Making the au i6 headwork count?

[Stav]

OMG!! 753 rwkws from a v8 capri from that website

[poolkeeper]

Originally Posted by useless

OMG!! 753 rwkws from a v8 capri from that website

Did you see the aeroplane, lol
Refering to the hard capri launch :evilsasmo

[Stav]

Im not scared to overport after seeing those heads.If only my angle grinder would fit!!!

[mik]

Originally Posted by jonbays

This is real world here. The Falcon six is a long stroke tractor engine with all the wrong bore stroke ratios to rev and get good flow from a head limited by the width of the bore and the short height of the head and the 90 degree turns of the inlet and exhaust.

probably some truth in that, but can always be tinkered with, shouldnt be too much trouble to get decent power , the xr8 motor can be made to rev ok with 105 mm stroke , my brothers 3.0 supra has a similar bore stroke ratio and runs happily too 6400 +

[jonbays]

Originally Posted by mik

probably some truth in that, but can always be tinkered with, shouldnt be too much trouble to get decent power , the xr8 motor can be made to rev ok with 105 mm stroke , my brothers 3.0 supra has a similar bore stroke ratio and runs happily too 6400 +

BA V8's bore stroke ratio is not ideal look how much better the 4.6 engine can be tuned in the US mustangs.

Even so the BA 5.4 heads 3V or 4V are streets ahead of the AU six.

E-AU sixes are truly tractor engines with BS ratio for Torque and you can't change that and make them something else. You can get good mid range and a flat torque curve 3-5000rpm but going further they will just get very peaky and blow up from the high piston speeds.

[Sapper]

Can we start having actaul figures put down rather than "this is good" or "this is bad" type comments. If the I6 engine has a bad/good characteristic, please quantify this. That way, we can start to get a genuine idea of what can be changed. Jonbays, what do you reckon is a ratio we should target for our rod length/stroke ratio and our bore/stroke ratio? You never know, it may be possible to get a hold of internals that helps fix up these problems.

For instance, the Falcon bore/stroke ratio is 0.93, the supra bore/stroke ratio is 0.91 for a MkIII and 1.0 for a MkIV. The AU's have a rod length of 153.67mm which gives a rod length/stroke ratio of 1.55. Now, how can we apply this? Well, if we wanted to reduce the rod length/stroke ratio, we could put some EL internals in (EL rod length is 149.33) and possibly shave the head to get back some compression. It will take more than just those little steps but you see what i'm getting at.

So what does this have to do with headwork? Well, according to my previous post, the reduced rod length/stroke ratio will increase flow for large ports and reduce detonation. Hopefully, making the most of a big porting job. Question is, can we make the ports flow well enough for this to be useful? Otherwise, it may be better to go the other way and try and maximise torque. That is, if there's enough room at the base of the cylinders for longer rods.

Does anyone else have any information to add to this list? What would be useful at this time is some information about the head, flow rates, valve and port diameters etc and what workshops offer what headwork options. I've heard that the Au head is good for 300bhp. Has anyone tested this? What were the results. When i get some time i'll dig through some old posts on here and on FordMods to find some porting results.

Please feel free to correct any information i've posted but if you do, please supply some evidence as i'd like to check it out for myself.

[FS5]

Originally Posted by hot xr6

Can we start having actaul figures put down rather than "this is good" or "this is bad" type comments. If the I6 engine has a bad/good characteristic, please quantify this. That way, we can start to get a genuine idea of what can be changed. Jonbays, what do you reckon is a ratio we should target for our rod length/stroke ratio and our bore/stroke ratio? You never know, it may be possible to get a hold of internals that helps fix up these problems.

For instance, the Falcon bore/stroke ratio is 0.93, the supra bore/stroke ratio is 0.91 for a MkIII and 1.0 for a MkIV. The AU's have a rod length of 153.67mm which gives a rod length/stroke ratio of 1.55. Now, how can we apply this? Well, if we wanted to reduce the rod length/stroke ratio, we could put some EL internals in (EL rod length is 149.33) and possibly shave the head to get back some compression. It will take more than just those little steps but you see what i'm getting at.

So what does this have to do with headwork? Well, according to my previous post, the reduced rod length/stroke ratio will increase flow for large ports and reduce detonation. Hopefully, making the most of a big porting job. Question is, can we make the ports flow well enough for this to be useful? Otherwise, it may be better to go the other way and try and maximise torque. That is, if there's enough room at the base of the cylinders for longer rods.

