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Old 08-06-2004, 06:26 PM   #1
budweiser_man
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Default 531 head question

How much better is the 531 head then the 530 head? I am going to do a canadan junkyard run in the next week or so. I plan on trying to find one for my 85 744ti. my car has the 530 right now, would it be a noticable difference with the 531?
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Old 08-06-2004, 06:31 PM   #2
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PM Philip Bradley. He gave me a lot of info on this head. I got one from a friend of mine, and I'm debating on what level of porting I want to do on it. Supposedly the intake is incredible on this head, and benefits from polishing alone. The exhaust needs work however, and will really benefit from larger exhaust valves. I just need to find out which size to use.
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Old 08-06-2004, 06:34 PM   #3
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I think the 531 did not come to North America at all on cars. Perhaps you are thinking of the Kjet 405 heads, which are available in Canada.
531 are available on some Penta engines, but which ones I'm not sure...

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Old 08-06-2004, 07:05 PM   #4
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yeah, call around some boat junk yards looking for a AQ151, should have a 531 and V cam, NA didn't get them at all on cars, only the BCP405's.

while over on this side of the pond we got

531 with A cam (B230ET)
531 with VX(3?) cam (B230FB)
BCP405 with H and K cam (79-84 B23E)
SCP405 with B cam (B23ET)
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Old 08-06-2004, 07:10 PM   #5
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They didn't come on car engines in North America.

The intake is better than the 530 (same valve size, though). The exhaust side is the same. The spark plug sticks out more into the combustion chamber.
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Old 08-06-2004, 07:13 PM   #6
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If you wanna pay the nice shipping I would gladly send you a 531 head

shipping: 150$

head: ~265$

totals: 415$
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Old 08-06-2004, 07:49 PM   #7
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Quote:
Originally Posted by benboy
I think the 531 did not come to North America at all on cars. Perhaps you are thinking of the Kjet 405 heads, which are available in Canada.
531 are available on some Penta engines, but which ones I'm not sure...
This is what I have been finding as well. I tried finding one of these heads for a few years up in Canada, but to no avail. I did however have not too much of a problem finding the 405 heads. However, I have modified a 530 head that will completely outflow a mildly ported 531!

For what it's worth. It would be good to look for a 405, or if you are going to be near any marine yards, you might find one of these heads on an AQ151 (I think that's the 8 valve version...)

Good luck!

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Old 08-06-2004, 08:34 PM   #8
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Quote:
Originally Posted by towerymt
They didn't come on car engines in North America.

The intake is better than the 530 (same valve size, though). The exhaust side is the same. The spark plug sticks out more into the combustion chamber.
but the exhaust ports are not the same because I have a 398, a 405, and a 531 head in my garage, and on the 405 and 531 you can see about a 1/4" of exhaust valve guide into the bowel, whereas on the 398 the port is smaller and the valve guide is flush to the port in the bowel. So the exhaust ports are slightly larger too.
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Old 08-06-2004, 10:40 PM   #9
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The 530 and 531 ex ports are the same. 160 looked close, too.

531 has a sweet intake port.
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Old 08-07-2004, 12:56 AM   #10
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Agree w/ coondog. Ex ports aren't the same. I keep hearing people say they are, and then corrected, and back and forth. Anyways they look different to me- 405/531 having a better bowl. Not majorly different like the intake but different.

What is better. Ha. For what? Define "Better". Loaded question imo.
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Old 08-07-2004, 01:22 AM   #11
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i can vouch for the two heads mikep had at his shop... both exhaust ports are the same. is the 531 you have from a penta mike? maybe the auto variety is different?

I'd rather have kenny's worked 398 then a 531 for the price though - its all in the numbers
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Old 08-07-2004, 01:29 AM   #12
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Default heads

In Mike Aaro's article here on the site he only mentions a plateau difference in the exhaust ports between the two head types. http://www.turbobricks.com/specs.php?content=sohc_heads It sounds like a very subtle difference.

