Stock MCS cylinder head:



MINI-Madness cylinder head:



Doesn't look much different to me, just cleaned up a bit.

Cooper S stage 1 head

 

Yes, exactly. Cleaned up intakes with stage one, I believe. And stage two is intake and exhaust (?). And stage three would be...? I need to go ask some questions.

R

 

Why don't they just come cleaned up straight from the factory?? Sure, exhausts I can understand being restrictive but quiet. But is there *any* downside to doing the head straight from the start? More expensive to make?

C'mon. These aren't English Muffins, we don't need "nooks 'n crannies"!!

 

Probabpy saves them a ton of money on machining. Remember these heads are just cast aluminium and then minor machining is done to the heads after they are cast.

Good head machine work takes a while to do and is expensive.

 

as far as I can tell from examining the head first hand, there is absolutely no port or combustion chamber work done on the stock head. the raw sand casting marks are clear evidence. the only place they are interuppted is from the maching of the seat recesses which are not exactly concentric with the as-cast hole in the port. Furthermore, the stock valves and seats are single angle ground. I haven't been able to check manifold-to head match, but I am guessing it ain't pretty.

 

Maybe these before and after pictures are not fully showing the extent of the machining done to the heads. More magnification may be needed before we can see the difference. After the work is done how much better is performance? What is the relative cost? Over $1000?

 

More machine time translates into higher costs and when you are talking about machinging cylindar heads, it translates into a considerable sum. It would only make sense the manufacturer would focus primarily on the surfaces that effect performance. Whatever it costs the manufacturer to do, the retail needs to wind up costing four to five times the actual cost (this varies depending upon the industry)in order to cover operational costs, distribution, sales, and marketing costs etc, etc, etc. At some point the retail price on the car falls into another price point, which means it gets compared to higher priced cars that usually have more robust technical specifications. Once the price of a Mini gets over 30m its playing in a different ballpark. While its possible for the Mini to play in higher priced venue, it probably made more sense for BMW/Mini to start off with a car whose base price was under 20m. No doubt many of us will make enough mods to our cars that put it over 30m, but the enthusiast part of any market (which covers anyone actively involved in MCO and Mini2) will always be the smallest segment of that market. All that said, manufacturers should always appeal to the enthusiasts market segment, thay are the ones that truly drive the geography of that market. Okay, I'll shut up now!

 

>>as far as I can tell from examining the head first hand, there is absolutely no port or combustion chamber work done on the stock head. the raw sand casting marks are clear evidence. the only place they are interuppted is from the maching of the seat recesses which are not exactly concentric with the as-cast hole in the port. Furthermore, the stock valves and seats are single angle ground. I haven't been able to check manifold-to head match, but I am guessing it ain't pretty.

Forgive me, I'm new to this. Can you please expand on your "valves and seats are single angle ground" and "manifold-to head match" concerns and what they mean? Are these issues easily addressed?

Thank you!
Jim

 

Good work can be very expensive. I'd say to have the head totally rebuilt, with a full port and polish, along with 5 angle valve job you'd be over 1000 dollars. Obviously the Mini's head can use some work so I'm willing to bet you'd see some pretty good gains with it, across the board. It's just a matter of who is going to spend the money to do it!

when they talkabout different angle valve jobs, 1 angle, 3 angle, and then there is also 5, and I beleive there may be a 7 but I'm not positive. What they are talking about is grinding down the heads casting irregularities so the valve sits perfect flush with the head at all those different angles. At least thats is what I think it is...correct me if I'm wrong.
Mike

 

>>as far as I can tell from examining the head first hand, there is absolutely no port or combustion chamber work done on the stock head. the raw sand casting marks are clear evidence. the only place they are interuppted is from the maching of the seat recesses which are not exactly concentric with the as-cast hole in the port. Furthermore, the stock valves and seats are single angle ground. I haven't been able to check manifold-to head match, but I am guessing it ain't pretty.

Jlm,
If you have the head there to examine, does it appear that material around the guides up to the valve seat has been removed? In the photo it looks like they've been gone over with a tootsie-roll. Is that what you are refering to as the seat recess area? Any way to tell if the valve seat has been narrowed? No traces of engineers bluing on the manifold surfaces? No signs of even slight material removal /polishing in the combustion chamber to indicate the chamber volumes have been CC'd? Sorry for all the questions (& i have a lot more!) it sounds like you are looking at a head that's basically stock.. ?

 

the head I have is stock-o.