Does anyone else have any information to add to this list? What would be useful at this time is some information about the head, flow rates, valve and port diameters etc and what workshops offer what headwork options. I've heard that the Au head is good for 300bhp. Has anyone tested this? What were the results. When i get some time i'll dig through some old posts on here and on FordMods to find some porting results.

Please feel free to correct any information i've posted but if you do, please supply some evidence as i'd like to check it out for myself.

to get you started,the best head to use on an au is off the later series 2/3 engines ,these heads have just the valve guide going through into the port.the earlier series 1 heads have a boss around the valve guide in the intake ports wich would restrict the flow to some extent.
as for flow figures my ported au 1 head flowed 368 @ 500 thou i didn't get it flowed before they ported it ,would have been a good reference if i did .
my original series 2 head i pulled off, i cleaned up myself .i just debured the ports .i got it flowed at the same shop where i got my series 1 done and it flowed 351 @ 500 thou .

[Sapper]

Originally Posted by FS5

to get you started,the best head to use on an au is off the later series 2/3 engines ,these heads have just the valve guide going through into the port.the earlier series 1 heads have a boss around the valve guide in the intake ports wich would restrict the flow to some extent.
as for flow figures my ported au 1 head flowed 368 @ 500 thou i didn't get it flowed before they ported it ,would have been a good reference if i did .
my original series 2 head i pulled off, i cleaned up myself .i just debured the ports .i got it flowed at the same shop where i got my series 1 done and it flowed 351 @ 500 thou .

Thanks for that mate. Excuse my ignorance but what units are applicable here? I'm guessing you got it ported at CNJ Motorsport. Have you have a chance to run it at the strip yet? Those were good numbers you made on the dyno last month so it'd be good to see what runs on the strip.

[FS5]

Originally Posted by hot xr6

Thanks for that mate. Excuse my ignorance but what units are applicable here? I'm guessing you got it ported at CNJ Motorsport. Have you have a chance to run it at the strip yet? Those were good numbers you made on the dyno last month so it'd be good to see what runs on the strip.

i should realy start a build thred but i'm to lazy ,
running the usual exhaust leads plugs cai and jmm street fighter cam stock head unicip it made 159rwk and a best of 14.597 @ 95 with 3.45 diff gears .
i got a au series 1 head ported by headsense hear in brissy (he's very highly recomended when it comes to porting)it made 156 and ran around the 15.1/15.3 @91 in summer heat with same mods as above .
i than fitted a gnd cam it made 158 annd constantly ran 15.o /15.1 @ 92 in the summer.with the same mods as above.once the weather cooled off it ran consistant 14.7's @ 93/93.5.when the original head /cam was running 14.6 @ 94/95.

i have since changed from 3.45 to 3.9 gears and from the lukey headers to pacey 4480's.i'm currently sorting some other bugs out then its time for a retune and back to willowbank for a run.

one thing i will do when i get the cash is get a bbm flow tested at headsense .

and then if all else fails i'l bolt the original head back on and see what happens.

we'll get there in the end

[Stav]

I am thinking that there is more power there other than the head.

[FS5]

Originally Posted by useless

I am thinking that there is more power there other than the head.

:

[Stav]

Well I can see that not one member has yet to have any proof of head port gains so far.

It looks like either they are not talking or even the best cannot get the au head to translate into more power. Perhaps it is the lack of tuning knowledge which sabotages the gains? We have seen tripower pull 14.2-14'4s on a standard head because of good tuning and a vernier gear.This is a credit to Chris from Blue power .

Im sure that many have attained great power out of other motors but maybe soon someone will come out with a head example for these cars.
It is looking to be a situation where the head is not too bad after all as not much improvement seems to be made. Perhaps a good sized cam to extend the upper limits of power slightly may be the most sensible way to go.

[Chrispy]

Firstly as noted before, head work needs to be done as part of a package. Just doing the head is not worth it, as its usually not the limiting factor.

The ford six has always had performance problems. It is the "tractor" factor. Don't forget the head has probably been improved on by the factory 30 times, form its XL days to now. The major changes have been V2 to crossflow, iron to alloy, OHV to OHC & OHC to DOHC. Tickford even sent a bunch of engines to the UK to create the first XR6. And all they got back was a couple of small improvements, just like all the other mods. There has never been a quantum leap in power, and there never will be.

Sure improvements in mid range torque can be made with the engine, but turning it into a horepower hero is a waste of time.

