Re: Ported Dart 215 pro1 platinum with port energy discussion 2.0

[maxracesoftware]

0311181226a.jpgBeen thinking of polishing out the radius under the 45 seat. Input welcome. Thanks, Charlie

by groberts101 » Sat Mar 17, 2018 11:15 am
Hi again, Charlie. Don't have much input on the flow and physics related to the task at hand here.. but I did want to take the time to commend you on your much improved porting quality as of late. That old saying "practice makes perfect" seems to be very true when it comes to shaping and carving metal.

i was thinking the very same thing when i saw that exhaust porting picture

[user-30257]

You can only learn so much chasing cfm or port energy around on a flow bench. At some point you need other data, like dyno and/or track info. And it's likely you have figured out the shapes that flow good.

And I also think your grinding skills are good.

CFM only tells you so much.

Randy

That's a nicer way of saying what I was thinking

[user-30257]

My .02 is min CSA does NOT set the peak RPM.

Do more testing. You will find it.

[user-9274568]

My .02 is min CSA does NOT set the peak RPM.

Do more testing. You will find it.

You can have the exact CSA some formula tells you. If the port is not balanced, it won't make it. So figure out what's more important.

And stop treating me like a dumb ass, please. I'll respect you if you do the same.

[groberts101]

IMO, CSA numbers can be highly subjective and only gets you in the ballpark when comparing different castings or for baselining a start point before removing more material in the porting process.

IOW.. you can have a huge bowl area with large throat and smaller fast entry section leading up to and slightly beyond the PR pinch of same CC size as another casting with much bigger entry section(sleeved/welded PR holes) and having smaller bowl/valve/choke area. Velocity profiles in different areas of the port can be considerably different and may not fit a particular application best. Having a very fast entry speed can also create other nasty side effects for an already challenged OEM style SSR as well.

Not going down the rabbit hole by implying one is correct over the other and sometimes we have to make do with what we have to work with by adjusting one area to suit another(ala SSR width, etc). Just pointing out that expecting a particular velocity throughout all areas/full length of the port can be extremely misleading when choosing heads based on volume ratings alone.

[Carnut1]

You can only learn so much chasing cfm or port energy around on a flow bench. At some point you need other data, like dyno and/or track info. And it's likely you have figured out the shapes that flow good.

And I also think your grinding skills are good.

I just dynoed a 468 cube BBC with a set of 781 casting heads I did some porting on. The math on the csa says it'd peak at 6800-7000 but it was way short on cfm when figuring cfm demand for that cube/rpm. But it peaked right in that rpm range.

CFM only tells you so much.

Randy

Randy, the 781's make good power when tickled just right. Early 2000's I did a 496 with 781's 2.25/1.88 for a monster truck. Guy loved em. Thanks for the compliment, hope you aren't getting soft in your old age. Charlie

[user-30257]

My .02 is min CSA does NOT set the peak RPM.

Do more testing. You will find it.

You can have the exact CSA some formula tells you. If the port is not balanced, it won't make it. So figure out what's more important.

And stop treating me like a dumb ass, please. I'll respect you if you do the same.

I'm not chad, you may see it that way. I see your work and it looks good, far better than most I see posted to the internet. And out of the internet community I think you are one of the top in porting skill.
However, think of it this way. When you do enough heads of a make you can simplify your work into csa, cut it and send it. Does a CNC port use flow figures you give it as datum?

More times then not, if you size it and it flows what it flows, cfm is right there. You can verify your work on the bench, dyno the engine and fine tune it from there if needed. Write down the tweaks you did and store it for the next similar build. See where I am going with this.

[user-30257]

Charlie, I see you are getting better at grinding. But the amount of time you are spending using this port energy and flow bench figures could be cut into 1/100.

Keep up the work on informing others how this is going for you.

[user-9274568]

Do more testing. You will find it.

You can have the exact CSA some formula tells you. If the port is not balanced, it won't make it. So figure out what's more important.

And stop treating me like a dumb ass, please. I'll respect you if you do the same.

