After promising a few members in a thread that I would make a thread that listed various specs and measurements on the j-series block and counterparts, I soon realized that one of the most important specs on this engine has never been found and/or posted.

I was curious if anyone had ever posted the measurement online and after searching numerous results on Google, I found nothing. So I took a few critical measurements and factored them into a formula and after having physically confirming the answer on the actual block itself, I am proud to say that I know it.

Can anyone, or DOES anyone, know the deck height of a j-series engine?



Ps- anyone with decent automotive knowledge should be able to answer this if you use the same formula I did. I will screen shot the answer on my iPad in the notes section so it shows the date and answer to confirm my claim. Anxious to see the results on this one...

 

Can use the following formula to calculate it:

Piston Compression Height
a = Block Length
b = Stroke of Engine
c = Rod Length
d = Deck Clearance
Formula: a - (b / 2 + c) - d
Example: 9.025 - (3.50 / 2 + 6.00) - .025 = 1.250

But you need the deck clearance, which is a value I don't have for the J32A3 with stock rods/pistons.

Do share though This is information I'd been trying to find previously when I was considering doing the 3.6L and would certainly be helpful for compression calculations when I do the PNP heads and camshafts.

Another value I'd really like is to be able to calculate the dynamic compression on a stock J32A3, but would need the intake valve closing ABDC in order to do so.

Here's a good bit of info on DCR.

http://cochise.uia.net/pkelley2/DynamicCR.html

 

That's it?

 

Isn't compression height the same as piston deck height (center of wrist pin to top of piston)? I've been looking for the block deck height (center of crank to top of engine deck), but that, as yungone says, is nearly impossible to find. I don't know the deck clearance either, nor have I found the piston dome height (haven't searched much for the last one.)

Don't leave us in the dark too long, I'd love to know this. Granted, there can be ever so slightly differences between every block, but I'd like Honda's listed spec.

 

You can calculate the piston deck height, I used ILC's specs from when he had his car at king motorsports to calculate the piston-deck height of the J35A8, since I didn't see it on his spec sheet.

I came up with a volume of .676cc by using the factory static compression of 11:1 which translates to .001" when you do the conversion, since the bore is 89mm.

You can actually calculate the piston dome volume the following way, since we know some variables and the SCR is 11:1 then using the data from when ILC had some stuff blue-printed for his build..

Since head gaskets are the same, and volume was 3.78cc on his spec sheet. Compression is the same and combustion chambers king measured at 53cc on a stock head while yungone gave a value of 53.5cc in his thread.

Clearance Volume = Piston Volume + Gasket Volume + Piston-deck Volume + Combustion Chamber Volume

Since the piston is domed, we actually subtract the piston volume so and here I'm using the piston-deck height calculated off the J35 since I don't have it for the J32 but it's also a 0 clearance motor so should be about the same..

This is all in cubic mm.

Here's how I got the total clearance volume:

SCR = (535017.829988 + Vc) / Vc

Using algebra...

(.785398)(89^2)(86)/x + 1 = 11

535017.829988 = 10x

x = 53501.7829988cubic mm = 53.501cc

Here's how I got the piston dome volume, subtracting it from the total since the piston is domed not dished it takes away clearance volume:

Piston Dome Volume: 676 (piston-deck) + 3780 (gasket volume) - x (piston dome volume) + 53000 (combustion chamber volume) = 53501 (clearance volume)

57456 - x = 53501

x = 3955 = 3.955cc = 3.2L Piston Dome volume

Now if the combustion chamber cc is what yungone measured it to be of 53.5cc then the piston dome has to be about 4.455cc to reach SCR of 11:1.

Here are the values I've been able to calculate or come up with from scouring the internet.. I have some heads at a shop for PNP and I'm going to have them CC a chamber so I can get another source of the combustion chamber volume, since I have a little discrepancy between ILCs numbers from King and what yungone has posted.

Also don't know if the piston-dome volume is correct, it could be off depending on what the actual piston-deck height is on the J32 and whether the chamber CC's at 53.5 or 53.

3.2L Calculated Values:
Piston Volume = 3.955cc (domed)
Gasket Volume = 3.78cc
Comb Chamb Volume = 53cc
Piston-Deck Volume = .676cc

 

Sorry but I don't remember ever claiming the j-series heads to have 53.5cc chambers. Unless I've mentioned it in a thread somewhere before actually measuring them myself but usually I will state that it's not "factual" information if I do not know 100%. Every j-series head I've ever cc'd the chambers on measured 58cc. Honda changes compression by altering piston dome/dish area for their v6 engines. All j-series (from the pistons I've measured) engines have the same 30mm piston compression height and also the same .027" compressed head gasket thickness. Also, the pistons mostly have 1/2cc reliefs and another 1/2cc's of volume removed from the outer ridge of the piston itself between cylinder walls and the top of the piston. Again, this is most pistons, not all.

Btw, deck height on the j-series is 9.251" or 235mm. That is a confirmed number on multiple displacement j-series engines.

 

I think the 53.5cc was because ILC milled his head to gain 1 or CR

 

I'm guessing this wasn't you then?

On this page?

https://acurazine.com/forums/showthr...ge=18&t=873314

I don't really want to get into an argument, regardless it's pointless to me the heads I have at a shop are being CC'd stock and modeled to see where they'll CC at with welded chambers.

Also ILC had 3 different CC's for his chambers,

1x was 53cc for his new heads that were stock
1x was 50.8cc for the heads he had picked up used
1x was 48.4cc after his .040" mill to raise compression

All the data is on a sheet he posted, also I won't need to know the actual piston-deck or piston volume for what I'm doing, since I can calculate it combined using the factory SCR of 11:1. Which gets me to a volume of either 3.279cc or 3.579cc depending on the CC of the chamber. Since I won't be changing the bottom I can still calculate everything else that I need to target my DCR.