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How much compression?
https://ausmini.com/forums/viewtopic.php?f=5&t=37470		 Page 1 of 2
Author:  mini-dunger [ Tue Nov 06, 2007 8:21 pm ]
Post subject:  How much compression?
Hi all

1098 +.60, RE13, How much compression should I run? I would do exctly what Sir Vizard says but he is a bit vauge in his book. I have no issues using premium and a octane booster if need be.

Thoughts ?

Thanks guys
Author:  drmini in aust [ Tue Nov 06, 2007 9:01 pm ]
Post subject: 
You can use up to around 10.5:1 with an RE13.
My 1310 ran fine with one at 10.4:1.
It used to be 11.0:1, that was too high. Couldn't stop it pinging. :lol:
Author:  sgc [ Tue Nov 06, 2007 9:04 pm ]
Post subject:  Re: How much compression?
mini-dunger wrote:
1098 +.60, RE13


What head you got there?
Author:  mini-dunger [ Wed Nov 07, 2007 7:04 am ]
Post subject: 
its a 12g202 with 33mm inlets and 27mm exhaust valves + about 50 hours :shock:
Author:  drmini in aust [ Wed Nov 07, 2007 6:30 pm ]
Post subject: 
mini-dunger wrote:
its a 12g202 with 30mm inlets and 27mm exhaust valves + about 50 hours :shock:

I did the valves, those inlets are 33mm. :wink:
Author:  Smegger [ Wed Nov 07, 2007 6:42 pm ]
Post subject: 
drmini in aust wrote:
mini-dunger wrote:
its a 12g202 with 30mm inlets and 27mm exhaust valves + about 50 hours :shock:

I did the valves, those inlets are 33mm. :wink:


:lol: :lol:
Author:  mini-dunger [ Wed Nov 07, 2007 7:25 pm ]
Post subject: 
thats what i said :D
Author:  sgc [ Wed Nov 07, 2007 7:28 pm ]
Post subject: 
Why such large inlets? I would have thought you'd get better performance with bigger exhaust valves than inlets... at least on a smallbore.. ?
Author:  drmini in aust [ Wed Nov 07, 2007 8:26 pm ]
Post subject: 
sgc wrote:
Why such large inlets? I would have thought you'd get better performance with bigger exhaust valves than inlets... at least on a smallbore.. ?

You have exhaust pressure to blow exhaust out. You have 1 atmosphere air pressure only to push it in.
GR uses these valves, and nobody I know gets better power from a smallbore with 202 head. 8)
They are Morris 1100S/1275LS valves, with the exhausts turned down to 27mm and the seat face recut. The inlets are stock dia but have the heads backcut 30° same as Vizard suggests.
To use inlets this size in a 202 head it must be deshrouded severely, it looks pretty much like a 295 chamber when finished.
Here's one I prepared earlier (before polishing)-
Image
Author:  Lillee [ Wed Nov 07, 2007 9:03 pm ]
Post subject: 
10.5:1 is good enough, anymore and you will ping if you have bad fuel. I run 10.2:1 and when cold and on bad fuel I can hear her ping...
Author:  willy [ Wed Nov 07, 2007 9:04 pm ]
Post subject: 
I run 11.4:1
With 98 Octane fuel.
And a special cam :lol:
Author:  drmini in aust [ Wed Nov 07, 2007 9:05 pm ]
Post subject: 
willy wrote:
I run 11.4:1
With 98 Octane fuel.
And a special cam :lol:

And, I now know what cam it is.... :wink:
I've now got one too. 8)

Chong, you aren't supposed to leave da fuel in da car for 3 months like you just did. It ain't 98 anymore, it's more like kero. :lol:
Author:  Lillee [ Wed Nov 07, 2007 9:28 pm ]
Post subject: 
yeah as I said, bad fuel... :P
Author:  slinkey inc [ Thu Nov 08, 2007 1:45 pm ]
Post subject: 
Sounds like a fun engine you building, Mini-Dunger. :)
Author:  mini-dunger [ Thu Nov 08, 2007 4:50 pm ]
Post subject: 
Should be,

Everythings been lightened and made all nice so it should be nice.
Heres my head, I still have to press the guides in, smooth out the roof of the chamber and have the valve seats cut and about an inch milled of the deck.

excuse the paint I was using it as kind of a guide coat...its darkish in my shed :D

Image
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