62T Detonation issues in 1st gen Proforce

long beach local

long beach local
Site Supporter
Location
Az
Wanted to share my experience running a big bore ,86mm pistons stock stroke 885cc in my Proforce . I got 65hours out of this top end running up and down the river which is the best I have gotten.This setup gives me nearly 11gallons of fuel and 3hours run time nonstop. Anyway I screwed up and may have put some 87octane gas in it and noticed my spark plugs had loosened up and knew I had damaged it. I usually run half Av gas or a gallon of 110 in a 5 gallon can mixed with 91 octane ,I have run straight 91 without issue. I run TL Zeel on the Wax curve and believe this ignition has saved detonation and runs amazing. My compression is 160psi and I have a .025 base gasket which gives me .050 squish.You would think this setup would be safe from detonation but it is Not. The pipe I run is a lay down TNT V3 race spec and has a 2” stinger and I love the power this pipe makes the midrange is Very Strong. I’m running a Kawi 145 skat setback with a 10/18 prop which spools up quickly and pulls ok if I want to hold it wide open for a decent top end. My carb is a 49 ATP Dasa intake ,V2 reeds 2.5ns 170m 130p 95g 1.5 turns out both high and low. I think the pipe makes a lot of power at the price of reliability and would like to hear other’s thoughts on this subject as I have gone thru a bunch of pistons learning about this. I have ran dual 48s and 44s the results are the same I think I’m just on the edge performance wise. I will post some pics of the cylinder it’s a big bore sleeved 62t that was port matched by a machine shop. It was a BCW race cylinder that I wanted to bring back to life but maybe the exhaust ports are tooo big and the rings are just going to catch anyways.
 

Attachments

  • 734FEB42-95ED-4B2D-BA2E-3749CD0BF2E0.jpeg
    734FEB42-95ED-4B2D-BA2E-3749CD0BF2E0.jpeg
    135.9 KB · Views: 58
  • B30F13AB-2E7F-443E-BE29-D552D19F54DB.jpeg
    B30F13AB-2E7F-443E-BE29-D552D19F54DB.jpeg
    133.1 KB · Views: 60
  • 18BAF314-8665-422B-8570-AC024A668D97.jpeg
    18BAF314-8665-422B-8570-AC024A668D97.jpeg
    134.5 KB · Views: 56
  • 4FF03912-AFE0-473A-9B68-313D7FBC8967.jpeg
    4FF03912-AFE0-473A-9B68-313D7FBC8967.jpeg
    85.8 KB · Views: 51
  • 48CB7850-D25E-4C56-BCEE-11AA9A5EFF14.jpeg
    48CB7850-D25E-4C56-BCEE-11AA9A5EFF14.jpeg
    82.7 KB · Views: 50
  • B7B0226A-C274-4E5A-BEA7-A35E8A65A44A.jpeg
    B7B0226A-C274-4E5A-BEA7-A35E8A65A44A.jpeg
    93.3 KB · Views: 48
  • F3E1F605-CD16-4BC8-B32E-05E98ADBAB87.jpeg
    F3E1F605-CD16-4BC8-B32E-05E98ADBAB87.jpeg
    71.5 KB · Views: 45
  • 84A90621-3B49-4596-A203-11728B58AB4E.jpeg
    84A90621-3B49-4596-A203-11728B58AB4E.jpeg
    75.9 KB · Views: 44
  • A3B56EF6-A6DB-4F4C-B23B-B1AB15F5DC84.jpeg
    A3B56EF6-A6DB-4F4C-B23B-B1AB15F5DC84.jpeg
    76.8 KB · Views: 45
  • 1129DE3E-AFE6-4C32-87A7-C62655B21C3D.jpeg
    1129DE3E-AFE6-4C32-87A7-C62655B21C3D.jpeg
    88.2 KB · Views: 46

long beach local

long beach local
Site Supporter
Location
Az
More pics of the domes.
 

Attachments

  • 3435CA4E-EFB0-4BDA-935D-0A4FE58A658A.jpeg
    3435CA4E-EFB0-4BDA-935D-0A4FE58A658A.jpeg
    151.1 KB · Views: 45
  • 01D8B198-07A2-43D9-B0B0-57FC3E75F784.jpeg
    01D8B198-07A2-43D9-B0B0-57FC3E75F784.jpeg
    140.2 KB · Views: 47
  • 36A0B249-6AEB-4074-96F1-26AEB268B5D7.jpeg
    36A0B249-6AEB-4074-96F1-26AEB268B5D7.jpeg
    136.3 KB · Views: 51

veedubs

Site Supporter
Location
Dallas, GA
Very cool build. I remember seeing your thread when you first got it. Looks like you’ve had some fun with it.


Sent from my iPad using Tapatalk
 
Looks like it just snagged a ring on the way down and knocked that chunk out of the piston crown. I've seen that a few times. Detonation is eroded looking , not just a perfect chunk missing like a jigsaw puzzle. I just saw that same thing on the new xs1060 motor that's been nothing but problems
 
Location
dfw
Full throttle mixture must be set rich of peak power and the ignition timing retarded well below the detonation threshold. Ive burned a piston on a 92 octane Superjet by letting the tank get low and running full throttle. This engine was 81mm, 165psi, and 21 degrees advance. A separate header tank and pump has so far prevented a repeat.. It appears that combustion temps are a wild card that can cause problems.
 
Top Bottom