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Old 08-07-2004, 03:13 AM   #13
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Do the heads you guys are comparing have valves in them? The difference is at the bowl- it would be hard to see otherwise.
I've ported a couple of each now and in my limited experience having only ported maybe 4 or 5 heads they're different- but you could make a 530 exhaust port like a 531. It isn't major but out of the box the 405/531 I've seen have been better all around even if just in terms of casting quality so to call the port the same is in my opinion misleading to someone who plans to just bolt a head on. Just my experience.

My 531 core was 200 canadian plus some old 164 parts, and my scp 398 was 100US. IME there's no real price difference if you source a penta one stateside. In terms of a major project I consider 100 or 200 bucks to be fairly negligible but that's just me. Sourcing one from europe definitely ain't worth it- if that's your only option then mod a 530- but their availibility here in the penta stuff makes them a pretty viable option these days. When i had no option, I spent 900 bucks to have a 398 ported. On my new project I had the option of a 531, so I took it. Cleaned up by myself and with new seats and bronze guides and oversized valves, the total price should be similar but the 531 should have a slight edge on flow and a definite edge in terms of durability and detonation resistance.
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Old 08-07-2004, 03:19 AM   #14
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you can often find them cheap enough in the Uk that it isn't that bad to sell them over there.

i think i sold mark one for 」195 shipped, which at that time was about $300, and Dlot a SCP405 for less then that.

the last one i had was 」1.20 off ebay (yeah i know +」20 traveling to pick up) which i put some money into in skimming and cleaning and parts and sold to griz for 」60

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Old 08-07-2004, 12:40 PM   #15
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I have to second Kenny's comment about the casting quality. I bought some of these heads now and everyone of them looks like higher quality metal. Pierre mentioned this to me and his comment was that when polishing the combustion chambers the 405 would polish up much higher/brighter than the metal used for the 160/398. The cost for getting a better base to start with is worth the extra effort it might take to buy one of these heads.

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Old 08-07-2004, 04:44 PM   #16
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Quote:
Originally Posted by tryckj舸el
i can vouch for the two heads mikep had at his shop... both exhaust ports are the same. is the 531 you have from a penta mike? maybe the auto variety is different?
Yes, it came from a boat, and had a V cam.
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Old 08-07-2004, 09:27 PM   #17
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Quote:
Originally Posted by NChoy
PM Philip Bradley. He gave me a lot of info on this head. I got one from a friend of mine, and I'm debating on what level of porting I want to do on it. Supposedly the intake is incredible on this head, and benefits from polishing alone. The exhaust needs work however, and will really benefit from larger exhaust valves. I just need to find out which size to use.
I should really slap the big Valve 531 head i aquirred on a car to see what the difference is i guess.

The valve Sizes are 38mm Exhaust and 46mm Inlet. Hope this helps Nick.
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Old 08-08-2004, 09:19 AM   #18
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I have had one stock 530 head flowed, one with just a 5 angle valve job, one with moderate porting and 38.5/44 mm valves, and one with moderate porting and 40/45 mm valves (my current head and the shop was happy enough with the results to do another one just like it for another customer). I have seen numbers for two 531 stock heads, and think the numbers I have seen for the two 531 heads are reliable because they were consistent with each other and with what I had heard and read in general.

Based on these numbers, the stock 531 head flowed dramatically better than a stock 530 head on the intake side and almost exactly the same (within 1-2 cfm) on the exhaust side. Thus, whatever perceived casting advantages there may be in the exhaust ports, in stock form, the 531 EXHAUST FLOW IS THE SAME AS THE 530 EXHAUST FLOW. The stock 531 head is a great starting point, but I would recommend investing some time and money on the exhaust side. With a street driven turbo motor, it is generally advisable to tighten up the intake to exhaust flow ratio over that generally advised for a non turbo motor.

Note that Volvo did not do any porting or change valve sizes for the turbo motors. The intake to exhaust flow is already less than ideal for the turbo motor. Obviously you can still make good power with it and run reliably for years, but there is power and efficiency to be had if you are willing to spend some time and money.

