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California98Civic 06-03-2014 03:49 PM

Machining a crank pulley
I want to get my three belt crank pulley machined to handle just the single alternator belt. Obviously preserving balance in the pulley is critical in the machining process. Any advice about good questions to ask the machinist that has agreed to consider the job?

Believe me I have searched online, and made five calls, and despite the huge aftermarket for Civics there are now no simple bolt-on options for a single belt crank pulley conversion on a sixth Gen (non-VTEC) SOHC Civic 1.6L engine. Unorthodox Racing is out of this game. Ralco makes them for the 1992-1995 but one guy on Honda Tech says he does not think it'll fit a 1998 D16 because, he says, he couldn't swap the stock pulley. Lastly, ATI's pulleys are for serious racing and too expensive.

I know the benefit is small, maybe enough rotational mass reduced to "save" a couple horsepower at the most. But I do a lot of P&G and I have to do the timing belt and therefore the pulley has to come off and therefore this is the simplest time to attempt this mod and so... I'm learning. :turtle:


Daox 06-03-2014 04:06 PM

Any local machine shop with a lathe big enough to chuck up your crankshaft pulley should be able to do this. You'll likely never see $ savings from it since machine time isn't cheap though.

I designed an underdrive crankshaft pulley for the 1st gen Aveo engine. Darin and I had a batch made at a local shop. I think the price per was around $100 to have them made, but we ordered 20 at a crack.

Superfuelgero 06-03-2014 05:15 PM

I'd go to the junkyard and try to swap the pulley's first (as much as I think this whole idea is a bad idea). The TDC marks are probably different, remarking would fix.
These guys and others can trim yours down to a single belt.
Or these

Frank Lee 06-03-2014 06:22 PM

Anyone with a lathe should be able to do it. But I agree, there are no gains to be had.

California98Civic 06-03-2014 06:46 PM

I don't expect big FE bonuses or that it will pay for itself soon, but if the OEM pulley weighs 9lbs, machining off the PS and AC positions will cut maybe 5 lbs of completely useless rotational mass. Losing that weight has to mean something for my acceleration pulses during P&G.

Frank Lee 06-03-2014 06:57 PM

Perhaps the "additional" mass allows lower rpms to be employed.

Superfuelgero 06-03-2014 07:08 PM


Originally Posted by Frank Lee (Post 427842)
Perhaps the "additional" mass allows lower rpms to be employed.

Not really. It does allow you to accelerate faster while maintaining lean burn. P&G is shorter cycles, not sure if it helps or hurts since I'm not much of a P&G'r. I also did the lighter flywheel at the same time too.

Frank Lee 06-03-2014 07:10 PM

When I P&G'd I wished for more flywheel so I could get down to even lower revs w/o lugging.

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