Jump to content


Photo

flat or dished pistons


  • Please log in to reply
19 replies to this topic

#1 red13

red13

    Senior Member

  • Senior Member
  • PipPipPipPip
  • 780 posts
  • Location:california
  • Cars:1973 datsun 620

Posted 11 April 2014 - 03:18 PM

trying to find pistons for my l16 the ones i have, have some damage and saw some nice ones on rockauto that are for a 240z they're 83mm just wondering if the would work,but also if putting flat pistons in a  l16 better or worse. http://www.rockauto....8137&cc=1209170



#2 ggzilla

ggzilla

    Road Warrior

  • Senior Member
  • PipPipPipPipPipPipPipPipPipPip
  • 19,058 posts
  • Location:Maui, HI USA
  • Cars:no cars

Posted 11 April 2014 - 03:42 PM

Flat tops are more fuel efficient but change the head to match.
Here today gone tomorrow

#3 red13

red13

    Senior Member

  • Senior Member
  • PipPipPipPip
  • 780 posts
  • Location:california
  • Cars:1973 datsun 620

Posted 11 April 2014 - 04:16 PM

well got a l16 210 head or a l18 head which one should i go with i am running a l16 engine block



#4 flatcat19

flatcat19

    Back in Black

  • Senior Member
  • PipPipPipPipPipPipPipPipPipPip
  • 20,709 posts
  • Location:Tri-Cities, WA/PDX
  • Cars:Smaller. Better. Slower. Lower.

Posted 11 April 2014 - 04:36 PM

Are the cylinders OK?

You can't hang if your nuts haven't dropped...it's physics


#5 red13

red13

    Senior Member

  • Senior Member
  • PipPipPipPip
  • 780 posts
  • Location:california
  • Cars:1973 datsun 620

Posted 11 April 2014 - 05:22 PM

well the block i got the guy had it honed so the bore still at 83mm, but i am going to get it magna fluxed hot tanked and see if i need to bore it .30 over



#6 flatcat19

flatcat19

    Back in Black

  • Senior Member
  • PipPipPipPipPipPipPipPipPipPip
  • 20,709 posts
  • Location:Tri-Cities, WA/PDX
  • Cars:Smaller. Better. Slower. Lower.

Posted 11 April 2014 - 05:25 PM

I would plan on a bore. 

Stuffing 83.xx into a honed 83.xx hole is merely a band-aid. 

 

Boring a block to fit oversized pistons is more like having a new block. 

 

 

 

For the price of machine work you can just source an L20B for more power out the box. 


You can't hang if your nuts haven't dropped...it's physics


#7 red13

red13

    Senior Member

  • Senior Member
  • PipPipPipPip
  • 780 posts
  • Location:california
  • Cars:1973 datsun 620

Posted 11 April 2014 - 05:28 PM

these are my current pistons the one in the middle has the worst damage

04111418251.jpg



#8 red13

red13

    Senior Member

  • Senior Member
  • PipPipPipPip
  • 780 posts
  • Location:california
  • Cars:1973 datsun 620

Posted 11 April 2014 - 05:29 PM

yeah i know the l20 is a better engine, but i like keeping my truck stock.  As much as i can.  Also its what i could afford right now.  I just spent 200 on a block for a l16



#9 ggzilla

ggzilla

    Road Warrior

  • Senior Member
  • PipPipPipPipPipPipPipPipPipPip
  • 19,058 posts
  • Location:Maui, HI USA
  • Cars:no cars

Posted 11 April 2014 - 05:34 PM

What is wrong with the piston? It looks OK to me a little carbon won't hurt.

And what's wrong with 83 mm pistons in an 83 mm bore? Measure both and if they are in spec, you don't need an overbore.
Here today gone tomorrow

#10 red13

red13

    Senior Member

  • Senior Member
  • PipPipPipPip
  • 780 posts
  • Location:california
  • Cars:1973 datsun 620

Posted 11 April 2014 - 05:37 PM

just the center one is beat up on the rim of the dish and some dimples i guess i an burnish them out.  The other 2 have valve damage,but i can do the same.