Absolutely no work in the combustion chambers. It looks like they spot faced and drilled the head for the valve guides, and then the recesses for the seats, from the combustion chamber side in one set-up (good), and machined about 1/4" beyond the seat into the port, removing a small amount of the casting surface. This bore is about .030 smaller than the ID of the seat, so there is a bit of a step. the remaining surface within the ports is as-cast. the seats are triple angle ground, but the blend angle into the cimbustion chamber is masked a bit by the aluminum of the chamber. The seal grind is about .05 wide.

Typcial stock conditions.

 

>>when they talkabout different angle valve jobs, 1 angle, 3 angle, and then there is also 5, and I beleive there may be a 7 but I'm not positive. What they are talking about is grinding down the heads casting irregularities so the valve sits perfect flush with the head at all those different angles. At least thats is what I think it is...correct me if I'm wrong.
>>Mike


Usually you have one angle for sealing the valve and the others are for blending the ports into that angle so the intake charge doesnt encounter the sharp edge of the machining. Theres a lot of science behind it. Sometimes the angles arent concentric!?

--
Cheese

 

>>Forgive me, I'm new to this. Can you please expand on your "valves and seats are single angle ground" and "manifold-to head match" concerns and what they mean? Are these issues easily addressed?
>>
>>

When porting-and-polishing, the main idea is to get the gasses into and out of the combustion chamber as smoothly as possible; You want to eliminate as many 'steps' as possible and let the gasses flow without obstruction or too many 'changes in direction'. Where you have separate parts meeting, you have the possibility of mis-match (manifold to head, for instance) and you want to grind and smooth to better match those parts.
The first sketch shows cross sections of a typical intake port with an intake manifold having a larger diameter than the port in the head - actually these may be diferent sizes or not concentric, but the step that alters the airflow needs to be removed.

 

8ball, wow! Great drawings (keep them in sketch form, it conveys the message perfectly).

Do you think that would still apply in our forced-induction environment?

 

>>>>Do you think that would still apply in our forced-induction environment?

... i've been debating this in my own mind ... I think that the elimination of obstructions (steps) is all that would be required in a forced-induction car - although more polishing wouldn't hurt!

In a normally-aspirated Cooper, the old tried-and-true tuner tricks still apply ...

 

8ball,

Those are great drawings, very informative. I'm not sure I understand why having a narrwoed valve seat is beneficial. I would think that the larger one-angle valve seat would make a better seal. Well if I were to guess I would say that the more narrow the valve seat the larger the opening becomes when the valve moves int othe combustion chamber. Is that close?

By the way, minimania has a stage 1 head as well. Anyone taken a look yet? They want 1900 but I'm not sure if you get some refund for returning your stock head or if that price already included the refund.

http://new.minimania.com/NewMiniSear...p;ShowIcons=No

Cheers,
Chuck

 

Narrowing the valve seat is particularly important for the intake valve for a couple of reasons: it improves the flow and it provides a smaller area for the transfer of heat from the cylindar head to the valve head.

 

Its a 4 valve 1.6 how much better do you think it needs to breathe? Dont get me wrong I know it wont hurt. Your wallet might not think the same way. My 2 cents. Make the intake charge colder and let the exhaust out.

 

Yes, this is getting to the point of diminishing returns - you are spending a lot of money to get that last horsepower ... and for a road car it is not worth the cost - but for racers (or serious hobbists) every little bit helps ...

 

Any idea what material is used for the valve seats? I presume the valves themselves are stainless steel, right?

 

>>Any idea what material is used for the valve seats? I presume the valves themselves are stainless steel, right?

No sir. The valves are Inconel.


--
Cheese

 

Ok, so it's the closest thing to stainless steel without actually being stainless steel. They are both Ni-Cr-Fe

 

>>Yes, this is getting to the point of diminishing returns - you are spending a lot of money to get that last horsepower ... and for a road car it is not worth the cost - but for racers (or serious hobbists) every little bit helps ...


Hey MiniMania claims that their stage 1 head should get 20-30 HP increase depending upon what other mods you have. I guess that is probably inflated but that does not sound like chump change to me.

 

Nobody wants to comment? C'mon guys thye claim 20-30HP doesn't that get anyone excited? I don't know enough (yet) to gauge whether or not this is total b.s. so I'd love to hear from some of the experts...

Here again is the link http://new.minimania.com/NewMiniSear...p;ShowIcons=No they even have a spiffy airflow graph (though sadly no dyno (guess that probably says it all huh?)).

Since it is sooo quiet here I'll just throw out that I really love the idea of throttle body, pully, header, head, ECU as mods. Keep the stock looks and sound and still have something like 210 HP. I'd rather sacrifice "that last few HP" for a lot of stealth.

Cheers

 

I'm holding out for the 50hp stage II....

:smile:

--
Cheese