Page 1 of 6 123 ... LastLast
Results 1 to 15 of 81

Thread: Compression ratio of hybrid JZ engines.

  1. #1
    Junior Member Backyard Mechanic
    Join Date
    Feb 2006
    Location
    QLD
    Posts
    338

    Default Compression ratio of hybrid JZ engines.

    When you muck around changing heads on RB's the CR changes. Like a 9:1 RB25 head on a 9:1 RB30 block ends up with a 8.5CR. But what about JZ's? Are the combustion chambers different volumes on the 1JZ and 2JZ heads?

    What CR do you get from the following?

    2JZGTE long block with 1JZGTE head.
    1JZGTE long block with 2JZGTE head (mate is doing this becuase his 2JZ bottom end is stuffed)
    2JZGE long block with 1JZGTE head.

  2. #2
    Toymods V8 Member Too Much Toyota CrUZida's Avatar
    Join Date
    Aug 2005
    Location
    WA
    Posts
    8,214

    Default Re: Compression ratio of hybrid JZ engines.

    Just a quick note 2jzr31, the section you are posting in here, is for conversions only.

    Any tech questions/posts go in the tech section.
    Peewee
    1985 MZ12 Soarer - 1UZ Powered
    2013 86 GTS

  3. #3
    Junior Member Backyard Mechanic
    Join Date
    Feb 2006
    Location
    QLD
    Posts
    338

    Default Re: Compression ratio of hybrid JZ engines.

    OK, thought that this would be related to engine conversions No probs

  4. #4
    Junior Member Backyard Mechanic 1jzracing's Avatar
    Join Date
    Feb 2006
    Location
    NSW
    Posts
    299

    Default Re: Compression ratio of hybrid JZ engines.

    Quote Originally Posted by CrUZida
    Just a quick note 2jzr31, the section you are posting in here, is for conversions only.

    Any tech questions/posts go in the tech section.

    HEY WHAT THE??????? ...... the title at the top of my page says: "Tech and Conversions Discussion of conversions and other technical automotive topics"

    sounds like the right section to me .... plus I have an interest here as im playing with similar information atm too

    would love to know the chamber volumes for 2jgte and ge heads.... ANYONE????

    i have the measurements for a 1j ... head is 40.5cc, piston valve cutouts are 3.6cc, 1.2mm gasket is 6.9cc and 1 cyl displacement is 415cc

    note std 1jzgte is more like 9:1 believe it or not! .... i KNOW thats not what they claim but if you actually measure it thats what it works out to be!

    will have the volumes for 2jzgte pistons soon too.... and comp if fitted to a 1j .... thats if they fit!

    .... think they are the pistons from your mates stuffed 2j bottom end

  5. #5
    Toymods V8 Member Too Much Toyota CrUZida's Avatar
    Join Date
    Aug 2005
    Location
    WA
    Posts
    8,214

    Default Re: Compression ratio of hybrid JZ engines.

    Quote Originally Posted by 1jzracing
    HEY WHAT THE??????? ...... the title at the top of my page says: "Tech and Conversions Discussion of conversions and other technical automotive topics"
    Its been moved from the other section to this one.
    Peewee
    1985 MZ12 Soarer - 1UZ Powered
    2013 86 GTS

  6. #6
    Junior Member Backyard Mechanic 1jzracing's Avatar
    Join Date
    Feb 2006
    Location
    NSW
    Posts
    299

    Default Re: Compression ratio of hybrid JZ engines.

    .......

  7. #7
    Junior Member Backyard Mechanic
    Join Date
    Feb 2006
    Location
    QLD
    Posts
    338

    Default Re: Compression ratio of hybrid JZ engines.

    Nice work 1JZracing and thanks for sharing your findings.

  8. #8
    Junior Member Backyard Mechanic 1jzracing's Avatar
    Join Date
    Feb 2006
    Location
    NSW
    Posts
    299

    Default Re: Compression ratio of hybrid JZ engines.

    re-checked the vol's for 1jzte heads and pistons with a more accurite burette ... slight update still works out to be 8.9:1 for a standard 1jzgte

    plus have piston volumes for 2jzgte, they do drop straight into a 1j the deck height is perfect!!

    2jzgte pistons in a 1jz works out to be 7.7:1 ... fine for 36psi and racing only maybe

    1jzgte head = 41.4cc
    1.2mm gasket = 6.9cc (edit: its 87mm x 1.3mm = 7.7cc)
    1jzgte piston = 4.2cc 498gms
    2jzgte piston = 13.8cc 504gms


    who has the chamber volume for a 2jzgte head?????????
    Last edited by 1jzracing; 12-07-2006 at 05:55 PM.

