Big Valves really worth it? (numbers/LTx geeks inside)
12-30-2010, 03:54 PM
#1
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St. Jude Donor '05
Big Valves really worth it? (numbers/LTx geeks inside)
Set just finishing up had them lflowed today. Going on a LTx 383 226/234 roller cam ported LTx intake.Not a "max effort" job but should run Ok. More in them
Will it go 400 at the tire well find out.
This is on the old valve job, will pick up some more with the new one expecting 6-8cfm no more than 10
Typically use 2 different benches, this one consistently reads 8-10 cfm lower on the intake side (fixture) the exh always are about the same.
No pipe used on this one, using one can pick #s up but we didnt.
When "done" should be Ok for stock junk
INTAKE
.100 57.8
.200 118.7
.300 175.0
.400 221.7
.500 252.6
.550 262.9
.600 260.4
Stalls from that point on
EXHAUST (No pipe used)
.100 53.0
.200 99.6
.300 138.8
.400 172.5
.500 188.4
.550 195.8
.600 203.7
.650 208.2
.700 212.6
.750 214.1
Now Im no expert but by reading over some other sheets I have where stock sized valves are used the real advantage to larger valves is from the .500-550 range on up otherwise a 1.94 intake valve works fine for the average 2xx @.050 duration/Hotcam type street car as the same #s can be pulled out of the head with them (1.94). Could be wrong though.
Will it go 400 at the tire well find out.
This is on the old valve job, will pick up some more with the new one expecting 6-8cfm no more than 10
Typically use 2 different benches, this one consistently reads 8-10 cfm lower on the intake side (fixture) the exh always are about the same.
No pipe used on this one, using one can pick #s up but we didnt.
When "done" should be Ok for stock junk
INTAKE
.100 57.8
.200 118.7
.300 175.0
.400 221.7
.500 252.6
.550 262.9
.600 260.4
Stalls from that point on
EXHAUST (No pipe used)
.100 53.0
.200 99.6
.300 138.8
.400 172.5
.500 188.4
.550 195.8
.600 203.7
.650 208.2
.700 212.6
.750 214.1
Now Im no expert but by reading over some other sheets I have where stock sized valves are used the real advantage to larger valves is from the .500-550 range on up otherwise a 1.94 intake valve works fine for the average 2xx @.050 duration/Hotcam type street car as the same #s can be pulled out of the head with them (1.94). Could be wrong though.
Last edited by cv67; 12-30-2010 at 04:21 PM.
12-30-2010, 04:06 PM
#2
Melting Slicks
There is no such thing as too big a valve as long as it does not shroud on the bore or edge of the chamber. The chamber fixes easier than the bore with a assmebled engine but the chamber easy while doing the heads. 2.02 to 2.05 which is might be to big to easily fit the head is a good choice. It is free airflow with zero loss in torque. It will make a significant difference until you become port limited so the biggest change is well before 500 lift. It exposes more sq.in for flow per degree of crank movement much like high ratio rockers only more than the rockers do. BTW any flow beyond max lift whileinteresting is not important. Sort of like what the weather is in Brazil nice to know but who cares if you don't live there.
Dave
Dave
12-30-2010, 10:15 PM
#6
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My Pro Flo Xt'd 355 with 275 cfm @.500 lift AFR's and a 228/228 flat tappet cam went 380-385 so if you don't get 400 something's wrong....
12-31-2010, 06:59 AM
#8
Very Nice Cylinder Head porting work by You !
I have been told in the past by a few cylinder head porting experts that Valve Sizing is important,
but even more so, a good valve job is the real key to Better Air Flow Numbers after Porting.
Any thoughts yourself or others can share with custom valvejobs ?
By custom, they are using other Cylinder head seating angles other than 45 degrees.
The Valve face is cut to match.
They often back cut stock style valves too. Unless the valve allready has a Tulip Back shape to the valve head.
Full Radius valvejobs used by engine builders - Serdi and Sunnen cutters ordered for their head machines, even heard of engine builders having cylinder head seat cutters custom made to their own specs.
