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Location:
melbourne
Registered:
November 2003
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modded bigport 4age = stock smallport power?
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Wed, 05 May 2004 13:12
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hey guys, i was just wondering how hard u think it would be to get a 4age bigport running at the same power as a stock 100kw smallport 4age.
what modds do u think would be needed to get the equal amount of power from the earlier bigport 86kw engine as a stock smallport 100kw engine?
remembering that these figures are a the flywheel, so power gains of even a couple of Kw at the wheels will have a good effect.
i rekon it could be done easy with a:
full exhaust
CAMS
good CAI
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I supported Toymods
Location:
sydney.au
Registered:
August 2002
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Location:
melbourne
Registered:
November 2003
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Re: modded bigport 4age = stock smallport power?
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Wed, 05 May 2004 13:33
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lol, the TRD oil cap would have to give u another good 10-15kw at the wheels!!!!
once i actually get teh car, i rekon id go almost all out on it.
full whiteline suspension/shock/strut brace/ swaybar kit.
CAI (homemade of course)
full exhaust (including extractors)
CAM's
and then go a aftermarket chip.
if i had trouble with the engine and ahd to remove the head, then i guess id have headwork done to it too. this would be a dream car for me!
what do u mean about decking the head? what's that?
also, how do u go about raising the compression? it would be a good idea to do it i rekon. the bigport 4age doesnt even neep hi-octane fuel stock, as its compression ratio is only 9.4! would allow some good power gains i rekon.
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Location:
Melbourne
Registered:
November 2003
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Re: modded bigport 4age = stock smallport power?
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Wed, 05 May 2004 13:39
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I wanna know how much the tougher 100kw bottom end would make with a big port head on it (with stock everything).
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Location:
melbourne
Registered:
November 2003
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Re: modded bigport 4age = stock smallport power?
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Wed, 05 May 2004 13:45
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im pretty sure it would make less wouldnt it?
they both run the same compresion ration, and teh new smallport engien head was supposed to be better that the older bigport head, as the bigport intake/exhaust valves were TOO big (thus the need for TVIS and hence the nickname BIGPORT engine).
id like to know what exactly they did to achieve the higher power output in the newer engine? ive heard the bottom end is stronger (7 ribs rather than 3), and the pistons became oil cooled or something, but what else was done?
wow, talk about getting off topic!
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I supported Toymods
Location:
sydney.au
Registered:
August 2002
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Location:
melbourne
Registered:
November 2003
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Re: modded bigport 4age = stock smallport power?
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Wed, 05 May 2004 13:56
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really?
awsome!
i had no idea?
do u know why this is so? anybody?
and once again, what was done by toyota to make the smallport rate 100kw?
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I supported Toymods
Location:
sydney.au
Registered:
August 2002
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Re: modded bigport 4age = stock smallport power?
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Wed, 05 May 2004 13:58
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the head design
the compression
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Location:
melbourne
Registered:
November 2003
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Re: modded bigport 4age = stock smallport power?
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Wed, 05 May 2004 14:13
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if u kept stock internals, stock ECU and used the 86kw 4age bottom end, how much power to u rekon u could get out of the engine?
does anyone know what the best power made by one of these engines without using forced induction?
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Location:
Adelaide
Registered:
May 2003
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Re: modded bigport 4age = stock smallport power?
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Wed, 05 May 2004 15:02
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Go look at Billzillas site, he has power upgrade ratings there.
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Location:
Victoria, Melbourne
Registered:
August 2003
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Re: modded bigport 4age = stock smallport power?
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Thu, 06 May 2004 05:31
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hey shraka, i just put the engine your talking about into my sprinter, the 100kw bottom end and the bigport head. No idea of the power its making its getting the exhaust put on as i speek.
The head on mine has been high flowed, and ported/polished...
You saw my car at mikes house didnt u??
Ill get an idea of the power its making if the dyno day is a go ahead!!! 
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Location:
melbourne
Registered:
November 2003
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Re: modded bigport 4age = stock smallport power?
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Thu, 06 May 2004 13:10
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hey comet,
how much did ur head work cost u mate?
and what car is the engine in by the way?
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Location:
melbourne
Registered:
November 2003
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Re: modded bigport 4age = stock smallport power?
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Thu, 06 May 2004 13:11
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*bump*
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Location:
Melbourne, Australia
Registered:
July 2002
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Re: modded bigport 4age = stock smallport power?
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Fri, 07 May 2004 11:05
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| carsanactra wrote on Thu, 06 May 2004 23:10 |
hey comet,
how much did ur head work cost u mate?
and what car is the engine in by the way?
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Green_Commet bought the engine that way, the work was either done by, or had done by the guy he bought it from. And his car is an AE86. And yes Ryan Nim saw your car at my place as i was working on it when he came round.
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Banned by his request
Location:
moved to tamworth
Registered:
July 2002
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Re: modded bigport 4age = stock smallport power?
