600 HP 350 SBC?

[KnightEngines]

All these graphs & equations have very little to do with an actual running engine.

Probe the port, is it at least 260ft/s at its slowest point through the pinch? Is it around 300 in most of it? Does it stay under 350? If so & it's flowing 280 or so then you're good.

Is it under 400 over the centre of the turn?
Above 220 in the roof over the turn?

If so, job done, run it.

Graphs and equations dont make a motor run hard, they just help people with less hands on experience quantify things, but they won't help those people if you put a grinder in their hand & tell them to make 600hp.
Hands on engine building & porting experience does that.

Set your sizes, check your velocities, cam appropriately etc & you'll get the results, you'll be done before these guys finish arguing about how to calculate the exact cross section of a port they didn't carve.

Yeah, I'm grumpy, I hurt my back - carting around bits of engines I'm actually building - and it hurts & is restricting my movement & making me a bit pissed off.

[Carnut1]

Feel better Tony, great post!

[PRH]

So then you can tell me what I need for the head I have posted here?

Probe the port, is it at least 260ft/s at its slowest point through the pinch? Is it around 300 in most of it? Does it stay under 350? If so & it's flowing 280 or so then you're good.

Is it under 400 over the centre of the turn?
Above 220 in the roof over the turn?

If so, job done, run it.

[RevTheory]

I thought the idea was to lay solder around the pinch area because the whole thing was hand-formed. Measure the length of your solder and get an area calculation. Did I miss the boat again?

Yup. Only gives you the area if it's a perfect circle. Other shapes have less area for a given perimeter.

Look at it this way, a 1 inch wide, 2 in tall rectangular port has an area of 2 square inches, and a perimeter of 6 inches. Mistakenly calculating it as a circle using the perimeter gives 2.87 square inches. Picture something like a clover shape and how little area and how much perimeter it can have.

Well shoot. Thanks for the correction; I'm pickin' up what you're puttin' down now.

[GARY C]

Gary,
You know measured the CFM it is constant for that lift. But the port is not a uniform shape / CSA. AS the port CSA varies so does the velocity.

Stan

ab-csa-383-6400.gif

Sorry I don't understand what the graph is saying?

[GARY C]

All these graphs & equations have very little to do with an actual running engine.

Probe the port, is it at least 260ft/s at its slowest point through the pinch? Is it around 300 in most of it? Does it stay under 350? If so & it's flowing 280 or so then you're good.

Is it under 400 over the centre of the turn?
Above 220 in the roof over the turn?

If so, job done, run it.

Graphs and equations dont make a motor run hard, they just help people with less hands on experience quantify things, but they won't help those people if you put a grinder in their hand & tell them to make 600hp.
Hands on engine building & porting experience does that.

Set your sizes, check your velocities, cam appropriately etc & you'll get the results, you'll be done before these guys finish arguing about how to calculate the exact cross section of a port they didn't carve.

Yeah, I'm grumpy, I hurt my back - carting around bits of engines I'm actually building - and it hurts & is restricting my movement & making me a bit pissed off.

If my conversion is correct then the port is over 380 mid stream from the entrance to nearly the bowl and 410+ over the apex floor and flowing 300 cfm.

[GARY C]

you asked if the maths was wrong. i simply explained why it isnt. thats why it hasnt been corrected

But the person presenting it says it is... So why not address him?

He did not use the word wrong at all in the quoted post. I'm guessing he already knows why there is a difference

Maybe wrong is the wrong word but if you use a math equation and get a different answer then the actual measurement can both answers be right? Thats all I am asking.

If both answer can't be correct then one of the methods has to be wrong, thats all I am saying.

I can't say that I have ever got the same answer from the math that I have from the measurement so I am wondering where the math came from and why it hasn't been corrected to fit the actual measured air speed or what am I missing here?

As best as I can tell some of the best performing engines have heads that are clearly smaller and faster then the math would suggest.

[PRH]

You could always send a head to Chad, pay him to flow it and probe it...... see how his velocity map compares to yours.

[GARY C]

You could always send a head to Chad, pay him to flow it and probe it...... see how his velocity map compares to yours.

I can have that done here local, in the last 14 years most of my heads as far as flow numbers have been tested on other benches and are within 1or2 CFM of what I am getting. My bench was 1 to 2 cfm higher above 250 cfm on a test done against DV's bench and Ultra Pro Machining using 2 test orifices so I take that into account.

So far from everything I have seen my cs, cfm and velocity are correct, I am just not sure making the head bigger to slow down the air speed to the widely published 300fps is the best way to go.

It seems the better power producing engines have smaller faster heads.

[PRH]

It seems the better power producing engines have smaller faster heads.

If you’re comfortable with that conclusion...... then it seems you should just run it.

Isn’t that what you have? The smaller, faster port?

