TorqueHD

Thank you Wretched, there's so much I don't know. Working on Harleys you buy big bore kits as a set of pistons and jugs, no one ever really gets them machined anymore.

strutaeng

I been told both ways: buy pistons first, then bore; bore then buy pistons.

I think in reality you need to measure to determine how much to bore out but at the same time know availability before you actually give the machine shop marching orders.

There's only like 20, 30 and 40 thousands over that I've seen and they say minimum boring to rectify taper, out-of-round, etc.

wretched73

iTrader: (1)

Why in the world would you buy pistons after your motor came back from the machine shop with a fresh bore and hone? I can't see the logic in that.

TorqueHD

By my math, running a 4.03" bore with the L8T crank, displacement would increase from 364 to to 394, only about an 8% increase. I know strokers tend to favor torque and the math isn't totally linear, but I wonder how much benefit you'd get from a 3.858" stroke.
I called Mast, they can install a 24x reluctor, and the guy I spoke with said 80% of the 4" strokers they have built since he's been there have been in daily drivers. I'm really leaning that way, I need to re-engage my local engine guy and make sure that the machine shop he uses is good with machining the block for the extra stroke. The guy from Mast also said that they can include whatever size pistons, they just have to order them from Wiseco so it will add 7 or 8 weeks which kinda sucks. But they can also balance the rotating assy. And there's a different oil/cam gear between the gen 5 and gen 3/4, he couldn't remember if it came with the kit but if not it's an $80 part.

shakenfake

You’re going to be rebalancing/checking at the machine shop anyway. Personally unless it is free then just skip the balancing lol I hear too many bad news of guys getting told it is ready to go when it isn’t

But all that is fear mongering anyway…

Bluecollar Hotrods

iTrader: (18)

That's the same one I've been using for years, it was cheap and does the job every time.

TorqueHD

Really stupid question here... I know the math on calculating compression ratio but my math is always wrong. I assume my error is that I am calculating cyl overall volume and not calculating the swept volume vs unswept, as I know most motors don't run the piston flush with the deck height at TDC.
Without putting the crank back together and measuring, is there a number for the difference in piston height at TDC from the deck or the mating surface on the block where the head gasket sits?
I need to start buying parts but it all centers around getting the right pistons, and so far I'm too dumb to know what pistons I need.

silentbravo

iTrader: (1)

Nice, answered my question there about the 24x. Any increase in cubic inch is going to give power so it just depends how much you want. I was really interested in that Mast kit because it is about the cheapest stroker kit you can get, even less than a forged 370 stroker kit and seems to be top tier parts from a good company.

BTR sells that oil pump gear for $50 (+ shipping which you may be able to bypass by ordering other stuff through them at same time)

Also you have to switch to a different flex plate because the Gen 5 crank (L8T) uses a different bolt pattern. I found those around $90

TorqueHD

Mast made a huge bulk purchase of new L8T cranks direct from GM several years ago so they have the corner on the market for those cranks. Also I asked about the flywheel, the 8 bolt is the same outer dimension as the gen 3 stuff and it bolts right up.

wretched73

iTrader: (1)

I'd suggest flat top pistons with valve relief. They are usually -4cc.

Stock pistons usually poke out a little, Then if your block has to be decked, that will increase, I made up the difference with the head gasket I used, which you can buy after you assemble your bottom end.

The motor I picked up got hot, very hot apparently, and had to be decked pretty good, but I don't remember how much was taken off.