Xu5Ja - Xu7Jp4 Pistons?

[eTiKeT 0 1 Cars]

Hi Guys.

I just wanna ask this. Can I install XU7JP4 pistons on my XU5JA engine ? If I can install what will be my compression ratio. Con rod lenght is same but block height is different.

Thanks.

[welshpug 1,661]

compression will be rather low due to the much lower compression height.

 

the rods are the same part number.

[eTiKeT 0 1 Cars]

compression will be rather low due to the much lower compression height.

 

the rods are the same part number.

Oke thank you for information. So is there any alternative to increase compression ratio with other oem pistons ?

[welshpug 1,661]

405 1.9 SRI flat top pistons

[eTiKeT 0 1 Cars]

405 1.9 SRI flat top pistons

Hmm. With this pistons how much increase compression ratio ?

[welshpug 1,661]

Cylinder Volume (cc) = Bore(mm) x Bore(mm) x (Pi*.00025) x Stroke(mm)


83 x 83 x .0007854 x 73 = 394.975 (cc)


Combustion Chamber Size (cc)=(32)


Gasket Volume (cc) = Gasket Bore(mm) x Gasket Bore(mm) x (Pi*.00025) x Gasket thickness (mm)



84 x 84 x .0007854 x 1.4 =7.758 (cc)

 

 

Compression ratio is total capacity /chamber volume+gasket volume + dish/dome volume, (if any)

394.975 (cc) +32(cc) + 7.758(cc)
------------------------------------------- = 10.93
32(cc) + 7.758(cc)

 

 

 

 

I believe that is correct.!

[309jazzpanda 41]

Wow that is in depth

[welshpug 1,661]

really? that's the only way to do it

 

that is assuming that what I have been told about these pistons is correct, that they come up flush to deck, I do know they have a flat top as I have a set.

 

if they weren't flush or even protruded there would be a few more numbers flying about on top.

[eTiKeT 0 1 Cars]

Cylinder Volume (cc) = Bore(mm) x Bore(mm) x (Pi*.00025) x Stroke(mm)

 

 

83 x 83 x .0007854 x 73 = 394.975 (cc)

 

 

Combustion Chamber Size (cc)=(32)

 

 

Gasket Volume (cc) = Gasket Bore(mm) x Gasket Bore(mm) x (Pi*.00025) x Gasket thickness (mm)

 

 

 

84 x 84 x .0007854 x 1.4 =7.758 (cc)

 

 

Compression ratio is total capacity /chamber volume+gasket volume + dish/dome volume, (if any)

 

394.975 (cc) +32(cc) + 7.758(cc)

------------------------------------------- = 10.93

32(cc) + 7.758(cc)

 

 

 

 

I believe that is correct.!

 

Oke thank you for information, I see. One more question. Can I install 405 sri 1.9 pistons on XU5JA conrods. Do I need to change pins.

[309jazzpanda 41]

clever stuff knowing that I might bookmark this page so I can sound clever

[welshpug 1,661]

all I did was google Compression ratio and found several pages with various ways to reach the same end result.

[petert 588]

or

 

CR = (Vs + Vc)/Vc

 

if you know two of the variables, you can move it around as much as you like.

[pug_ham 244 3 Cars]

Can I install 405 sri 1.9 pistons on XU5JA conrods. Do I need to change pins.

You can fit the SRi pistons onto the XU5JA rods using the same pins.

 

g

[309jazzpanda 41]

Welshpug, you should've said it was just something off the top of your head

[welshpug 1,661]

the details were but not how to work out the end result

[eTiKeT 0 1 Cars]

Thank you guys. I will bought pistons within 2 days. And I will post photos when I try them on engine block.

[eTiKeT 0 1 Cars]

Hi again, I can not find where the piston 405 sri 1.9

 

 

Do you have the full picture as the piston? thnx

Edited January 11, 2013 by eTiKeT