Hi guys!
I am in the process of finally getting an engine built for my LC
bottom end is gona be a red 202 with a fair bit of goodies in it. it will mostly be street driven on the weekends however i want it to have as much HP as possible so i can have some fun in it as well..
WHAT head should i use and why?? i ive been told some conflicting stories laitly from various engine builders about what head to use...
i have the option of going 9 or 12 port ..
i want the engine to have approx 250 FWHP
ur experiences & advise would be greatlyappreciated!
nik.
9 or 12 port head?
Started by
_LCGTR71_
, Feb 16 2009 05:51 PM
12 replies to this topic
#2
_Bomber Watson_
_Bomber Watson_
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Posted 16 February 2009 - 09:57 PM
9 port. can be hoged out a lot further.
#3
yel327
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Posted 17 February 2009 - 11:15 AM
If you can afford it, one of the new Yella terra alloy 12 ports.
#4
_Drag lc_
_Drag lc_
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Posted 17 February 2009 - 01:25 PM
lcgtr71,
you say "i want it to have as much HP as possible " well i dont know a great deal but i think that the iron 9 port can be hogged out to flow more than the 12 port but might no be very streetable but if you are looking for 250fwhp i am sure a iron 12 port would be able to be ported to make that much hp either way you go they will have to be ported out to a fair degree even a alloy 12 port would need porting done to get that hp. proberly recomend you use a 12 port might give better down low and midrange than a hogged out 9 port. also what sort of induction are you going to use?if you are going to use webers or the like , the 12 port would be the go.
Thanks Hayden
you say "i want it to have as much HP as possible " well i dont know a great deal but i think that the iron 9 port can be hogged out to flow more than the 12 port but might no be very streetable but if you are looking for 250fwhp i am sure a iron 12 port would be able to be ported to make that much hp either way you go they will have to be ported out to a fair degree even a alloy 12 port would need porting done to get that hp. proberly recomend you use a 12 port might give better down low and midrange than a hogged out 9 port. also what sort of induction are you going to use?if you are going to use webers or the like , the 12 port would be the go.
Thanks Hayden
#5
_NZ Toranaman_
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Posted 17 February 2009 - 02:53 PM
Above advice is wise.
The 12 Port head is often thin and if you port them and have big valaves you run the risk of going through the water jacket, Yella Terra knew this and thats why they cast their own heads with more meat where it counts although they did other things like using oversized valve stems which limit them.
After porting do a crack test as better to throw away a head than a complete motor.
There are lots of little things other than the head that all add up to additional HP, like longer rods and floating pistons etc but they all come at a price and if you want to force feed your 202 you could get even more.
The 12 Port head is often thin and if you port them and have big valaves you run the risk of going through the water jacket, Yella Terra knew this and thats why they cast their own heads with more meat where it counts although they did other things like using oversized valve stems which limit them.
After porting do a crack test as better to throw away a head than a complete motor.
There are lots of little things other than the head that all add up to additional HP, like longer rods and floating pistons etc but they all come at a price and if you want to force feed your 202 you could get even more.
#6
_oldjohnno_
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Posted 17 February 2009 - 05:37 PM
I think Hayden's advice is spot on. At 250hp you'll be pretty close to the limits of a what you can get from a ported 12 port head, though 250 is probably about as far as you could go with either head and retain any sort of streetability anyway. Manifold availability might be a factor too. What's your budget? This article might be helpful.
#7
_runna_202_
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Posted 18 February 2009 - 06:09 PM
gday,
myself and hayden (draglc) both had our heads hogged by the same guy,my head being a standard commy type 12 port and haydens a 9 port. The guy said the 9 port flowed a few cfm more on the flow-bench(not sure exactly how much) than the 12 port as he thought the 9 port seemed a thicker casting and was worried about breaking though with the 12 port.
