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531/405 vs 530 heads with camshafts under 12.5mm

So do we have flow numbers to support this claim?

I would like to see the differences worked out with real numbers and data, so far I am only seeing words.
 
So do we have flow numbers to support this claim?

I would like to see the differences worked out with real numbers and data, so far I am only seeing words.


No, you can't just blindly look at the flow numbers. It's not that simple.

This is an issue of the "ratio" of port volume to port flow. That's not quite the right wording, but the point is that in order for the port flow "numbers" you want so desperately to actually count for something, the engine needs to be capable of actually demanding the flow rate.

"Engine VE" is really interchangeable with the term "% cylinder fill". You need gas speed AND low inlet pressure drop in order to maximize VE. The reduced pressure drop associated with the higher flow of the 531 will only result in a net gain when the engine as a system breathes well enough to take advantage of it. Otherwise all you have is reduced gas speed which actually makes VE worse. Even though the port "flows" more.

Having a higher potential peak airflow means nothing if you don't have the cam lift and other associated equipment necessary to actually make that airflow happen in the real world.
 
So do we have flow numbers to support this claim?

I would like to see the differences worked out with real numbers and data, so far I am only seeing words.

We'll I've posted up flow data plenty before. I'll see if I can find the graphs.
Would valve curtain area ratio's be sufficient or would you like me to overlay some dyno data?
I have NA complete and turbo is nearly done.

Eric, you know this stuff, so if a B230 NA race motor your goal is 175 bhp, in our situation you need 175 cfm for a given lift, lets assume 12mm. The 531 flows 175 at 12mm of lift but the port is so big that velocity is slowish. With a nice 530 you can see 175cfm at 12mm of lift and still have nice velocity to maximize cylinder filling.

As I started writing this I realized that I was up WAY tooo late last night. I graph some graphs from the engine dyno and some more data once I've slept a bit more.
 
I think your trying to say think of it as two hoses one smaller then the other
and the same amount of water flowing threw it, the smaller hose will have water coming out faster then the larger one unless the larger one had more water or higher pressure of water goin threw it?


Please correct if im off
 
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Jonathan and Kenny-
I understand how these things all work together, was looking for more specific flow data, cfm & velocity @ specific valve lift to compare. I also know how to properly compare the stats from one head to another for proper application. I didn't just crawl out from under some troll rock and into this thread, I have a few different heads to choose from and I would like to properly be able to compare them to fit the best to my application.

Not looking at numbers blindly, you have to test at various lift with heads that are what will actually be used in the application (valve size, porting the same) to get a picture of what is happening. There's enough to this that I don't feel the need to get into a long, drawn out discussion, I can look at flowbench data with a 530 and 531 at various valve lift and see what it's doing, I have looked at enough of them by now.

If you can find the data I would like to see it. If it's incomplete, what will it take to get a bench test on a stock 530, ported 530, 531 and ported 531 to get some real data? The manifolds will make a difference, but not all of us have that option. I have to keep my car looking stock under the hood for smog and I don't plan on swapping parts every time smog testing is due.
 
Was going to pick up a used KG2T to try out. Also looking at the RSI stg 3 and probably would replace the valve springs at the same time.

Thoughts? Goal is still broad power and quick response. I'll probably change the intake first and go back on the dyno.

Wait for me to put the STG3 and springs on. If it's too much for the f+t, I'll make you a good deal.
 
So the b21f intake manifold is a much better choice than the b230 in terms of flow?
 
i was told the tb was the biggest problem with stock manifolds

By who, based on what?

I'd rather have a stock TB and a better manifold than a big TB on a stock B230 style manifold any day of the week.
 
kenny was saying that the stock intake picked up a lot of flow just by removing the tb.

honestly i don't like either(tb or stock intakes), just saying that i doubt the gains from a b21f intake over a b230 will be much if they're both using the stock tb
 
Jonathan and Kenny-
I understand how these things all work together, was looking for more specific flow data, cfm & velocity @ specific valve lift to compare. I also know how to properly compare the stats from one head to another for proper application. I didn't just crawl out from under some troll rock and into this thread, I have a few different heads to choose from and I would like to properly be able to compare them to fit the best to my application.

Not looking at numbers blindly, you have to test at various lift with heads that are what will actually be used in the application (valve size, porting the same) to get a picture of what is happening. There's enough to this that I don't feel the need to get into a long, drawn out discussion, I can look at flowbench data with a 530 and 531 at various valve lift and see what it's doing, I have looked at enough of them by now.

If you can find the data I would like to see it. If it's incomplete, what will it take to get a bench test on a stock 530, ported 530, 531 and ported 531 to get some real data? The manifolds will make a difference, but not all of us have that option. I have to keep my car looking stock under the hood for smog and I don't plan on swapping parts every time smog testing is due.

Eric,
I know you are one of the more knowledgible folks around here on the generalities of this stuff along with the specifics of it in some other apps. So I was fearful my response would come off wrong....part of my sleep deprivation I spose. If an offense was taken I offer my apologies.

I do have plenty of data, I was just curious what you were looking for. Flow sheets with velocity plots is what I have, as well as some dyno data utilizing different intakes.

To get the most from a B230 manifold it needs to be cut apart and ported. Truly the B21F manifold with injector bungs welded in and yoshi fabs 90* elbow with 960 tb is the way to go for a stock looking car.

Eric if that info is what you are looking for char wise I will work to get it posted up here for folks to see.
 
Or a 405 head with modified fuel rail to fit injectors in the k-jet ports;-)
B23ET.JPG
 
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