I have been told in the past by a few cylinder head porting experts that Valve Sizing is important,
but even more so, a good valve job is the real key to Better Air Flow Numbers after Porting.
Any thoughts yourself or others can share with custom valvejobs ?
By custom, they are using other Cylinder head seating angles other than 45 degrees.
The Valve face is cut to match.
They often back cut stock style valves too. Unless the valve allready has a Tulip Back shape to the valve head.
Full Radius valvejobs used by engine builders - Serdi and Sunnen cutters ordered for their head machines, even heard of engine builders having cylinder head seat cutters custom made to their own specs.
12-31-2010, 08:23 PM
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St. Jude Donor '05
Yes but nice to know it could carry further if needed. Does it matter at the end of the day probably not. Would like to cc the intake port to see where its at.
12-31-2010, 10:11 PM
#10
Race Director
Don't know if this helps...
LE said bigger valves --on his ported 113 heads-- gets ~10 more cfm. I'd expect that to = ~20hp gain.
LE said bigger valves --on his ported 113 heads-- gets ~10 more cfm. I'd expect that to = ~20hp gain.
12-31-2010, 10:21 PM
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St. Jude Donor '05
These are 2.00 int valves
Seems the advantage to them are realized for the most part at .500 lift and up
stock sized valves, similar cfm can be pulled out of the same heads. If theres a variance it would be small
would have to dig up some old sheets. Sure, with more chamber work etc you could widen the gap (maybe pick up low lifts, .100 and .200 are a little weak) and sure cam size plays a role in it too power wise just interesting to compare notes.
The next set will be an all out effort wont have them done for a few months but will post findings on that too.
noones reinventing the wheel just like doing it.
Never been able to get more than 253 cfm out of a small valve LTx head, L98 forget it lol. 230ish tops
Sure there are pros who might be able to though.
A good one with a blend afterward is money well spent. Not doing so after the valve job can hurt flow, last one we didnt blend afterward and lost up to 15 cfm! Send valvejobs out to someone who does it everyday dont do my own. Just a backyarder here lol. (know the pics look bad)
Seems the advantage to them are realized for the most part at .500 lift and up
stock sized valves, similar cfm can be pulled out of the same heads. If theres a variance it would be small
would have to dig up some old sheets. Sure, with more chamber work etc you could widen the gap (maybe pick up low lifts, .100 and .200 are a little weak) and sure cam size plays a role in it too power wise just interesting to compare notes.
The next set will be an all out effort wont have them done for a few months but will post findings on that too.
noones reinventing the wheel just like doing it.
Never been able to get more than 253 cfm out of a small valve LTx head, L98 forget it lol. 230ish tops
Sure there are pros who might be able to though.
Any thoughts yourself or others can share with custom valvejobs ?
Last edited by cv67; 12-31-2010 at 10:52 PM.
12-31-2010, 11:17 PM
#13
These are 2.00 int valves
Seems the advantage to them are realized for the most part at .500 lift and up
stock sized valves, similar cfm can be pulled out of the same heads. If theres a variance it would be small
would have to dig up some old sheets. Sure, with more chamber work etc you could widen the gap (maybe pick up low lifts, .100 and .200 are a little weak) and sure cam size plays a role in it too power wise just interesting to compare notes.
The next set will be an all out effort wont have them done for a few months but will post findings on that too.
noones reinventing the wheel just like doing it.
Never been able to get more than 253 cfm out of a small valve LTx head, L98 forget it lol. 230ish tops
Sure there are pros who might be able to though.
A good one with a blend afterward is money well spent. Not doing so after the valve job can hurt flow, last one we didnt blend afterward and lost up to 15 cfm! Send valvejobs out to someone who does it everyday dont do my own. Just a backyarder here lol. (know the pics look bad)
Seems the advantage to them are realized for the most part at .500 lift and up
stock sized valves, similar cfm can be pulled out of the same heads. If theres a variance it would be small
would have to dig up some old sheets. Sure, with more chamber work etc you could widen the gap (maybe pick up low lifts, .100 and .200 are a little weak) and sure cam size plays a role in it too power wise just interesting to compare notes.