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Fri, 07 May 2004 11:16
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i suppose i should write a tech article but here you go! the big port head is useless on a 7rib bottom end, you will loose horsepower.the small port is a far more effient head as it has a much better velocity into the ports. that said a big port works well on a turbo 4ag as you are craming air in I.E forcing inducting the air in. i use big port for turbo and smallport or twenty valve for atmo. its all to do with port velocity, the small port creates a venturie effect until it cant allow anymore air through, for its given size, which would be about 240{with head work) or so hp.
there is alot more to it than above but its a good over view.
mick
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Location:
melbourne
Registered:
November 2003
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Re: modded bigport 4age = stock smallport power?
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Fri, 07 May 2004 15:45
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yep, id agree with u there mick. if the bigport head was better, why on earth would they have changed it to smallport?
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Club Member
Location:
sydney
Registered:
May 2002
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Re: modded bigport 4age = stock smallport power?
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Fri, 07 May 2004 21:33
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the big port head is useless on a 7rib bottom end, you will loose horsepower.the small port is a far more effient head as it has a much better velocity into the ports.
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thats funny, cause theres a few very powerfull and competitive IP cars running bigport heads that dont seem to be having too much trouble making more power than the small port 
maybe you need to do more testing Mick 
eg....
http://forums.toymods.org.au/index.php?t=msg&t h=28208&rid=2&S=7e0ca51e615e8a849f754babf8 10b6bb&pl_view=&start=0
read Johnnys post on page 2
the engine hes referring to easily puts out over 100Kw at the rear wheels and theyre still pushing for more from tuning in the next few weeks
Ill let you know what mine pulls on the dyno hopefully next week with the same configuration your talking about, i dont think it will be anywhere near 100Kw@the wheels but im sure itll flow just fine
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Banned by his request
Location:
moved to tamworth
Registered:
July 2002
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Re: modded bigport 4age = stock smallport power?
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Sat, 08 May 2004 02:19
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lol and his hp figure would be on a chassis dyno not engine dyno.
i would imagine the 7age we did is about the highest hp one in the country as its 240hp on the engine dyno. using motor bike pistons etc and using the small port head. we had to work the ports then weld them up to get the right shape as there isnt alot of meat in them. in order to get the big ports to work aswell we would have to weld them up and go from there. most people wouldnt have the money to do it so the small port is by far the best option. what people write and say about hp figures and what is real are two diffrent matters. lol as i deal with the larger majority of race engine builders and engineers in australia and OS i can tell you what is possable on paper doesnt usally work aswell when put into practice. i find it a bit ruff you compare a national sport sedan crew cheif (professional as its what i do for a living) against IP guys, i am just doing IP car at the moment and have picked a car that will put me behind the 8 ball to start but am going to show the guys what can be done with knowledge and experiance. i learn new things everyday about racing and i do it from 6am to 9pm 5-7 days a week.
lol so small port is the way to go unless you have loads of money to do head work.
mick
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Club Member
Location:
sydney
Registered:
May 2002
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Re: modded bigport 4age = stock smallport power?
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Sat, 08 May 2004 04:39
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yeah chasis dyno.. we dont all have access to nice equipment like you mick
7AGE IMHO is completely different to what were talking about here but yes they make some nice power.. reliability.. well thats another issue.. just ask Johnny why hes pulled his out of the rally car 
Bills site has plenty of info on welding up the bigports too, and yes in terms of costs and outcomes of course itd be easier to throw the smallport head on, but i dont think he was asking what it costs more what is feasable, i was merely responding to people replying smallport is better than bigport, when it has been proven time and time again to be the reverse, even FA stayed with the bigport head. They must have done so for good reason .. maybe its because they were getting 220+HP from it.
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i find it a bit ruff you compare a national sport sedan crew cheif (professional as its what i do for a living) against IP guys
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Mick ... as you well know im not comparing anybody against anybody ... let alone an open class racing segment with a limited modification segment, im merely putting facts on the table... as you know... people informed or not will read it all how they would like it to be for thier own case irrelevant of what either of us write anyway.
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so small port is the way to go unless you have loads of money to do head work
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considering money wasnt mentioned doesent this contradict what you said earlier here....
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the big port head is useless on a 7rib bottom end,
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what people write and say about hp figures and what is real are two diffrent matters
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agreed.. im just going on the figures i know as FACT off (chasis) dynos known to be consistent
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i can tell you what is possable on paper doesnt usally work aswell when put into practice.
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anybody whos read a cusco/mugen/etc product performance claim can confirm that 
just add stickers... 10Kw improvement
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Location:
Melbourne
Registered:
November 2003
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Re: modded bigport 4age = stock smallport power?
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Sat, 08 May 2004 05:55
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Hey Green_Comet, I wanna see what you make on the dyno. Then we need to get another 86 with similar mods on a 100kw and see what makes better power, better response, and smoother torque.
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