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PostPosted: Wed Aug 19, 2009 2:00 pm 
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Mini Porn!


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PostPosted: Wed Aug 19, 2009 2:17 pm 
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Yay For Hay!
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GR wrote:
This photo is showing the centre exhaust and the route it has to take to get out on the original 8-Port Head

Image


It's not as bad as it looks as it flows quite well.

This is the 7 Port for comparison:
Image


NOW I understand why a 7 port instead of an 8 port - so does the 7 port work better than the 8 port because of that, or are there other reasons?

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PostPosted: Wed Aug 19, 2009 2:55 pm 
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simon k wrote:
NOW I understand why a 7 port instead of an 8 port - so does the 7 port work better than the 8 port because of that, or are there other reasons?


In addition to this question, how well does the 7 port scavenge vs the 8 port? Is it easier, harder (or impossible) to tune the exhaust harmonics with the siamesed central exhaust?

Seriously looking forward to seeing the results of one of these on your engine dyno :twisted:

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The adventures of an owner builder in the Tallarook Ranges

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PostPosted: Wed Aug 19, 2009 4:19 pm 
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848cc
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Location: Melbourne, Edithvale
GR,

Isnt the maxium capacity aloud under the CAMS rules for catagoy 5 in NC 1330 not 1360...

1275 plus 060. equal less than 1360ccc

1.5mm max

Just curious thats all ?
PG


Engine:
(i) Reciprocating engines: The bore may be increased by a maximum of 1.5mm, and the stroke must remain
standard as specified for the make and model.
Where increasing the bore size up to 1.5mm increases the engine cubic capacity above the original
capacity class limit, for competition purposes the vehicle will remain within its original cubic capacity
class.
Toothed belts driving engine ancillaries are permitted. Engine pulleys are free.

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1976 911 3.6 Circuit Car
1969 911T Grp Sb Historic Racer
2009 LC200 V8 TDI.... 660nm..
2011 Golf VI, TSI


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PostPosted: Wed Aug 19, 2009 7:40 pm 
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Oh dear, worry, worry...

Joined: Fri Jun 19, 2009 5:31 pm
Posts: 686
Location: North Rocks
Hi Simon and Simon
The 7 port layout was designed so you can use the std cam and
and the std exhaust manifold to cut costs down with the conversion
The siamese exhaust port does flow better than the 8 port.
You can still tune your exhaust as with the 8 port because you still
have 4 inlet ports and the centre exhaust being siamese to cyl 3
and 4 still dont exhaust at the same time so theres not really a
problem, personally ill take 7 port over the 8 port.
Graham Russell


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PostPosted: Wed Aug 19, 2009 7:52 pm 
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girtp wrote:
GR,

Isnt the maxium capacity aloud under the CAMS rules for catagoy 5 in NC 1330 not 1360...

1275 plus 060. equal less than 1360ccc

1.5mm max

Just curious thats all ?
PG


Engine:
(i) Reciprocating engines: The bore may be increased by a maximum of 1.5mm, and the stroke must remain
standard as specified for the make and model.
Where increasing the bore size up to 1.5mm increases the engine cubic capacity above the original
capacity class limit, for competition purposes the vehicle will remain within its original cubic capacity
class.
Toothed belts driving engine ancillaries are permitted. Engine pulleys are free.


All Gr's race engines are 1330, the 1360 is being used as another example.

Doogie

PS, kettle on Graham?

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 Post subject:
PostPosted: Wed Aug 19, 2009 8:10 pm 
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Oh dear, worry, worry...

Joined: Fri Jun 19, 2009 5:31 pm
Posts: 686
Location: North Rocks
Hi Paul
Yes your right i was thinking plus 60 and typed 1360, do i have beg
for forgivness? its not my first mistake and it sure won,t be my last
one, if only you knew how long it takes me to type this thing out
my fingers are about 3 lines behind my brain then they start to
FIGHT


the key board gets the sh--s then i wind up with a hell of a mess
and have to start again or call josh or aaron(he lives closer now)
but josh came round for lunch so he posted the photos for me and
set it all out, see what a cupa can do.
Graham Russell


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PostPosted: Thu Aug 20, 2009 7:46 am 
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848cc
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GR,
No forgivness required, just want to check I wasn't missing out on that extra 30cc's........

