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Old 03-19-2011, 06:14 PM   #1
Stereophile33
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Default 531/405 vs 530 heads with camshafts under 12.5mm

I just want to post this up so hopefully it will become internet lore.

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.

A well ported/filled 530 will make more power than a 531 anyday with a cam under 12.5mm. If going to a bigger cam, you bet, make the jump for the 531/405 heads, but you should also consider one of Nathan Kahler intake manifolds at that point.

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Old 03-19-2011, 06:22 PM   #2
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What about the 530 becomes a restriction after 12.5mm?
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Old 03-19-2011, 06:25 PM   #3
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port size. Which is why our stage II 530 is as good as 95% of the ported 531's out there. But the point of this was for all the advice that is given for someone with a k-cam, or a v-cam, or IPD turbo cam, or one of our stage I or II cams to upgrade to a 405/531....its not an upgrade with a cam that small, its too big for the cam. Whereas the stock 530 is a touch small for a 12mm-12.5mm cam and can be ported with ease to work beautifully with those cams.
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Old 03-19-2011, 06:30 PM   #4
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Quote:
Originally Posted by Stereophile33 View Post
A well ported/filled 530 will make more power than a 531 anyday with a cam under 12.5mm.
Is that a bone stock 531?

What about a 531 with minor exhaust porting and 38mm valves?
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Old 03-19-2011, 06:30 PM   #5
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Interesting. So unless someone is building a max effort 8v a worked 530 is sufficient? How much are you charging for port work on a 530?
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Old 03-19-2011, 06:36 PM   #6
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Originally Posted by Tom Wiley View Post
Interesting. So unless someone is building a max effort 8v a worked 530 is sufficient?
I wish the link to the excellent cylinder head article Mike Aaro wrote about 10 years ago was still linked on the main page. I guess we had to take it down?

Obviously RSI has taken the actual details of woring thiese heads to a more advanced level than we had back then, but nobody should be shocked about facts like this that were common knowledge 5+ years ago. I guess the board has devolved in some ways.

At any rate thanks for (re) pointing this out Jon!

What are your thoughts on the supposedly more centered sparkplug location on the 531? Is it significant? If so that might be an advantage of the 531 that is not evidenced by flow/power numbers....
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Old 03-19-2011, 07:09 PM   #7
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Kenny,
Good words.

The spark plug is better in the 531, however it alone does not make up for the port variations to warrant it being run over a 530.


I guess another way to say some of this. For those folks running a 405/531....consider going to a bigger cam and ditching your stock intake, as its KILLING the power of having a 531 head on there.

I used to poo poo anyone complaining about intake manifolds since for 6-7 years PeterL has been making 400+ whp on factory intake and exhaust manifolds...however further testing shows that much like when Peter switched to one of our headers and he gained 75whp....similar gains are to be had by going to a better intake.
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Old 03-19-2011, 08:21 PM   #8
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thats very useful information, thanks Jon
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Old 03-19-2011, 09:04 PM   #9
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thats very useful information, thanks Jon
I guess I make a living selling people really fancy parts...but at the end of the day I hate it when people spend money un-necessarily...even if it benefits me.

I'd rather folks have a complete package of an engine designed to all work together and use some of what they have then go out and spend a whole lot and not get much in return.
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Old 03-19-2011, 09:04 PM   #10
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Default cams

Well, I'm angling after a 531 with sodium filled valves and V cam right now so this is interesting.

I'm not aware of a readily available Volvo cam with over 12.5mm lift - can you point me to one? The clever non-volvo cams at over GBP500 per unit are surely hard to justify in bangs per buck.

The other question is what will let a B230FT rev cleanly round to 6000 rpm? I have a big flat spot at 5,000 rpm but it clears by 5,5.

HT leads good, plugs good, dizzy and rotor arm believed good, injectors about to be cleaned next week, AMM and throttle body done.
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Old 03-19-2011, 09:37 PM   #11
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we now sell turbo and na cams with greater than 13mm of lift for those that need it and want to take advantage of their 531 heads.
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Old 03-19-2011, 10:32 PM   #12
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I've been thinking about whether I should replace the IPD cam.

