Connecting rod options?

[nando]

if you're getting custom pistons, IMO go straight for the S52 crank and don't look back.

[Cabriolet]

if you're getting custom pistons, IMO go straight for the S52 crank and don't look back.

thx man. will do.

[digger]

with custom pistons there are more options with engine size and CR but it will cost alot more, you never stop at just new pistons.....with custom pistons best to go as big as you can afford IMO for the better torque. the bigger engine will unlikely make more peak power than a similarly build slightly smaller engine but will have proportionally more torque and not need to be revved as much to access it

[nando]

yeah, basically once you choose custom pistons the cost adder for a 2.8 vs a 3.1 is a couple hundred bucks.

[digger]

yeah, basically once you choose custom pistons the cost adder for a 2.8 vs a 3.1 is a couple hundred bucks.

yeah for a barebones 3L+ its peanuts in difference but ideally you need a better sorted head, exhaust and intake etc and once you go down there is gets spendy.

[nando]

well, you need all that anyway IMO. if you build a stroker with a stock head you're going to be spinning your wheels.

also once you've built the bottom end it's not hard to swap in a better head/cam/headers later on.

[Cabriolet]

I will keep it under 3L. I need it to be DD-able, smog-able, etc.

M52b28 crank, M50 rods, 1mm over bore which should be a 2.9L, 10:1cr bc in ca we can only get 91octane

already have a new 272/272 IE cam. and ill get headers lined up shortly

[digger]

well, you need all that anyway IMO. if you build a stroker with a stock head you're going to be spinning your wheels.

also once you've built the bottom end it's not hard to swap in a better head/cam/headers later on.

yeah bottom end is not any different, but head requirements can be different when you start stepping up from the eta crank to the S52. it does depend on what you are trying to do though.

for example most still use stock valve sizes on a big stroker, stock valve size would still work well on a mild 2.7-2.8L but a 3L+ might prefer bigger. also a big engine needs a bigger camshaft which requires a bit more compression but also might mean slight valvetrain differences e.g. a step up in valve springs or a better quality rocker or retainer etc.

im all for big cubes infact a 3.1L just isnt enough ;)

[digger]

I will keep it under 3L. I need it to be DD-able, smog-able, etc.
M52b28 crank, M50 rods, 1mm over bore which should be a 2.9L, 10:1cr bc in ca we can only get 91octane
already have a new 272/272 IE cam. and ill get headers lined up shortly

The bigger the engine the more streetable it will be for the same cam. the cam will govern the emissions more than anything (obviously a proper tune is needed)

Tinkerputzer had good results with the MM sport cam and that is a low emission camshaft. Otherwise look for a wider LSA cam

[nando]

yeah I think a 3.1 will be more "ddable" than a 2.9. it'll simply make more torque at a lower RPM and you don't necessarily have to go so wild with the cam, it'll just mean your peak power might be lower than it could be.

[Cabriolet]

the 3.1 would blow out my budget. i cant afford 12 new larger valves and seats. thats another 1k. im even wondering if 2.91L will be too much for the flow. i already bought the 272 cam and the HD rockers. so im limited to that. but also im not looking for mad power but rather a lively m20.

[nando]

it's not going to be "too much for the flow". All it will do is limit your VE. your peak HP will be about the same, essentially - but your low end torque will be greater, thus why it would still make a better DD motor. you don't have to go super fancy on the head, like I said you can always swap that out for a better built one later if you want.

[digger]

yeah you dont need to go crazy unless you want more hp than what the more standard sort of builds achieve. i was speaking in general not necessarily for your possible build. you can still make 210-220whp with cast intake manifold and stock valve sizes and very mild head.

i agree a standardish head is a good place to start and go from there, the bottom end you want done right first time. its an afternoon job to swap out a new complete head

with good compression and short duration cam it will have alot of bottom end and midrange noticeably more than a 2.8L

[LJ851]

Torque is primarily dependent on engine capacity, and a longer stroke boosts torque more than a larger bore.

I agree with nando and digger, go big.

[abit]

ok, I won't start new tread so I will ask here.

engine is NA m20b28 stroker.
Im trying to get some more power out of it, so thinking about forged rods.
Now Im using m20b20 130mm rods which weight is about 650grams, forged rods weight about 550g. Is about 0.6 kilos on all assy, thats feels like big number

And the big question is.. is it worth money? Will I feel some real difference in power or engine response?