Cylinder Head Porting and Power Production

[PRH]

To touch on RRR’s question, particularly in terms of the traditional OE SBM 340/360 head castings.........

The way I look at the flow vs cost ratio is this......(and it assumes the one doing the work is reasonably proficient with these heads).......

In a nutshell....... the first 15-20mins per cylinder is the biggest bang for the buck....... especially if you’re not worried about what it looks like.
After that, the time spent vs flow gained goes up pretty quick.

The 1st 20cfm is pretty easy, the next 20 is harder, the next 20 is harder still, etc.

 

[rumblefish360]

Thread title;

Cylinder Head Porting and Power Production

Let's make the hypothetical model engine a 10.0 comp .530" flat tappet , dual plane manifold, 750 carb, street headers, 408/416 SBM since they're so popular.

Let's throw out a flow rate of 250 cfm @ .500" @ 28" H2o for our discussion:

1st your going oputsie the basic info RAMM wantewd to work with.

Thanks. His case is an extreme use of the head. He is limited by class. It is an excellent use of the head.
Now let’s do similar to an aluminum head.

I don't think so

"I had a stock crank .04 overbored 360 in the Demon that went 10.25 at 129.99 mph. Ported 587 heads,.590 racer brown flat tappet cam, victor 340 intake, crane gold 1.6 rockers, 11.75 to 1 comp ratio. Motor in car now is a .04 over 360/ w a 4.100 stroke crank, [418 c.1.]. Still has the racer brown .590 cam and ported 587 heads, a little adtnl. work to heads, flat top piston out of the hole .080, 13 to 1 comp ratio, Victor 340 intake, Crane 1.6 rockers. Burns 110 octane race gas or would be fully streetable. Never over 190 degrees even when it's near 100 deg. outside. Has gone as fast as 9.68 at 135 mph and as far as 450 ft on the rear wheels. Definetly over 400 to 500 horse . Not to shabby for a junkyard headed small block in a car that weighs 3060lbs. I never recall seeing a brand X sm block w/ junkyard heads anywhere near my e.t. at or near 3060lbs. I chase alcohol burning, roller cammed, aluminum headed sm block chevys all the time."

Oh yea, this is within the basic idea RAMM posted up. GOOD JOB Hysteric, GOOD JOB!

If you think this discussion is about heads
(Interuption in his quote to remind everyone of the thread title = Cylinder Head Porting and Power Production, back to his quote!)
you're sadly mistaken as his heads were used to prove a point that you now want to totally ignore. If think airflow is everything than how come Dan makes power with the stuff you think isn't worthy of your time. There's more to making power than just airflow. If you ignore the fueling aspect then an engine is just an air pump and you need bigger heads. Oh and if you build an engine with all that exotic stuff and it doesn't make the power you think it should then it needs bigger heads....

My response below.

Incorrect and if you have been reading my posts on this subject (not just cylinder heads) you would have never ever wrote what you wrote.

Let’s revisit his head choice and what he could do by moving away from OE iron. Would be to with aluminum if he could?
Yea... thought so...

If anyone could use an aluminum head and save 50lbs. and get a better port, would you? Why wouldn't you?
CLASS rules? OK, then your stuck within the rules. Carry on.

Lets revisit the fact that he's making power with the stuff you all think you cant. Your still caught on airflow.......

Where? WHERE? Still insisting? Your turn.. go find it where i'm putting up an issue over your iron heads vs aluminum heads.
Don't bother, it's not there. Still trying to say things I didn't say. Dang shame.


Perhaps you should looka little closer to where I have often said the OE head is a good way to go but I do caution the member about possible expense vs an aluminum head that has been proven to make more power. Now this is readily done because it is an error ontheside of caution since I do not know if that person can fix or port there own heads or even want iron heads. I'll agree there is more than 1 way to skin a cat, but with what you list on ..... sorry, your car? Right? Running the 9's...correct, you ported the heads? Correct? 2005 dollars spent to the tune of $1600? Correct? I just wannabe on the same page..... Anyway, on a well sorted drag car you claimis streetable minus the 13-1 compression ratio? Right?
Double checking RAMM's posted idea of for this discussion...
(Let's make the hypothetical model engine a 10.0 comp .530" flat tappet , dual plane manifold, 750 carb, street headers, 408/416 SBM)

So I think your heads should be considered. Lets say you'll send them to Ramm for a dyno run. Would you be up for that?

 

[rumblefish360]

Just wanted to update on the exhaust port question I asked early on. I apologize if this is ridiculously obvious to some here but looking at it this way helped me to see things more clearly.

