Need opinion /help sr20 ptw

Good day !

would really apprrciate an advice on piston to wall clearance for sr20 wiseco pistons.

Target is 400 wheel horse power. Car is gonna be used as daily and weekend drift warrior . Will use 98 pump gas.

Should i go for what is written on wiseco piston spec sheet or should i add abit of clearance on top of whats listed?

Spec sheet gives .030" or 0.762mm

If someone knows a good recipe for reliable 400 whp bottom end please share it , iv saved money for 4 years🤣 just to be able to build this engine so really want to build it as good as possible 😄

The figure you're using is the oversize, it's 100% NOT the P2W clearance, which would be somewhere near a tenth of that, and generally be in a minimum/maximum range.

Exactly what are the pistons - the engine they're for, full part number - there are two different alloys on offer, with different expansion rates, what modifications you have that will affect the clearances, and what you're using them for.

You may wish to read this - https://www.wiseco.com/frequently-asked-questions-faq/

In the end, though, unless you own and/or are operating the boring and honing machine, there's nothing you can do, orther than find an experienced machinist you trust, who will finish the bores to the diameter, and finish, required for the pistons and rings.

Thanks for reply

Iv read the wiseco faq allready :D we have great machine shops here in Lithuania. Just that itw better to tell what you want exactly. And Sorry, the clearance number i wrote is wrong.

Its 0.0030" or 0.0762mm.

Material is 2618.

Piston size 86.5

I will attach the spec sheet.

Between the Wiseco recommendations for the pistons, knowing they're for a turbo'ed engine, and the additional clearance recommendations, I'd be looking at around 0.0035"- but I'm not experienced with that application and others may suggest differently.

You would normally get slightly longer engine life, etc, with the tighter piston card suggested clearance, but if you put enough heat into them with a higher than expected boost and/or run a little hot, you may end up with the piston picking up and seizing. If you go more than a thou' bigger, you may notice a slightly noisier engine, especially when cold, and maybe a slight increase in oil consumption. paradoxically, going too big on P2W clearance can also increase the risk of picking up and damage to the piston and bore, as the piston wil tilt slightly more.

Hopefully, someone with experience of this engine/piston combination can better suggest the best fit for you, and you can also do a search here, and on the inter-web, for others with similar combinations.

Gord, your figure is right on the money- 0.0035 is most reasonable gap for this type of pistons and level of forced induction.

Thank you mister! Tons of info ! just left the machine shop , showed the wiseco card and after abit of talk we decided to go with .00315" / .008mm. Fingers crossed that its gonna be allright 🤟 ofcourse if someone thinks that it will be to tight let me know please :D