A 530 head can be made to flow like a stock 531 head on the intake with relatively minor work. I assume, but do not know, that a 531 head can be worked to flow much more due to the different casting. However, why do even the minor work necessary to make a 530 head flow like a stock 531 head if you have access to a 531 head in good condition?

The 531 head definitely should get larger exhaust valves if used on a turbo motor and the 530 head should if it is being more than very lightly modified. The exhaust flow is valve limited much more than port limited. Port all you want, but you still cannot get more than about 123 cfm of air through a 35mm valve according to Superflow.

As I understand, once the 530 combustion chamber is opened up to the 531 size, the 531 will take no bigger valves than the modified 530. Neither can be opened further due to the piston bore size. The advantage in the 531 is that the intake flows more and perhaps that the intake and exhaust will both take more porting. The walls on a 530 definitely have limits and it is possible to hit water without too much effort. Maybe someone has details on the 531.

For the money that you will invest to make a nice bigger valve 530 or 531 head, you could probably do a 16V head. I bought one fully rebuilt on the internet for $275 and one used but verified to be good for less than $100. Even a stock 16V head will outflow a moderately worked bigger valve 530 head. I think, but cannot be certain, that it will also outflow a moderately worked bigger valve 531 head. I suspect that in stock form, it will outflow all but the most seriously worked big valve 530 or 531 heads. Pretty impressive. But you need a $100 tensioner from Dick Prince (or buy the Penta part or adapt your own) and a $150 manifold adapter or $300 log header or $600 custom header to use the 16V head and you have to factor those costs into the conversion cost. Since I had a shop work the head, I spent a lot and would have done better with the 16V conversion.

Don't be unhappy with your 530 or 531 head. You can still make great power with them, perhaps have better low end torque if the porting job is well done and the cam well chosen, have a much simpler and less expensive valvetrain, and you can always turn up the boost a little to compensate.

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Old 08-08-2004, 09:50 AM   #19
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pbonsalb:

Do you have any flow # for the 531 you can post?
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Old 08-08-2004, 10:26 AM   #20
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I cannot seem to find them, but I did find some for a 405, which is reportedly very similar. The numbers are about the same as for the 531, to the best of my recollection. All cfm are at 28 inches of water, but I don't know whether the rest of the details were consistent with what my shop used when doing work on my 530. Things like the bore tube, the intake, the exhaust, and the seals can all be important and create large variables. This is why you have to be careful comparing flow numbers when the tests were not done by the same person on the same bench. Before and after tests by the same person on the same bench are the best.

Here is data for a 405 head that seems to be reliable and comparable based on what I have seen for 160/398/405/530/531 over the years:

intake with lift at .1/.2/.3/.4/.5 inches flowed 51/102/146/161/169 cfm, respectively

exhaust with lift at .1/.2/.3/.4/.5 inches flowed 39/78/100/108/114 cfm, respectively

The 530 intake will more or less top out in the .350 range in stock form. The 531 keeps flowing like this 405. On the exhaust, both the 530 and 531 crept up in flow right to the end, like this 405.

With my current 530 head with moderate porting and 40/45 mm exhaust/intake valves, the flow at 28 inches of water was

intake with lift at .1/.2/.3/.4/.5 inches flowed 54/113/156/164/168 cfm, respectively

exhaust with lift at .1/.2/.3/.4/.5 inches flowed 48/83/107/125/135 cfm, respectively

Again, what is most important is not these numbers I have supplied, but what your head flows now based on your testing methods and what it flows afterwards. My gains were generally in the 10% to 20% range. The other important thing to remember is that flow numbers do not necessarily translate into driveability. You could hog out ports, lose velocity, get great flow numbers, and create an engine that is really inefficient in daily driving and that runs poorly everywhere but in a narrow, elevated rpm range. Numbers are not everything. There is a science to it, which is why good shops get $75 per hour and say they need to spend at least a day on your head slicing up old heads, mocking up ports with clay, doing numerous flow bench tests, and so forth. A "fluff and buff" that is pretty much light clean up work without fitting larger valves will help a little and is much cheaper. You could probably do this yourself without much risk

In my view, the multi angle valve job is the best bang for the buck, and costs not much more than a regular valve job, yet might get you 10+ cfm at some lifts on the intake. But before pulling your head and spending any money on it, try a performance cam -- it will make much better use of what you have (but will trade low end for top end).

