Decking head/ compression

[alexg89]

Good questions, only thing i could find on a quick search is https://www.engine-specs.net/nissan/ka24e.html

has majority of the info 

Piston pin outer diameter:

20.989-21.001 mm (0.8263.0.8268 in)

Connecting rod center distance:

164.95-165.05 mm (6.4941-6.4980 in

Edited February 7, 2020 by alexg89

[Stoffregen Motorsports]

15 hours ago, G-Duax said:

If you ever get a chance, look through old hot rod magazines, and books from the '50s & '60s.

The amount of work people went through, like stretching rods, and welding up piston domes.

This was way before you could enter an order with a speed shop like Summit, and order H-beam rods, or off the shelf high compression pistons.

 

We used to cut valve reliefs in the piston domes with a drill press and a valve-turned cutter by welding and grinding on it.

 

Performance has come a long way.

[Lockleaf]

Here's a combo I came up with a while back, though I've never done anything with it.  Caveat emptor, but here is what you can use to create low 9s:1 compression in a single cam KA.  You can even junkyard all the parts if you are feeling super frisky 👍.

 

You will need:

Ford 5.4 L connecting rods

Honda/Acura J32A3 pistons (specifically these pistons.  they have the correct compression.)

 

You will need to have the big end of the connecting rod bored to the KA crank.

You will need to have the small end of the connecting rod narrowed to fit inside the piston.

The big end of the connecting rod is narrower than the stock KA rod by some amount.  In theory could allow the rod to walk back and forth in the journal, but I don't know how that would play out in fact.

 

Build, return, and report.  I want to know if that crazy combo actually assembles a running engine 😄 

[datzenmike]

Or mill the KA24E head 0.5mm for a 9.03 compression.

 

Or mill the KA24E head 0.75mm for a 9.13 compression.

 

Or mill the KA24E head 1.0mm for a 9.3 compression.

 

 

The KA pistons stop 0.45mm from the deck surface so the above plus mill the deck 0.5mm for 9.68 compression.

 

The above plus a 0.5mm (0.020") copper head gasket for 10.09.

 

 

That's got to be cheaper and easier and likely you will be having the head milled anyway.

[Lockleaf]

1 hour ago, datzenmike said:

Or mill the KA24E head 0.5mm for a 9.03 compression.

 

Or mill the KA24E head 0.75mm for a 9.13 compression.

 

Or mill the KA24E head 1.0mm for a 9.3 compression.

 

 

The KA pistons stop 0.45mm from the deck surface so the above plus mill the deck 0.5mm for 9.68 compression.

 

The above plus a 0.5mm (0.020") copper head gasket for 10.09.

 

 

That's got to be cheaper and easier and likely you will be having the head milled anyway.

FINE!  Spoil sport.  

 

If its any help, mine is a long rod.... 😄

 

 

[alexg89]

Nissan KA24E 2.4L SOHC 12 valve						89-90 240SX
Stock Bore: 3.504, 89mm   Stroke: 3.780   Rod: 6.496   Head cc: 62.0   Gasket: .045   Deck: .000
Bore	Comp.	Dome	Compression RatioComp.	Gram	Part	Required
in/mm	Height	CC	w/ Stock Head	Wt.	Number	Ring Set
Dome top						All motor/Nitrous
3.504 / 89.00	1.340	10.4	10.7	364	3530100	1012283504
This is what i will be buying from Carrillo .. Local shop has them in stock and will be about 520 bucks ..

[alexg89]

On 2/7/2020 at 10:59 AM, Stoffregen Motorsports said:

Performance has come a long way.

By chance do you know with the above information if i deck the head .020 or .030 will there be an issue with valve clearnce? 

information i have on my cam is 270 duration and 445 lift as to where the stock was 232 duration .382 lift

Edited February 19, 2020 by alexg89

[Stoffregen Motorsports]

Valve clearance only becomes a problem with pop-up pistons and huge cams.