Minimum Cross Sectional Area: Question

[raynorshine]

. Yet you want to reinvent the wheel.. .

I'm not trying to reinvent anything mt.
I asked a question about MCA. Seeing as I'm trying to avoid "something that's been done before", I'll continue to ask.
Yes. Good suggestions have risen up. And I check them all out. Funny in that these suggestions often have a different spin. So what's right? What's rubbish? And what fits my unique combination of parts? And before everyone goes off all half-cocked, they're not unique in the sense that no one else has them. But unique in the sense that I have them.
Once all the dots line up, then I'll be good to go.

By the way mt, while you're here I've a question.
How would you spec a cam for the following dyno engine? 383, 9.8:1, 255@.500-.550 iron heads, 6" rods, RPM Air Gap. Pump gas. (I can provide additional details should you want them). I want good on paper results. Forget any application.

-that doesn't seem like very much information to spec (more like speculation) a camshaft...?

-how could anybody make a recommendation without considering application..?

[skinny z]

How about a crate engine? Not built to any particular spec. Purchased based on one, sure.
I want to see best results on paper dare I say, like a magazine engine! Plenty of those around. You're just stuck with heads really.
But that's not really what this thread's about. It was about MCA. I think I've got enough to make an informed decision now. And it was something I hadn't considered in the engine spec before.

[gmrocket]

. Yet you want to reinvent the wheel.. .

I'm not trying to reinvent anything mt.
I asked a question about MCA. Seeing as I'm trying to avoid "something that's been done before", I'll continue to ask.
Yes. Good suggestions have risen up. And I check them all out. Funny in that these suggestions often have a different spin. So what's right? What's rubbish? And what fits my unique combination of parts? And before everyone goes off all half-cocked, they're not unique in the sense that no one else has them. But unique in the sense that I have them.
Once all the dots line up, then I'll be good to go.

By the way mt, while you're here I've a question.
How would you spec a cam for the following dyno engine? 383, 9.8:1, 255@.500-.550 iron heads, 6" rods, RPM Air Gap. Pump gas. (I can provide additional details should you want them). I want good on paper results. Forget any application.

That kind of CFM can make more power than you think...your underestimating your goals. Forget the 5500 thing...a fatter power curve is what you need

Maybe that program is on the conservative side of the power numbers?

[GARY C]

In around 8 would work for what I have in mind. But having said that, the final engine package and application hasn't been entirely determined. Hence the point of this thread.

Application is going to play a key part, if you are looking at DRC in relation to pump gas then you have a somewhat narrow window to hit that number, if you want to increase rpm then the cam needed is going to lower DCR unless you increase compression in relation to cam but then you start getting out of the range of pump gas.

I only started looking at DCR on my last 2 street engines because my concern was idel quality and drivability and with an iron head and 10.1ish compression I didn't want a cam that put my DCR over 200 psi and run the risk of trying to tune something that should not be on pump gas.

Funny, ive had some big block chevys for motor homes with that kinda number at 9.5:1 375hp 461" .. No tuning problems, detonation problems. Once you guys realize DCR is a BS number along with cranking compression , You will start to be on par with real engine builders that dont care what some made up formula says. They learned to try what works vs some arbitrary calculation.

Bottom line. Is you arent building anything different from whats been done before. Yet you want to reinvent the wheel.. A kot of good suggestions were presented. Once you waste all your time and money on a underperforming cam, it will seemingly run great. Because you wont know how well it would have run if you would have listened to people that actually build engines day to day.

Keep it simple stupid.

A stock motor home with 200 plus cranking compression?

[skinny z]

That kind of CFM can make more power than you think...your underestimating your goals. Forget the 5500 thing...a fatter power curve is what you need
Maybe that program is on the conservative side of the power numbers?

I haven't run any simulations on any of this. It's the MCA I've been investigating and then TM became available to me. I've been messing around with that and am seeing some interesting (to me) engine spec data. And I haven't even looked at the estimated power numbers although I can see that I can make a ton of torque. Not unlike, say, a tow truck engine. Maybe even a motorhome.
Anyway, I'd like to keep everything light and entertaining. It's not anything important is riding on this. Just information. Ultimately an engine. And that's one that's built in an informed way.
As for 5500. Maybe 5700. Shift a 6000. But that said, at that RPM, it would play nicely into a potential project. The supporting parts are there and would probably yield better results than the 6500 peak, shift close to 7000, that's currently alive (but barely). That's another story though.

[GARY C]

In around 8 would work for what I have in mind. But having said that, the final engine package and application hasn't been entirely determined. Hence the point of this thread.

Application is going to play a key part, if you are looking at DRC in relation to pump gas then you have a somewhat narrow window to hit that number, if you want to increase rpm then the cam needed is going to lower DCR unless you increase compression in relation to cam but then you start getting out of the range of pump gas.

I only started looking at DCR on my last 2 street engines because my concern was idel quality and drivability and with an iron head and 10.1ish compression I didn't want a cam that put my DCR over 200 psi and run the risk of trying to tune something that should not be on pump gas.