#11 datzenmike

datzenmike

    KING RAT

  • User Administrator
  • 72,265 posts
  • Location:Vancouver Island
  • Cars:'74 710 sedan, '76 710. prevoius... '78 620, '71 521, '68 510 new '76 B-210

Posted 11 April 2014 - 05:45 PM

The piston to bore clearance is 0.001" to 0.0018" or roughly 1 to 2 thousandth of an inch. Newsprint is about 2 thou. Stock pistons are not 83mm, they range from 82.985mm to 83.035mm and the same goes for the bore. No bore is exactly 83mm. Those that are slightly over get a 'larger' piston to maintain that 1 to 1.8 thou clearance. Definitely measure the bore in 6 places and check for oval and taper and over size if needed. Oversize pistons cost the same a stock ones.
Posted Image

#12 red13

red13

    Senior Member

  • Senior Member
  • PipPipPipPip
  • 780 posts
  • Location:california
  • Cars:1973 datsun 620

Posted 11 April 2014 - 05:56 PM

i really wanted to know though is flat better or should i go with ones with a dish. and what head i should use.



#13 ggzilla

ggzilla

    Road Warrior

  • Senior Member
  • PipPipPipPipPipPipPipPipPipPip
  • 19,058 posts
  • Location:Maui, HI USA
  • Cars:no cars

Posted 11 April 2014 - 06:03 PM

Flat tops are more fuel efficient if a closed chamber head is used.

Get a 210 closed head (peanut-shaped chambers). There is also a 210 open head which is low-emissions.
Here today gone tomorrow

#14 red13

red13

    Senior Member

  • Senior Member
  • PipPipPipPip
  • 780 posts
  • Location:california
  • Cars:1973 datsun 620

Posted 11 April 2014 - 06:09 PM

this is the head i got thats a 210

04111417101.jpg



#15 datsunaholic

datsunaholic

    Senior Member

  • Senior Member
  • PipPipPipPipPip
  • 5,027 posts
  • Location:Monroe, WA
  • Cars:Not quite the whole set yet

Posted 11 April 2014 - 06:17 PM

Those aren't even stock pistons.  I don't know what they're from.  L-series pistons don't have valve cutouts, and those aren't Z-series pistons either.

 

Flattops would increase compression, and with that semi-closed chamber 210 head might increase it so you'd need to run higher octane fuel to prevent detonation.  But maybe not.  Those valve reliefs had your compression a bit low to begin with.


-----------------------------------------------------

Well, at least he gets 24 hours notice. That's more than most of us get. All most of us get is, "Mind that bus!" "What bus?" _splat_!

#16 datzenmike

datzenmike

    KING RAT

  • User Administrator
  • 72,265 posts
  • Location:Vancouver Island
  • Cars:'74 710 sedan, '76 710. prevoius... '78 620, '71 521, '68 510 new '76 B-210

Posted 11 April 2014 - 07:31 PM

Stock 210 L16 head...

 

head210L16.jpg

 

210 head with stock 7.01cc dish pistons...... 8.58... with closed head... 8.21... with open head.... 6.72

210 head with true flattops.......................... 9.75... with closed head... 9.29... with open head.... 8.63

 

 

.


Posted Image

#17 ggzilla

ggzilla

    Road Warrior

  • Senior Member
  • PipPipPipPipPipPipPipPipPipPip
  • 19,058 posts
  • Location:Maui, HI USA
  • Cars:no cars

Posted 11 April 2014 - 07:43 PM

You list three figures but only two types of heads?

9.29 compression ratio would be good. Max fuel economy.
Here today gone tomorrow

#18 datzenmike

datzenmike

    KING RAT

  • User Administrator
  • 72,265 posts
  • Location:Vancouver Island
  • Cars:'74 710 sedan, '76 710. prevoius... '78 620, '71 521, '68 510 new '76 B-210

Posted 11 April 2014 - 07:53 PM

210 head, closed chamber (41cc) and open chamber (45.2cc). Three heads. There was a closed chamber 210 head but it's almost the same as the regular 210 for size.

 

The A87 closed or the SSSL16 219/V912 head actually drops the compression on an L16 unless you have the flattop pistons to go with it. An open chamber U67 head drops a stock L16 into the 6s.


Posted Image

#19 red13

red13

    Senior Member

  • Senior Member
  • PipPipPipPip
  • 780 posts
  • Location:california
  • Cars:1973 datsun 620

Posted 11 April 2014 - 07:55 PM

thanks guys see ill look into flat top pistons then.  Those ones i found are for a 240z.



#20 ggzilla

ggzilla

    Road Warrior

  • Senior Member
  • PipPipPipPipPipPipPipPipPipPip
  • 19,058 posts
  • Location:Maui, HI USA
  • Cars:no cars

Posted 11 April 2014 - 08:13 PM

Arent those are the ones used in an L16?
Here today gone tomorrow