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L series dimensions - Stroke, Bore, Chamber cc's, etc


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  • 2 weeks later...
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well Kameari have a custom 85mm stroke crank for their 3.2L engines with 88.5 to 89.5mm custom pistons & rods!

 

http://www.kameariusa.com/

 

 

For those who want to play with bore & stroke ratios for capacity theorising, try this simple math:

 

0.7854xborexborexstrokexno#cyl = displacement (/1000 for cc)

 

 

Or alternatively....

 

bore in mm divide by 2, now square it (times by itself), times Pi (~3.14), times stroke in mm, times number of cylinders, divide by 1000 = capacity in cc

 

((╥r^2 * L) * no# cyl) /1000

 

note: you can divide again by 16.4 to get cubic inches!

 

 

 

eg: 89mm x 85mm = 3172cc approx.

 

 

 

>>>keep in mind that if a stroke is say 6mm longer than you were previously using, the piston is going to travel 3mm higher & 3mm lower than previous, in the cylinder! So theoretically you would want a rod that is 3mm shorter, to keep the same deck height as before! (the piston will now sweep 6mm lower in the bore) Other than custom machined rods, you will have to play with compromises to get it to work :ie rod lengths, piston pin heights, decking/milling, gaskets etc...!

 

note: this will effect your compression ratio too! (~increase it)

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  • 3 weeks later...
  • 3 weeks later...
L20a uses ~128.016mm rods!

 

Are you sure about that L20A rod length PandaZ?

 

The early L20A uses 78mm diameter pistons with a piston pin height of 40.1mm and a stroke of 69.7mm from what I've researched.

With 128 mm long rods that L20A piston would be down the bore 4.9mm at TDC. That'd give about a 6:1 compression ratio.

128mm rod = 202.95mm installed piston height

133mm rod = 207.95mm installed piston height

Deck Height = 207.85mm

Plus, the FSM states that the connecting rod center distance is from 132.94 mm to 133.08 mm.

 

Some of your other figures seem to be right on though I don't agree with the L24/L16 rod measurement either. It's the same length as the early L20A rod in the FSM as well as any other reference source.

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L20a uses ~128.016mm rods!

 

L18 are ~130.3528mm

L16/24 are ~133.9436mm

L13 are ~139.9032mm

 

L20b are ~~145.9mm

Having pulled/owned 3 sets of L20a rods I can confirm the following.

 

Pre 79 L20a have 133mm rods ie the same as the L24 and with 9mm rod bolts too. The post 79 L20a and the L20et have 135mm rods but with 19mm little ends and the smaller big ends aka L24e/Maxima journal sizing. I have not seen L20a rods that are 128mm ever and all the Japanese sites use L20a rods when building strokers as they are 133mm and the numbers work out.

 

Plus as stated at 128mm the piston would be 4+ mm below the deck height.

 

And one last thing the pin height of the pre 79 is 40.1mm and the post 79's are 38.1mm like most L series engines.

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  • 2 weeks later...
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i skimmed through this post and didnt find what i was looking for and

 

instead of making a new post i thought i would ask here.

 

what is the specs on the stock cam. and what is a good aftermarket size

 

but still streetable, i'm not looking to build a race car:weird:

 

thanks

 

 

Welcome to HybridZ. We understand that most people sign up and quickly click “accept” to the rules so they can start posting. Problem is sometimes these new members are unknowingly violating the rules to which they agreed to abide by because they didn't take the time to read them. :wink:

 

As your second reminder, :wink: you may want to go through and read the rules of this forum because we do run a very tight ship here and have a few rules that are not typical of most forums such as rule #2 that covers the forum archives, rule #5 that covers post structure, etc. Regarding rule #5, we don’t expect college level grammar but we do expect grade school level sentence structure including making an effort to capitalize and punctuate, no IM text shortcuts etc. We have a couple stickies at the top of the new members forum linked below that cover the staffs feelings on that topic, we encourage all new members to read those.

 

Click ME for the "New Members Forum".

 

 

Also, you may want to post your question in a thread that better suits the topic of your query.

 

Thank you for your understanding,

Paul

HBZ staff

Edited by BRAAP
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I read the whole post and didn't see these tools...Maybe I missed them. But here are the links:

 

PS with the Auzdat you need to scroll down and select a base engine (motor) and then manipulate the figures with the drop down menus...It also alerts you whan the piston is above deck and if you don't match pistons with bores.

 

http://www.ozdat.com/ozdatonline/enginedesign/ oooops I see it now on page one!!!

http://www.zhome.com/ZCMnL/tech/128combo.html

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