AU porting..why?

[Stav]

Where is the problem with restriction in the AU head??Is it the intake or exhaust? Can it not get enough in ,or not enough out?

[LG]

Autospeed did a write up of the AU head, and explained what areas could be improved.

To get a copy of the article, goto:

http://www.google.com/

Search for: "autospeed turbo daihatsu charade"

Click on the first link that comes up.

Then in the article search field on the left search for: "porting gains"

Click on the first link that comes up ("Porting Gains" - 05-June-2003)

[LG]

According to the tests they did, the AU has only a 302hp design. And exhaust valves and ports only flow 81cfm. Both less than the comparrison EB Head.

After working on the AU head, it had an exhaust flow 76 per cent of the intake, an improvement on the 73 per cent achieved with the stock head.

It's definately worth the read, and it tells you, where gains can be made from modifing the head.

The restrictions seem to be the exhaust valves (slightly), shape of the combustion chamber. And...

"One of the main restrictions in the AU intake is that the [cross-sectional] area directly over the short-side radius is a bit too small and so it's accelerating the air and creating turbulence - the port necks-down at that point. I've increased the cross-sectional area there, mainly in width although there's also a bit taken out of the roof. I've also streamlined the guide to get a bit more area in there as well."

[loxxr6]

Useless I posted the whole article from Autospeed on the old FF site.

If you want it I think I still have access to get a hold of it.

It was quite a good read.

Here's the link to the actual article if you have an account with autospeed.

http://www.autospeed.com/cms/A_1792/article.html

[LG]

If you use the steps i said, it doesn't matter whether or not you have an account.

[loxxr6]

If you use the steps i said, it doesn't matter whether or not you have an account.

I just tried that then and it worked....hmm you normally need an account to access it.

That makes life easier then.

[LG]

Originally Posted by loxxr6

I just tried that then and it worked....hmm you normally need an account to access it.

That makes life easier then.

Yeah you do need an account, but It's a glitch in their system.. :voldar02:

[jonbays]

The AU isn't bad at 302hp. The easiest way to improve flow of any head is use a high lift cam or higer ratio rockers. More lift = more flow. well if the turbulence isn't too bad and that is an oversimplification but it works on I6's and Windsors all right.

The AU head has large enough inlet and ex valves for the long stroke small bore engine it has that is limited to rev to about 6300rpm max and most modded engines will peak around 5000-5300rpm anyway. The AU head problems are the bulge between the valves in the middle of the head the Valve guide intrusion in the inlet and the inlet and exhaust port sharp curve and small x section area that squeezes the air as it makes the last turn into the head causing turbulence.

A good ported AU head will flow 25% more 380hp which is more than you can get with a N/A motor because of the bottom end rev limitations.

Real world I have seen a ported head I6 engine with similar mods to mine pull another 10rwkw so a heads worth another 6% power gain in the mid range and about 10% at the top end.

As an example lets say a JMM dev3hl 136rwkw vs 145rwkw with head work
or a JMM dev5 150rwkw or 161rwkw with head work is what I can guess from all the dyno days i have gone to.

[SpoolMan]

Good advice there jonbays after much playing with Hamo's Au i have seen very simular things.
i would say if you have a manual and you want to build a engine to race do the head.... otherwise leave the head alone especially with an Auto..