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Calling all DIY cylinder head porting gurus ! Now with flow bench testing + progress
i recently picked up a set of 862 heads for next to nothing and watched videos, read articles on how to port these heads and well, i ported my heads and didn't gain as much cf. as id link so i want to know is there anything else i can do in my port work to gain even more cfm? i want these heads to flow the same as the 243 but with the smaller chamber and added compression on my lq4
will a bigger valve get me all the way there ?
what else can i do to the port too get more cfm ?
i have full and unlimited access to a SF1020 flow bench at my disposal
the tests were done without a radius inlet guide which i believe are why the numbers are so low if i add the guid will this bring the numbers further apart ? example i flowed about 200 stock and 210 modified so if i add a guide and gain cfm will it be 220 stock 230 modified ? or will there be a greater variance ? i will be adding a radius inlet guide but not anytime soon.
i was thinking about touching the valve guide boss more and removing more material
my setup is as follows
07 LQ4
arp rod bolts (I'm not resizing)
stock internals
862 ported heads with 2.00'' intake valve
PP 102mm intake with rails not sure what injectors work in this setup ?
NW102mm intake
1 3/4 in LT headers
MS3 cam
all other supporting mods
hoping to crack 470whp through a t56 and a mazda diff
any input is greatly appreciated guys thanks a lot
Last edited by nick Ritter; 05-03-2016 at 01:50 PM.
Reason: pics added
One of the big goals of porting is to smooth out the air flow, and decrease turbulence. Turbulence decreases air flow. Especially around obstructions in the air flow path. Think of a rock in a stream. There's a lot more to it than hogging out the port.
In the picture, the valve guide hump is pretty irregular, and even has some sharp edges. Straighten and smooth all that out.
The pocket also is pretty irregular. When the air becomes turbulent in the pocket, it inhibits flow through the open valve.
For a given pressure drop, which is typically 28" of H2O on most Flowbenches, air will only flow about 140 CFM per square inch at best. With all the angles and turns in a cylinder head, most ports will flow well below that.
This is a picture of me measuring the area just above the valve seat where the smallest cross sectional area typically is located. As a general rule of thumb, it shouldn't be any more than about 91% of the valve diameter. So, for a 2" valve, it shouldn't be more than 1.82" in diameter or 2.6 square inches of cross sectional area.
Clearly its a rookie attempt.....gotta give some credit for taking the initiative
I think the biggest problem lies more in his expectations than anything else.....doubt those goals will be achieved with a 1st attempt home grown ported head but I give the OP credit for trying and asking for some advice.
Mine is to scale back your expectations some and enjoy the process and learn as much as you can. Maybe there are some local guys with a little more experience that can give you a few pointers. Also the right valvejob is everything.....invest money with a quality performance shop that can handle the right valvejob for you.....save it for last and blend that into the port and chamber when you have more experience with the grinder
For a given pressure drop, which is typically 28" of H2O on most Flowbenches, air will only flow about 140 CFM per square inch at best. With all the angles and turns in a cylinder head, most ports will flow well below that.
This is a picture of me measuring the area just above the valve seat where the smallest cross sectional area typically is located. As a general rule of thumb, it shouldn't be any more than about 91% of the valve diameter. So, for a 2" valve, it shouldn't be more than 1.82" in diameter or 2.6 square inches of cross sectional area.
Clearly its a rookie attempt.....gotta give some credit for taking the initiative
I think the biggest problem lies more in his expectations than anything else.....doubt those goals will be achieved with a 1st attempt home grown ported head but I give the OP credit for trying and asking for some advice.
Mine is to scale back your expectations some and enjoy the process and learn as much as you can. Maybe there are some local guys with a little more experience that can give you a few pointers. Also the right valvejob is everything.....invest money with a quality performance shop that can handle the right valvejob for you.....save it for last and blend that into the port and chamber when you have more experience with the grinder
Good luck!
-Tony
i think I'm getting better guys ? I'm trying over here...... i went out and bought new burrs and wow is makes a difference. this is still the rough cut, every port now looks like this without being sanded I'm going to flow test them tomorrow but as you can see there is a pin hole in the runner !!! so now I'm going to have someone weld it up for me and keep plugging away at this i know i can make these things flow ! i just need some time I'm trying to find a 2.02 valve without buying a hole set. i have a feeling with a bigger valve its really going to wake up read a thread someone put a 2.00 valve in on a stock port 862 and picked up 8 cfm and yes i will be sending these out for a 3 angle valve job with 2.02 valve, now I'm just hoping i can get these to flow what 243s do but with way more compression thats my goal. stay tuned
thanks to everyone who is encouraging me, never knew why ported cylinder heads cost so much until now. these take a lot of work !!!!!!!
I do agree with Tony though in that it seems you have set a goal for these that a quality ported set of 243s would struggle to put down.
Keep in mind a large majority of ported 243 head cars are making 440-450rwhp through a t56 and 10 bolt rear end. While there are some making 470-500rwhp it's not as common and requires either attention to detail or a happy dyno.
FWIW my head guy had a bit of effort in my 799 (same as 243) to get ~300cfm out of them and that was on a larger bore plate.
I do agree with Tony though in that it seems you have set a goal for these that a quality ported set of 243s would struggle to put down.
Keep in mind a large majority of ported 243 head cars are making 440-450rwhp through a t56 and 10 bolt rear end. While there are some making 470-500rwhp it's not as common and requires either attention to detail or a happy dyno.