Specs:
B23ET, 531 w/46/38 valves, mild combustion chamber work (deshroud valves), mild port on exhaust side (mainly smoothing the short side radius), GT2871 on ported 90+, and coming soon, yoshifab modified b21f intake w/plenum and 960 TB.

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.
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Old 03-19-2011, 11:30 PM   #13
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Michael,
I would throw the intake on for certain...
And I sent ya a PM.
Jonathan
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Old 03-20-2011, 12:25 AM   #14
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I bought your Stage 2 turbo cam and today I started installing it in my 531 head. I didn't finish getting everything moved over. So you think it wouldn't be worth the effort to swap, and I should just put the 530 head back on?
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Old 03-20-2011, 12:41 AM   #15
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I bought your Stage 2 turbo cam and today I started installing it in my 531 head. I didn't finish getting everything moved over. So you think it wouldn't be worth the effort to swap, and I should just put the 530 head back on?

I would consider using a nicely ported 530 or swapping out that stage II for our stage III. All depends on power goals and other bits and pieces.
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Old 03-20-2011, 09:20 AM   #16
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since this is more of an informative thread, i'll junk it up with my confusion

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Originally Posted by Stereophile33 View Post
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.
so you're saying, if running stock intake and unported 405/531 get a big cam(over 12.5mm lift) or don't bother?

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Originally Posted by Stereophile33 View Post
one of our stage I or II cams to upgrade to a 405/531....its not an upgrade with a cam that small, its too big for the cam.
again, makes it sound like a stock 405/531 flows hella well, so well most cams on the market don't take advantage of it(most are under 12.5mm lift)


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Originally Posted by Stereophile33 View Post
The spark plug is better in the 531, however it alone does not make up for the port variations to warrant it being run over a 530.
just confused about "port variations"


i guess i'm just kinda disappointed, i thought i was doing well with my build. ported head by kenny, homemade tubular exhaust, homemade intake manifold, big turbo(holset most likely), big ic, and rsi stage II cam(was the biggest one advertised in the sale thread so i jumped on it), but it sounds like i could have done better with my cam choice

i know it'll do fine, but makes me wonder how much more that $40-$50 upgrade to a stage III would do
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Old 03-20-2011, 10:52 AM   #17
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Default Old cam list from Turbobricks

Here is a list that covers lots of cams. http://www.turbobricks.com/resources...ontent=camspec Info within makes me question the mini rebuild I had planned with a 405 and B-cam with Dales gear on my B23FT.
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Old 03-20-2011, 11:47 AM   #18
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Someone not that long ago did a bunch of flow testing on some heads which also pointed this out- the exhausts are (more or less) the same on all these heads. 405/531 intakes flow better than 398/530, so if you're not helping the exhaust out, you're not getting much benefit.

And I guess on the flip side, if your intake doesn't support the capacity of the head, same situation.

I really wish i had a chance to dyno a standard intake to compare with my b21f/b23e...
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Old 03-20-2011, 05:17 PM   #19
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i found the same too , a ported large valve 530 only really was flowing the same as a 531 with std valves . but if you don thave the cam to support such flow the 531 isnt an upgrade as such .

do you have any on road feed back from part throttle ?

what intakes are we talking about here ?
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Old 03-21-2011, 12:55 PM   #20
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So basically you're saying that Ryan's ported 398 will be useless if I don't throw one of your Stage 2 cams or better on?
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Old 03-21-2011, 01:22 PM   #21
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your 398 is the same as a 530. You should be fine.
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Old 03-21-2011, 01:52 PM   #22
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But I'm using a K cam. I might have understood wrong...
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Old 03-21-2011, 02:07 PM   #23
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port size.


So where do the differences in short side radius figure into this? Or do they?
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Old 03-21-2011, 02:22 PM   #24
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So where do the differences in short side radius figure into this? Or do they?
It does, which is why the 531 naturally flows more. But more flow at a slower velocity is not necessarily a good thing.
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Old 03-21-2011, 02:38 PM   #25
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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.
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