM in the blueprint ATI made for Ken Sampson. In any case, I hope those OD measurements from my OEM five speed crankshaft pulley help.

 

[jones83]

Yes, that's the blueprint for an ATI crankshaft pulley that was designed to drive an eight rib supercharger belt on the side of the pulley that's closer to the wheel well. The drawing mentions OEM next to some of the dimensions, though. For example, it lists the overall thickness as 3.175 and OEM as being 3.125.

To double check the dimensions, I just dug out the spare OEM five speed crankshaft pulley I bought in 2009. That's built to drive two belts: a four rib belt on the side closer to the engine block and a five rib belt on the side closer to the wheel well. The section that drives the four rib belt has a slightly larger diameter than the section that drives the five rib belt. Measuring with my vernier caliper, the largest outer diameter on the side facing the engine block is 150.5mm. The largest outer diameter on the side facing the wheel well is 145.5mm. Those are the outer diameters of the lips surrounding the belt drive areas of the pulley. The belt drive area on the engine block side has an outer diameter of about 145.7mm and the belt drive area on the wheel well side has an outer diameter of about 141.7mm (the lip on the engine block side is slightly higher than the lip on the wheel well side).

I measure the overall width of the OEM five speed pulley as 66.1mm. For whatever reason, some of my measurements don't agree with what's listed as OEM in the blueprint ATI made for Ken Sampson. In any case, I hope those OD measurements from my OEM five speed crankshaft pulley help.

This thread should be stickied. I appreciate the measurements. That is exactly what I needed to know. Specifically, the OD of the side facing the wheel well. That definitely changes my calculations, but in a good way. I don't think that the side facing the wheel well is specified in the drawing for the ATI pulley. It also sounds like the ATI pulley is bigger than OEM.

The measurements are needed towards figuring out which Rotrex I can run safely without overrevving it and ruining the bearings.

 

[greenberet]

The measurements are needed towards figuring out which Rotrex I can run safely without overrevving it and ruining the bearings.

Very cool!

Just for reference, here's a picture of the OEM manual transmission crankshaft pulley / harmonic balancer I measured. It mounts with the snout facing towards the engine block.

 

[jones83]

That's the pic I used for a visual reference. Still debating on if I will replace my current pulley with another OEM or ATI pulley. Looks like a Rotrex C38-71 or C38-81 will be what I need. Should make 400whp easily, quickly, and capable of spinning up to 8500 with the NSX crank or ATI pulley.

 

[solidol]

That's the pic I used for a visual reference. Still debating on if I will replace my current pulley with another OEM or ATI pulley. Looks like a Rotrex C38-71 or C38-81 will be what I need. Should make 400whp easily, quickly, and capable of spinning up to 8500 with the NSX crank or ATI pulley.

I would go with ATI. Especially considering you can get one from Summit Racing for $495 shipped. Just so you know.
pn: 917757

 

[Mark911]

don't go much larger than stock as the pulley will hit the oil cooler housing (on an NSX). 6.78" Dia sounds way too big.