The engines where pretty much the same,both had a 250 deg cam,webbers,similar compresson,manuel g/box and haydens ran i think 12.7 @ 105 and mine 12.9 @ 103 mph,so maybe roughly 20 hp at the wheels difference? not alot though. The main annoying thing i found was if you wanted manifolds, headers the majority of them are for a 9 port and the need modifying to fit on a 12 port.
cheers peter
myself and hayden (draglc) both had our heads hogged by the same guy,my head being a standard commy type 12 port and haydens a 9 port. The guy said the 9 port flowed a few cfm more on the flow-bench(not sure exactly how much) than the 12 port as he thought the 9 port seemed a thicker casting and was worried about breaking though with the 12 port.
The engines where pretty much the same,both had a 250 deg cam,webbers,similar compresson,manuel g/box and haydens ran i think 12.7 @ 105 and mine 12.9 @ 103 mph,so maybe roughly 20 hp at the wheels difference? not alot though. The main annoying thing i found was if you wanted manifolds, headers the majority of them are for a 9 port and the need modifying to fit on a 12 port.
cheers peter
#8
_LCGTR71_
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Posted 19 February 2009 - 08:59 AM
thanks for all the info guys!
i have seen the new yt 12 port alloy head but its just so pricey! for the HP i want im sure i can spend almost 1/2 of that on porting work on an iron head and get the same results.
runna_202 those are some great 1/4 mile times for a 202! what kinda compression are those engines running?
i have seen the new yt 12 port alloy head but its just so pricey! for the HP i want im sure i can spend almost 1/2 of that on porting work on an iron head and get the same results.
runna_202 those are some great 1/4 mile times for a 202! what kinda compression are those engines running?
#9
_runna_202_
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Posted 19 February 2009 - 05:41 PM
lcgtr71,
compression wise i had around 11.5:1 and i think haydens was in the high tens. If you want some decent specs to work with when you build your engine,pm hayden im sure he'd be happy to help,as hes helped me imencely over the years.
cheers peter
compression wise i had around 11.5:1 and i think haydens was in the high tens. If you want some decent specs to work with when you build your engine,pm hayden im sure he'd be happy to help,as hes helped me imencely over the years.
cheers peter
#10
_Squarepants_
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Posted 19 February 2009 - 06:09 PM
Hey, how much have you got to spend???
There are a couple of crossflow options available, Duggin Heads and Irving Heads. (dunno if you can still get these new)
Otherwise JZ Engineering have some really sexy looking (non-crossflow) alloy heads with offset exhaust ports. They have manifolds to suit (Injection seems to be the go with these, along with the throttle bodies they supply). (they have the worlds quickest red motor powered car in the world, 7.something seconds, but it's a rail)
For cheap (and more streetable) horses I'd be looking at the 12 port, if you want a "worked as pig" go the 9 port.
The Yella Terra alloy heads look like a good thing aswell, all depends on how much you wanna spend.
I have an article from "Street Machine" with a 300HP red 202 using a 9 port extensively worked. If you like I can supply more detail (as per article) as to what was done to it.
There are a couple of crossflow options available, Duggin Heads and Irving Heads. (dunno if you can still get these new)
Otherwise JZ Engineering have some really sexy looking (non-crossflow) alloy heads with offset exhaust ports. They have manifolds to suit (Injection seems to be the go with these, along with the throttle bodies they supply). (they have the worlds quickest red motor powered car in the world, 7.something seconds, but it's a rail)
For cheap (and more streetable) horses I'd be looking at the 12 port, if you want a "worked as pig" go the 9 port.
The Yella Terra alloy heads look like a good thing aswell, all depends on how much you wanna spend.
I have an article from "Street Machine" with a 300HP red 202 using a 9 port extensively worked. If you like I can supply more detail (as per article) as to what was done to it.
#11
_Drag lc_
_Drag lc_
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Posted 19 February 2009 - 08:34 PM
Hi Squarepants,
i think this link might have something to do with the sm mag you are refering to?
Cheers Hayden
http://www.gmh-toran...amp;hl=group nc
i think this link might have something to do with the sm mag you are refering to?
Cheers Hayden
http://www.gmh-toran...amp;hl=group nc
#13
_1QUICK LJ_
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Posted 14 April 2009 - 03:29 PM
9 port is the go on a tuff six, then beyond that a JZ head is the go
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