K24A2 Port & Seat Development - K20A.org .:. The K Series Source . Honda / Acura K20a k24a Engine Forum
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Old 06-14-2019, 08:34 AM   #1
Scider
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Join Date: Feb 2019
Posts: 23
Default K24A2 Port & Seat Development

Because I want to build a K24 normally aspirated for my Exocet project, doing valve seat and port development will be extremely useful. I came across an early RBB head on eBay at a good deal. It's got 35mm intake and 30mm exhaust valves.

I stripped the head down and cleaned it up a bit, but I don't have any sort of soda blaster so there's a bit of carbon still around. The intake seats are in amazing condition all things considered.



I pulled out one of the flow bench adapters. It allows inserts for various bore sizes, the last of which was for a BMW 2002 with an 89mm bore. It wasn't as nice as I would like so I bought another PVC fitting and some epoxy to make a new one. It's the cheapest way to get a representative 87mm bore, but its' only 2 or so inches deep. Seemed a waste to bore a 4.5" Aluminum bar, and I'd be on the lathe all day. The adapter is using locator pins and I'll use clamps to secure the head.




Not bad on alignment, the cylinder looks to be very well centered between the 109mm x 94mm head bolt pattern.

I still need to make a gasket for the head and machine up a device to allow opening the valves and measurement of the valve location.



Because I have a few cylinders to play around with I'm going to split development into two areas. Development at the seat, and then development in the port. Here's what I'm thinking so far:
  • Stock valves and ports
  • Back cut stock valves and port
  • Ferrea 6000 series 35mm valve and stock port

The Ferrea valves are of their "Super-Flo" design, meaning they come with a 30 degree back cut and necked down valve stem below the guide. After I get the baseline and a few valve mods, I'll start with removing casting marks and blending the bowl in a bit.

I need to get a 5.5mm pilot to play around with changing the seat angles, but I'd like to try a 75 degree back cut to blend the seat into the throat a bit nicer and see if that yields any improvements.

Lastly I'll start looking at changing the ports themselves. I don't want to make too many changes to the port just yet. I'm still working through some flow calculations to approximate some averaged air flow velocities. Anyone can get big CFM numbers hogging a port open, the challenge is to improve flow while not reducing velocity. Velocity helps with mixture distribution, and helps with getting that last little bit of air-fuel into the cylinder at high engine speeds, when the intake valve is closing after the piston is trying to push the intake air back up the port.

I also made a silicon mold of the intake port to try to see where changes could be made. Incredibly difficult to visualize so far, but stay tuned for results.


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