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531/405 vs 530 heads with camshafts under 12.5mm

We've been doing alot of head stuff and for turbo and NA folks using camshafts under 12.5mm of lift and for that matter stock unported intake manifolds, the 531/405 head is a waste of your time as it won't make more power, especially under the curve.
More info on NA cars and other camshafts available that won't throw shims and can be used for 100k+ miles without wearing out anything? :lol:

Seriously though, I need a package. This partial package obviously isn't working. The H cam would be good with this header(or none!) in a stock car.
Is that a bone stock 531?

What about a 531 with minor exhaust porting and 38mm valves?
The exhaust sides of the two heads are basically the same... We're talking about the differences in flow through the intake side. The 530 is able to keep up some good velocity for good cylinder filling/efficiency below 12.5mm of lift whereas the 531/405 heads have a large port that will not be as efficient/powerful at lower levels of lift. You can see better than stock 531/405 flow numbers with a professionally(Erland Cox, etc.) ported 530 head that still uses stock sized valves.

Flow numbers of one component don't tell all. Hell, my car with a basically stock head would likely make almost the same power it does now after bigger valves and port work(2018 update: crappy port work and blending of the larger valves). I hope to be getting rid of the stock intake manifold soon to see if that limitation will go away and provide decent gains. Then I'll have to look at getting a larger exhaust manifold and larger cam, again. At that point though, decent power should be achieved.
I'd rather folks have a complete package of an engine designed to all work together
That actually makes power and is somewhat efficient...
 
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Jonathan- I am not disagreeing with what is being said here, I was just looking for numbers so it could be illustrated as to where the point is that the 531 is superior. When there is flow data it can easily be determined at which point one or the other is superior. Not talking just at one specific lift of camshaft, there are other factors involved here. It's more about matching components, and flowbench data is much better than opinions.

Maybe I am a little worn out too, working too hard lately at a job that doesn't pay enough.

I would like to see what you have, being able to have real data along with personal experience and the expeience of others will make it easier to select the right head, porting, valves, cam, intake. You know, make a MATCHED package rather than cobbling parts together in hopes of big HP.



But I guess some would just rather talk to some of us like we are retards, I'm CERTAIN that this flow data isn't worth anything at all:roll: and I have no idea what to do with it. BUt I guess we all know who has his tit in a vice over this.

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Eric, its ok.

I'm trying to get 3 cars to the dyno today/tomorrow. I'm headed to LA on friday for the weekend, I will compile all the data I have and post over the weekend.
 
Sounds good. It will be nice to have that information readily available as there is so much misinformation on this forum combined with opinions that are delivered in a less than stellar fashion in regards to this topic.

I like what you are doing with the 530's, might have to go that route once I am ref'd as 2.2 turbo, but I also have a nice 405, so it depends on the real data for my decision. Either way I am spending the same money, just starting with a different casting.
 
I actually think a 405 can be a great head. The intake just requires some decent porting and a good cam to take advantage of it. So hold on to it for sure.

BTW Eric is your car going to be a Auto-x car or what are your plans.
J
 
I like what you are doing with the 530's, might have to go that route once I am ref'd as 2.2 turbo, but I also have a nice 405...
n/a or turbo? BCP or SCP 405? I'd rather a 530 than BCP 405...unless it's n/a, then it won't really matter.
 
It does, which is why the 531 naturally flows more. But more flow at a slower velocity is not necessarily a good thing.

So in other words, the advantage of the improved short side radius makes itself known as the flow increases?

Reworded again, we are seeing boundary layer separation (or just more of it) on 530's as the flow goes up?

I know you are busy so answer whenever you get a chance. ;-)
 
n/a or turbo? BCP or SCP 405? I'd rather a 530 than BCP 405...unless it's n/a, then it won't really matter.

Turbo is the current build. I have 2 405's, one is BCP stock, the other WAS BCP, now it's got inserts and drilled for proper coolant flow. I have choices.

I'm building 2 motors right now, one for the autocross car, the other for the DD. For the DD I am just freshening a B230FT and dropping it in with a new cam, 90+, turbo and some other minor goodness. I just want a nice torque motor. The 244 is getting head work, big cam, intake mods and a heavily ported 90+ with super 60, 3" dp.

So there's 2 totally different applications.
 
