Drilling holes in piston

[3racers]

Do all of you drill the little holes in the wisco piston? Do they come already drilled sometimes?

[fearlessfred]

are u talking about ,to cool the exhuast bridge

[norcalduner]

Yes you do unless you have a powervalve cylinder.

[machwon]

Wiseco's come pre drilled unless they are special orders then its up to who ordered them. You could drill the piston for the outer bridges on a pv cylinder if you wanted too.

[3racers]

Hey thanks guys thought some were already drilled.

[Ruf Racing]

I add a third hole and enlarge them .020.

Working from inside the piston, using a 1/8” Diameter ball burr create one shallow vertical runner connecting the 2-3 holes, add short horizontal runners running 5MM-6MM from the center of each respective hole…

Keep the runners shallow, .5MM (.020”) is deep enough…this feature increases flow significantly through all holes and helps keep the exhaust bridge cool.

Old builders trick…

Carlos.

[speedfreek]

Carlos, What would you recommend doing to the intake port on the 87-89 pistons. I always widen them a bit and raise the roof , if I remember correct a few millimeters.

Also, is there anything that you do to the 86 and earlier half moon shaped pistons?

[fearlessfred]

Originally posted by speedfreek
Carlos, What would you recommend doing to the intake port on the 87-89 pistons. I always widen them a bit and raise the roof , if I remember correct a few millimeters.

Also, is there anything that you do to the 86 and earlier half moon shaped pistons? on the 86 pistons we use to drill a hole between the halve moon and rings i think it was 3/8s

[speedfreek]

This thread needs to be added to the mods and tricks sticky!

[Chino886]

Any one got pics of this?

Without getting to deep into Piston materials & designs; here are some basic modifications I have seen on Team Honda Racing engines and run on my engines:

• Teflon or Low friction coatings on Piston skirts (similar to Wossner)
• Ceramic or Hard Chromed Piston Crowns
• Added cooling/lubrication holes on exhaust bridge
• Added runner channels to cooling/lubrication exhaust bridge holes inside piston
• Added cooling/lubrication holes on each intake bridge (below ring locating pins) on 87-89
• Added runner channels to cooling/lubrication intake bridge holes inside piston on 87-89
• Generous chamfer of all skirt edges , including windows or piston ports
• Added piston intake window or port on 85-86 pistons
• Added piston ports on front transfer port area, sometimes matched to extra added sleeve ports.
• Reducing weight by machining inside of piston
• Re-balancing of piston
• Flat top pistons
• Aging pistons & rings through heat Treat (before & after running)
• Reducing top piston diameter by .0005”-.0015” to 1mm below second ring grove. This is for drag applications, or engines performing over 10,000 RPM’s
• Re-cutting piston diameter, and taper from top to bottom of skirt to match application. An example would be an Aluminum Sleeve (different expansion rate than the equivalent steel sleeves) benefiting tremendously from a matched piston with tighter clearances and a different piston taper to match the Aluminum Sleeves expansion rate.

These are some basic modifications; depending on the access to metal cutting machinery you may have, the amount of work you can perform on pistons, sleeves and cylinders is endless.

Carlos.

[3racers]

Hey this was some good info learned a few things. Thanks