Cheers

PG

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1964 Grp Nb Cooper S
1976 911 3.6 Circuit Car
1969 911T Grp Sb Historic Racer
2009 LC200 V8 TDI.... 660nm..
2011 Golf VI, TSI


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PostPosted: Fri Sep 04, 2009 1:27 pm 
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1098cc
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How much development is there on the camshafts for 7 & 8 port heads? Are they very different from the 5 port cams to get the benefit of 4 inlet ports as opposed to 2?

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1970 Mini Deluxe - 1275, Weber, Clive 346 cam, MS 4-pot slotted discs, Megajolt ignition Now with new improved Mambas... almost on the road
1966 Van with Traveller rear seat conversion
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PostPosted: Fri Sep 04, 2009 3:56 pm 
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Fat Boy Dave wrote:
How much development is there on the camshafts for 7 & 8 port heads? Are they very different from the 5 port cams to get the benefit of 4 inlet ports as opposed to 2?


Dave, the 7 port head uses the standard cam used in the 5-porter -- that's the attraction of the 7-port over the 8-port, it's way cheaper as you don't need a special cam grind (and you can use your normal extractors, too).

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The adventures of an owner builder in the Tallarook Ranges

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PostPosted: Fri Sep 04, 2009 4:10 pm 
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sgc wrote:
Fat Boy Dave wrote:
How much development is there on the camshafts for 7 & 8 port heads? Are they very different from the 5 port cams to get the benefit of 4 inlet ports as opposed to 2?


Dave, the 7 port head uses the standard cam used in the 5-porter -- that's the attraction of the 7-port over the 8-port, it's way cheaper as you don't need a special cam grind (and you can use your normal extractors, too).


true, but the 7 port head might allow for more aggressive valve overlap etc. given the engine doesn't have to deal with siamese ports etc. etc.

maybe... :)

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 Post subject:
PostPosted: Fri Sep 04, 2009 5:05 pm 
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Quote:
true, but the 7 port head might allow for more aggressive valve overlap etc. given the engine doesn't have to deal with siamese ports etc. etc.


That was more the angle my thinking was going.

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1970 Mini Deluxe - 1275, Weber, Clive 346 cam, MS 4-pot slotted discs, Megajolt ignition Now with new improved Mambas... almost on the road
1966 Van with Traveller rear seat conversion
2008 Prado GXL
All in various states of repair...


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PostPosted: Fri Sep 04, 2009 5:15 pm 
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Fat Boy Dave wrote:
Quote:
true, but the 7 port head might allow for more aggressive valve overlap etc. given the engine doesn't have to deal with siamese ports etc. etc.


That was more the angle my thinking was going.


I don't think it'll make any difference, the two valves exhausting into the siamesed port on a 5-porter are 360º apart, so the pulses are spaced far enough apart that cam timing shouldn't come into it. I think.

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The adventures of an owner builder in the Tallarook Ranges

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PostPosted: Fri Sep 04, 2009 5:23 pm 
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sgc wrote:
Fat Boy Dave wrote:
Quote:
true, but the 7 port head might allow for more aggressive valve overlap etc. given the engine doesn't have to deal with siamese ports etc. etc.


That was more the angle my thinking was going.


I don't think it'll make any difference, the two valves exhausting into the siamesed port on a 5-porter are 360º apart, so the pulses are spaced far enough apart that cam timing shouldn't come into it. I think.

He's talking about it relative to a 5 port- there's no charge robbing in the inlet ports so you can perhaps use more agressive duration and overlap.

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PostPosted: Fri Sep 04, 2009 5:51 pm 
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When i dropped down for a cuppa, GR was bouncing off the walls, He was playing cams, specifically cams for 7 ports....
funny how he's on it and someone asks the Q.
I didn't even get a cuppa... He must have been excited by it.

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