Funny, ive had some big block chevys for motor homes with that kinda number at 9.5:1 375hp 461" .. No tuning problems, detonation problems. Once you guys realize DCR is a BS number along with cranking compression , You will start to be on par with real engine builders that dont care what some made up formula says. They learned to try what works vs some arbitrary calculation.

Bottom line. Is you arent building anything different from whats been done before. Yet you want to reinvent the wheel.. A kot of good suggestions were presented. Once you waste all your time and money on a underperforming cam, it will seemingly run great. Because you wont know how well it would have run if you would have listened to people that actually build engines day to day.

Keep it simple stupid.

The main thing you fail to recognize here is that I have already built the engine you and others think I should build and for what I was trying to achieve I found what you think I should build to be under performing, so as opposed to following what everyone else does I chose to try something that others say wont work and refuse to try and in doing so I found a simple way to achieve exactly what I was looking for the first time around and I didn't need a dyno, 3 cams and 2 sets of heads to get there. I just utilized what I had learned from all my past builds.

[GARY C]

. Yet you want to reinvent the wheel.. .

I'm not trying to reinvent anything mt.
I asked a question about MCA. Seeing as I'm trying to avoid "something that's been done before", I'll continue to ask.
Yes. Good suggestions have risen up. And I check them all out. Funny in that these suggestions often have a different spin. So what's right? What's rubbish? And what fits my unique combination of parts? And before everyone goes off all half-cocked, they're not unique in the sense that no one else has them. But unique in the sense that I have them.
Once all the dots line up, then I'll be good to go.

By the way mt, while you're here I've a question.
How would you spec a cam for the following dyno engine? 383, 9.8:1, 255@.500-.550 iron heads, 6" rods, RPM Air Gap. Pump gas. (I can provide additional details should you want them). I want good on paper results. Forget any application.

The problem with "Forget any application." is that application determines the answer to every question you are asking.

[skinny z]

The problem with "Forget any application." is that application determines the answer to every question you are asking.

Except one.
Let's put things this way. Build a spec with the most horsepower and torque. I'll make the application fit. Rather than the other way around.
Take my heads (the only thing confirmed other than the engine architecture and CID), and build the best you can for "Engine Masters". Call it "Skinny's Engine Competition".
I can do the rest. Seriously.

[GARY C]

The problem with "Forget any application." is that application determines the answer to every question you are asking.

Except one.
Let's put things this way. Build a spec with the most horsepower and torque. I'll make the application fit. Rather than the other way around.
Take my heads (the only thing confirmed other than the engine architecture and CID), and build the best you can for "Engine Masters". Call it "Skinny's Engine Competition".
I can do the rest. Seriously.

If you are settled on the CI, heads... what rpm, pump gas? race gas? porting? converter? gears? No advice will fit a plan that you don't have?

[raynorshine]

-this is the most BIZARRE....thread i have ever seen/read/followed/ witnessed..... here on Speedtalk...

-talk about circular conversation....... absolutely no direction.........

[gmrocket]

-this is the most BIZARRE....thread i have ever seen/read/followed/ witnessed..... here on Speedtalk...

-talk about circular conversation....... absolutely no direction.........

It's dynamic

[Orr89rocz]

-this is the most BIZARRE....thread i have ever seen/read/followed/ witnessed..... here on Speedtalk...

-talk about circular conversation....... absolutely no direction.........

It's dynamic

Lmao! Indeed

[skinny z]

-this is the most BIZARRE....thread i have ever seen/read/followed/ witnessed..... here on Speedtalk...

-talk about circular conversation....... absolutely no direction.........

Entirely due to the original question getting derailed.
To refresh memories, will the MCA of these heads limit RPM to a 5500-5700 HP peak?
Although I can say that buried in there somewhere is the answer. So, not entirely without direction. Or satisfaction.

Gentlemen ,
Here is a copy of a portion of my 1st post.

).
More calculations predict a max peak HP RPM less than 5500.
I'm aware there's more to it than just the raw numbers (as one build I'm following uses the smaller head to its advantages namely higher velocity).
The question is then, how far off the mark would this be from the actual result?
And for purposes of this discussion let's limit this to a dyno engine and we're looking for best torque with an RPM ceiling as mentioned.

See the limitation imposed by the last paragraph?
Got a few solid answers but then as usual with forums, it goes off the rails. Getting into the application just messes it up as my question was very simple and don't have to go any further.
The reason the thread became what it is is because the topic went off track. My fault there I suppose.
So that said, I'll thank everyone for their contributions, helpful or otherwise. And move on.

[Orr89rocz]

Lol this thread was over on page 1. What else are you looking for? Or are you looking for an answer you had in mind but waiting for someone to confirm your bias

[CGT]

Lol this thread was over on page 1. What else are you looking for? Or are you looking for an answer you had in mind but waiting for someone to confirm your bias

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