Iron head testing (update on post #65)

[Mike T]

Thanks Mike. I'm going to have to get busy finishing up this pair and stop playing so much on the bench. I am about ready to start assembling engine hopefully end of the month. Pistons should be in next week. Getting excited!!

I do plan on continuing on with the heads though. I've done some work on other heads at the shop and there's a lot of that work coming in. I need to keep at it. Plus I have a few buddies that need some decent heads.

Please do keep me posted on the pic of that area, thanks! I'm right on your heels!!

I edited the post as you were replying. Take a look at # 99

 

[TURBOELKY]

Got it. Yeah I think the 7cfm loss was the Chevy valve I tested with. In going to leave the heads as is until I get my valves in. I'll keep you posted though. Your ports look prettier than mine though

 

[Mike T]

Your ports look prettier than mine though

Thank you. Your numbers are telling you that shine doesn't count for much.

 

[Mike T]

Got a couple of pic for you.

 

[TURBOELKY]

Hmm. Looks like you took more of that hump off. Also looks like you took a lot more material off leading up towards valve guide too. I'll see what I can do on Monday. Thanks Mike!

 

[turbofabricator]

View attachment 280394 Hey Mike, how far were you able to take this bump down? This is probably the worst thing that could have happened to the head....other than the valve size

Be VERY careful with that hump. There is water right under there. I have 8445 castings all cut up in pieces from 25 years ago, just to see where to stop. Core shift can BITE you there. Also on the long side of the exhaust port. I'll dig up my chunks and post some photos if anyone is interested. Might even ship them to someone, that would get pricey just to look at wall thickness. Photos should probably suffice.
That hump was put there to help induce swirl, best as I can tell.
On a turbocharged engine, I have found that port volume is helpful, even though it shows nothing on the bench. Thankfully, even my heads make power........thanks to the turbo!!!!
Here is a set of TA heads I recently finnished

 

[turbofabricator]

Duplicate post

 

[bison]

I am no expert but continually fascinated by air flow and ended up re-porting a TB professionally ported set of heads that disappointed me. Took me 6 months of studying , measuring and porting. I know I am crazy but love doing that stuff. Lol.

Anyway. . . . . The max flow is typically around 25-30% of seat diameter. It's about the curtain area. What that means is that there really is no need to have anything over about .520 lift and tax the valve train over very minimal gain.
Great stuff, lots to learn.

Usually lift is a product of the ramp. To increase duration at .200-.300" where the flow is good you need to either add overlap (not usually good) and open at the same rate, or keep overlap similar and increase the ramp. Increasing the ramp will require additional time to slow the opening valve down and because of it added lift. We can't run a square lobe unfortunately but can do other things to get the valve where we want it sooner. All at the mercy of the space available and the $$$. I agree the gains are minimal if the exhaust to intake pressure ratio is increasing. If it's not adding in overlap and increasing the valve opening speed will definitely increase cylinder fill.

 

[TURBOELKY]

Duplicate post

I actually cut up an 8445 head the other day right where that bump is. And yes, there's is VERY little material in that area. What a fucked up design.

 

[Reggie West]

Wow did they machine that pattern to increase turbulence going through the port ?

Damn!!!

View attachment 280375

That's SEXY !!!

Almost looks like an engine-turned or jeweled surface. Can you imagine the investment in man-hours?

 

[Pronto]

5 axis cnc machining. It's amazing what can be done milling.

 

[34blazer]

Wow did they machine that pattern to increase turbulence going through the port ?

I don't think the floor was designed for anything special other than keeping the port lower, for space constraints. From what I have seen, there is little "flow" on the port floor.