Anyway, the presumptive reason the intake gets focused on when porting (and generally why the intake valve is larger than the exhaust) is because of pressure differential.

It is much harder to fill the cylinder with the intake charge because you are relying on atmospheric pressure to do it. That pressure is reduced further (vacuum) in the intake tract when the piston is pulling down so it makes sense that any extra volume of the A/F mixture combined with a less obstructed pathway into the cylinder would clearly help to overcome the lack of pressure.

But once combustion occurs and the mixture is pushed out, the pressure of the mixture becomes much greater so the extra volume is not needed. Making the pathway less obstructed is obviously beneficial in both instances but again, the exhaust port volume is not as important. I'll be honest, I never thought about it like that.

Carry on.

Greg, next time you dyno the engine, after the distributor and carb are tuned, mess around with a header extension. Once you find out what the engine likes in terms of the added pipe length, you'll find more power down low to maybe mid rpm range due to the pulse wave. This should help out of the hole a bit. Then add the pressure wave cancellation box there at the pipes end and so onto the exhaust piping.

I'd also use a bigger primary tube header.

 

[MOPAROFFICIAL]

Trash

 

[Hysteric]

How much HP/TQ should an LA style head flowing 250 cfm be capable of producing

Remember this from his first post? SHOULD? CAN? WILL?

Some ports just "work" and some ports don't "work as well". I don't really have a hard and fast reason as to why

It might have some thing to with the fuel and the quality of the mixture. Maybe look at what swirl does and that might help see what's happening

Now how do you make the mixture more homogenous and what impact does fuel droplet size have on combustion efficiency?

 

[512Stroker]

A Super Stock racer?

Alot of this is way over my pay grade.
For what it is worth I have seen the dyno and track results of a local engine builder that specializes in NHRA stock class Mopar engines.
Two years ago one of his 340 builds won the Indy Nationals in a 69 Dart driven by Larry Gilley he constantly ran mid 10's and passed an NHRA tear down inspection.
That engine dyno'ed right at 500 corrected bhp with stock spec X heads and stock iron intake.

 

[rumblefish360]

Remember this from his first post? SHOULD? CAN? WILL?

Yup sure do and how does this work with your examples.

OH WAIT! IT DOESN'T!!!!!
Here’s a whopper!

“Still has the racer brown .590 cam and ported 587 heads, a little adtnl. work to heads, flat top piston out of the hole .080, 13 to 1 comp ratio, Victor 340 intake, Crane 1.6 rockers. Burns 110 octane race gas or would be fully streetable.

So truly streetable and within the parameters set up by RAMM.
Good job. Pump gas friendly to the point I’m sure everyone here will follow your example.

It might have some thing to with the fuel and the quality of the mixture. Maybe look at what swirl does and that might help see what's happening

Now how do you make the mixture more homogenous and what impact does fuel droplet size have on combustion efficiency?

This very direction is what I stated in an another thread.
Maybe here? I’m not looking back. You can.

But enough questions for me. How about my questions being answered since you have this down to a science.
I’ve already stated I’m game for the answer!

There have been a few questions out to you. many plans on answering them or is it you don’t know?

Let’s start with an easy one!
Is that your Duster?

 

[rumblefish360]

Alot of this is way over my pay grade.
For what it is worth I have seen the dyno and track results of a local engine builder that specializes in NHRA stock class Mopar engines.
Two years ago one of his 340 builds won the Indy Nationals in a 69 Dart driven by Larry Gilley he constantly ran mid 10's and passed an NHRA tear down inspection.
That engine dyno'ed right at 500 corrected bhp with stock spec X heads and stock iron intake.

That’s awesome. It really Doesn’t fit the guide lines set up by the original poster. But it is cool nonetheless. You can catch a glimpse into what it takes and how it is done if you ask the iron head flag wave’r above, Hysteric. He has up there an excellent example of maximizing. Is it full tilt? IDK.
What I will say about it is that it is not a combo I would drive around even sparingly, much less on a daily basis. To each there own, but I’d bet if you took a pole on that combo vs others, the masses would choose otherwise and such as this thread is designed after more or less IMO.

So I’ll ask you, how would you go about finishing building this basic idea;

By RAMM
Let's make the hypothetical model engine a 10.0 comp .530" flat tappet , dual plane manifold, 750 carb, street headers, 408/416 SBM since they're so popular.

Not trying to be a dick here, but....
I personally don’t care how you finish it.
According to Hysteric, anything but an iron OE head is wrong and you screwed up and wasted money.

