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b20 flywheel options/alternatives

71142volvo

71142volvo

Member
Joined
Jul 26, 2014
Location
Long Island, NY
Hey Everyone,

My b20 is in the final steps of getting built: double 40's Weber sidedrafts, 279 cam, double springs, headwork, alum/steel timing gears, aluminum radiator, electric fan, header, T9 5spd tranny with a short shift kit.

The question is: who makes an aluminum flywheel or should I get the one I have lightened up? also, how light is too light?

Thanks
 
Weight depends a LOT on intended use. Mine is a street car, went with 17lbs when I had mine lightened, really nice honestly. Has enough weight to be nice on the street, way happier to rev than the stock 24lb flywheel.

Also gotta know if it's 6-bolt or 8-bolt. If it's 8 you can use a B21/23/230 flywheel.
 
gsellstr said:
Weight depends a LOT on intended use. Mine is a street car, went with 17lbs when I had mine lightened, really nice honestly. Has enough weight to be nice on the street, way happier to rev than the stock 24lb flywheel.

Also gotta know if it's 6-bolt or 8-bolt. If it's 8 you can use a B21/23/230 flywheel.
Click to expand...

I'd also like to hear what people are running and how they like it. I've got a spare that needs a surface anyway so I might just take it to work and see about milling some weight off.

Anyone know better places to take the weight from?
 
IPD used to sell lightened flywheels for B18/B20. The 6 bolt flywheel weighed ~16 lbs (20ish is stock) which is about right for a street driven car.

They took some material off from the outer edge , but left a nice radius. They also removed material from the back side.

Here's some pics for comparison.

6BoltFlywheelStock.jpg


6BoltFlywheelIPD.jpg


This IPD flywheel had some additional holes drilled to lighten it. You can see how much material was removed if you compare it to a stock flywheel.

FlywheelRear.jpg


Aluminum is just too light for the street.

6BoltFlywheelTilton.jpg
 
b230 is 20lbs, Should bolt right up, I have notice the b20 flywheels are a bit thicker than the b230 flywheels
 
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Depends on the weight. I actually grabbed a flat flywheel from a B23 (had free access), weighed in at 24lbs. I agree with everything hiperfauto mentioned. :)
 
^I *think* that's only true of my earlier 6-bolt flywheels.

The 74-75 B20 8-bolt flywheel has a little more material forward of the ring gear and less on the engine side but everything stacks up in the same place (clutch face and starter ring gear) from the rear mounting face of crankshaft if that makes sense when compared to its SOHC cousin.

The dowel pins things used for the volvo multi-tool crank angle pickup can sometimes barely hit the back of the B20 engine when using the SOHC flex plate or flywheel on an 8-bolt crank in a B20. You may need to file//grind/remove them.

Otherwise, they seem to swap back and forth no issues 8-bolt to 8-bolt SOHC or OHV. About the same ~20lb-22lb lump of iron either way.

14-17lbs is drivable for the street. Aluminum probably really isn't for all practical purposes. Even the 911 guys who run really light stuff on the street don't usually go below 10lbs, even in lighter cars with 3.6L motors.
15-17lbs (depending on where you carve it away...I stayed closer to 17lbs and just trimmed the outer edge and re-drilled for a larger clutch that was easy on my foot/didn't beat me up in traffic). Drove nicely and didn't beat me up.
 
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I took my stock heavy 6-bolt flywheel by my favorite machine shop and they did basically what looks like the IPD lightened flywheel up above:

6BoltFlywheelIPD.jpg


I think they charged me $20. They said they'd have also done it for a 12 pack of half decent beer. Reeeealy easy to toss it on a lathe and take off that low-hanging fruit on the outside edge. You could spend more time and take off more weight, but that is by far the biggest bang for your buck.

The engine feels so much more lively with a lighter flywheel on it. Takes a lot of the tractor out of it.
 
HAH, wish it was that cheap when mine was done John. Only 1 shop in the area at the time that could also balance it, otherwise it was have 1 shop lighten, another balance, and setup charges for both. They did most of mine on the outer, same as yours, with a little on the backside as well.
 
My shop swore that it wouldn't need to be rebalanced, since they didn't hit any of the balancing drill marks. I figured why not try it, it's perfectly fine spinning at 7, 7.5K rpm.
 
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