AFR 210cc SBC Eliminator ported numbers update

[hoffman900]

The flow definitely reaches sonic in the Throatfor quite sometime, I don't know if it exceeds it though I'm rusty on what is needed to achieve supersonic speeds. My recollection was that it couldn't exceed it in Throat

Honda only found sonic conditions in the throat to be true on their single cylinder test engines, not multi cylinder engines with shared collectors due to residual pressure.

[WeingartnerRacing]

Eric,

What are the real port volumes here?
DV

I just poured the head 230cc

Before 210cc 2.08 45degree
Now 230cc 2.10 50degree seat

I’m not cc exhaust
Eric,
thanks - but could I trouble you with the valve sizes and the port volume of the before head as well of two ex port vols please?

I am doing some graphs here which I will send to you via a PM. You can publish or not as you may choose.
thanks
DV

[digger]

The flow definitely reaches sonic in the Throatfor quite sometime, I don't know if it exceeds it though I'm rusty on what is needed to achieve supersonic speeds. My recollection was that it couldn't exceed it in Throat

Honda only found sonic conditions in the throat to be true on their single cylinder test engines, not multi cylinder engines with shared collectors due to residual pressure.

i shouldn't have said throat, rather the "curtain" area aperture. the throat is in the actual port proper. by the time the port throat becomes the smallest area the cylinder pressure has dropped alot and the exhaust port pressure (from other cylinders and resonance effects?) means the delta has fallen. its still very high but not quite enough to get sonic closer to Mach number 0.7/0.8 in the sims in ENGMOD4T

[randy331]

Eric, did you figure the port energy before and after your port work ?

Randy

Neither

I look at the engine needs (size and rpm band) then figure out the size the port should be then go about making the head that size or as best as the casting will allow. Then it’s better.

On heads that are close to the right size I try to get the most air out of them without altering size dramatically.

I guess size and cfm is my answer in short. No port energy formula.

Then what criteria do you use to base an improvement on ?

Randy

How differently do you go about it when it's a un ported factory iron casting when about anything you do gains power vs, this AFR porting where it's a decent flowing ported casting already, vs someone with a very good running engine with nicely ported heads already on it but they want even more power ?

How do you approach those situations differently ?

Randy

[David Vizard]

Eric,
Your post of 11-24:-

I look at the engine needs (size and rpm band) then figure out the size the port should be then go about making the head that size or as best as the casting will allow. Then it’s better.

On heads that are close to the right size I try to get the most air out of them without altering size dramatically.

I guess size and cfm is my answer in short. No port energy formula.



On heads that are close to the right size I try to get the most air out of them without altering size dramatically.

Conceptually this line of thought will move you to end up with a high energy port.

I guess size and cfm is my answer in short. No port energy formula.

Size and CFM or more accurately mass are the two components of port energy. I suspect your heads work well because you are conscious of what's needed. Why not let IOP put a number on it so you can optimize it?
DV

[WeingartnerRacing]

I look at the engine needs (size and rpm band) then figure out the size the port should be then go about making the head that size or as best as the casting will allow. Then it’s better.

On heads that are close to the right size I try to get the most air out of them without altering size dramatically.

I guess size and cfm is my answer in short. No port energy formula.

Then what criteria do you use to base an improvement on ?

Randy

How differently do you go about it when it's a un ported factory iron casting when about anything you do gains power vs, this AFR porting where it's a decent flowing ported casting already, vs someone with a very good running engine with nicely ported heads already on it but they want even more power ?

How do you approach those situations differently ?

Randy

When the sizes are right, it flows great, and it makes good power. I see what personal preference I do on the head that the other porter didn’t do. If it is a head I ported I start doing trial and error things. Usually after I port a head I always have a few things I think I could have done differently. Sometimes it works but not always.

[randy331]

When the sizes are right,

What criteria do you use to decide on valve size?

CSA?
Whatever fits?

Randy

[David Vizard]

When the sizes are right,

What criteria do you use to decide on valve size?

CSA?
Whatever fits?

Randy

I maybe wrong but I get the feeling this thread could, at this point, start down a road of misconceptions I have often seen in the past so I thought I would throw in my ten cents worth before the dam broke.

Here, in short form, is how I tell it to my students.


If maximum output is the goal then the valves used should be those that are functionally the most effective. That is - the biggest the cylinders will accommodate while optimizing the airflow that they can pass into said cylinder. All the tuning ie the CSA , is done on the port. For an all out head I don't make the decision on the size valves used ---- the flow bench (and subsequently the dyno) does.

