hi

The supply of these is sporadic at best and the quality seems to be dropping off as well, what pistons do you guys use for a 998 plus 40 running a compression ratio 13-1.

The mini7 racers over here seem to be machining pistons to take thicker rings to improve compression?

Any advice?

http://www.precisionintl.com/Part.aspx? ... &EID=74417

In stock. $96.88 a set. Any size you want.

GR has 998 pistons...

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did I tell you that I won a trophy?

Where are these guys out of PK? It looks local, but I can't see an address..

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

They have warehouses in a few states, I only know of Silverwater (NSW) and Notting Hill (Vic), I'm sure if you ring they could give you their exact locations

I've been seeing a few of these pistons pop up in engines, as 998 pistons like you see there or some have modified them for use in 1100's. If you machine the crown down to lower the compression height they slot right in. I've pulled a few out of engines now that seemed to be running fine, the crown still has enough meat in it to be reliable. One set I pulled out looked like it had crashed into the dizzy drive, so you need to modify the skirt length, and also the heights have been a bit all over the place. But they seemed to be all working reliably, even with the reduced crown thickness.

I've even modified some myself this way, only with a less chewy finish on the crown and to tighter tolerances






If anyone wants me to modify their 998 pistons for use in an 1100 I'll do it for $15 a piston





.

Hi Alex
First of all if your going to shoot your mouth off on thr other forum get your facts straight i am the only one making 1100cc flat top piston they are not cut down 998 pistons, they do not hit the dizzy shaft, and if you knew any thing about piston design you would not turn the top off 998 pistons for the 1100 as the crown height is .250 thick if you take .145 off you wind up with less than .100 in places which is way to thin for a crown height and it is going to crack.
Graham Russell

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"It's better to be not informed than ill-informed"

Graham,

I didn't I mention anyones name about anything on any forum. Annnnd with regards to the exact amount to take off, I don't remember what it was off the top of my head, I usually measure it before I start, I have a lot of numbers rattlling around in my head so I always check before I start. I remembered you mentioning machining crowns down so I looked up what you said about it here. That is where I got the 0.140" figure from.

http://www.minimania.com/article/1881/P ... re__Part_1



One set of modified 998 pistons I pulled out of an engine did hit the dizzy shaft, that's how I ended up with it, and that's how I know to check for it. I don't know who did them, it's not a hard modification to do, anyone with a lathe could do it. As for the thickness in the crown, if you do it with the pistons I listed above, the thinnest part of the crown is still just as thick as a as what it is on a 10cc 1275 piston, and no, I don't remember how thick that was, only that I checked it against a few other pistons to see how thin they were and realised there was a similar amount of matterial left to what was on other piston designs standard. The ones that I pulled out had a crown thickness of something like 3 or 4mm thick from memory and working reliably, and the last time I spoke to 850man, the modified set I sent him were still working fine as well, even in an engine making 70hp atw. So as far as reliablity goes, it looks like the proof is in the pudding on that one.

I didn't come up with the idea, I found it, and it was working. If it wasn't I wouldn't have done any myself this way, nor would I mention doing it this way.

Precision is also in brisbane, but i have only ever dealt with them through work. They actually supply a lot of the local parts stores as well.

I didn't realise they did retail.

Hi Alex
No you did not mention any names but it is'nt hard to figure out who you were talking about thats why i recieved 5 phone call about my pistons to see if they were turned down 998 but i assured them that they were not, so thanks to you i sold 2 sets of pistons thank you boys from vic
And if you turned down a set of 1275 pistons to have 10cc in the you will still have .250 left in the crown be cause to get that you will not go down to the bottom of the dish which is .250+ in the middle.
Yes i did mention about machining down the 998 pistons in the artical that why i had the 1100 pistons made because we cracked them when we put some good hp and reves through them, and i do not know any piston manufacture forged or other wise who will go any thinner than about .170 for a high performance piston.
Graham Russell

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"It's better to be not informed than ill-informed"

Hi j666era
If you get in touch with Keith Calver in UK he sells my pistons which are used in a lot of race engines over there specially in you grass track class, no they are not as cheap as the Hypatec that Alex is talking obout but they are a better piston, they have a better ring package than the Hypatec they are shorter and lighter and the ring pack is much higher up the piston for better piston control and compression.
The rings are changed after 12 months of racing but not the pistons and they are given a hard time in your grass track racing using only first or second gear for the race.
Graham Russell

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"It's better to be not informed than ill-informed"

Ok, if you or any of your band of merry arse kissers bothered to read what I said, I said that one of the sets I pulled out was hitting the dizzy drive. The others were not. Ok. I was under the impression that these were done by two totally different people, and was an emerging trend. You would have to be pretty bloody arrogant to assume that you are the only person pulling apart A series engines and trying new things, these could have come from ANYWHERE, as I said above, anyone with a lathe could have modified these. No where did I say anything about you. You've said you get your own pistons made in the past, there's not really much to argue about there, I've never bought a set from you nor been given a set of your pistons... I didn't say I've measured up a set of GR's pistons and found that they appear to be turned down 998 pistons.

But hey, I'm glad you got some business of the back of this discussion




Who said anything about machining 1275 pistons? I said I used the standard crown thickness of 1275 pistons for comparsion before I sent 850man a set of pistons I modified. Again, stop being such a nervous nelly, and start reading what people say.




Good to know. Now stop trying to see the worset in anyone who opens their mouth about anything that looks like it could conflict one of your business interests. If it's not flat top 1100 pistons, its $600 chinese conrods. Bloody hell mate, the other day I was complementing you on your work with the CNC milled combustion chambers and offering advice on programs to use that you for flow analysis.... why would I turn around and start trying to rubbish you in the next breath? I've had enough of this crap, I'd had enough of it years ago when you were trying to tell me I must be lying about getting an engine to run with a copper head gasket without blowing it. I'm not going anywhere, and obviously neither are you. I'd rather get on with life than keep this bull crap going

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Planet Earth is blue and there's nothing I can do...



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Please keep comments polite and constructive on all Ausmini posts and respect other member's opinions, whether you agree with them or not. The health and therefore the success of this fantastic resource for real Mini enthusiasts depends on it.

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Sorry wasnt planning on upsetting people with my question.