Head porting

[minimivic]

I've built the engine now, scat rods etc, and have a set of supertech valves (thanks bill).

The exhaust outlet is smaller than the manifold so there is a lip, do I need to match the port to the manifold to help flow?
Other wise is there a great benefit to getting the head professionally ported and matched. Can the inlet be taken out to large port size ready for a better intake manifold at a later date
Turbo will be a GT3071r
who is good for head flowing? any recommendations?

 

[Triple D]

and that engine is going in a mini fukcing hell mate, you going 4wd aswell?
sory i cant answer any questions on how to port the exhaust manifold though.

Good luck with the build chap

 

[YIN]

minimivic is this a pic of your car then and the owner of the vtec one

 

[minimivic]

Yes its my car in the pic.
Yes it is 4wd and 400hp
yes its cost a fortune
and no im not totaly certifiable (YET)
This is what it looks like at the moment. LOts of carbon and fiberglass work to do yet.

http://www.16vminiclub.com/gallery/thumbnails.php?album=597 for more pics
Some bits have changed

 

[Triple D]

That looks fooking amazing that is gonna be one hell of a sleeper when its done

 

[cupra_matt]

WOW, totally amazing. WOW

 

[air121005]

thats going to be a beast!

engine looks a good fit btw!

if your just going to open the lip of the port to match the manifold, i wouldn't have thought that would make much improvement as the ports diameter would be mostly unchanged.

serious gains would be achievable from opening the whole port out, multi angled valve seats, have the valves turned down polished and reduced in mass, contouring the valve stem seats, polish the exhaust ports to a high mirror finish for extremely good air flow and heat reflection.
do the same the inlet ports except leave these un-polished as this agitates the air / fuel mixture and creates better combustion!

 

[ibizacupra]

thats going to be a beast!

engine looks a good fit btw!

if your just going to open the lip of the port to match the manifold, i wouldn't have thought that would make much improvement as the ports diameter would be mostly unchanged.

serious gains would be achievable from opening the whole port out, multi angled valve seats, have the valves turned down polished and reduced in mass, contouring the valve stem seats, polish the exhaust ports to a high mirror finish for extremely good air flow and heat reflection.
do the same the inlet ports except leave these un-polished as this agitates the air / fuel mixture and creates better combustion!

you say this but have you ever looked at the valves on 1.8T?????

in this case LEAVE the valves ALONE.
they are black nitrided one piece intakes and inconel exhaust valves, hard chromed & are profiled correctly, with only 6mm stems as std.

and follow the advise in this KS bulletin>> http://badger-5.com/bin/5v-installation-note-supertech.pdf

 

[max_torque]

If you really mean the exhaust port (rather than the inlet port) do NOT under ANY circumstances make it a smooth lip-less flow from the actual port into the exhaust manifold!!! There needs to be a lip here, something around 2.5 to 3mm (i.e. exhaust manifold flange port is bigger than the head port) to form a deliberate step between the exhaust port in the head and the entry to the exhaust manifold. This "anti-reversal" step prevents backflow into the head, especially important on big boost turbos. where typically EBP is 2 or 3 times boost pressure.

 

[h17och]

If you really mean the exhaust port (rather than the inlet port) do NOT under ANY circumstances make it a smooth lip-less flow from the actual port into the exhaust manifold!!! There needs to be a lip here, something around 2.5 to 3mm (i.e. exhaust manifold flange port is bigger than the head port) to form a deliberate step between the exhaust port in the head and the entry to the exhaust manifold. This "anti-reversal" step prevents backflow into the head, especially important on big boost turbos. where typically EBP is 2 or 3 times boost pressure.

agreed, step = good

the 1.8t heads are pretty crappy, you will get minimal gains from porting it, idealy they need to be total reshaped and start a fresh as the shape they are as standard is a total down fall

i belive to get a good shape they need to be filled and re cut

ive looked into it and its big money!

HoocH

 

[adamgardiner]

what a project mate

 

[DPJ]

Yes, I thought step=good.

An incredible project, well done. Why have you left a gutter round the roof? When we used to de-seam them, we always took the gutter off.

 

[h17och]

i dont like them with the gutter of!

pillars deseamed yes
roof deseamed no

 

[minimivic]

Yes, I thought step=good.

An incredible project, well done. Why have you left a gutter round the roof? When we used to de-seam them, we always took the gutter off.

I needed something to bond the carbon roof onto so a 12mm lip is usefull and I think they look better with the roof gutter anyway

 

[DPJ]

I needed something to bond the carbon roof onto so a 12mm lip is usefull and I think they look better with the roof gutter anyway

I guessed you'd got a carbon roof. It would be a sod to make inst flanges to fit down the inside of the pillars. If you like the look of the gutter then fair play.

 

[Yumann]

If you really mean the exhaust port (rather than the inlet port) do NOT under ANY circumstances make it a smooth lip-less flow from the actual port into the exhaust manifold!!! There needs to be a lip here, something around 2.5 to 3mm (i.e. exhaust manifold flange port is bigger than the head port) to form a deliberate step between the exhaust port in the head and the entry to the exhaust manifold. This "anti-reversal" step prevents backflow into the head, especially important on big boost turbos. where typically EBP is 2 or 3 times boost pressure.

So going by this I take it when you enlarge the exhaust port you must enlarge the mani to create a step

 

[h17och]

aslong as there is a difference to create a restriction from the airflow flowing backwards. i believe its because of the pressure in the mani

 

[DPJ]

Say the gas pressure at the exit point of the exhaust port is x psi. As it goes out into a wider diameter tube, its pressure will drop because it is not contained in the smaller space any more. It's the pressure differential that helps prevent reversed flow.

 

[Yumann]

Cool cool, i'm going to give porting a go

I take on the intake the transistion should be flush?

 

[ibizacupra]

aslong as there is a difference to create a restriction from the airflow flowing backwards. i believe its because of the pressure in the mani

and the firing order... from a 4 stroke... pulse pulse pulse pulse