I just finished porting my head (I've been porting about 30 years). I put oversize valve seats in so I can run 32mm intake & 27mm exhaust valves. Now I have to ream the valve guides, do a valve job, & surface the head.

Based on my experience with previous heads, I expect about 30% increase in flow.

 

How much are you saving vs buying a Thumper or RMW?

 

It's not so much about saving money (though I am). I feel I can do a better job than the production stuff. I made custom 27mm valves for the exhaust. If I did it again, I might make 33mm for the intake.

 

cut7-

Intake side -
In the two "passages" between the port wall and the valve guide (each side) on the roof of the port, why wouldn't you open that "passage" by narrowing the guide some on each side ? Moving the cutter left and right to make the passage wider.
Afterall, that is where the higher speed flow is going around the valve stem. don't want to choke it off.
It seems you might have done a little of that on the exhaust side, hard to actually tell, but...

I've also done a lot of porting in my 69+ years and have found that the flow bench seems to like it...wide adjacent to the guides..

I just cut up a Mini head myself to find out where the thin wall locations are. This way I can be more assured of not going into water or causing a wall to crack from being too thin..!
One thing surprised me, is how thin many of the areas actually are. Like from the seat to the bend in the roof, near the guide. A large valve is desired, but to do this on a positive note, (to gain flow), you can't go too large a seat because of the thin port walls.

As soon as I finish some other reshaping work, I'll be digging into a spare Mini head that I have also.

Have fun.

Mike

 

OCR,

I did more than what appears; the picture is somewhat deceiving. As I'm sure you are well aware, most gains are found not the throat of the port, but in the bowl. That where I spent most of my time.

 

The finished product.

 

Pictures of the cut up head would be greatly appreciated.

 

Cut -

I don't have any pictures. I can take some this weekend and make them available.
I'm actually not sure what good they will do, because as as you know, you need to see / feel the inner and outer wall of a given location at the same time. Espicially in various areas of the exhaust ports. Like between the ports, there is water and the port seems kind of thin, a picture won't show that.

I just thought of something. I had the head cut, top to bottom in a few slices. Nothing horizontally. Maybe I can use my sawsall and take a sideways cut out of a section or two. Let me look into doing that.

Will get back to you.

Mike

 

Thank you, Sir.

 

Damn that's pretty. I am struck by the volume of valves! I'm hoping somewhere in this tale there's a dyno plot, as this surely looks promising.

Cheers,

Charlie

 

Where did you get your custom made, low restriction, ultra quiet, mufflers from? I got a custom muffler made by Coast Fabrication a number of years ago but it definitely wasn't quiet. They used to make them for Burns Stainless but Coast sold out to Pro Fabrication, in N.C. a couple of years ago. It's possible I should have gotten the Fiberglass version but as I planed to put it immediately after the cat, I figured the high temp resistance of the "scrubbable mesh", was a better choice.

 

Thank you, kind Sir! I will be putting this car on the dyno soon. I am putting in a custom cam that will allow it to rev to 8000 rpm.

 

It's a muffler of my own design; I built the entire system myself. It's all steel, no packing (not even steel wool) it attenuates sound by a different principle. It's not much louder than the stock mufflers, certainly quieter than any else on the market (that I've heard anyway). It has a larger tube header with a much better collector. It's 65mm Ø (2.5 in.) from the collector back, & I have a high-flow catalytic converter installed; so no check engine light, & you can pass smog. It has about 5 kPa (0.75 psi) of back pressure — virtually nothing — so it appears to the motor to be an open pipe. I'll make a video of my daughter & me driving in the car. There is no drone, & you can carry on a conversation driving at 130 kph (80 mph) without raising your voice.

 

See your PM for cylinder head interior photos.

Mike

 

Yes, thank you.