 

[Hysteric]

This very direction is what I stated in an another thread.

Since you understand it so much how about you explain it to RAMM so he can make more power with the airflow he already has.

According to Hysteric, anything but an iron OE head is wrong and you screwed up and wasted money.

Thanks for the straw man. It has nothing to do with OEM or After market heads.

 

[RustyRatRod]

Can we put the dicks up please? This could be a great thread. Thanks.

 

[moper]

The thread has zero to do with heavily scienced Stock or Super Stock efforts. while I understand where Hysteric’s coming from, I would say take it elsewhere. You’re talking about overall output, not strictly head related (13:1, essentially closing the chamber and reducing the need for timing, major reworking of a factory casting). Nothing fits here. Start a new thread.

 

[lead69]

I always try to put the smallest port with the best low lift flow number's to get the peak hp where I want it depending on the cid. I know that's pretty simplistic but my stuff has to run on the street and do it well with a less than stellar chassis and still be able to run respectable at the track when/if it ever gets there. There are other factors but those are the main criteria, for me a street engine has to have a big usable power curve and not be lazy down low which is also why I am a big fan of strokers.

 

[RustyRatRod]

My understanding has always been it's all about velocity. How FAST you can make the air move in and out, because by doing THAT you also aid how MUCH moves in and out.

 

[lead69]

My understanding has always been it's all about velocity. How FAST you can make the air move in and out, because by doing THAT you also aid how MUCH moves in and out.

To borrow a phrase from you, puzackly!

 

[rumblefish360]

Since you understand it so much how about you explain it to RAMM so he can make more power with the airflow he already has.

Me?!?! Aweeeee geeee mister, your the one that’s the expert. I defer to your expertise since your the one that has been there done that and still doing it as I understand it since it is your duster correct?

Noticed you still can’t answer a question.
(Is that your Duster?)
I’ll save the harder questions for you later. We’ll just keep it 1st grade simple for you.

(I think your full of it.)

Thanks for the straw man. It has nothing to do with OEM or After market heads.

Really? Then you’ll be more than happy to explain it to those who have asked the question that has been asked several times already.

I tell ya what. I think via your not answering the members but also as well but just simply leaving links to what others have written and done.

Im callin you out on this & on behalf of everyone else you did not answer. Come on smart guy! Lay us on your almighty wisdom. Brake out the science. Do tell!

(Straw on the house.)

 

[rumblefish360]

I always try to put the smallest port with the best low lift flow number's to get the peak hp where I want it depending on the cid. I know that's pretty simplistic but my stuff has to run on the street and do it well

for me a street engine has to have a big usable power curve and not be lazy down low which is also why I am a big fan of strokers.

That is a damn good recipe for a strong and pedal responsive engine of any size.

My understanding has always been it's all about velocity.

I agree. But I chopped up your quoted message some and rewrite the below into a question.

How FAST you can make the air move in and out?

As in when does it become to fast or just the reverse?
I was watching an Engine Masters episode where Dave Freiburger had a 400 SBF stroker, small cam and swapped out 3 different AFR heads to see if he could get to much head on top of the engine. The short answer is no, but! The smallest head made as much power as the largest head while the medium head did best all around by just a little bit. The differences were super small between biggest and smallest.

I’d like to see EM revisit this. And I would like to see some (honestly, everything possible there set up for if possible) engine parameters that could very well be very telling.

Since RAMM set up a parameter of 400 or so cubic inches, even though this was a Ford engine, IMO, the working idea is within the scope of the intentions of the threads idea.

Unlike Hysterics 13-1 engine.
Which doesn’t fit.
Good job Hysteric!
Is that your Duster?

 

[moper]

Every engine has its sweet spot. The heads are important but a piece of that “spot”. Street engines with long rods and long strokes are going to be most efficient (at least imo) with a smaller higher velocity port. The physics of the running engine helps there, in the operating range of the intended use. All other factors excluded, thats where the Vortec/Magnum/small-volume-big-speed-lots of swirl-induced-type head prevails.

 

[MOPAROFFICIAL]

Deleted my posts.
Op disappeared.
This turned into a sponge..dumpster fire...

I have other notions of the intentions of this.

 

[RAMM]

Deleted my posts.
Op disappeared.
This turned into a sponge..dumpster fire...

I have other notions of the intentions of this.