I'm not chad, you may see it that way. I see your work and it looks good, far better than most I see posted to the internet. And out of the internet community I think you are one of the top in porting skill.
However, think of it this way. When you do enough heads of a make you can simplify your work into csa, cut it and send it. Does a CNC port use flow figures you give it as datum?

More times then not, if you size it and it flows what it flows, cfm is right there. You can verify your work on the bench, dyno the engine and fine tune it from there if needed. Write down the tweaks you did and store it for the next similar build. See where I am going with this.

But, you don't think that's what I do now? Dyno 6-8 engines a month...

And as far a this internet, what exactly does that mean? I wish I knew who you were so I can judge for myself if your as important as you think. See where I'm going with this?

Been doing this stuff far longer than you think.

[Carnut1]

Charlie, I see you are getting better at grinding. But the amount of time you are spending using this port energy and flow bench figures could be cut into 1/100.

Keep up the work on informing others how this is going for you.

Thanks, Guy. Since I started porting in my teens and I am 52 now I am starting to figure a bit out. As far as the flow numbers and port energy, I think it is funny how I have graphed one porters heads who said port energy was b.s. his heads were up near 29 hanging right with Chad's cnc 205's. Today I did a quick rough out of an intake, exhaust and chamber.... 300cfm 211cfm. That was a reserved rough out no polishing the ssr. To bring them to 322cfm 232cfm. I need to do some measuring, flowball action and Pitot airspeeds.

[user-17438]

Looks good Charlie. Now put them on an engine to quantify your results.

[Carnut1]

Looks good Charlie. Now put them on an engine to quantify your results.

I know! It should be easy.... I need to figure out if one of my stock 400 two bolt blocks are good enough. Figure out which rotating assembly I can afford and will do what I want. Which intake compliments the heads and cubic inch and desired rpm range. Change out my fuel system and pick an injection system. Lets not forget another 40 page thread on choosing a cam that makes it all work together. Finding the funds without cleaning out the kids college accounts. This would be a good time to be a 1% er! Thanks, Charlie

[user-17438]

Looks good Charlie. Now put them on an engine to quantify your results.

I know! It should be easy.... I need to figure out if one of my stock 400 two bolt blocks are good enough. Figure out which rotating assembly I can afford and will do what I want. Which intake compliments the heads and cubic inch and desired rpm range. Change out my fuel system and pick an injection system. Lets not forget another 40 page thread on choosing a cam that makes it all work together. Finding the funds without cleaning out the kids college accounts. This would be a good time to be a 1% er! Thanks, Charlie

scat, eagle, molnar. would be a nice starting point, putting anything nicer in a stock block will just cost you more money. and the power level you will make wont need anything outrageous. Just do a 420" and hope the block lasts long enough for some fun.

start building, we are getting getting old man.. lol

Teach the kids responsibility. go have fun and tell them to get an internship with a company that will pay for their education. lol

[WeingartnerRacing]

Randy is right you need to dyno after awhile you are chasing cfm but the dyno might show nothing or a loss. After you dyno you will have more questions you will need to solve to help your Porting. Also stop comparing your flow numbers to other people’s numbers. Unless that Head was flowed on your bench too those numbers will mean nothing. What if there bench reads high or yours? Then they look different with the port velocity charts you have. Something to think about.

[Stan Weiss]

Do more testing. You will find it.

You can have the exact CSA some formula tells you. If the port is not balanced, it won't make it. So figure out what's more important.

And stop treating me like a dumb ass, please. I'll respect you if you do the same.

I'm not chad, you may see it that way. I see your work and it looks good, far better than most I see posted to the internet. And out of the internet community I think you are one of the top in porting skill.
However, think of it this way. When you do enough heads of a make you can simplify your work into csa, cut it and send it. Does a CNC port use flow figures you give it as datum?

More times then not, if you size it and it flows what it flows, cfm is right there. You can verify your work on the bench, dyno the engine and fine tune it from there if needed. Write down the tweaks you did and store it for the next similar build. See where I am going with this.

What am i missing? Last I saw a CNC is nothing more than a fancy Xerox machine.

Stan