I'm sorry, but naturally aspirated you are flogging a dead horse with the 6 cylinder engine.

Chrispy

[The Mighty Red]

I tend to agree, 20 years ago guys were pulling 13's with tricked up N/A 250ci engines , which is unheard of with the I6 AU .

[xr8ute]

I dont think $500 port jobs on these i6 OHC cylinder heads are going to yeild any significant improvement in power.

It takes a lot of R&D to develop a head/cam/intake (and exhaust) package, and a $500 port cleanup is not going to do much....especially when the castings look pretty good as they are compared to the rough casting/finishing in a lot of the V8 heads. (although to be fair, ive seen way more v8 heads than i6 OHC heads)

Some simple questions though....

What is the length of the intake port?

What is the volume of the intake port?

Same as above questions for the Exhaust...(?)

What (and where) is the minimum CSA of the intake port?

What is the ratio of chamber to quench area?

What is the top of the piston like? Is it a dish, flat top, valve reliefs?

[Stav]

Originally Posted by Chrispy

Firstly as noted before, head work needs to be done as part of a package. Just doing the head is not worth it, as its usually not the limiting factor. Chrispy

It is widely accepted that if you can improve head flow with the same cam and setup then you should get better power i it is done properly.
The six cylinder engine is a horse still kiking and kicking quite hard.Soon to be alot harder.

One point worth mentioning is that JMM have the most experience with six heads and their best while not one of their customers' sure says something for their know how.13.3 in an eb isnt too bad.

The 250 ford motors were also branded as too long bore stroke ratio but with time they were intimidating alot of v8's

[Futura01]

headwork is good on motors that rev !!! not ones that are designed for only torque...
to get gains from a head the motor has to rev first...
old saying . .. there's not point in blowing through a bigger straw if you arnt gonna blow any harder ? it will only come out even !!!!!!

[Stav]

what is revving hard? I rev the wagon to 6000 rpm without a hiccup. My brothers bmw revs to 7500 rpm no problem.It is also a straight six. I have heard (heresay) that the sohc 4.0 ford can rev to 9000 rpm if balanced and oil windage fixed.

[jonbays]

Originally Posted by useless

what is revving hard? I rev the wagon to 6000 rpm without a hiccup. My brothers bmw revs to 7500 rpm no problem.It is also a straight six. I have heard (heresay) that the sohc 4.0 ford can rev to 9000 rpm if balanced and oil windage fixed.

No way its a dead duck if you do that to it.

The HLA's will pump up around 6300rpm just short of where the bore stroke rod length means that without a really well built and balanced example it will lunch itself.

I like the Falcon sixes but they are tractor motors that you can hot up well enough within reason.

[mik]

Originally Posted by jonbays

No way its a dead duck if you do that to it.

The HLA's will pump up around 6300rpm just short of where the bore stroke rod length means that without a really well built and balanced example it will lunch itself.

I like the Falcon sixes but they are tractor motors that you can hot up well enough within reason.

ok so perhaps we can find out what is the safe rev limit to take these engines, has anyone broken a rod or a crank from huge rpm, etc some of the guys on here must have the limit removed or even increased with an edit or chip or suming, who has run at highest revs with stock internals?? we have seen many many v engines obliterated, we need feed back

[poolkeeper]

I took mine once up to around 6300 or something (2nd to 3rd) dont think it liked it, but it sounded good and strong.

[mik]

not many replies we can`t be revvin em up much.

[stiddy]

Ive seen them spin to a little over 7,500rpm. Definately not stock though.

[mik]

at least not 1 report of any one breaking internals :

[waylander_jobby]

well ive pinned the tacho on my EF and that was at 6000rpm and it was still accelrating befor i changed gears so it was more rpm that that, probably 6300 something.

[xr8ute]

Originally Posted by waylander_jobby

well ive pinned the tacho on my EF and that was at 6000rpm and it was still accelrating befor i changed gears so it was more rpm that that, probably 6300 something.

Depends on how accurate your tacho is...

On my AU XR8, when the tach is indicating 5800rpm the engine is actually doing 5500rpm.

[NeishaXR8_347]

Originally Posted by waylander_jobby

well ive pinned the tacho on my EF and that was at 6000rpm and it was still accelrating befor i changed gears so it was more rpm that that, probably 6300 something.

What cam are you using to pull past the 6000rpm mark? Is it a I6 or V8?