I would like to start this thread to shed some light on aftermarket heads..... I have had some off NAM talks with some knowledeable people and there is a diference of opinion as to what head makes the most power when and where..... some claim the large valve heads rob low and mid range but give you much improved top end....others disagree...... many claim to have the best "flow" ...why should a prospective customer for an "upgraded" head care.....what is the role of the cam in this ......

As I have said often that the performance of a part on a bench is only one dimension..... how does the product perform in the "system" that it is integrated into.... are there before and after dynos or numbers of any kind that support claims one way or another....... The Mini world is far behind some of the other marques in the evolution of solid knowledge about what works and what doesn't......let's close the gap

unfortunately, I will be out of the country and away from computers starting Sunaday afternoon for 10 days

 

So, you propose to start what could be one of the most contentious threads in NAM history, and perhaps also the most technically fascinating, and then hastily leave town!!?? Why, sir, that is the action of a provocateur!

WELL DONE!!

 

First big question.
Are the bigger valves necessary or just better valves and optimized flow?

Simplification statement warning:
Smaller runner cross section= better low end performance, quicker throttle response, etc. Sacrifice breathing at high rpm.

Larger runner cross section = Improved top end performance. Sacrifice low rpm response.

The big hole I see in this is you can't seriously discuss head performance without, at a minimum, speccing the cam.
So do we bracket this discussion by limiting it to a stock spec cam or do we open it up to the far wider discussion of including cam specs.
Inevitably intake and exhaust design will come into play.

So? What are the parameters? Do we care?

 

 

I honestly think that you should include cam's in this discussion. The main reason I feel this way is most people would not do a head w/out throwing in a new cam... I guess you could go the other way around and toss a new cam in w/out a head but it would be rare I'd bet.

In short, since they are so closley related and most of the time swapped at the same time, Throw the cam in there. Besides when you are spending 2-3k on a head whats the difference in another 500 in a cam?

go go gadget nam thread

 

often overlooked is the combustion chamber shape and remember that the floor of the CC is the piston dome. read about it (roller wave) at
www.theoldone.com

 

OK, now spec the cam

Let's at least specify how we plan to use the car.

Me? Torquey and quick.

 

This is tricky for us to write about, because I feel we have some secrets that others don't. I will say that ratio of intake to exhaust flow is very important, as is combustion chamber shape - and tied to that valve size and angle. We include the cam with our head because I think it is required to make big power at more than a narrow band range.

Are bigger valves necessary? You can certainly flow more with them at all lift measurements. It typically relates to a few horsepower and lb/ft of torque. That's why we use them. It is more important on the exhaust side than intake side - that's more than I should be saying.

Well, I know it wasn't much, but I am worried about how much to offer the public forum!

Hope that helps!
Randy

 

We'll see where we end up.....



Matt

 

Well, so far 2 vendors agree that the exhaust side needs the most work.
That's a start.

 

I posted both of these comments in another thread...
--There are different configurations available depending on what the needs are: cam, porting, springs, hydraulic rockers/tappets, and valves. There is no one size fits all and that is why I do not stock heads. I put together each as a custom package.
--You have to keep in mind the information/knowledge is power. You will not get it for free; especially from most racers/tuners. That is the "scarcity" part of our economic equation. NAMer Gandini will know about that one.

 

Make it 3.

 

The purpose of this discussion is to be educational to the "market" ..... absolutely, cams should be included but an explanation why for the people who don't know might help more heads and cams find homes on our Minis......

We are not looking for proprietary secrets but giving "us" an education backed up by real performance data of some kind would be useful.....

btw I am also leaving town while my car is in the final stages of "tweek" no computer or cell etc

 

Internal Combustion Engine Fundamentals by John Heywood is an excellent source.

 

Well, we use the cam because it allows us to change when, how long, and how high the valve moves. By altering these things, you change flow and how much air you can move - and when. You should optimize the cam with the porting you are doing and valves you are using. You want to optimize the flow and circulation of the combustible mixture as well as the ratio of intake to exhaust. Forced induction changes things quite a bit, so glean info on that rather than NA stuff.

Hope that helps!
Randy

 

I dont see this thread as educational to the public - For that, just do google research on how cams and heads work.

I see it more as a fishing move by some who need the secrets that others have worked hard and long to figure out.

If the aim of this thread is to figure out which Tuner's head to purchase (because everyone wants the best for their MINI) then I can give everyone the answer right here and right now, and save all the bogus pretend talk.

Get the Webb Motorsports Head.

It's the best one out there. Not only that but it comes with a specifically spec'd CAM, and hate to say this out loud, but it's cheaper than alot of the other performance head packages out there.

Now... time for me to /duck from the other tuners out there who want to give me head.

 

I disagree but then that's the nature of discussion.

 

Since the guy who started this thread has a WMS head, how is it that he's "fishing"?

 

"Torquey and quick." me too....

Specing the head can only realy be done after you figure the, HP, TQ, range you are looking for. There's a lot to specing a head. Just the valve springs can be dificult, install hight, spring length, seat presure, compresion to coil bind, nose presure ( top of cam ) all need to match the cam as the ramp speed will effect the way the springs react. Valves are also depend on cam duration. Big valves flow well but they can be too big. A high winder may need better rockers. The good thing is there are not 100s of cams to choose from & the posibility of building a head for a spec range is very possible.
I'm glad to see that the exhaust side of the present head is where some of you are looking for improvment. One of the reasons for the famous "flat spot" has to do with the intake in relationship with the exhaust. This relationship could bring back the header argument since there are only a few headers that address this problem ( the big reason there is no header on my car ).
To make big numbers, the head is the best place to do it, however everything must match, intake to intake port, header to exhaust port, header primary length.......... Then you throw a blower in the mix.... and a 1.6l.
My wife says I can do anything in 10 minutes...... What is she thinking????? Wait don't answer that.

 

...and as stevecars60 knows, the flat spot is one area that my exhaust system (that is soon to be released) is geared toward.
And as mentioned above, that is why I do not inventory heads. They are all built custom to fit the application by people with many decades of professional racing experience. If you want to go fast you must first understand that an engine is a system -- and that one size does not fit all.

 

Because they dont want to take it off to check out it's specs and or it's an older version and or they dont wanna spend 2G's for new one to find out.

 

I think this discussion was started in good faith to revive a question that each of us has- "what makes a good head, and who makes the best?" We are once again reminded that there is no set formula, and that in the end, the head you purchase must conform to what you are looking for re: power and power delivery. I doubt that anyone is looking to steal the secret recepie, and I doubt that someone could accidentaly give it way in a post lasting, at most, 100 or so words.

 

I love the secrecy part, especially when it extends to offering any performance measurement.

 

Not true. The secrets to a head can be given in less than 20 words. It's the numbers that matter, not some 200 word essay.

Let's revise the 2 main questions:

what makes a good head,
Why do we need to know? Not knowing the answer to this won't make our car any slower. The only way knowing the answer to this question will help an individual is if that individual produces a head to the specs from the answer, and if he did do this, the person who discovered the answer doesnt get any reward for doing so. Therefore, the holder of the answer to this question really has no good reason to answer it. And they shouldn't. What they should do is wave their hand like a jedi and say "Nothing to see here, move along."

and

who makes the best?"
Lucky for you I already answered this one in an above post.

I answered this thread in good faith by telling you truthfully which Head is best.

 

While I have no idea what Camelpilot is trying to say in post #24, I can say with all certainty that he has been raving about it ever since he got head from Randy.