  9. #9
    Junior Member Backyard Mechanic
    Join Date
    Feb 2006
    Location
    QLD
    Posts
    338

    Default Re: Compression ratio of hybrid JZ engines.

    Cool. Did you get the pistons from Al? Maybe he can do the tests on his 2J head?

    mmm the large difference in piston crown volume might suggest the 2JZ has smaller combustion chamber to achieve a 8.5 CR. What are your thoughts?

    Some people have reported 1JZ engines with 2JZ heads to be sluggish. Whether or not this is BS, I have no idea. But if it results in a low CR it might explain it. I know the VVTi 1JZ has a cr of 9:1, you are not measuring one of these but hey?

  10. #10
    Junior Member Backyard Mechanic jzk25's Avatar
    Join Date
    Jan 2006
    Location
    Qld
    Posts
    316

    Default Re: Compression ratio of hybrid JZ engines.

    Wouldn't the 2J head on a 1J give a higher comp ratio given the smaller piston volume? Or will the different swept volume change that? That's assuming the head volume is the same or similiar to a 1J.
    I would measure the 2J head volume but I don't have any accurate equipment to do it with.

  11. #11
    Junior Member Backyard Mechanic
    Join Date
    Feb 2006
    Location
    QLD
    Posts
    338

    Default Re: Compression ratio of hybrid JZ engines.

    I think all you need is a piece of glass with a hole in it and syringe??

    I am a bit hazy on this so please correct me someone if I am wrong. The way see it is the 2JZ piston needs more volume as its pushing up more air because the extra displacement (assuming the same chamber volume) IE the capacity is bigger so there needs to be more volume somewhere to accommodate the extra air to maintain the same CR of 8.5. The fact that there is extra volume in the piston is promising as it hints towards the chambers being similar sizes to achieve the same CR. If the piston volumes were the same it would impossible for a head swap to not alter the CR's because of the difference in displacement. (IE the combustion chambers would have to be different to get the same CR or 8.5:1)

    Clear as mud? My head hurts.
    Last edited by 2JZR31; 11-07-2006 at 08:21 PM.

  12. #12
    regular fella Conversion King chris davey's Avatar
    Join Date
    Oct 2005
    Location
    QLD
    Posts
    2,608

    Default Re: Compression ratio of hybrid JZ engines.

    1jz racing: So 2jz pistons are direct fit into 1jz and you reckon about 7.7:1 CR. That is interesting
    Quote Originally Posted by MR 1JZ View Post
    that interior is so jap...just looking at it makes me want to kill a whale
    QUICKEST 1JZ'S IN OZ

  13. #13
    Junior Member Backyard Mechanic 1jzracing's Avatar
    Join Date
    Feb 2006
    Location
    NSW
    Posts
    299

    Default Re: Compression ratio of hybrid JZ engines.

    yes 2j pistons are a direct fit into a 1j... i havnt checked the little oil squirter but it doesnt foul anyway

    I will say it again 1JZGTE are all close to 9:1 .... i have 3 to measure and they are NOT v vti engines

    a quick calc for a 1j head on a 2j - will yeald the same comp of 9:1 so it looks likely the heads are almost identical, if anything the 2j may be ever so slightly larger

    to measure a head:

    small piece of perspex with 6mm hole near one end, put grease around the hg surface of the chamber on your 2jzgte head to act as a seal, place the perspex over the chamber and set the head up on a very slight angle with the hole at the high end, now fill the void with kerosene using a syringe or better yet a burette, note the volume .... write down the figour and rush back to toymods forum to post youir findings

    someone must be a member of www.supraforums.com someone there will know chamber vol for a 2j surely

  14. #14
    Junior Member Backyard Mechanic
    Join Date
    Feb 2006
    Location
    QLD
    Posts
    338

    Default Re: Compression ratio of hybrid JZ engines.

    Give it a go Al

    I posted some threads on other forums looking for the chamber size. Lets see if we get answers.

    Strange shit about the high CR I wonder why they would state 8.5 if its not true?

  15. #15
    Junior Member Backyard Mechanic
    Join Date
    Feb 2006
    Location
    QLD
    Posts
    338

    Default Re: Compression ratio of hybrid JZ engines.

    Interesting, but relies on assumptions. But there is also claimed specs of the factory stated volume.

    http://www.supraforums.com/forum/sho...chamber+volume

Similar Threads

  1. Selecting a compression ratio for a 20V
    By Sam_Q in forum Tech and Conversions
    Replies: 3
    Last Post: 05-07-2006, 10:09 PM
  2. 2T-G/3T Hybrid Compression Problems
    By sillycar chick in forum Tech and Conversions
    Replies: 41
    Last Post: 05-02-2006, 07:03 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •