Using the 2006, S engine I just bought -

I was curious this evening, I measured a stock (unported) exhaust port (in inches !) = .897" tall x 1.350" wide. As measured as close to the edge as I could repeatably do (three times).
Then, I measured the OEM header (yes, by definition, it's a header) = .956" tall x 1.353" wide, I measured all four openings.

So...how much taller is the JCW port ? I think I read about .200"..!?

Doing the simple math, that exhaust port, porting is a waste of time..! .956" - .897" = .059". So figuring about (on the large side) .010" for any error, that leaves about .149" or so of header overhang into the port..!
What were they thinking ? So much for the "ported" head..!

Mike

 

I went out and measured the exhaust ports on my JCW head, measurements are:

.983" tall x 1.372" wide

Hope that answers your question.......

I have another JCW cylinder head still on the engine that is still in the car that I'm replacing.....the header is still attached, as are much of the other items that I need to remove in order to install the wrecking yard engine.....not sure how long it will be before I can get the dead engine out, but I'm sure the measurements will be the same if the cylinder head in the car is in fact a JCW head......

Bryan

 

Interesting find...thanks A383Wing for checking.

It appears the JCW exhaust port is "both" taller (as many reported) and wider (no one's noted that, that I've seen) than a stock, unported head..!
So...the OEM header over-hangs in both height and width to the cylinder head, basically negating the cool port work done by whomever at the factory (or where-ever it may have been done).

Seems everyone stands to "possibly" gain a little power with a properly sized header. In a quick look at my header, is doesn't look too promising that the flange can be opened to match the head dimensions.
We (JCW owners) waz cheated...

Mike

P.s. - As a side note here, I'm looking to get a stock, junk head. Cracks, blown head gasket damage is ok.

 

I also was surprised by my measurements compared to yours......I knew the ports were taller, but I didn't know about the wider opening in the exhaust ports

Which, as you noted, I wondered bout the opening match of the JCW head to the exhaust header if it was a close match or not.....I found they only make one exhaust gasket for all the Gen 1 engines.....and if what you say is true, the header may choke the exhaust coming out of the head and negate any real major power gained. If one could "gasket match" the header so it's the same size as the cylinder head, it may prove to be helpful.....but I'm not sure if there's enough "meat" on the header to open it up......and if you could open up the header openings, they may be so thin that the header would crack or split from the heat because it was thinner......

Does anyone make a header that is matched to the head openings? I don't know.....my header is still in the car and still attached to the "dead engine".......if and when I get the engine out, I'll look at my header and see if anything can be done.......

Bryan (and yea, I think the JCW owners was cheated....LOL)

 

This is exactly why I'm looking for a first generation cylinder head.

Anyone just digging into a cylinder head with "porting" as a reason is asking for trouble.
I've been doing port work for over 40 years. Back in my formative years, yea, I went into water... I learned...the hard/expensive way. I've not got more cylinder head "sections" than I know what to do with. I want/need to learn where the thicker sections are, where not to get too heavily into it. I don't have a flow bench, but have spent a lot of money at a well known shop about 35 miles away. They keep their engine dyno's, chassis dyno's and flow bench certified every six to twelve months, depending on the items use.

All this is to say, be careful with "gasket matching", it "could" leave you with too thin walls.
In doing some Mini head research in the last few months (I'm new to the Mini Cooper world), I noticed a "professional" shop doing some "funnel" shaping (intake AND exhaust)...HUGE mistake. The port side walls OR the roof vs. floor, should never form a funnel or wedge shape (by more than about .03" or so because of some sort of unmovable restriction) or major influences in overall head design. At least in the all of the porting vs. flow bench vs. drag strip work that I've done.

I'm looking at a (used) header with slightly larger primary tubes this weekend to fix THAT problem in my car..! Hopefully not too large !

Mike

P.s. - Yea, in my OEM header, you can do a little opening touchup, but not enough. Plus the small primary tube diameter, and the crummy collector design.

 

I would be interested in seeing the larger header if you get it......from my searching, I can't find a "larger or thicker" header flange that would solve the "size" difference issue that you would need for gasket matching

Bryan

 

Not sure about the flanges, most are advertised as being about .375" thick.
I've seen a couple of different sized primary tube diameters advertised. I'll check the (stock) port corner to opposite corner to see what that dimension is just for reference. Normally aspirated (unblown), 1-1/2" primary tubes are plenty for less than a 7000rpm engine need. You don't want to go too large even with the blower (belt driven), or you'll loose low rpm power, but want to add thru the whole range, especially the midrange. And since my car is a street car, that MAY hit the Auto-Cross track once or twice a year, I don't want to loose too much low rpm power.
I'm in favor of the 4.2.1 design (provides a lot of the best of both worlds for midrange and higher rpm power), which is the design I'm hoping to look at this weekend.

Mike

 

 

Very expensive but oh so good ;O)

 

You fabricate that yourself? What size doughnut gasket you using?

Would think that the weld points would create something like an air eddy. Do not know how they would affect overall flow through the pipe.

 

Exclusive -

Nice work, who-ever built that header.

Whine -

There a VERY small amount of disturbed material if welded correctly.
Plus, at the interior surface of the tubing, just like any surface, the flow is the slowest near the surface, fastest near the center.

Mike

 

Nice isn't it, I didn't make it, I just had to pay a lot for it haha.

This is my other one which I've yet to test, I'm very pleased with the first, I haven't decided yet which car or engine configuration I want to use with this one yet.