I am making this statement as I have heard just too many times that a smaller intake valve helps low speed torque. That is simply not so.

About a year back I posted the road test of my push rod, all iron, 2 valve per cylinder 1500 cc Chrysler Avenger Vs the 16 valve Cosworth 1600 BDA powered Ford Escort. Those who took the time to read the story will remember that my Avenger dominantly outpaced the Escort to the point that it wasn't even close in every single acceleration test. As I mentioned back then Motor Magazine test drivers were amazed at the width of the power band (400 -8000 rpm) and the valves filled the cylinders!

Eric - as a porter you appear to be very good - heck, let's go the whole way here - damn good! But, even at the high competency level you are currently at, I really don't think you will see your best work until you start quantifying what you do to a greater depth.

If there is anyway you feel that with my 60 years of experience on 2, 3, 4, and 5 valve heads from street to F1 could be of help then just PM me.

[WeingartnerRacing]

When the sizes are right,

What criteria do you use to decide on valve size?

CSA?
Whatever fits?

Randy

The bore size and the placement of the valves determines what size valve I put in a head. I want the largest intake valve I can put in there without becoming overly shrouded. I have never increased a valve size and the engine make less power or torque. Just as an example on a 4.030 bore sbc with standard valve placement I will go 2.08 with 40/60 split then 2.10. If it were an LS the valves would be much larger because they are in a better position.

There are a few exceptions. Such as they don't make an affordable steel valve and customer doesn't want to pay for custom. Rules dictate a spring and the added weight of the larger valve put the system into valve float early.

[WeingartnerRacing]

Eric,
Your post of 11-24:-

I look at the engine needs (size and rpm band) then figure out the size the port should be then go about making the head that size or as best as the casting will allow. Then it’s better.

On heads that are close to the right size I try to get the most air out of them without altering size dramatically.

I guess size and cfm is my answer in short. No port energy formula.



On heads that are close to the right size I try to get the most air out of them without altering size dramatically.

Conceptually this line of thought will move you to end up with a high energy port.

I guess size and cfm is my answer in short. No port energy formula.

Size and CFM or more accurately mass are the two components of port energy. I suspect your heads work well because you are conscious of what's needed. Why not let IOP put a number on it so you can optimize it?
DV

The reason is its not that simple.

On some heads I want as much cfm as possible because the situation demands it. IE the head cannot be made right size so go after cfm becuase you will break through on the casting if you wanted things ideal. Another scenario where two heads flow close to the same about the same size but one is significantly faster because of a couple reason. 1. One head has a better chamber design than the other for flame travel and wet flow. 2. The actual shape of the port is much better on one head. 3. Consistency of size through the port. No dramatic size changes through the port. 4. One head uses wings and other manipulations to make the head flow more but doesn't make more power or vica versa.

That is the problem with just a number. Good heads have many considerations and number might only deal with a few.

[zums]

{The bore size and the placement of the valves determines what size valve I put in a head. I want the largest intake valve I can put in there without becoming overly shrouded. I have never increased a valve size and the engine make less power or torque. Just as an example on a 4.030 bore sbc with standard valve placement I will go 2.08 with 40/60 split then 2.10. If it were an LS the valves would be much larger because they are in a better position.}



On the larger size 23 degree heads, what is your typical expansion rate from pinch to throat
Tom

[WeingartnerRacing]

{The bore size and the placement of the valves determines what size valve I put in a head. I want the largest intake valve I can put in there without becoming overly shrouded. I have never increased a valve size and the engine make less power or torque. Just as an example on a 4.030 bore sbc with standard valve placement I will go 2.08 with 40/60 split then 2.10. If it were an LS the valves would be much larger because they are in a better position.}



On the larger size 23 degree heads, what is your typical expansion rate from pinch to throat
Tom

Typically I like to keep throat and pinch as close to the same area as the throat as possible with welded pinch. However it usually is about 97% of throat. The larger area of the port is over the shortside were it is about 5% larger than throat. This also varies depending on bowl depth, short side height, and shortside shape.

[randy331]

Eric, have you done any heads for a pulling truck ?

Working on a set now. rec port set.
Any suggestions you'd share ?

Randy

[WeingartnerRacing]

Eric, have you done any heads for a pulling truck ?

Working on a set now. rec port set.
Any suggestions you'd share ?

Randy

What Head?

[randy331]

Eric, have you done any heads for a pulling truck ?

Working on a set now. rec port set.
Any suggestions you'd share ?

Randy

What Head?

Guess that would make a difference. lol
We have to use factory Iron heads. 026-990 casting rec ports mostly.

Randy