Philip Bradley
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Old 08-08-2004, 11:53 AM   #21
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thanks

the way i was thinking is to pull the head and just clean up the ports, and maybe do some more work to the exhaust, IF someone can give me som pictures and explain what to do, so i don't screw things up. I figured that cleanig up the head would give med the same amount of power increase as a performance cam, but it's almost free, minus new gaskets.
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Old 08-08-2004, 01:12 PM   #22
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Phil, as you mentioned, flow numbers on the exhaust side are more an an indicator of what the valve is flowing, not the head in the case of a stock valve- they both nearly max out the flow for that valve. So, if the valve is the major restriction in both cases, can we reliably say that the 531 exhaust port has the same flow? Another thought is that regardless of port shape the 531/405 are less shrouded around the exhaust valve as well and unshrouding a 530 to the same degree makes a noticeable difference from what I understand. Just a thought.

I'm not trying to argue one way or the other at all- and much thanks on posting the numbers- just saying it might be hard to compare the two when they are both being limited by the valve so much. I plan to get before/after of my 531 stock and then with 46/38mm and some porting.
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Old 08-08-2004, 05:32 PM   #23
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If anyone is iterested i have a 531 head ill sell for 175 bucks or best offer plus shipping from ireland, i reckon another 150$,
I also have a VX cam which i will sell for 50 bucks plus maybe 20 for shipping,
Pm me if any of you are interested.
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Old 08-08-2004, 06:57 PM   #24
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Quote:
if the valve is the major restriction in both cases, can we reliably say that the 531 exhaust port has the same flow?
I would not jump to that conclusion. There are 8 cfm to be had between the stock exhaust flow of about 114 cfm and the theoretical maximum exhaust flow of 123 cfm with the 35 mm exhaust valve. If the ports were better, that gap should be diminished. 8 cfm is a lot even if it does not seem like much.

Volvo may not have bothered improving the exhaust flow because the 405 and 531 heads were fitted to non turbo motors and non turbo motors don't need much improved exhaust flow; they need much improved intake flow.

When you fit larger valves, you have to do some bowl work, so if you left the ports stock and fit larger exhaust valves, you would still be doing a little work and I would expect that flow would pick up. The only way to know for sure would be to compare a 530 and a 531 head that are both done with minimal port work and fitted with larger valves. I would not bother doing this test. You might as well do a little more port work while you are at it to get the most that is reasonably possible from the investment.

I commonly read of 38 mm exhaust valves being fitted as an upgrade. I used 38.5 on my first head, which was what Peter Linssen used. Peter had a hotshot head porter check out his head and it was what the guy recommended. My shop knew the guy -- he is nationally known. My shop thought it would have been worthwhile to try slightly larger valves, but I had already bought the same as Peter. The next time (I had a little valvetrain damage due to excessive heat -- probably lean running), we used 40 mm and the shop thought they were better. Low end flow picked up quite a bit. We probably would have used 46 mm intake valves, but we decided not to use new intake seats (for 2 mm larger valves, larger seats would probably be a good idea), so we went up just 1 mm, to 45 mm.

In short, I would say that the common 38/46 combination is a little short on the exhaust side. I would go at least 40 on the exhaust.

I am not sure at what point you start going too thin on the material inbetween. 40/46 is certainly doable. But 42/46 or 42/48 or 44/48 may require siamesed seats. More work, more money, and probably less head life.

The Turboford guys get good results using 1.89/1.60 valves, which is 48/40.5 mm. They may have more room for porting, though. We ran into water once or twice on the 530, even though we had cut up a head to check for thickness. Apparently, casting differences are common. Maybe the 531 is better in casting quality and consistency. Perhaps someone with a bad 531 would donate slices of it to the cause. A good porter would not go very far without knowing what he had to work with.