I didn't disappear, I just have nothing else to add at this time. It seems many involved have it all figured out. I was trying to distill it down so I could and maybe help others gain a deeper understanding of what makes some cylinder heads work so much better than just flow numbers would indicate on their own. I'm not just talking WOT/dragstrip style performance here alone but an all around great performing engine with manners that could be described as mundane--until you experience it. Anyways, this thread can fizzle out it was good while it lasted. J.Rob

 

[MOPAROFFICIAL]

it was good while it lasted. J.Rob

Indeed.
More could have been learned too, but it turned into a circus.imo
Maybe you understand more why i get the way i do, maybe not. Good thread.

 

[yellow rose]

My understanding has always been it's all about velocity. How FAST you can make the air move in and out, because by doing THAT you also aid how MUCH moves in and out.

How FAST you can get it and CONTROL it. You are trying to control air speed, equalize air speed, manipulate air speed...all in the name of volumetric efficiency and continued cylinder filling after BDC and before IVC.

That’s why swirl, twirl, tumble, swumble and all that kill power. It takes energy to make the air column do that. That’s the exact opposite of what we are trying to accomplish.

 

[yellow rose]

Thanks for taking all those measurements Rob. I had my numbers off. I do know that when the W5 heads are bolted on you need to use about .750 worth of spacers on the China rails to make up for the added height.

And that’s outside the scope of what RAMM wants to discuss, but I think it’s part of understanding how two ports, seemingly flowing the same CFM can have very different HP a numbers.

Valve angle, port angle, pinch and pinch location all change how well a head uses air.

 

[PRH]

I think when it comes to tech topics, where the thread starter has some specific views and ideas they want to share, it might be better if they could be presented in a “read only” format, so it would end up being more of an on line “article”, rather than a discussion.

The problems that can happen when they are discussions is that people try interjecting their interpretations/views of the subject, which may not align with the points the OP is trying to make........ and the next thing is often the whole thing going sideways.

So....... maybe an “article”, with there being some room for a discussion or some comments posted at the end, after the entirety of the information has been laid out by the one writing it.

 

[rumblefish360]

No problem there YR. Anytime.

Well, the heads as intended, IMO, and I guess.... LOL .... from Mopar are race heads.
The "Let's make the hypothetical model engine a 10.0 comp .530" flat tappet , dual plane manifold, 750 carb, street headers, 408/416 SBM since they're so popular.

Let's throw out a flow rate of 250 cfm @ .500" @ 28" H2o for our discussion:"

AS cast, they would about fit this description. As well as a W2 head. While the head itself via there "W" description and MoPar race backing status, do not fit as intended like an Edebrock, SM or TF head would, I do so think that there price tag (Valve gear mostly) was the only draw back to there use, but would fit in otherwise for the guy looking to make a bit more of a average hot street engine. I'm not fond of the big china rail gap, but it is a small issue to over come if one is handy or crafty.

Edit, I'll have to mount the heads on a spare short block that is a bit buried right now and lay the intake on top, snap a shot, keep it on hand with a measurement note.

 

[yellow rose]

I didn't disappear, I just have nothing else to add at this time. It seems many involved have it all figured out. I was trying to distill it down so I could and maybe help others gain a deeper understanding of what makes some cylinder heads work so much better than just flow numbers would indicate on their own. I'm not just talking WOT/dragstrip style performance here alone but an all around great performing engine with manners that could be described as mundane--until you experience it. Anyways, this thread can fizzle out it was good while it lasted. J.Rob

I’m not sure how far we can distill this down without ending up in the weeds.

I’m 100% sure that shape is everything, CFM is at best secondary a that the valve job may be the most overlooked aspect of part throttle drivability there is.

I’ll say it again...if we focus on flow and not shape, we will get engines that hate overlap, hate properly sized exhaust or is at least not responsive to header and exhaust changes. And to that end, the engine becomes, for lack of a better term...stupid to tuning changes.

I’ve had engines that would run the same from 36-44 total. It didn’t care. The plugs showed that the timing was changing, but nothing on the dyno or time slip.

Those same engines would run the same across 10 jet sizes. The plugs would show the fuel ring moving up and down, but literally zero HP on the dyno and time slips.

I love a nice, wide tune up window, but a 2 degree timing change from optimal either way SHOULD make a change in power, but when an 8 degree swing does nothing, something is wrong.

On one particular engine I traced it back to the valve job on the intake. For whatever reason, the guy who did the heads put a radius seat on the intake.

I fixed that, lost a bunch of flow in all the wrong places and the car went quicker and tune up changes were much more sensitive.

Flow isn’t always good. I think everyone can agree on that. It’s where the flow is and when it is that matters.

What goes on at TDC is far less important than what happens later, especially when dealing with reversion.