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| Turbo Pistons https://ausmini.com/forums/viewtopic.php?f=2&t=630 |
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| Author: | MiniK [ Wed May 19, 2004 3:17 pm ] |
| Post subject: | Turbo Pistons |
Ive asked this before on the old Ausmini but thought id ask it again, seeing as more people frequent here now. Does anyone know where dished pistons can be sourced? I think most of the poms are using cast Hepolite's with a 10cc dish( which i think are standard on the metros). Anyhow any help will be greatly appreciated 
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| Author: | drmini in aust [ Wed May 19, 2004 5:19 pm ] |
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You can buy Hepolite 21250s from MiniSpares. They are 9.4:1. Bit high, I reckon, if you are adding a serious amount of boost. But you can hack the chambers out in the head... 
Whatever, DON'T use 21251s. They are too weak for this application.. 
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| Author: | MiniK [ Thu May 20, 2004 8:46 am ] |
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Crikey...yeha 9.4:1 is a tad high...... i think im going to have a proper look around...... 
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| Author: | turbomini [ Thu May 20, 2004 3:42 pm ] |
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you could use the 9.75:1 standard hypertec or hepolite pistions... but u could only run SFA boost like 5 pound.. (on regular 98 fuel that is) or just find some stocker pistions 8.8:1 i used them for quite a while as long as its not pinging theres no problems.. my cars still running with them.. no problems yet |
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| Author: | kazjim [ Thu May 20, 2004 7:02 pm ] |
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Mine's a 998, and I run the AE (Hepolite) 20773's (all 3 compression rings ON !) Running 14+Psi regularly.. no reliability probs yet! J |
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| Author: | drmini in aust [ Thu May 20, 2004 7:18 pm ] |
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21251s (8.8:1) will work, but they are a bit weak for lots of boost and high rpm. There's not a lot holding the crown on- as the oil drain slots are huge. Yes they are cheap.... I've got a set in my wife's 1293A+, but it ain't getting revved hard or boosted.. 
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| Author: | MiniK [ Wed May 26, 2004 11:49 am ] |
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drmini in aust wrote: 21251s (8.8:1) will work, but they are a bit weak for lots of boost and high rpm. There's not a lot holding the crown on- as the oil drain slots are huge. Yes they are cheap....
I've got a set in my wife's 1293A+, but it ain't getting revved hard or boosted.. any idea what amounts of boost these things would hold though? |
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| Author: | drmini in aust [ Wed May 26, 2004 5:37 pm ] |
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No idea whatever. They are a cheap low compression road piston and not designed for turbo use... You blow it, you risk it.. 
I'd get some Hypertecs, grind the head chambers out if you have to. |
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| Author: | MiniK [ Wed May 26, 2004 6:09 pm ] |
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drmini in aust wrote: No idea whatever. They are a cheap low compression road piston and not designed for turbo use... You blow it, you risk it..
I'd get some Hypertecs, grind the head chambers out if you have to. Hypertecs? Where do i find them? The standard metro items would be ok wouldnt they if i could find them...there part no. is 20831. |
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| Author: | drmini in aust [ Wed May 26, 2004 7:36 pm ] |
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Dunno that number. Hepolite 21250 is a 9.4:1 piston made for Metro turbo. Thicker crown etc than 21251... Just open out the chambers... stock is 21.4, mine are 28.0cc, you can get them made even bigger.
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| Author: | MiniK [ Thu May 27, 2004 3:02 pm ] |
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well karcraft said that Hepolite dont make the 20831's anymore:( i might have to look into those 21250's then.... Kev do you have any idea what the comp ratio would work out to be using those pistons, with a chamber say 28cc's in size or larger, and 20" overbore? |
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| Author: | minitec [ Thu May 27, 2004 3:28 pm ] |
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dave, all I can say is what James had as a sig on Minimania..... vvvvvvvvvvvvvvvvvtttttttttttttt psssssssssshhhhhhhhhhhh........ vvvvvvvvvvvvvvvvvtttttttttttttt psssssssssshhhhhhhhhhhh.......... vvvvvvvvvvvvvvvvvtttttttttttttt psssssssssshhhhhhhhhhhh......... |
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| Author: | MiniK [ Thu May 27, 2004 5:01 pm ] |
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minitec wrote: dave, all I can say is what James had as a sig on Minimania.....
vvvvvvvvvvvvvvvvvtttttttttttttt psssssssssshhhhhhhhhhhh........ vvvvvvvvvvvvvvvvvtttttttttttttt psssssssssshhhhhhhhhhhh.......... vvvvvvvvvvvvvvvvvtttttttttttttt psssssssssshhhhhhhhhhhh.........
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| Author: | MiniK [ Thu May 27, 2004 9:13 pm ] |
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Got a qoute from MED in the UK for 210 pds for a set of dished omega pistons 20" over.......plus 40 pounds shipping...... So about $680....... Naturally if theres a cheaper option i wouldnt mind taking it
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| Author: | kazjim [ Thu May 27, 2004 9:22 pm ] |
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And Everyone still wonders why i did a 998 ? sheesh, for the money you spend on a set of pistons, i could build a whole engine !!! only 300cc's less ..... just wind another 7Psi into it, and you've increased the "theoretical" displacement another 50% ! (so a 998, at 14psi has the torque of a 1500cc !!) - something like that anyway........ J |
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