factory 11.5 pistons for a 400??

[73Runner4spd]

Cleaning out the back room of my shop today and found 8 in the box pistons with quite the dome. Punched the part number on Google and found something saying that it is a .060 over 11.5 to 1 400 piston can anyone give any insight to that? Part number p3690832

 

[Photon440]

That number matches the info on this page:
http://www.scribd.com/doc/24470110/B-RB-ENGINE

 

[Meep-Meep]

Early Direct Connection replacement pistons for racing and are most likely made by TRW. Much lighter pistons available now but these are still quality pieces. I'd use 'em.

 

[73Runner4spd]

Early Direct Connection replacement pistons for racing and are most likely made by TRW. Much lighter pistons available now but these are still quality pieces. I'd use 'em.

No kidding? So I'm assuming they are forged? What kind of over heating issues would I run into running it .060 over bore? They're. Brand new in the box less the rings. Also any idea what the actual compression would be with a stock deck 400 and did they get the 11.5 out of closed chambered heads or open? Thank you!

 

[daredevil]

Dont think you can run a pop up piston with close chambered heads.Couldnt drop em deep enough in the block not to interfere and they wouldnt quench.

 

[73Runner4spd]

Good excuse to buy some aluminum heads!

 

[dellortox4]

Any chance you might sell them?

 

[dvw]

Any chance you might sell them?

They certainly are not modern design, heavy, forged and pretty strong. Street or bracket use in a 400? I would use them, they'll be more than adequate. They do tend to use a little oil, not smoke just consumption. i believe if you look in an old Direct Connection manual it will list the comp ratio with various chamber volumes. As long as you mantain deck hieght of zero or less they should work with any factory head. That being said factory iron heads on pump gas will only tolerate about 9.5-1 on pump gas.

Doug

 

[Cranky]

That being said factory iron heads on pump gas will only tolerate about 9.5-1 on pump gas.

Doug

With the right cam and combo, you can go up over 11-1 on pump premium......been there done that.

And I'd run those pistons too but would ball end mill about 200 grams or so out of them first. Just had to measure how thick the heads were first.

 

[Mopars & Missiles]

Cleaning out the back room of my shop today and found 8 in the box pistons with quite the dome. Punched the part number on Google and found something saying that it is a .060 over 11.5 to 1 400 piston can anyone give any insight to that? Part number p3690832

Direct from the source -

 

[Meep-Meep]

From the catalog pic (assuming that is what you have) they are forged and likely a 2618 alloy - so they will run about .005" to the wall. That clearance is considerably looser than stock cast but normal for these. I would be more worried about bore distortion on a .060" over 400 rather than overheating. Get it sonic checked before you go that far.

 

[dvw]

With the right cam and combo, you can go up over 11-1 on pump premium......been there done that.

It would have to be an VERY BIG cam. My bet is it still would detonate at higher RPM whether you can hear it or not.
Doug