 

Well, I got the head & cam on the car yesterday. I had to replace one of the exhaust rockers, as one of the exhaust lobes on the original cam was about 0.5mm worn, & the roller showed slight pitting; I didn't want to take a chance with a new cam. As my signature states, I have a very free-flowing exhaust, 17% overdrive pulley, 450cc injectors, JCW cold air intake — in my not-so-humble opinion, the best engineered airbox out there, it will flow enough air for 500hp; & it's quiet too! — ARP studs, & a lightweight aluminum flywheel. I reset the ECU (test 21) to learn the mods & went out & drove it through the twisties for about 240km (150mi.) All I have to say is...HOLY SMOKES! That thing is FAST! The engine revs very freely. I hit 160 klicks (100 mph) more times than I care to mention, without even trying!

I still have some tuning to do, as I am getting P0108 code (high boost) above 7000 rpm; & the idle is sometimes ever-so-slightly rough. Also, I'm sure the AFR & ignition timing isn't quite right, but so far, I'm VERY pleased with the results. A JCW is rated at 215 crankshaft horsepower (about 183 to the wheels). I'm guessing I'm putting down at least 250hp to the wheels (which would be close to 300 crankshaft hp). Yes, I will post a dyno sheet as soon as I get the fine tuning done.

 

My otherwise stock engined, 2005 JCW was dynoed at 211 at the tires.
Somewhat obviously all dyno's measure slightly different, but 183 to 211 is a pretty large difference.
Nothing but JCW parts installed. Since buying the car, I've installed the Miltech cat-back system. I don't know if it added any actual power, it DID get rid of a flat spot at about 2500rpm that it had with the JCW exhaust. Overall, it's also running much leaner. With the JCW system, clean the exhaust tips bright and shiny, drive it 15 miles, the tips are black, all the way around. With the Miltech, cat-back system, clean the tips shiny, I put about 95 miles on it in one day about a month back, not even a shadow of exhaust soot in the tips. So I know that it's much leaner now. My butt dyno says all is good, but I don't know as fact.

Air cleaner assembly - The JCW cleaner assembly is worth 500hp ? On what dyno, on what drag strip ? I'd be interested in witnessing this..!

Mike

 

What I said was the amount of air it can theoretically flow is enough for 500hp (not that a tritech motor can produce this much!) Meaning the airbox can far out flow the motor; which is a good thing. For the record, bolting on a JCW — or any other — airbox is NOT going to give you 500 hp.

Also, I said 183 wheel horsepower based on the long-held industry standard of 15% loss through the drivetrain. (215 x 0.85 = 182.75) This corroborates the stock cooper S cars I've seen on the dyno making about 143 wheel horsepower (168 x 0.85 = 142.8). Of course, I've also seen some wildly optimistic dynamometers.

I think we can all agree that all car manufactures are quoting crankshaft HP figures, & that there will be some parasitic losses through the drivetrain.

I hope that clarifies my statements.

 

Air filter housing -
I agree that it's better than the base housing, but, and not to argue about it, but I've been around enough (almost 70) dyno work and drag racing, to say...I "seriously" doubt that that little opening will support 500hp in any internal combustion engine. I would wonder if it would be large enough to properly cool a 500hp electric motor. Add to that the length of the inlet tubing, is an effective choke. The longer it is, the harder the air has to work to get from one end to the other. I know that that's not the "opening", but...

Horse power wise -
If you go back and reread your post, I believe that you mentioned the JCW, not the base "S" engine. That's why I mentioned one JCW car that I know of.

Mike

 

I addressed the JCW figures in my last post. Also not to argue, because I'm really not interested in offending anyone, & I appreciate intelligent dialogue with people such as yourself who actually have experience building & tuning motors; even if it's a different opinion than mine. Having said that, the JCW air box has 2 openings one in front, & one in back that opens at 4500 rpm. Even if I'm off by 30% (& I don't think I am) it's still a great airbox, & it's quiet. Virtually no intake drone until the rear flap opens up; & by then you're going fast so what little drone there is doesn't really matter.

 

Great job on those heads !
Lol, I dont want a quiet intake ! I wish my filter wasn't enclosed but it REALLY helps fight iat's. Haha mines loud and im proud. I actually removed plys from my intake too make it larger internal diameter and fit a 70mm filter to match.

 

If that suits your fancy. I'm an old man & I like it quiet.