The next set will be an all out effort wont have them done for a few months but will post findings on that too.
noones reinventing the wheel just like doing it.
Never been able to get more than 253 cfm out of a small valve LTx head, L98 forget it lol. 230ish tops
Sure there are pros who might be able to though.
A good one with a blend afterward is money well spent. Not doing so after the valve job can hurt flow, last one we didnt blend afterward and lost up to 15 cfm! Send valvejobs out to someone who does it everyday dont do my own. Just a backyarder here lol. (know the pics look bad)
No excessive polishing also.
Kept the surface slightly rough. Helps Laminar air flow over the surface. Actually gain a couple of CFM's verses a highly polished surface.
You have a Very Good Eye and a highly skilled- deft hand with a die grinder.
From what I can see, the cross sections of all ports shown are very consistent to each other.
Like a CNC 5 axis machine did the porting.
Impressive port job that you did from home.
I do valvejobs at home for myself and sometimes others.
Own Sioux Valve grinder- coolant style, and seat grinder. (#624 & #1710 respectively).
Self taught using them and picked up many pointers from a friend of mine that runs an automotive engine machine shop.
I like using 15 degree blend angles on the seat. Such as 45 degree seat, with 30 degree top cut, and lower cut of 60 degrees.
Have not tried any trick seat angles like 50 degrees or 48 degrees.
Just wondered if you have ever used them yourself.
Done fairly often on NASCAR and NHRA Superstock and Prostock engines I have been told.
By a few professional head porters around Chicago I have met.
Brought a few of my old Pontiac V-8 cylinder heads to check my valvejobs and actual airflow numbers.
One guy said I do pretty respectable work for such Antique valvegrinding equipment. LOL
Cant justify $10K for a Serdi or Sunnen Head machine.
But the Full radius valvejobs they can perform are really nice.
My friend with the engine machine shop has a Sunnen head machine.
Your 113 heads should perform nicely for you !
12-31-2010, 11:23 PM
#14
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St. Jude Donor '05
These are the LTx heads, wouldnt mind picking up some equiptment and doing valve jobs but no money or time.
Thanks for the words but the pics look horrible they are actually nice in person. Light bounces off the lines and makes them look bad
never was good with a camera
As these were shot they were still being fooled with as you can tell there are some walls that need straightening out. I never polish any port except for combustion chambers, soon as its fired up the exhaust is covered with soot anyway.
Could play with the camera and finer finishes for the ooh ahh factor but doesnt make a bit of difference in the way it runs.
Thanks for the words but the pics look horrible they are actually nice in person. Light bounces off the lines and makes them look bad
never was good with a cameraAs these were shot they were still being fooled with as you can tell there are some walls that need straightening out. I never polish any port except for combustion chambers, soon as its fired up the exhaust is covered with soot anyway.
Could play with the camera and finer finishes for the ooh ahh factor but doesnt make a bit of difference in the way it runs.
Last edited by cv67; 12-31-2010 at 11:26 PM.
12-31-2010, 11:30 PM
#15
These are the LTx heads, wouldnt mind picking up some equiptment and doing valve jobs but no money or time.
Thanks for the words but the pics look horrible they are actually nice in person. Light bounces off the lines and makes them look bad never was good with a camera
As these were shot they were still being fooled with as you can tell there are some walls that need straightening out. I never polish any port except for combustion chambers, soon as its fired up the exhaust is covered with soot anyway.
Could play with the camera and finer finishes for the ooh ahh factor but doesnt make a bit of difference in the way it runs.
Thanks for the words but the pics look horrible they are actually nice in person. Light bounces off the lines and makes them look bad
never was good with a cameraAs these were shot they were still being fooled with as you can tell there are some walls that need straightening out. I never polish any port except for combustion chambers, soon as its fired up the exhaust is covered with soot anyway.
Could play with the camera and finer finishes for the ooh ahh factor but doesnt make a bit of difference in the way it runs.
Much better than I can do. lol
Shine means very little.
The Short turn radius ( bottom of the Port floor) is the key to a head performing good as intended. Along with consistent cross sections along the entire intake and exaughst ports.
You can that correctly.
