Pinto Porting

[nismo.capri]

You tend to get the carbs poping back under accelleration from idle (side draughts of course) with trying to get the gases flowing straight through the port.

Any idea why that is? ...lack of turbulance in the chamber?

If you go to your toilet flush it and watch how the water exits about 10 times you will get the picture of the valve opening in a well directed port. Thats the extent of the similarities of water and atomised fuel. (it sounds fucked up I know but it works, also its hard to explain to your partner why she can't use the toilet due to scientific reasons)

So am i putting this together right..... You said that the river and stick analogy didn't hold, I'm guessing this is becasue I was thinking of a straight constant flow. The toilet analogy does becasue it's "pulsing" and the lines you were talking about aren't creating the swirl more promoting the natural swirl?

I'm still coming to grips with this idea but I think I see what you are getting at.... in nature you very rarely see linear flow and with the addition of the valve pulsing it's not going to be a linear flow you'd get with a static pressure like a river, more a swirl like water flowing around rocks at a beach with the pulsing of the waves?

I always make the pinto heads spin the atomised air/fuel so the sheilded piece of the combutsion chamber is only blocking the operlap efficiency.

Looking top down with the head sitting as it's installed is that clockwise or anti?

You are doing a great job with your tooling and are getting close to the right path thats why I posted the last post.

The most important thing also not listed in any books....

Thanks, I'm here to learn which is why I ask so many questions!

If a head is set up for turbo (only talking about ported ones) it will never give a good result on a carbed engine below almost peak RPM.

This is due to the volume of air that a turbo can push through the port as oppossed to the amount a piston can suck through the port.

Here's yet another question.... or 2....

What about part throttle/off boost responce? ..or are you talking full out race engine that will always see 3/4 to full throttle all the time or street engines too?

I'm on a course for work from today and won't be back till Saturday, hope it goes good.

By the way the tools from Super Cheap are fine but a rotary burr is the way to go and last longer than stones.

It's been epoxyed and it's going on the bench tomorrow. I use the dremil rotary cutters and 2 of them costs the same as the rotary tool.

For you guys wanting to have a go when I was using only stones I'd work a specific area of the port on all ports because the stones chane shape as you use them. I found this easier to keep the ports similar shape.

[nismo.capri]

Here's the epoxy port... This is a berfore/after of stage 1 and stage 4 so you can see the difference.

The results on the flow bench were really good

Here is is compaired to stage 3, it had gains over the full range of lift and is flowing about 20% better than the stock head.

Here it is against Vizards head.

So this head is now making more flow through a smaller port. This shows that bigger isn't always better with ports and is definitly not the case with the Pinto. The best thing about this is that flowing more air through a smaller hole means that the port velocity has increased, the faster the velocity the better ram effect filling the cylinder.

The thing I found really interesting was that the sound of the flow test was different. It was alot quieter and it stopped the beat frequency. This happened because the new short side radius had stablised the flow big time, it sounded happier to me.

(http://en.wikipedia.org/wiki/Beat_(acoustics))

[slipsittin]

You tend to get the carbs poping back under accelleration from idle (side draughts of course) with trying to get the gases flowing straight through the port.

Any idea why that is? ...lack of turbulance in the chamber?

The ports are to big to create a rush when the valve is opened

If you go to your toilet flush it and watch how the water exits about 10 times you will get the picture of the valve opening in a well directed port. Thats the extent of the similarities of water and atomised fuel. (it sounds fucked up I know but it works, also its hard to explain to your partner why she can't use the toilet due to scientific reasons)

So am i putting this together right..... You said that the river and stick analogy didn't hold, I'm guessing this is becasue I was thinking of a straight constant flow. The toilet analogy does becasue it's "pulsing" and the lines you were talking about aren't creating the swirl more promoting the natural swirl?

Now you are starting to really get it

I'm still coming to grips with this idea but I think I see what you are getting at.... in nature you very rarely see linear flow and with the addition of the valve pulsing it's not going to be a linear flow you'd get with a static pressure like a river, more a swirl like water flowing around rocks at a beach with the pulsing of the waves?

Around rocks sortof pulsing like waves no. there is another thing we will discuss when you get your head finished, just don't touch the maniflods yet please and I will give you another very simple plan to more efficiency in the head

I always make the pinto heads spin the atomised air/fuel so the sheilded piece of the combutsion chamber is only blocking the operlap efficiency.

Looking top down with the head sitting as it's installed is that clockwise or anti?

I honestly would have to see some more pics of the head as I only do it when they are in front of me.

The ports are however shaped to spin just not so well

You are doing a great job with your tooling and are getting close to the right path thats why I posted the last post.

The most important thing also not listed in any books....

Thanks, I'm here to learn which is why I ask so many questions!

Ask away man it costs nothing to listen or speak in turn

If a head is set up for turbo (only talking about ported ones) it will never give a good result on a carbed engine below almost peak RPM.

This is due to the volume of air that a turbo can push through the port as oppossed to the amount a piston can suck through the port.

Here's yet another question.... or 2....

What about part throttle/off boost responce? ..or are you talking full out race engine that will always see 3/4 to full throttle all the time or street engines too?

If it was set up for a turbo it is set up to have the air forced through it.

carbs need the air to travel through with speed under vacume not pressure.

Therefore it will make no difference the application the head will only be good for a turbo unless it is filled and altered.

I'm on a course for work from today and won't be back till Saturday, hope it goes good.

By the way the tools from Super Cheap are fine but a rotary burr is the way to go and last longer than stones.

It's been epoxyed and it's going on the bench tomorrow. I use the dremil rotary cutters and 2 of them costs the same as the rotary tool.

For you guys wanting to have a go when I was using only stones I'd work a specific area of the port on all ports because the stones chane shape as you use them. I found this easier to keep the ports similar shape.

Very true about the stones changing shape. The average steel head I do takes around 30 stones of different shapes and grits. Then I have 6 different burrs for the micro tool and the same amount for the 6mm or 1/4 tool depending on the country they were made in.

A NOTE TO ALL READING THIS:

YOU MUST MAKE SURE OF THE SHANK SIZE OF THE STONE OR BURR TO GET THE RIGHT COLLET FOR YOUR TOOL AS THEY COMOUT AND CAN DESTROY ALL YOU HAVE DONE VERY FAST!!

[slipsittin]

Here's the epoxy port... This is a berfore/after of stage 1 and stage 4 so you can see the difference.

The results on the flow bench were really good

Here is is compaired to stage 3, it had gains over the full range of lift and is flowing about 20% better than the stock head.

Here it is against Vizards head.

So this head is now making more flow through a smaller port. This shows that bigger isn't always better with ports and is definitly not the case with the Pinto. The best thing about this is that flowing more air through a smaller hole means that the port velocity has increased, the faster the velocity the better ram effect filling the cylinder.

Get hold of the webber and or the delortto carburator books.

The reason for the increase you have is the same reason all of these carbs don't have the same size tubes as the butterfly size.

Port size arguments have been going on for over a century but one thing remains common in all arguments.

The exhaust side is also relative in all aspects right through to the end of the tail pipe unless its a drag car.

I wish I could put this in better words but what you have successfully done is as you said sped up the air flow using a venturi effect (a very cool thing in itself).

The air slows down if the size is the same all the way through due to it not having any direction (even though it is directed by the port).

With what you have done you are stalling the air flow until the valve is opened then the action of the piston on the downward stroke causes a vacume and the shape of your port determins the volume and speed of the flow and amount of air. As the air is sucked through your port venturi it speeds up(port shape dependant) and ends up sucking the air through rather than it needing to be forced through or pulled through.

What you need to do to make a true statment of comparison is to say the capacity of the chamber full of air is "X" amount and my port shows it can flow "Y" amount of air in the space of the time it takes between the overlap of the (inlet valve opening and the exhaust valve closing completly) intake stroke cycle til the piston is about 5 degees before Bottom Dead Centre (BDC).

That way you will know if the full efficiency of the port has increased or just changed trully

The thing I found really interesting was that the sound of the flow test was different. It was alot quieter and it stopped the beat frequency. This happened because the new short side radius had stablised the flow big time, it sounded happier to me.

(http://en.wikipedia.org/wiki/Beat_(acoustics))

Shorter flow can be a good and bad thing but is RPM determined as well as the factors listed above.

Its looking good man and I think you are well on the way to a good end product there but just make small changes from now on and make cardboard or thick gasket paper templates to keep them the same throughout all the cylinders.

D porting the exhausts on the right side will make the gases escape better due to the vortex you will create.

Lastly remember the venturi effect works here also.

Corey

[slipsittin]

Just so everyone knows the colour I was replying was for easy reading not because what I said was to correct what was writen.

Corey

[eke_zetec_RWD]

ex

1mm 17.5

2mm 37.2

3mm 61.3

4mm 74.1

5mm 84.5

6mm 94.5

7mm 104.0

8mm 108.4

9mm 111.2

10mm 112.3

11mm 113.2

12mm 114.1

13mm 114.7

14mm 115.2

15mm 115.6

inlet

1mm 21.7

2mm 46.2

3mm 71.6

4mm 100.0

5mm 125.2

6mm 141.1

7mm 148.0

8mm 154.2

9mm 160.0

10mm 164.8

11mm 169.0

12mm 172.5

13mm 174.5

14mm 176.9

15mm 177.4

done at 28"

exhaust is shit. and one got good exhaust port pics?