The smart thing to do is to flow your head, find out the intake to exhaust flow ratio, decide what you want for a target ratio, and then start work on the poorer flowing side -- the exhaust side. Do as much as you can there. Maybe don't buy intake valves until you are done with the exhaust. The intake will be comparatively easy to bring up. Then reflow the head and see what sort of improvements you made and choose the intake valve size as best you can.

Or do some more research on the intake to exhaust ratio theory. Maybe it is old science now and there is a new theory that would give you more flexibility if you adopted it. Sort of like turbo cam theory -- supposedly once you get EBR way down you don't really need a "turbo" cam with lots of lift and little overlap -- you can use a naturally aspirated cam with more overlap.

I am going 16V next time -- maybe in a year. I have a long way to go still to reach the potential of the 8V motor that I have.

Philip Bradley
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Old 08-08-2004, 09:05 PM   #25
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"I would not jump to that conclusion. There are 8 cfm to be had between the stock exhaust flow of about 114 cfm and the theoretical maximum exhaust flow of 123 cfm with the 35 mm exhaust valve. If the ports were better, that gap should be diminished. 8 cfm is a lot even if it does not seem like much."

That flow is assuming a basically "perfect" port isn't it? Gains in port flow get smaller as you approach the ceiling-but maybe you're right. Either way I made no conclusions. It was just a suggestion. All I can speak from is my own experience having played with a few of them- that experience tells me that the port is different. Better, worse, I don't know. I just know it's different. That's what I see with my own eyes and grind with my own grinder.

Re 405/531 and turbo motors:

Where did you get that info? I'm quite certain b23et and some b230et had "big heads" but I'd call that all just speculation anyways- It's probably Volvo didn't develop the head with any specific ebr in mind- definitely not as a priority anyways.

"In short, I would say that the common 38/46 combination is a little short on the exhaust side. I would go at least 40 on the exhaust."

In the land of people without unlimited funds to spend melting drivetrains, the 38/46 represent a good improvement over stock at a good price. That's why I bought them. Besides, i'm confident they will support lots of power considering what the group a b21's made with stock sized ones.....


Re valves sizes and seats:

I know it's 90mm total diameter w/ siamesed seats... not sure what you can do in a boosted app with existing seats. I'll never bother to find out I don't think. the 46/38 combo is so affordable I'll never be able to justify anything fancier. Being that valveseat installation is beyond the ability of most- I'm sure the machine shop would advise on a per-project basis.

"Or do some more research on the intake to exhaust ratio theory."

It is valuable to me in that it gives an indication as to how the head will affect ebr- which is very important to me. Just part of the system though. the actual flow ratio needs to be measured against the whole system though which is where people misuse it imo. One needs to look at TOTAL intake pressure drop vs TOTAL exhaust side back pressure- from the air filter to the chamber, and then from the chamber to the end of the exhaust system.



"Sort of like turbo cam theory -- supposedly once you get EBR way down you don't really need a "turbo" cam with lots of lift and little overlap -- you can use a naturally aspirated cam with more overlap."

Well, that is a given, not even a "supposedly", because as ebr approaches ratios similar to those experienced in a normally aspirated engine, valve overlap and clyinder filling/scavenging act in a similar way as well. So yeah, definitely a fair assumption.

"I am going 16V next time -- maybe in a year. I have a long way to go still to reach the potential of the 8V motor that I have."

being that the record is well over 500hp, I'd say we all do. I think a guy needs to build one engine and build it right. We have both had failures due to not doing things right. My engine mated to that old m46 was a bad call. IMO your well built bottom and and nice valvetrain deserved proper engine management as you know. I think even relatively unmodified engines should make good numbers if they have the rest of the "support systems" taken care of. I have 80% of what I need to do the new engine and I'm trying to resist coblbing something together. I'm sure I could put something together and have fun with it until it turned itself into an expensive mistake, but good things come to those who wait I guess. ;)

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