243 intake and exhaust volume's before and after porting diy head porting
08-26-2013, 08:57 PM
#43
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Working on the new exhaust port as we speak on DIY set dosII.. Learned alot today got some good data. Been about 6 years since I ported a set of heads so set dos will be better.. intake port numbers are fine with me the exhaust I'd like to improve by 10-25 cfm
08-27-2013, 09:43 AM
#47
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Yeah I'm thinking that's what happened. I paid for bench time and was supposed to be there but 95 percent of the heads where flowed when I showed up.. I'm kind of scratching my head on the flow numbers as the exhaust seem way to soft IMO.. All though the main improver would be playing with the valve seats. I'm on to the next set of heads will use the data to improve for the next set.. Those heads are for a ls1 head swap so there was a differance of 60 cfm on the intake and 23 on the exhaust over the stock 241 casting..
Here is set DoS..remember these are super budget 375 dollars there is much more to be gained but everything comes with more dinero.. Kind of why I work on porsche for a living much More budget to play with lol.
These seem to be a nicer port shape At 83 cc's so far. Again most of the are replacing factory 241 heads.
Here is set DoS..remember these are super budget 375 dollars there is much more to be gained but everything comes with more dinero.. Kind of why I work on porsche for a living much More budget to play with lol.
These seem to be a nicer port shape At 83 cc's so far. Again most of the are replacing factory 241 heads.
08-27-2013, 04:39 PM
#49
You have actually created a pocket under the seat? Behind the guide when looking in from the exit?
I've never seen anything like that in a port before.
What kind of flow numbers do the CNC guys attain with the 243 heads on the exh side?
If your flow bench guys didn't notice the hole in the intake port where the rocker stud goes, are you confident they did the exh port correctly?
Was the exh measured with or without a pipe?
The LS likes a much larger header than one would expect, I'm thinking a pipe on the port when measuring flow would be important.
Did you measure the heads stock?
Ron
I've never seen anything like that in a port before.
What kind of flow numbers do the CNC guys attain with the 243 heads on the exh side?
If your flow bench guys didn't notice the hole in the intake port where the rocker stud goes, are you confident they did the exh port correctly?
Was the exh measured with or without a pipe?
The LS likes a much larger header than one would expect, I'm thinking a pipe on the port when measuring flow would be important.
Did you measure the heads stock?
Ron
08-27-2013, 04:54 PM
#50
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Without a pipe.don't really trust the numbers as I asked to pay for time to run the machine myself.. That pocket is the factory cut for the seats.. If you look at the entry to the port on the bench you can see how little time was spent there were missing pieces of clay on the entry when I got there..
08-27-2013, 11:35 PM
#51
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Here is a few pics of the exhaust for set dos.. I'm very happy and excited to test these.. I raised the port straightened short side didn't grind the seats flat trimmed around the guide boss and opened up the bowl more. Anyone want to sponsor some flow bench time lol.. I do plan on flowing
08-28-2013, 12:04 AM
#52
Ah, easier to see now. Just a bit different casting in that area beneath the seat on that head.
Can you share the exit dimensions?
BTW...not that I know squat, but the work around the seats looks a lot like what I did. I can't seem to get good photos though.
I'll try again.
I also didn't get the casting line ground all the way out either.
Ron
Can you share the exit dimensions?
BTW...not that I know squat, but the work around the seats looks a lot like what I did. I can't seem to get good photos though.
I'll try again.
I also didn't get the casting line ground all the way out either.
Ron
Last edited by RonSSNova; 08-28-2013 at 12:58 AM.
08-28-2013, 09:03 AM
#53
You have been right on with what you are doing. The intake on these is pretty good, but nearly all the power gains on a 243 head are on the exhaust side. A fully ported 243 will not make much more power over one with a ported exhaust and stock intake port.
You can raise the port considerably on these, my last set had a 91cc volume and flowed a ton of air, made great power.
You can raise the port considerably on these, my last set had a 91cc volume and flowed a ton of air, made great power.
08-28-2013, 09:32 AM
#54
You have been right on with what you are doing. The intake on these is pretty good, but nearly all the power gains on a 243 head are on the exhaust side. A fully ported 243 will not make much more power over one with a ported exhaust and stock intake port.
You can raise the port considerably on these, my last set had a 91cc volume and flowed a ton of air, made great power.
You can raise the port considerably on these, my last set had a 91cc volume and flowed a ton of air, made great power.
How close does this get you to the water jacket?
I can't seem to find a good x-section of the exh port.
Ron
08-28-2013, 09:51 AM
#55
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Looking good Ron don't worry about what the port looks like its all about the shape but most importantly the seats have a LOT of influence on how good the head is.. From .050-.300 the main restriction is not port texture or valve guide boss shaped its all at the seat the better you can direct air around the seat at low lift the better the head will be at the curve... All the porting you have done will probably only benefit from .300-.700..
If the budgets allowed on these heads first thing I'd do is cut the seats then port the heads then retouch seats with stone or lapping.
If the budgets allowed on these heads first thing I'd do is cut the seats then port the heads then retouch seats with stone or lapping.
08-28-2013, 10:18 AM
#56
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With trying to match the seat to the bowl we have probably gone backward as you can see in the second pic we have taken some of the radius out of the seat by grinding It.
08-28-2013, 03:31 PM
#57
08-28-2013, 08:33 PM
#59
Looking good Ron don't worry about what the port looks like its all about the shape but most importantly the seats have a LOT of influence on how good the head is.. From .050-.300 the main restriction is not port texture or valve guide boss shaped its all at the seat the better you can direct air around the seat at low lift the better the head will be at the curve... All the porting you have done will probably only benefit from .300-.700..
If the budgets allowed on these heads first thing I'd do is cut the seats then port the heads then retouch seats with stone or lapping.
If the budgets allowed on these heads first thing I'd do is cut the seats then port the heads then retouch seats with stone or lapping.
My C5 has AFR 205's on it, but they aren't available for easy viewing of the ports.
Headers on it are supposed to be 1 3/4....but the tubes measure 1.9" od and are visibly larger than any 1 3/4 I've seen.
The heads I'm working on of course will have manifolds.......but I believe porting is certainly beneficial to a turbo engine.
Ron
Last edited by RonSSNova; 08-28-2013 at 08:46 PM.
08-29-2013, 03:07 PM
#60
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Just touched down in Chicago couldn't bring heads with me just got to busy. Now I need to drive to road America the. I need someone to show me where the girls hang out lol.