Cylinder filling

My fluid flow theory is pretty rusty - finished engineering degree 1970 - but what is said does not look right simply on mass flow. Up the pipe size - more mass. Simple as that. The place velocity counts (changing from simply mass to fuel in air) is to reduce deposit on manifold/port walls and to ensure that the charge enters the cylinder well mixed.

The world may have changed since the 60s and 70s but surely the simple issue here is to minimise flow restrictions on the intake side which is going to mean the 531 is better than the 530 in all situations - unless you can demonstrate that increased turbulence generally or at the edges of the stream produce an advantage.
 
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?
 
The world may have changed since the 60s and 70s but surely the simple issue here is to minimise flow restrictions on the intake side which is going to mean the 531 is better than the 530 in all situations - unless you can demonstrate that increased turbulence generally or at the edges of the stream produce an advantage.
Less resistance to flow does not equal more power, necessarily. Flow velocity typically increases as port size decreases. Greater velocity = greater cylinder filling, depending on other factors.

The benefits of the larger intake ports in the 531 head typically aren't seen with a stock intake manifold and lesser amounts of lift.

Seeing flow numbers on a chart won't tell you exactly how well directed and with what velocity the airflow will be through a port and give you the ability to determine what is better than another at x lift. Then again, in reality we aren't even just looking at how much flow will go through a head's port, if what goes through the intake manifold and/or exhaust manifold is much less. It's like if you toss on an exhaust manifold after developing/testing exhaust port flow with a 6-8"(?) straight pipe on it - if you lose flow when you put on your actual header, your header isn't right for the application and your portwork is now moot.

Eric, who has your tit in a vice? :roll: Or maybe I'm misinterpreting your many posts in this thread.
 
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Well Jonathan I guess we will need your pitot tube readings overlaid to all your flow Data. How else can we continue to bench race?
 
I actually think a 405 can be a great head. The intake just requires some decent porting and a good cam to take advantage of it. So hold on to it for sure.

BTW Eric is your car going to be a Auto-x car or what are your plans.
J

244 will be at the autocross. Trying to get one of the B230FT's in there with LH by that time but need some dry weather. Got to get the dry so I can do the swap! If not it will be there NA, it's slow in a straight line but it's like a Miata, keep the momentum and it does great. Not a lot of cashflow that I can put in it right now, still looking at a move/business purchase/relocation/new job or whatever is the best choice.
 
Eric, who has your tit in a vice? :roll: Or maybe I'm misinterpreting your many posts in this thread.

Maybe, just maybe, I am a little tired of the resident 'know-it-all's' thinking their methods are the one and only way to do things (not Jonathan, he has provided data in the past). I have built engines since I was 13, everything from 2CV's and air-cooled VW stuff to 1100+whp street driven 4.6 Ford mod motors. Pretty sure not much has changed in the 4 years since I stopped doing that for a living.

If flowbench data was worthless then why would anyone bother? Getting flow numbers off the heads at various lift points can determine the best camshaft for a given application, the needs of the intake and exhaust to maximize the VE, and generally make for a more driveable combination.

Or we could just believe what someone says, build another mediocre redblock and deal with it.

Maybe I should just sell all my redblock **** and throw a 5.0 in it, I already have one.
 
Well Jonathan I guess we will need your pitot tube readings overlaid to all your flow Data. How else can we continue to bench race?

also with the flow numbers i would like to see them up to 16mm of lift if possible. from what i have seen comparing two heads with the same motor, if one head flows better to a desired lift but falls off severly after that lift it will not perform as well as the head with less overall flow that doesn't drop off after that point, when put on the dyno.

also port volumes would be helpfull in this discussion.

and are we comparing heads with the seats and port beginings in the stock location?
 
also with the flow numbers i would like to see them up to 16mm of lift if possible.
***WARNING, THIS FLOW CHART IS BOGUS!*** Flow numbers don't make sense at low lift, as if there was a gap between the flow bench and the head. Also, my ports weren't actually opened up behind the valves for who knows WTF reason.

I wish my head flow sheet went up to 16mm...
Kyleshead.jpg
 
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So from 10mm up you saw no further improvement in flow on the head alone on the intake side? Longer duration will help on that intake side to compensate for the lack of flow at higher lift by allowing more volume. And that's not even getting into the intake manifold as a restriction.

Now who has data on a 531 stock and a modified 531 so we can compare?

16mm lift on that head would be a waste on the intake for sure, probably the exhaust too unless the bench ran out of air at 202.57.
 
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