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4g63 cylinder head flow bench results

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Some things to consider when porting the exhaust side, and flow bench testing a head.
1: Flow bench testing should be done with the valve seat work done (I.E. a completed valve job, be it a standard grind, ar a five angle) One of the more critical elements of port flow is how well the air flows around the seat and valve. Try comparing a stock head with a fresh standard valve grind, and the same head with a five angle valve grind. If you are interested in doing the testing, I will make my shop available for the machine work on the cylinder heads.

2: generally a dial indicator is used to measure valve lift while testing, while a bar and screw assembly is typical for valve adjustment.

3: I have found that when porting the exhaust side a radius under the valve seat area will improve flow. Think of it as a venturi between the valve seat and the exhaust port. Of course it is difficult to hand port a concentric radius, and repete it seven more times to complete a single 4G63 head, so this procedure is useually done on a machine (CNC, seat & guide machine, vertical mill etc.)

Well let me know it you are interested in doing some testing, and I do have a cylinder head that could be used for the testing.
 
i would reall ylike to see numbers on a ported 2g if that is at all possible, i am gretly impressed with the flow of your cylinder head... good job
 
BOOSTIN21 said:
i would reall ylike to see numbers on a ported 2g if that is at all possible, i am gretly impressed with the flow of your cylinder head... good job

thanks. i would also like to do a 2g head and compare the shittyness of it to a 1g. id like to see if i could pull as much out of a ported 2g as i could a stock 1g, or at leats see how far i need to go to acheive the numbers a 1g has stock.
 
Ok i have been very interested in what a 2G head flows as well against a stock 1G, on the 1G @ .450 lift we got 280.5 cfm so i put a .250 (1/4") of putty in the base of the 1G port tapering off to the valve radius and flowed again, F##k 5cfm gain!! this was with rough putty job will get back and do a proper job with putty next week (No big finger prints) and no beers, give me a week and i will post with gradual build 1/8, 3/16 and higher see how it goes.
 
blue1 said:
Ok i have been very interested in what a 2G head flows as well against a stock 1G, on the 1G @ .450 lift we got 280.5 cfm so i put a .250 (1/4") of putty in the base of the 1G port tapering off to the valve radius and flowed again, F##k 5cfm gain!! this was with rough putty job will get back and do a proper job with putty next week (No big finger prints) and no beers, give me a week and i will post with gradual build 1/8, 3/16 and higher see how it goes.


280 cfm....damn, how many inches of water are you runnig when testing this?
 
overdoseheroin said:
thanks. i would also like to do a 2g head and compare the shittyness of it to a 1g. id like to see if i could pull as much out of a ported 2g as i could a stock 1g, or at leats see how far i need to go to acheive the numbers a 1g has stock.

Ported 2G heads outflow ported 1G's.
 
Coup D E'Tat said:
Ported 2G heads outflow ported 1G's.

you are a f-in tardmonkey. it might if they are flowing the 2g at like 40 inches of water an dthe 1g at the standard 28 inches. ur on crack, show me the results with how many inches of water they used to test it and the lift points and then maybe ill consider the fact, otherwise, shutup.
 
i stand partially corrected. you can go back and fourth all day long but it all depends on the setup you are lookin for. sure the 2g head has better flow in the actual design, but you can do the same with a 1g. many people will epoxy the floor to raise it up to get the same effect as a 2g. when i ported mine i paid particular attention to how i was porting, i made the radius of the angle where the air travels along on the inside of the bowels very smooth and round. thats where i picked up the most. i barely touched the intake other than the lips in the bowels and rounding the radius' off with a 50 grit sanding bit, i also polished it up wit hthat bit. i didnt take any material out really on the intake, i just made the air get into the combustion chamber easier and more effeciently and picked up 30 cfm from doing so. now on the exhaust, i paid the same attention to the radius' as i did the intake, but also focused more on opening it up, just to get it all out. in a sense you were right about the 2g head stock for stock against the 1g, but like they said in the posts, a 2g flows better, a 1g flows more. but a 1g that has been ported to flow "better" along with flowing more, i would think, would be the better of the 2. id liek to do the same with a 2g head tho and see first hand the differences.
 
28" of water, Overdoseheroin the 2G has better port design for flow and the 1G has more flow, i am just experimenting to find a happy medium to get the best of both worlds! its hard because a flow bench utilizes vacuum where as a turbo engine will force Sh#t loads more through at 30psi. so the bench work to me is to get the port and manifold as efficient as possible and go from there!. i still think the cyclone mani design has potential, i am at the moment going through the wooden core mould structure for a mani' with a tapered plenum (detachable), 9" tapered runners 1G size, with and aero foil for air direction at low RPM rather than closing off 1 port. its a lot of work and will take some time, made the plenum detachable for reasons of multithrottle body trials without designing complete new manifold just plenum!
Paul
 
blue1 said:
28" of water, Overdoseheroin the 2G has better port design for flow and the 1G has more flow, i am just experimenting to find a happy medium to get the best of both worlds! its hard because a flow bench utilizes vacuum where as a turbo engine will force Sh#t loads more through at 30psi. so the bench work to me is to get the port and manifold as efficient as possible and go from there!. i still think the cyclone mani design has potential, i am at the moment going through the wooden core mould structure for a mani' with a tapered plenum (detachable), 9" tapered runners 1G size, with and aero foil for air direction at low RPM rather than closing off 1 port. its a lot of work and will take some time, made the plenum detachable for reasons of multithrottle body trials without designing complete new manifold just plenum!
Paul

i was actually going to try something like that using the stock intake manifold with no luck. let me know how it . and as for the 1g vs 2g thing, i made my 1g flow better like the 2g by radiusing the corners and such while still flowing a shit load. it flows more and now flows better because i paid close attention to it. i didnt touch the walls or floor of the intake other than with a 50 grit sanding bit to make sure i had good air/fuel suspension. i gained that 30 cfm just by radusing the turns and taking the lips out of the bowels. i would love to get my hands on a 2g head and try the same and see the comparison.
 
This thread needs an update on the whole adding putty to the bottom of the intake ports. I'm thinking of adding epoxy and was wondering the results of your test, how much did you build it up? I know it's been forever but was hoping someone had some info.
 
This thread shows why an unported,stock 1g(or 2g) head will make a retarded amount of power. Its interesting. Thanks for dragging it out of the grave Mercaholik
 
My head flows about 20cfm better than a stocker, yet I saw no power gains with it. I'd love for one of these shop pushing the whiz ang porting job to actually do a stock vs ported dyno on an engine dyno, and be honest about it.

Lots and lots of people go pleny fast on a stock head. I'd wager cam and intake have a much greater effect. I'd like to play with bigger valves, but I think the cylinder shrouds them to much.

I also clayed up the bottom of a port and it lost flow. Can't remember how much though.
 
For the most part, hogging out intake runners wont do much. Yes it will flow more, but velocity will drop. The quicker you can move air, the better. Cleaning up the cast is about as much as you need to do for the intake runners, along with removing all pitting in the bowls.

For the exhaust side, port matching to the manifold is more than enough.
 
Thanks bastard, that's what I was hoping for cause I'm currently cleaning up my 1g head and I have a bunch of jb weld. I read that crazy motoman web site and thought he might have SOME valid points, I don't think a Yamaha r1 head can really be improved. The have designed some really good heads, including the 3sgte and Ford sho v6. I did say I know it's been forever, but see some cool still gave me a real world answer. Thanks again guys.
 
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