Dave walks us through why we blend and what we blend after a head comes out of the CNC. Many believe the CNC just does everything, but that is not true!
Dave, ran across your video today. Haven't seen you since SAM, 25 years ago. Glad to see that you're doing good and still in the game. I have a pic of all of us around the SS Camaro sitting on my desk. Cheers brother! Josh M.
I have experienced that too, shops really do not care, sometimes they get a little insecure then get mad at you for simply reading a sentence from an ASE book on the specs for your car to machine it. Told me I was making stuff up, when I have talked to a real engineer that designs optics and told more than I could ever ask for about that unit of measurement. In the end I called up and down the state, and concluded that people do not know and or get mad so I just did what ever with the engine too it seems to work for them anyways.
yeah I probably would tell you to pound sand if you told me what a book said to port the head too. Machining wise, that would depend on what part we were speaking about and if it actually mattered. Like, BMW states you can't use there heads after milling. Same with Nissan GTR. We have milled some heads many times with no adverse effects.
When I see a CNC port - I actually PREFER to see some spots left raw... it suggests their program isn't simply "hogging it TF out", but rather - has been programmed to only remove the bit of material necessary to create a good, high velocity airflow.. Regarding the bit of extra deburring work. In the machine shops I've worked in, this is called "benching" or "benchwork". Theoretically, the CNC operator is supposed to do the benching on the last part while the current part is being run in the CNC. In reality, the operator stands around, BS's with the other operators, or plays on his phone instead - leaving the benchwork undone. Nice to see you take pride in delivering a quality, finished product to your customers.
I agree, some are hogged out just so they don't have to blend it. We prefer to not make the port bigger than it needs to be to save us from doing work.
Hello. Thanks for these videos, not everyone wastes time teaching and explaining the why of things. They only show the beauty of the CNC's work, but all these details are not reported to the people. This week we are going to order the burrs that you have in stock, when they arrive in Spain, I will tag you on instagram. Best regards
Personally, I VERY much appreciate the blending. I recently expressed my disappointment after my client paid $4,500 for a pair of heads and 60% of the ports were untouched. 🤷♂️
I would love to lock at your process. I have made programs for other industries that use probs to pick out casting moldes and run different parts of the program for them. For the debur you could do that in the machine! the question is then how are you staffed and the fixtures that you wether to should.
It is very eye opening just how sqewed these casts can be, unique like fingerprints. I have seen modern BMW engines being made and noticed that the sand is falling apart as they are pouring the liquid alloy. Why not add material to the port before CNC-ing it so they are a little more identical? I've seen 2-stroke guys add filler to really smooth out the curves.
not sure what you mean by filler. You cannot add aluminum to the heads and epoxy would just come out. You might be seeing them do that because it's a race head. If we did aftermarket castings then we can add material. That is what Trickflow and others do. Cast them small, so they all look uniform. That would be great!
As always, great stuff. One question, it looks like the third port has a significant crack in the middle of the fin. Is this a junk head? What's the story there?
First and foremost, thank you for the content! Keep it up! On EJ s20 heads going on a hybrid motor, would +1mm valves and porting be recommended at the 4-450whp mark?
We don’t install oversized valves in a Subaru at all. You can make 1400whp on stock size valve. The +1 valve is only .004 smaller than the seat so you run into heat transfer issues and it doesn’t flow better till .350 lift. The highest lift you can possibly get is .420ish. So you lose more than you gain. Stock cams for up to 550whp. Stock size valve.
