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turbo pistons and head
https://ausmini.com/forums/viewtopic.php?f=5&t=9071		 Page 1 of 2
Author:  mini_matt [ Thu Jul 14, 2005 7:00 pm ]
Post subject:  turbo pistons and head
alright every thing else is set but pistons and or head mods for the turbo motor. sugestions what pistons to use ( 20 thou so availibility) hoping to drop comp under 9 slightly so whats pistons and what size chambers .
this ones gunna hurt the pocket. for the clubby estate
Author:  kazjim [ Thu Jul 14, 2005 10:09 pm ]
Post subject: 
Throw us a little bone here....

850?998?1100?1275?Bigger?

J
Author:  drmini in aust [ Thu Jul 14, 2005 10:31 pm ]
Post subject: 
If 1275 based I would use Hypatecs. They have plenty of meat in the crown, so you can make the dish bigger for more volume without hacking hell out of the combustion chambers... 8)
They are tuff enough that guys race with them.
Author:  Boostedmini [ Fri Jul 15, 2005 11:23 am ]
Post subject: 
it also comes down to what you want out of it,

if all out turbo i would go forged pistons as for head a good modded 12G940 will be fine, if you want to run more than 10psi i would lower comp down to 8 if not 7.5
Author:  TheMiniMan [ Fri Jul 15, 2005 2:20 pm ]
Post subject: 
JP-> 73mm pistons & BMW K1 Motorbke twin cam 16v cyl head :-)

sorry, couldn`t help it :-)
Author:  mini_matt [ Fri Jul 15, 2005 6:39 pm ]
Post subject:  engine
hypatecs sound good. dont think droppin the comp that low will be needed. wanna run bout 10 psi max on occasions. aslong as setup right should be fine. :?
Author:  drmini in aust [ Fri Jul 15, 2005 7:10 pm ]
Post subject: 
I wouldn't use JP pistons in a turbo or any competition motor. Broke one once in a 1098 Mini and was not impressed with how it was cast... :cry:
Author:  TheMiniMan [ Sat Jul 16, 2005 1:02 pm ]
Post subject: 
yeah Kev, the small bore JPs arn`t much good at all,,,YUK!!!...but the big bore 73mm ones are exccelleennnttttt!!!!!!!!!!!!!!!!! un-breako!!!!!!!!
Author:  drmini in aust [ Sat Jul 16, 2005 1:32 pm ]
Post subject: 
TheMiniMan wrote:
yeah Kev, the small bore JPs arn`t much good at all,,,YUK!!!...but the big bore 73mm ones are exccelleennnttttt!!!!!!!!!!!!!!!!! un-breako!!!!!!!!

Matt,
Do tell- my mate Dave managed to bust the ring lands off a couple.. it was an NA motor too, no turbo... :lol:
OK so it is an Nb racer, it revs to 8K... :wink:
Author:  mini_matt [ Sat Jul 16, 2005 1:46 pm ]
Post subject:  a
so GR engineering my man for the pistons. what about getting them machined same place?? and i wanna get my cam reground GR as well if so what do ya recomend.

cant wait for the clubby estate to be finished
Author:  drmini in aust [ Sat Jul 16, 2005 2:48 pm ]
Post subject: 
GR sells Hypatecs, he can also mod their dish to whatever you want. And grind your cam... :P
kazjim has one of his grinds in the 998 turbo... :wink:
Author:  TheMiniMan [ Sat Jul 16, 2005 4:51 pm ]
Post subject: 
Kev,,,My old man put a heap of time in with the old guy (Frank) who used to work for Laurie at JP years ago, & they basically produced a pretty good piston from both the "S" one & the old datto 1200 one,,,then there were a few issues with the ring lands breaking very early in the peice as they were a little too close to the crown & a bit thin in the land,,,they then dropped all the rings down a fair bit & spaced the lands more to make them way thicker,,,we`re now on (i think) the 5th design piston & have stuck with it now for many many years,,,it`s pretty dam good & i don`t believe you can break em...,,,BUT!!!,,,,that piston design is only on the 73mm ones,,,i don`t think they have changed their """Normal""" 1275 & oversize pistons to that design tho

i`ve run my 1415cc stroker speedway mini with those JPs in it up to 9000rpms nearly every sat night for about 4 years solid (with a "re-ring & bearing" job every year tho) & those pistons are still good & still in that same engine & is still quite a good runner, altho they do have a little more clearance now than they used to, but it`s because of that it`s still a good hard race donk :-)

It`s the small bore pistons that are no where near as good a design as the 73mm ones, i won`t use the small bore ones for that reason & i know heaps of people who bag the crapper out of em too & therefore , heaps of people feel that the big bore ones are bad also, add to that, is the ring lands cracking on the early-er 1275 pistons, end result was that JP ended up with a bad name for mini pistons because of all that,,,but i can assure you that the 73mm ones that my dad designed with Frank are actually the bees knees :-)
Author:  mini_matt [ Sat Jul 16, 2005 6:15 pm ]
Post subject: 
what do you reckon it'll cost me for pistons, mods and cam?
whats the number i can contact GR on please
Author:  Coop [ Sat Jul 16, 2005 8:45 pm ]
Post subject: 
what about ARIAS pistons they dont have pistons in stock that will fit a mini, but.... they can custom design a piston to your own specifications, forged, flat top, special insignias anything !
but its gana rip you a new ar$e
Author:  drmini in aust [ Sat Jul 16, 2005 11:24 pm ]
Post subject: 
mini_matt, PM sent.

Coop, sure... Arias (or Wiseco, or whoever) could make you some but unless you want a bunch of them it'll cost $$$big. :wink:
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