Don Terrill’s Speed-Talk

Above average understanding... but humble enough to talk about how it will benefit us, the ST listeners. NICE !

Frankshaft wrote:

BradH wrote:

David Vizard wrote:PM me with your contact details if you are of a mind to push forward on this proposal.
DV

I'm curious as to whether the offer that DV presented to Frankshaft was even discussed between them. It struck me as a very interesting opportunity for both.

Actually, I just seen this, and read the offer above. I am actually kind of surprised. I have sent 2 sets of 7721 edelbrocks, some gv2's, and a set of d3's for evaluation . Just kidding, but seriously, I am not as closed minded as I may come across as, I can be blunt, but at least I am not afraid to speak what's on my mind. To be fair, I probably should have gotten more info, and learned more about this port energy stuff, before I gave such a strong opinion. I am open to talking with David. I sorta did that with the 128 rule too, before I was explained what it was all about. I noticed he sent me a pm, so, I will reply.

Frankshaft,

I really liked the tone of your response here. Really looking forward to talking.

I am keeping a keen eye open for that PM.
DV

David Vizard wrote:Frankshaft wrote:- As far as port energy, you can call it whatever you want. That's fine. Its not a necessary "measurement" or one of the many port dynamics that exist. Someone that understand port "dynamics" knows that. Porting cylinder heads isn't about grinding, sticking it on the flow bench, flowing it, grinding more, sticking it back on there to see if it flows more. Its simply about sizing the port for the given application, creating complimenting areas within the runner, and then tuning the velocity profile to compliment the application. Its different for every application. maximizing what you refer to as port energy, will in most cases create a port that is to fast. One of the most misunderstood "dynamics" in cylinder head porting is velocity. Its not the most velocity you can create, but the correct velocity for the given application, that's the trick, knowing what you need. So, respectfully, I am not a follower of port energy. Sorry. I would blow most peoples minds on here, what I have made for power with every application under the sun. The kicker, at least half or more of the time, the heads NEVER went on a flow bench. One time, I hand ported a set of Indy 600-13x cnc castings from scratch, for a local dyno shop friend of mine, to replace a set of cracked and burnt up castings that BES did originally. My heads made 30 more hp on the same short block, vs BES's cnc'd set. The heads never went on a flow bench. I have a Saenz S-600 for the record, its my 3rd flow bench I have owned over the years. This usually bugs people, when I say this, but, a flow bench is an intermediate learning tool. I know its not, but I make that joke all the time. That quote was actually from Billy Glidden. I have picked up no less than 20 sets of AFR whatever. Fill in the blanks. BBC 357's, sbc 195,s,210's, 220's, 227's, 235's, etc etc, HUGE. Not even kidding. Usually to the tune of 40-60 hp. Why, because they have killer port energy. Reducing it makes WAY more power. Its not even about flow. Recently I re ported a set of RHS 200 heads I did for a 331 sbc road race engine. They were originally ported and had I would bet good port energy. Small port, fairly high flowing port. He built a new 377 short block, redynoed, and it quit a bit early. Re ported the heads for the new application, mainly to adjust the velocity profile, it gained minimal cfm, but made 35 more hp. The port energy as described was lower, but it made 35 more hp. I could go on and on with this stuff. Might not be able to articulate as well, with fancy graphs and the like, but I promise you, I know how to make real power, as well as anyone, and better than most.

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I thinking the same way than Frankshaft, it´s all about sizing the port, no matter how it flows but usually it´s flow well enough when everything has made wright for a given application.

somewhere in all this DV has said his program gives the target area (port size). so its about optimizing the port energy with a given target area.

if your target area/port size is wrong then i think it is quite possible a bigger port with less port energy can function better than a port that is just a bit too small but has slightly better port energy.

Digger, you got it.

I should add depends on the rpm!

Sorry guys, I was doing my "Cool hand Luke" impersonation in the worlds hottest shed most of the day. A bit fried. Digger I think you are right, if the port energy is higher but the airspeed is above the target airspeed it will make less power than the bigger port with the target airspeed and the port volume to feed the air. On my 289's I just couldn't get the airflow with the smaller valve and port to match my first pair. The air on the bench wasn't any faster either! Port volume is a huge part of this equation. I think Frankenshaft is on the port volume track when he ports out high velocity heads and lowers the airspeed and picks up power.

How do you calculate your desired intake velocity & x/ section area with your intake port temperature as surely this has an effect over varying applications . Eg drag racing compared to curcuit etc . Thanks in advance

a1_aus wrote:How do you calculate your desired intake velocity & x/ section area with your intake port temperature as surely this has an effect over varying applications . Eg drag racing compared to curcuit etc . Thanks in advance

The flow test IOP program does all this for you. Essentially it not only tells you what you have but also tells you where you need to go.
'
check with stan Wiess but this program should be on sale soon.
DV

Hi David! You said that I could test the program so I sent my email adress to Stan but then nothing happened?

Erland

Erland Cox wrote:Hi David! You said that I could test the program so I sent my email adress to Stan but then nothing happened?

Erland

ERLAND,

i WILL SORT THAT OUT FOR YOU RIGHT NOW.
DV

Thank you David!

Erland

Erland Cox wrote:David, what is your target on port energy for best hp?
There must be a point where getting more port energy is starting to cost power?
This is the formula for calculating velocity from pressure:



From reading your books you claim that if the piston driven pressure in the cylinder is more than 25" of water there is something wrong with the head.
But in other discussions it is said that an engine starts loosing power at 620 fps mean intake velocity.
620 FPS if I have not miscalculated takes 83" of water to achieve.
25" of water will only give 340 fps.
I would like some clarification here if possible.

Erland

Hi David, Just reminding you about this question.

Erland