CNC headporting for 20v head.

[LHD_Kid]

As far as I know, if you want a CNC head, THESE are the people to go to....

Chris

[JP]

They're machining is lovely their actual flow work is pretty pants. Had a turbo head from them through a tuner lovely valve and seat work choked right down on the exhaust port. Flowed so well straight through the valve into sonic choke in the port so badly that they managed to melt an inconel exhaust valve due to heat build up directly under the seat. Didn't replace the guides and numerous other little flaws. They can machine a nice multi angle job I give them that but thats about it.
Needless to say I now have that tuners contract.

Truth be told cnc heads are nice they are consistant they look good and perform repeatedly across the board assuming everyone is running the same application and setup. My guess would be that the head shown in the first post is a close replica of the original through scanning. You will probably find that the original was welded up in the correct places resulting in pockets in the cnc copy that are spotted on their pictures. Likewise the original head will have been hand finished in order for the computer to scan the ports. So you will most likely find that the original 1100+ps head was either a cnc head that had been hand finished afterwards or just a hand ported head in the first place.

[Ross]

I don't understand why someone would want to get a CNC head. The costs are significanly above getting a decent, reputed engineer to port + finish a cylinder head by hand and the results are inferior. I appreciate they'll all be consistent.... but consistently inferior! My head was turned around really quickly too

[JP]

What you'll find is that its a dying profession due to age and health. So with modern technology being available when a decent head is come across or developed once scanned that knowledge is there for ever and ever to be repeated as and when.

Never quite as good as the original but there forever to be turned out whenever required. Unfortunately the cost of the machines also mean there is an associated price tag for the end consumer. Like all old school engineering its a dying trade where there is very few engine shops you walk into and see anyone under 50 in this country. Give it another ten years and you will be hard pushed to find anything other than bodged diy jobs and cnc'd heads. Especially as modern day casting techniques are getting better and better. Heck a lot of the later M* BMW's are cnc Ported from factory.

[Sonic]

Another shout out for JPs work here - although i'm still a bit short on the boost, the car is unbelievably smooth to drive since the work he did on my head, and revs effortlessly. I can only assume this is as a result of his work.

[JariP]

You don't need to weld the intakes. They infact are a very good design and need lots of small tweaks for big gains. Unfortunately one of the most important tweaks has not been done on their pictures and the cnc'ing looks like it hasn't been able to reach all parts correctly. Meaning the engine has to rev higher to get enough airspeed before it starts making power.

Yes the intake side isn't that bad at all. It mostly needs little bit more CSA at and after the valve guide, I quess. Is the important tweak you are talking about removing the port biasing from the roof side? I can't figure out anything else from those pictures, as surely you are not talking about cutting the valve guides down? I don't have a flow bench yet to play with, so I've been porting by measuring the CSA's and doing the math to find the problem areas.

[rs2infiziert]

Hi, guys, i am going to get a cnc Head from Ng-Motorsports. I will hand over a fine 7a head and the 0.5 mm oversized valves. If interessted i can give a feedback and some pictures of the job. Unfortunately I haven't made a measurement before, but I know how the spool up is. The former head was just a little bit ported and with 0.5 exhaust valves... But the cam run dry and the crank pulley broke... Therefore I have a need for a new head. ( it's the former car from lukach) I hopefullz get it back on the road before may regards from Denmark, Basti

[JP]

Jari P If you're willing to learn I'd be happy to give a few pointers but not on a public forum. PM me your email and I'll try and dig out a picture that wasn't carefully taken to conceal

Error404 one day when I'm old and decrepit

[Jonnybravo]

We use a guy who has been doing cylinder heads for years, he has done work for all sorts of teams and manufacturers, you may know him JP ? Its been asked many times about cnc heads but the truth is the only benefit I see is the repeatability of them, Nicks heads have out performed any cnc head, I would be curious if he has done any I5's before actually.

http://www.youtube.com/watch?v=Ofwlejxve90&feature=bf_next&list=UUPVWwGZcpoctOG3pcy8eIQw&lf=plcp

http://www.youtube.com/watch?v=n9_8BN67Acg&feature=bf_prev&list=UUPVWwGZcpoctOG3pcy8eIQw&lf=plcp

[quattro84]

Wow i've started quite a discussion here.

@rs2infiziert: Yes, do share the after results please of your infected head.

Any of the gurus capable of supplying some visual stimulation for my limited brain to get an insight where (and perhaps more important where not) to stick my grinding tools to accomplish this comprehensive task on our 20v head?
I get the shivers of the idea reaching coolant areas or leaving tin foil as a sidewall...

[JP]

I believe in the boot of my car there is still a cut up head that shows the waterways if you want can take a pic tomorrow.

As for where to stick your grinding tools there is plenty of tips scattered through this thread you will have to read into them carefully. However the biggest two tips I can give any novice is the following.

Air flows in a straight line and doesn't like going round corners

Sometimes it's the little things that count not the big ones.

And the last hint:

As an example I can guarantee any porting work you do as a first attempt on the I5 intake I can better by only touching the area between the combustion chamber and the guide

[JariP]

Some visual stimulation or something like that:

Exhaust1
Intake1
Intake and exhaust
Intake2
Intake3

[SteveH]

better get them down to Ann Summers, you could make a fortune

[DJones]

better get them down to Ann Summers, you could make a fortune

I thought that to, the current Mrs Jones walked in on me and i had to explain what they were.....

[SteveH]

Now this is head porting, somebody really knows their stuff here.