Compression ratio for modified Mi16 - Page 2
  • Register
  • Help
Page 2 of 2 First 12
Results 26 to 49 of 49
  1. #26
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,247

    Default

    What part number are they? If solid, then leave them and just set them up on 106/109 centre lines.

    I assumed they were these:Compression ratio for modified Mi16-screen-shot-2018-04-12-10.26.49-pm.png

    Advertisement

    '92 205 Mi16
    '90 Mi16x4

  2. #27
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    Sorry, can't now find the listing except for that one you put up, I did see it a few days ago though, listed next to the hydraulic version they are 285 degrees.

  3. #28
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,247

    Default

    You've built an engine with a 4000-7000 usable rev range, thus you need to gear it accordingly. Removing the TB's would be a backward step. Why detune it? It's far better to make all the components work together. Having the higher CR will improve low down torque, making the engine more efficient everywhere. Driving at 4000 and 110km/h may seem excessive, but it will still achieve excellent fuel economy. Some decent 4-2-1 extractors will remove the 3500-4000 dip caused by the standard Mi16 pipes. Do it right, do it once.

  4. #29
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    Trouble is that it is 5000 to 7000 currently with the standard D6C spec engine. Extractors no good due to ground clearance issues and positioning of flexible joint. I know what you mean but I have persevered for a year with the 309 trying to keep all of the specification recommended to me but at the moment I much prefer to drive my stock 205 Si in the events that is eligible for (no cage) and I don't think it is much slower results wise.
    I'll take it for a drive this afternoon with the power assist back on the brakes and hopefully some clearance on the master cylinder/timing cover, I did get some some gains mainly on part throttle in a Dyno session a couple of days back and haven't had a chance to try that out yet.

  5. #30
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    I have followed your suggestion and obtained a 4.78 to 1 final drive. I'll leave the 4.43 box as is so need another Quaife, anybody? I have a 3J plate diff if someone wants to swap. Otherwise still waiting on a reply from Palmside in NZ.
    I will also be assembling the modified engine, still no answer on anyone for the compression ratio, Piper Ultimate Road cams so maybe 11.4 to one, the original motor had 11.8 to 1 but pretty big cams.
    If this doesn't work I'll build an 8 valve for next year, driving Craigs Little Silver is a revelation, far more go in the mid range than the present 16 valve and it is only a stock 75kw!!! Maybe I should lift the cam cover on that to see if it has had a tickle up. At any rate it is the quickest 205 I have driven.

    Quote Originally Posted by PeterT View Post
    You've built an engine with a 4000-7000 usable rev range, thus you need to gear it accordingly. Removing the TB's would be a backward step. Why detune it? It's far better to make all the components work together. Having the higher CR will improve low down torque, making the engine more efficient everywhere. Driving at 4000 and 110km/h may seem excessive, but it will still achieve excellent fuel economy. Some decent 4-2-1 extractors will remove the 3500-4000 dip caused by the standard Mi16 pipes. Do it right, do it once.

  6. #31
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,247

    Default

    Piper's cams, I suggest you ask them.

    '92 205 Mi16
    '90 Mi16x4

  7. #32
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    OK, although they say the cams work from 2500, so not sure if they have done much testing, if that was the case they would be better low down than the standard ones. I bought the Piper cams on someone's recommendation not sure I've done the right thing.
    Callums GTi6 205 has been completed, seems to have a pretty flat power curve, if possible I will post that and mine on this thread to compare.

  8. #33
    Fellow Frogger! Bluey's Avatar
    Join Date
    Oct 2003
    Location
    Sydney
    Posts
    585

    Default

    Quote Originally Posted by GRAHAM WALLIS View Post
    ...... seems to have a pretty flat power curve,
    Flat torque curve. Linear power curve.

  9. #34
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    Yes, that's what I should have said!

  10. #35
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,247

    Default

    Where are you up to with this Graham? Did you confirm the part number of the cams? Have you contacted Piper?

    '92 205 Mi16
    '90 Mi16x4

  11. #36
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    Not yet, very busy getting a rally organised. Will have a go next week. Getting 8v rods fitted to the Wossners at present. CR will be the next step, then put it together, headwork is all done.

  12. #37
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    Slight problem with rods, may be using the PEC rods as before. No answer back from Piper as yet, something will come through tonight I would think.

  13. #38
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,247

    Default

    what happened with the 8v rods?

    '92 205 Mi16
    '90 Mi16x4

  14. #39
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    Not 100% sure (got second hand report) but something to do with bushes not having enough thickness for the rods. I need to talk direct to engine shop.

  15. #40
    Fellow Frogger! CEyssens's Avatar
    Join Date
    Jan 2016
    Location
    Berwick VIC AUS
    Posts
    964

    Default

    Graham, did you end up checking the cam? it's definitely got some good torque, and felt very strong when I gave it it's test run....

    Quote Originally Posted by GRAHAM WALLIS View Post
    .........If this doesn't work I'll build an 8 valve for next year, driving Craigs Little Silver is a revelation, far more go in the mid range than the present 16 valve and it is only a stock 75kw!!! Maybe I should lift the cam cover on that to see if it has had a tickle up. At any rate it is the quickest 205 I have driven.

  16. #41
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    I'm finally finishing the car off tomorrow morning, will take a look before refitting the aircleaner. It would be good to check the compression, if up around 200 or above it would have been modified I would say.

  17. #42
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    Piper don't list the solid lifter ultimate road cam in their spec sheet, although listed in their sales information! They suggested I send it back to be measured!
    https://www.pipercams.co.uk/Camshafts-Car/Make-Peugeot/

    Quote Originally Posted by PeterT View Post
    Where are you up to with this Graham? Did you confirm the part number of the cams? Have you contacted Piper?

  18. #43
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

  19. #44
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,247

    Default

    Use this DCR calculator. It's very good.

    Dynamic CR


    With 11:1 static and the 280 cam, I get 8.7:1.
    Last edited by PeterT; 17th July 2018 at 09:49 AM.

    '92 205 Mi16
    '90 Mi16x4

  20. #45
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    So, after reading up on DCR, this looks to be OK.
    Last edited by GRAHAM WALLIS; 17th July 2018 at 08:57 PM.

  21. #46
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    Cam looked stock, 380 thou lift, maybe the compression has been increased? I'm thinking a set of flat top pistons in one of these could be a go, would be around 9.5 to 1.
    Car ready to go, are you going to help Kosta come and get it?


    Quote Originally Posted by GRAHAM WALLIS View Post
    I'm finally finishing the car off tomorrow morning, will take a look before refitting the aircleaner. It would be good to check the compression, if up around 200 or above it would have been modified I would say.

  22. #47
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,247

    Default

    I'm confused Graham. What are you talking about?

    '92 205 Mi16
    '90 Mi16x4

  23. #48
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    8,595

    Default

    Sorry Peter, answered you and Craig in separate posts. My reply to you suggested that 8.7 to 1 DCR may be OK for the 16V. Answer to Craig was about his 75 kw engine. I have finally found the complete specs for the Piper Ultimate Road cam with solid lifters.

  24. #49
    Fellow Frogger! CEyssens's Avatar
    Join Date
    Jan 2016
    Location
    Berwick VIC AUS
    Posts
    964

    Default

    Quote Originally Posted by GRAHAM WALLIS View Post
    Cam looked stock, 380 thou lift, maybe the compression has been increased? I'm thinking a set of flat top pistons in one of these could be a go, would be around 9.5 to 1.
    Car ready to go, are you going to help Kosta come and get it?
    Interesting.... Iíll send you a PM
    cheers
    Craig

Page 2 of 2 First 12

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

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