FWIW my head guy had a bit of effort in my 799 (same as 243) to get ~300cfm out of them and that was on a larger bore plate.
what was the test pressure he was using ? that makes a huge difference. there seems to be a lot of people saying and doing that home ported 862s with larger valves will outflow a stock 243 by quite a bit but i read all these threads about ported heads and no where does it indicate what test pressure they're using, if you use more pressure it will "flow" more period.
forgot to mention i have a dyno and a bone stock 07 lq4 in my car made 301 WHP SAE corrected so yeah its a happier dyno but numbers don't mean to much i just want a nice set of heads that I built and i started this thread to get some pointers but have only had 2 decant replies no one has yet ti answer y radius inlet guide so I'm going to figure that one out on my own
this is the stock head with a clay radius inlet guide (above)
this is the mod port still without a valve job and the stock 1.89'' valve pretty confident i can get these to flow 250 with a 2.00 valve and a nice 3 angle valve job what do you guys think ? read the sticky on ls1tech about head porting they say a 20CFM -25 CFM increase on a mod port with larger valve and valve job
huston trucks. net is also claiming in their sticky the 862 stock casting is supposed to flow 226 @ 0.600 lift and my results showed only 215peak so im thinking these are flowing about 240 on their scale they also claim in the same sticky the 243 head flows 256 @ 0.600 lift so...... i think im doing well ?
i really want to test a stock 243/799 head if anyone has one that is damaged let me know all i need is one good intake runner i could also do a sweet cut-away of the port also looking for a intake valve(s) that is a 2.00 or a 2.02 before i go out a drop the coin on nice valves all i need is one !!!
Don't know the specifics, I assume whatever is the typical standard.
My point was if you're looking for 470rwhp a stock 243/799 isn't going to do it, it would take a very well ported 243/799 head. A home ported 862 is just probably not going to be capable of that.
Be proud of your work, it looks like you're making excellent progress...but be aware the goal you stated is lofty is all. Either way the car should be a hoot and you can say you did it yourself.
Don't know the specifics, I assume whatever is the typical standard.
My point was if you're looking for 470rwhp a stock 243/799 isn't going to do it, it would take a very well ported 243/799 head. A home ported 862 is just probably not going to be capable of that.
Be proud of your work, it looks like you're making excellent progress...but be aware the goal you stated is lofty is all. Either way the car should be a hoot and you can say you did it yourself.
it should be very damn close to 470whp especially if i run E85 170whp gain from H/C/I with corn should be close
making great progress i think learned a lot so far and i think i can say im never going to hand port again for while after this. i now fully understand why ported cylinders heads cost as much as they do.
i know my goal is out there, my original plan was to out flow 317s and im already probably past that im guessing if im getting 10cfm lower than what people claim. remember im still on the stock 1.89 valve with no valve job !
exactly what i want, just want to have a set of decently badass cylinder heads i built myself either way im looking to break this car into the 10s and have something thats a threat for roll racing i might even try to get a lq9 block and smash these heads on there but we will see ill update the thread regardless
it should be very damn close to 470whp especially if i run E85 170whp gain from H/C/I with corn should be close
making great progress i think learned a lot so far and i think i can say im never going to hand port again for while after this. i now fully understand why ported cylinders heads cost as much as they do.
i know my goal is out there, my original plan was to out flow 317s and im already probably past that im guessing if im getting 10cfm lower than what people claim. remember im still on the stock 1.89 valve with no valve job !
exactly what i want, just want to have a set of decently badass cylinder heads i built myself either way im looking to break this car into the 10s and have something thats a threat for roll racing i might even try to get a lq9 block and smash these heads on there but we will see ill update the thread regardless
thanks !
If anyone knows of a good method to polish the chambers please let me know did some searching sounds like this ......
80 grit everywhere with cartridge rolls
120 grit
Flap wheel
Polishing bit with compound
I hate to tell you this, but This head in the picture above, is now junk. You went through the casting into the water jacket that whole are has had to much material removed and will not be easily welded if it can even be welded enough. You basically need to start over on another set.
While I Always applaud those who want to learn, I think it's time to take a step back and review what you are trying to accomplish as stated above.
While I am no Pro, There have been a few good threads on the DIY head porting. These threads have some great info in them as well as pictures. I hope you find them useful in your next attempt.
Basically you want to smooth the casting walls and the transition between the valve seat and the bowl. A little work in the bowl around the valve guide will help as well.
You're not looking to hog anything out as the castings can be thin especially on the roof area.
Too much material removal and you can actually cause the air speed to slow down or even stall and hurt the flow. A good valve job will also help the flow numbers.
I hope you find some of this helpfull on the next set.
Last edited by 1FastBrick; 05-10-2016 at 06:16 PM.
04-26-2016, 09:34 PM
Calling all DIY cylinder head porting gurus ! Now with flow bench testing + progress 
so now I'm going to have someone weld it up for me and keep plugging away at this i know i can make these things flow ! i just need some time I'm trying to find a 2.02 valve without buying a hole set. i have a feeling with a bigger valve its really going to wake up read a thread someone put a 2.00 valve in on a stock port 862 and picked up 8 cfm and yes i will be sending these out for a 3 angle valve job with 2.02 valve, now I'm just hoping i can get these to flow what 243s do but with way more compression thats my goal. stay tuned 
