Wow, thats impressive.

 

I agree. A well executed set-up with proper tuning is ideal for nitrous. Although I don't see many EVO owners use it?

BTW, that is beautiful work done!

 

Whats with the attitude from some for just asking a question, sheesh. Anyways, thanks darkhorse, I was just wondering if each chamber is now matched up at 45 ccs?

 

I was seriously wondering what you were attempting to ask... I didn't say anything about your momma or anything.

I'm sure the chambers were all the same volume within any relevant tolerance bone stock. That is not a typical component of improving a cylinder head. If you google for it you can probably find out what those things are.

 

cc'ing the combustion chambers is not a component of improving the cylinder head?

 

I have no idea whether you invented this "cc'ing the combustion chambers" term or if you read it, what person did invent it, but it's a nonsense term to me.

that post from 9:45 AM by darkhorse explains exactly what he did. removing the casting flash from the entire head is typical (depending on casting, ports can sometimes be very bad), unshrouding the valve seat is typical, smoothing and polishing is typical. all these things can be done without a flow bench.

dramatically reshaping or resizing the combustion chamber is not typical. #1, the chamber is typically optimized for the valve angles already. #2, the engineers who shaped it probably knew a lot more than the person modifying it and had access to more powerful modeling/simulating software.

the ports are modified. the specific techniques depend on the way the head is built, the power level desired, the engine's operating RPM, and whether it is turbocharged or not (to expand this discussion beyond just a 4g63). oh and most importantly, the knowledge and experience of the machinist. this requires a flow bench.

if darkhorse or anyone else wants to take it from here, great, but I will stop now and say again-- try google.

 

oh wait, I do have a question for darkhorse: what's your opinion on the HLAs for high rpm use? I saw your modified cam journals and thought of that. at what point is it desired/necessary to ditch the HLAs to avoid aeration/foaming issues and switch to shim & bucket?

 

I think he was asking if he used a C and C machine. To recut the head after it was welded up. Surely you know what that is.

We used to use this same process on Banshee heads (2 cycle twin cylinder ATV).
We would completly weld up the combustion chamber, then re-cut it to accomplish a higher compression ratio and better squish angle.

Nice work Darkhorse.

 

So does this mean you can add some quench area to a specified area... not that the evo engine needs it?

 

oh... that's CNC, Computer Numerical Control machining. it means that you programmed the cutting machine using some kind of CAM software like CATIA. I'm sure darkhorse has one since he's making parts, like the valveguides, but not sure it was necessary or even helpful for this project.

 

cc'ing means something altogether different. It's late, I'm lit... and just climbed off Ma, so you can "google" "cc'ing heads" and come up with a wealth of info on the subject. It "better" applies to the old rough V8 heads.

 

Yes, all of the chambers are equal in volume, to within a fraction of 1 cc, but that fraction can depend on when you shut the valve off on the burette when you fill each chamber, so yes, they are all equal.

I wish i had a CNC, woudl be nice for some jobs, but no, all of my work is done on manual machines or by hand. On a side note, a CNC, machine really only buys you repeatabilty, not better quality. A CNC is only as good as its program, and a program is only as good as its writer. I have seen tons of CNC work, some of it is beautiful, ohter stuff looks like junk since parameters on area of the program of surface finish, tool bit speed, feed and stroke were not carefully optimized, etc. I recently have been seeing more and more CNC ported heads, which arent that impressive, since most of it looks like they program the machine just to touch the port walls and make it look like something was done, when in actuality, the shape is the same, and the volume is slightly increased. On a bunch of CNC ported heads, I have seen area where the tool bit doesnt even touch, since the casting shifted or sunk. SO it may sound cool, but a CNC cannot recognize surface flaws, or casting variances and compensate for it on its own- its all running on a program. I had a conversation one time with a company that specialized in CNC ported head, and after looking at the finished product, asked him why they dont clean up any of the ridges left from the tool bit, and what about the area behind the bend where the machine couldnt reach- why not finish it by hand. He replaied- oh, we dont do any work by hand, it takes too long, and you can make a mistake and we cannot risk that, this is good enough.

Hmmm, interesting.

Shoudl I go and drop a few hundred grand on CNC, write a program, pay someone $10 an hour to just push the button and go retire on a beach somewhere? Nah, I think my way works better for what I am trying to do.

In closing , dont get me wrong, CNC does and can have tremedous merits, but like I mentioned, it depends on the program and how well the person wirtes it. The CNC mahine doesnt know if the tool bit is wearing out or has broken, it doesnt know that there is a low spot in the casting over in this corner, it doesnt see that its about to cut through the water jacket and into the port, it jsut does what its told. So in this day and age of do it once, make it memorize that, hit the button and walk away, I would not trust it, unless I knew that everything that is getting strapped to the bed of the machine was %100 consistent, and like I have mentioned before, as much as you may think so, none of these motors are excactly the same.

 

This is Awesome work Darkhose .

 

Not to mention the demand for ported evo heads is small. CNC porting is only efficient if you keep the machine running the same thing over and over.

Ford 5.0 heads...yeah CNC makes sense becuase they probobly sell a hundred sets of "off the shelf" ported streetcar heads in a week. I doubt Evo owners are buying even one ported head a week.

 

nice repair, quality work.

Ah the dangers of nitrous. A coworker of mine said his friend had a 200 shot on his modified C5 vette and it sprayed too long, pooling up n2o in the intake manifold. It proceeded to all ignite at once and blew the manifold off the engine in a ball of fire. What a video that would be!