I'd say this engine has a head on it by now... But I wouldn't spend the money on a bottom end like that and not go with the alloy 12 port with extra porting... They will flow easy 300hp and 12 ports to me feel more responsive but the non yt generally don't have as much raw flow as 9 ports after porting etc. (which I'd assume this would be being done for this type of engine). So a yt alloy has both flow and better port design with the heat transfer and weight saving of alluminium, I'd have thought it would be best choice.
I've got two engines one 12 port the other 9, and I have only used the 9 port to keep it nostalgic. My next big upgrade is swapping my cast 12 port for alloy.
Just my thoughts...
9 port or 12 port
Started by
_daf67_
, Oct 29 2010 04:51 PM
36 replies to this topic
#27
orangeLJ
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Posted 27 September 2011 - 11:54 AM
Id be interested to see where this ended up.
The bottom end build list read like a science classroom, but didnt actually say a whole lot...
the one thing I found interesting was that for all the V8 supercar and NASCAR technology they put into the rings and pistons, they stuck with plain ol' starfire rods (although "race prepped")
If I was spending big coin on a bottom end, Id like a knifedged, counterweighted crank, aftermarket rods, JE pistons etc etc. and I damn well want to look at the cam specs, head etc before I go buying a set of pre-jetted webers (it amazes me they sell them as a "race jetted" carby, its no where near one size fits all)
Just seemed a bit of a "fluffer" description for a reasonably basic bottom end.
The bottom end build list read like a science classroom, but didnt actually say a whole lot...
the one thing I found interesting was that for all the V8 supercar and NASCAR technology they put into the rings and pistons, they stuck with plain ol' starfire rods (although "race prepped")
If I was spending big coin on a bottom end, Id like a knifedged, counterweighted crank, aftermarket rods, JE pistons etc etc. and I damn well want to look at the cam specs, head etc before I go buying a set of pre-jetted webers (it amazes me they sell them as a "race jetted" carby, its no where near one size fits all)
Just seemed a bit of a "fluffer" description for a reasonably basic bottom end.
#28
_Bluejinx202_
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Posted 27 September 2011 - 12:19 PM
Just seemed a bit of a "fluffer" description for a reasonably basic bottom end.
I think the guy that sells these engines in his eBay shop is pretty good at that...
#29
greens nice
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Posted 27 September 2011 - 12:28 PM
i have ported a new yt alloy head, it flowed 335hp, but didnt make power because they are an open chamber head, 9.5 comp doesnt work with cams of upward of 250 @50 but if i put the same time into a closed chamber 9 port it probably would have done 12.7 1/4 instead of 13.3 and you would have another $1300 in you pocket
#30
_Bluejinx202_
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Posted 27 September 2011 - 12:48 PM
What's the most comp you would get out of open chamber?
#31
_CHOPPER_
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Posted 27 September 2011 - 01:25 PM
A 186/202 open chamber head that hasn't been surfaced normally has 55-56CC chamber volume. Work out your bore size, compressed head gasket thickness, deck height and piston dish ( if applicable ) and the c.r. can be worked out from there.
#32
_Bluejinx202_
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Posted 27 September 2011 - 01:47 PM
So I get about 10.1:1.... How much can be surfaced to get max comp?
That's flat tops 0.010 above deck and 0.040 gasket
That's flat tops 0.010 above deck and 0.040 gasket
Edited by Bluejinx202, 27 September 2011 - 01:49 PM.
#33
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Posted 27 September 2011 - 04:34 PM
On those figures, 10.2:1 comp with a stock bore 202, 10.5:1 if it was +0.060". Not sure how much can be safely taken off the head.
#34
greens nice
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Posted 27 September 2011 - 08:03 PM
dont quote me but i think that the 12 ports are around 60cc chamber. yes 56cc is for 9 port
you would probably need to take another 3cc out of the chamber (if not more) to unshroud the valve on a 12 porter.
so basically, not enough for that cam.
you would probably need to take another 3cc out of the chamber (if not more) to unshroud the valve on a 12 porter.
so basically, not enough for that cam.
#35
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Posted 27 September 2011 - 08:24 PM
"choice of 56 or 68cc for turbo applications" just checked. Just thinking out loud here, but being alloy can they have combustion chambers welded up?
#36
_Bomber Watson_
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Posted 27 September 2011 - 09:06 PM
Would want to either be running a shitload of boost or a real crap setup to want a 68cc chamber......
I've been eyeing these YT 12 ports off for my next combo, The 56cc chambers will suit a lot better even with the turbo....
Cheers.
I've been eyeing these YT 12 ports off for my next combo, The 56cc chambers will suit a lot better even with the turbo....
Cheers.
#37
warrenm
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Posted 28 September 2011 - 08:57 AM
I fitted a 9 port open chamber head to a mates 202 a couple of years ago, It had been shaved enough for the chambers to measure 50cc, not much more than a small chamber. Not sure how it will go if we up the compression & start to push it though, it may flex a bit & blow gaskets, maybe?
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