Lets raise the roof!

[Bos's5.0]

I'm remembering a thread about raising inlet ports with a bunch of weld. Chad was going to do the ports. I wonder how they came out?

I "think" I remember a set he did where the whole thing looks like it was epoxy. I think I know who the heads were for, too. The search engine on this site is the biggest POS I've ever seen.

[The Badger]

Found the thread. Don't know how to link off of phone but thread is "raising runner,not short turn?"

[Geoff2]

When I bought my 4 cyl Honda 750 m/cycle, I got a spare cylinder head with it. looked at the small intake ports & said no way they can 'work', need to be bigger. So opened the ports up, not a whole lot..............& went slower.

Lesson learned!

[mk e]

Found the thread. Don't know how to link off of phone but thread is "raising runner,not short turn?"

A lot of weld going on there! If its going to be more than 1:4" thick I normally add a plate, its a whole lot easier and things warp a lot less.

Also i saw getting the right torch mentioned, amen to that. I like the wp-24 but it's really only rated to 80a, I push mine to 150s for short durations and it lives. A WP-125M is also very handy and about the only thing that will work in smaller ports....they say it's 125A if you have the quartz cups, again I push mine to 150A, and replace a lot of parts because really it's a 70-80A torch.....but it gets into the port and works.

[randy331]

You need to learn to grind out where the restriction is for whatever givien port shape and area you are trying to improve on, also you may soon find that on most heads flow improvements up to .300" lift come by means of reworking the 1/2" or so on either side of the valve and doing something like kicking the roof up will lower port air speeds on the roof path and actually make for a flow loss in the range of .050" to .300" lift!

So raise the roof ?,... or work the 1/2 inch each side of the valve ?

Randy

[groberts101]

IMO, if you want to be successful at redesigning factory ports?.. then you need to study each ones particular airflow dynamics as they relate to that specific ports geometric restrictions(available metal and surrounding port/component architecture). Sure you can cut a big honking hole into the roof all the way towards and even into the spring seat on most cylinder head intake ports(dry roofs) and re-clay them to make massive gains in flow. But no engine mentioned here works without it's valve springs keeping things under control so we are limited by space in every direction we try to move things around. As for the intake ports roof angle requirements.. there's only so much material that can be whittled away under a spring seat without raising EVERYTHING up, using hella-long push-rods and moving towards tiny ratio rocker arms as the valve-train gets crowded closer together at the very top.

Also IMO, the ultimate head needs to be designed from the chamber towards the inlet valve and throttle blade/s. Otherwise you end up applying band-aids and crutches to try and fix piss-poor pressure recovery and the combustion chamber design/space will be a mess for port cross-talk, dead zones and shitty combustion dynamics. Sure the raw dry flow numbers will look good on the printout but the head will not make power like another casting with less raw flow numbers and much better combustion chamber design/dynamics. Think of it as shooting a double barrel shotgun down into a tube and then trying to make the various sized bb's bend around corners and perfectly hit the combustion spaces bulls-eye. Not easy at these constantly changing speeds and pressures.

As also mentioned, maximally sizing the throat within that specific castings allowance(limited by metal and gasket/bore shrouding of course) before deciding where your airflow enhancement efforts are best spent would be prudent in such a time consuming experiment. Cast iron is a bitch to modify, remove and put back compared to aluminum. And my final words of advice would be that welding is far more expensive and time consuming than most will ever realize so pick your battles if you catch my drift. Good luck and have fun learning!

PS. like I said via PM.. I'll post a few progress pic's in that old thread for the other "hi-port dreamers" like myself.

[CGT]

You need to learn to grind out where the restriction is for whatever givien port shape and area you are trying to improve on, also you may soon find that on most heads flow improvements up to .300" lift come by means of reworking the 1/2" or so on either side of the valve and doing something like kicking the roof up will lower port air speeds on the roof path and actually make for a flow loss in the range of .050" to .300" lift!

So raise the roof ?,... or work the 1/2 inch each side of the valve ?

Randy

I guess the question always goes back to if the flow loss in that .050 to .300 range is a positive or a negative.