I bought an SF-110 new in January of 93.
Used it until I bought a Saenz S-600 in the summer of 07.
I had them both here for a couple of months.

In general terms........ testing on both benches....... smaller heads flowed less on the new bench, bigger heads flowed better.
With a big head on the small bench when you’re down around 5-6” test pressure, it didn’t seem like “area” bought you much in terms of gains on the bench.
At 28”, those differences showed up.
Heads like a std port BB Mopar, flowing in the 300cfm range(think Edelbrock RPM or Mopar Stage 6).....seemed to be about the crossover point(heads showed within a couple cfm between benches)....... where bigger higher flowing flowed more, smaller lesser flowing flowed less(on the new bench).

Example: Ported Indy 440-1 that flowed in the 350 range showed 10-15cfm more, something like a ported SBC Dart 200 in the 285 range showed 10-12cfm less....... than what the numbers were on the SF-110.

But occasionally........ you’d flow something that bucked that trend....... a “bigger” or “smaller” head that showed the flow between benches to be pretty close.

I had hoped to be able to refer back to my previous 14 years of testing to gauge how I was doing on new heads, tested on the new bench........ but eventually I found that I couldn’t consistently rely on the trends to pan out....... started a new database with the new bench.

[GARY C]

It seems the better power producing engines have smaller faster heads.

If you’re comfortable with that conclusion...... then it seems you should just run it.

Isn’t that what you have? The smaller, faster port?

I bought an SF-110 new in January of 93.
Used it until I bought a Saenz S-600 in the summer of 07.
I had them both here for a couple of months.

In general terms........ testing on both benches....... smaller heads flowed less on the new bench, bigger heads flowed better.
With a big head on the small bench when you’re down around 5-6” test pressure, it didn’t seem like “area” bought you much in terms of gains on the bench.
At 28”, those differences showed up.
Heads like a std port BB Mopar, flowing in the 300cfm range......seemed to be about the crossover point....... where bigger higher flowing flowed more, smaller lesser flowing flowed less(on the new bench).

Example: Ported Indy 440-1 that flowed in the 350 range showed 10-15cfm more, something like a ported SBC Dart 200 in the 285 range showed 10-12cfm less....... than what the numbers were on the SF-110.

Yes I have compared 180, 195, 200, 220, 227 and 240's ish heads from my bench to SF 600's, I am not to concerned about the total flow numbers as I know they don't really matter except for looking at changes, and it will all change when I start adding the intake.

On an OTB set of EQ 200's (poured 195) I got a base line flow and then did mild port work and gained nothing, I thought maybe it was an issue with my bench, so I payed a shop to flow the ported and unported ports that I had checked on their SF600 (I never told them my results) and then also to do a valve job on both ports and retest them. They ended up flowing them twice and cking the calibration on their bench thinking they also made a mistake.
After the valve job the port I ported picked up exactly what it should have and the OTB port lost flow, rechecked on my bench all lift points were either that same or within a cfm or 2 up or down.

I had to order cc-ing equipment as mine has magically disappeared, at this point I think I will end up in the 2" cross section and would like to see 350 to 360 fps but I don't want the port to be bigger than 210.

I think the heads I ran on this combo years ago in my "bigger is better" days were 240cc+ but never exceeded 317 cfm and I never checked air speed, didn't even know what it was supposed to be, so if all goes well I will ck those and hopefully dyno these with all things being the same except for heads and intake and what ever else I screwed up on the first time to see if I have learned anything.

[GARY C]

I will add this to the mix...

Does anyone know what port speed should be through the head with intake vs without and what should it be at the plenum?

I have always wondered why all engine discussion and math equations exclude the intake?

[Stan Weiss]

Gary,
The math that Chad and I posted has to do with the relationship between cfm, csa and average velocity in fps. It does not matter if that CSA is in the head or the port. To be honest at this point I am not sure what you are looking for.

Stan

[digger]

But the person presenting it says it is... So why not address him?

He did not use the word wrong at all in the quoted post. I'm guessing he already knows why there is a difference

Maybe wrong is the wrong word but if you use a math equation and get a different answer then the actual measurement can both answers be right? Thats all I am asking.

If both answer can't be correct then one of the methods has to be wrong, thats all I am saying.

I can't say that I have ever got the same answer from the math that I have from the measurement so I am wondering where the math came from and why it hasn't been corrected to fit the actual measured air speed or what am I missing here?

As best as I can tell some of the best performing engines have heads that are clearly smaller and faster then the math would suggest.

The equation is correct, the application of the equation can be wrong or the inputs of flow or area can be subject to measurement error . Same measurement of velocity usibg a probe has error and it's not measuring the same thing as what the equation is as there is always some amount of gradient in the velocity

[KnightEngines]

Gary, open the valve till its flowing 280cfm, probe at that lift.

Fast is good, just not too fast.