I'll send you the complete 6th chamber, ports, valves, spring, retainers.
i'll basicly lop it off between 5 and 6.

this is what you'll get.

I was talking about something like this. BTW, whats the CFM rating on the standard i6, say one from an EF?

A DIY Flow Bench just like the following is on my 2010-to-do-list.

http://www.gofastnews.com/board/technic ... bench.html



This article/thread will be great. Hopefully I will be able to positively contribute!

Almost forgot to mention flow benches only flows one way. even if you spend hours making highflow ports flow beyond it's capability it'll flow backwards just as easy during the charging phase when the piston travel up.

also high velocity ports starts off slow and gains s**t loads of flow at high revs, not the other way around...


Nice link phillyc!

I'll read up on whats on there and cross reference it to other hard wired high-flow port standards a lot of people have accepted!

No worries tickford_6. Will pm you some details in the next day or two. I've just been too busy to be anywhere near my computer the last couple of days.

There are tricks to getting ports to flow well in one direction while flow poorly in the other.
People have been doing it for years. Given a well tuned exhaust system should actually draw harder onthe intake charge then the piston does goes a fair way to negating reverse flow of an intake port anyway.

I understand you have a fixation on that particular porting method. And yes it's not a new idea and has been proven to work well the few times if seen it applied to some bike heads. i've also seen the same porter try it on other heads and fail big time.

On the heads that worked, the ports were all massively over sized from factory and very port air speed. None of them gained a great deal of peak flow (as this is function of the valve window)
they did gain alot of mid lift flow, which is to be expected given the original port.


you'll find no mater port you have it will flow more air the faster the engine revs.
faster the piston moves down the bore the greater the pressure differential the more will pass through the port, untill the point that for what ever reason the port cannot pass anymore air.


posting photos of ports that are a complete opposite to the I6 heads and claiming you can apply the same porting and achieve the same results isn't helping you.

go get a head and port it. stick it on an engine prove the point

Wouldn't closing up the ports like that on an I6 result in choked flow, therefore self imposing a low rev limit on the engine? Say it would rev no higher than 4000rpm?


I've been thinking about how many porters clean up the guide bosses and valve guides. That's what I want to flow test first. Some prefer to cut the guide flush with the port roof. Whilst others clean it up. And herein lies the mother of all misunderstandings. You pick up any text book on fluid mechanics and you will read that a perfect aerofoil (resulting in minimum turbulence) is actually a teardrop shape with the air first coming into contact with the bulb of the teardrop and not the point. I've seen far to many pictures posted online by porting guru's which show some weird s**t head work around the guides. Some have the teardrop shape but backwards (air hits the point first) whilst others have had a big night in bed before and their guide work looks like a pair of \|/ flaps. And as for the ones that chop their guides flush (especially on the intake), well they are probably the same ones who gasket match the port entry thinking bigger is better without paying attention to the rest of the job.

Tickford_6, would there be a great deal of difference between a good forced induction port job and N/A application. Some of us are chasing s**t power with forced induction whilst others are happy with mid 140-150kW aspirated setups.

The photo was actually suggesting if you have a spare head and if you're so kind to cut one exactly the same way and post it up. I was more interested in how thick the ports are. surely, this isn't about attacking your intelligence!

you wouldn't happen to know the CFM of a EF standard i6 or Barra would ya? it'll help the course for a better understanding and also deviate away from the main stream text book copy cats we've been hard wired too for over 50 years. basically we've been relying on cam grinds to compensate for the large high flow porting.

What I was thinking of is actually play around with reducing the throat area, not the port. the port you can grind away to your harts content by increasing the volume but funnel the port exit into the cylinder. think of it as how affective your respiratory system is when your lungs fills up quietly when you inhale through your nose very fast... did you feel dizzy?

Yep, I know what you mean by working on most heads but not on poorly design one's but there is still room for improvement by stepping out of the box. why? maybe we've been making the same mistake and restricted to it...

+1 for seeing a diy head porting doco.ive got a spare head and dremel sitting in the shed but havent got the nuts to have a crack at it yet. will be intersted to see what comes of this..

I don't approach a forced head any different to an N/A head.


for s**t power forced you still need s**t port flow. 15PSI into a stock intake port wont put as much air into a cylinder as 15PSI into the best flowing port currently available.
This whole you don't need a ported head with boost is IMO crap.

For guys wanting 140-150rwkw with a manual i wouldn't even bother with porting. there are cams out there that will make this power and still idle like a stocker and be just as drivable under 2000rpm.

With an auto for that you normally need a little more cam and some basic porting. nothing over the top just good seat cut, back cut valves and well done "pocket port". The really is no reason to touch the port beyond 15-20mm on either side of the valve. (something you should be testing along side the guide boss tests)



Sorry about that, the heat must be getting to me today. (we all know i have these moments)

I have three heads here. an AU VCT head that is now a 5cyl head. the rear cyl is going to xcabbi.
an EL none hybrid head, that is untouched and completly bare.
and a EF XR6 that i ruined about a 4 or 5 years ago. no point cutting it up and all the ports are stuffed. (well stuffed by what i consider good porting these days, its f**k good head with what I 'knew' back then)

The AU head is going to be sectioned the way you posted on the number 5 cyl, the remaining 4 cyls will be test cyl for different porting ideas. the EL i really dont want to cut up, as it a corrosion free crack free 98 000km old gem. and even though my wife thinks its not a good idea i want buy an old box car as a test mule and spend some time and money on it to develop a few things.

I don't think i have any flow figure for the EF head how ever you can get EB and AU figure from one of the auto speed porting articles and 'wagon dad' has a bunch test from of his heads.

With the stepping out the box. i'd like to see it work, i just don't think shrinking the throat is the way to look at it. Even with HV approach the valve is still going to be a limiting factor and the size of the throat aswell. you going to need to know what sort of pressure drop there will be across the 'venturi' ( the throat area of a HV port) to determine optimum size for the power you want. Too small and you will choke the cylinder, too big and the effect you are after just wont be there.


I've got a few BBM manifolds here too. one of those is going to go through the drop saw aswell.
there is no point in having the 'I6 Super Head' if you are going to kill it by putting a BBm manifold on it.

Last edited by tickford_6 on Thu Jan 07, 2010 10:55 pm, edited 1 time in total.

while we are all here trying to solve the issues of big power I6s
and we all seem to have spare bit laying around, can any one help with the piston and rod comparo i'm trying to sort out.

the link is in my sig

Just got some pics of the 94AB head. Anyone got a photobucket account that I can borrow, or can I email you these pics as they are over 1.5MB each?

Tickford_6. Since you have lopped off cylinder 6 maybe its a better Idea that you keep it and section it up as I was thinking of sectioning it up myself.



I would so love to compare the flow rates of a falcon head against an RB30 just to see what they've got up their sleeve. Was talking to a mate today who owns a 9 second 140+mph VL turbo and he has a virtually stock motor (200,000km bottom end) with a cam and 30psi pumped into it. Head castings are untouched.

here is section of an AU VCT intake port










and an EF BBM runner

cant wait to see this all come together, some great pics there