Traditional split, 2 , 4, 6 Degrees between intake and exhaust
08-12-2005, 09:01 PM
#1
Traditional split, 2 , 4, 6 Degrees between intake and exhaust Looking for theories and experiences on Intake and Exhaust duration splits for traditional split cams.
Futral tends to use 2 degree split. Tony (AFR) likes 4 degrees, etc…
What is the science behind the magic???
Thanks for input…
Futral tends to use 2 degree split. Tony (AFR) likes 4 degrees, etc…
What is the science behind the magic???
Thanks for input…
08-13-2005, 09:38 AM
#4
Originally Posted by PREDATOR-Z
The science is to keep a 75>80% exhaust flow potential Vs intake.
08-13-2005, 09:42 AM
#6
Originally Posted by PREDATOR-Z
Not on exhaust system but on head intake VS head exhaust runner potentials.
75-85% of intake potential??? That sounds like reverse-split, I am talking about traditional split, i.e. 224/228, 230/232, etc....
08-13-2005, 10:20 AM
#7
Scott,
Just an FYI....I dont simply grind every cam I spec out with a 4' split. A lot of variables come into play. Total duration, application, type of exhaust system, idle quality I'm searching for, etc., just to name a few.
To simplify things, had I put a smaller exh. lobe on your cam, you would have made a little less peak power and slightly more in the middle. Also, your idle would have been a hair smoother due to less overlap. Seeing as we were trying to fatten the peak portion of your power band, I left more of a foward split in it to help evacuate the cylinder at high RPM when there is so little time to do so. It's all a give and take, not to mention a little bit of educated guesswork unless you had the opportunity to run every cam in question on an engine dyno.
Hope this helps...
Just an FYI....I dont simply grind every cam I spec out with a 4' split. A lot of variables come into play. Total duration, application, type of exhaust system, idle quality I'm searching for, etc., just to name a few.
To simplify things, had I put a smaller exh. lobe on your cam, you would have made a little less peak power and slightly more in the middle. Also, your idle would have been a hair smoother due to less overlap. Seeing as we were trying to fatten the peak portion of your power band, I left more of a foward split in it to help evacuate the cylinder at high RPM when there is so little time to do so. It's all a give and take, not to mention a little bit of educated guesswork unless you had the opportunity to run every cam in question on an engine dyno.
Hope this helps...
Trending Topics
08-13-2005, 11:02 AM
#9
TECH Senior Member
Originally Posted by SideStep
75-85% of intake potential??? That sounds like reverse-split, I am talking about traditional split, i.e. 224/228, 230/232, etc....
Let us say that cam X flows Y amount of air through the head intake runner
So ideally the Exhaust flow amount capability should be 75>80% of the
value Y.
So you base your splits to achieve this value or close to it while maximizing HP as Tony said.
08-13-2005, 02:22 PM
#10
10 Second Club
iTrader: (47)
Join Date: Nov 2001
Location: Pace, FL
Posts: 1,453
Likes: 0
Received 0 Likes
on
0 Posts
Great question! I'm looking at the TR 230/236 and was curious on the 6 degree split. So a split like this would make more power up top then a 230/232, but lose some in the midrange?
John
John
08-13-2005, 03:45 PM
#12
Originally Posted by EDC
Please remember....
The .050" spec is only one spec on a lobe! There are a hell of a lot more parameters...
As for the amount split... forward? reverse? at what point?
It all depends on the overall combination and the usage...
There is no "magic formula"... So if you really want a custom designed camshaft versus a shelf piece, you need all the data to do it...
Maybe there is a blue pill that will help though...
Ed
The .050" spec is only one spec on a lobe! There are a hell of a lot more parameters...
As for the amount split... forward? reverse? at what point?
It all depends on the overall combination and the usage...
There is no "magic formula"... So if you really want a custom designed camshaft versus a shelf piece, you need all the data to do it...
Maybe there is a blue pill that will help though...
Ed
08-13-2005, 04:53 PM
#13
Originally Posted by EDC
Gee... I'm sorry...
Thanks though…
08-15-2005, 06:44 PM
#15
Step,
Don't take it to personally Ed's response was as close to a good answer as you can get. I spend a lot of time trying to turn what I know into something the average guy can understand but I/E splits and the why of them is like me trying to explain how to go thru a slalom section of a autoX fast... I know how to do both of them but for the life of me can't explain it as well as I can do it.
Bret
Don't take it to personally Ed's response was as close to a good answer as you can get. I spend a lot of time trying to turn what I know into something the average guy can understand but I/E splits and the why of them is like me trying to explain how to go thru a slalom section of a autoX fast... I know how to do both of them but for the life of me can't explain it as well as I can do it.
Bret
08-15-2005, 08:53 PM
#16
Originally Posted by SStrokerAce
Step,
Don't take it to personally Ed's response was as close to a good answer as you can get. I spend a lot of time trying to turn what I know into something the average guy can understand but I/E splits and the why of them is like me trying to explain how to go thru a slalom section of a autoX fast... I know how to do both of them but for the life of me can't explain it as well as I can do it.
Bret
Don't take it to personally Ed's response was as close to a good answer as you can get. I spend a lot of time trying to turn what I know into something the average guy can understand but I/E splits and the why of them is like me trying to explain how to go thru a slalom section of a autoX fast... I know how to do both of them but for the life of me can't explain it as well as I can do it.
Bret
Well I an engineer and all my undergraduate work was concentrated in math, so let us pretend I can understand all those fancy numbers the "average guy" cannot ... if your are not going to post real material why post at all....
08-16-2005, 06:53 AM
#17
TECH Resident
Join Date: Sep 2003
Location: Working in the shop 24/7
Posts: 848
Likes: 0
Received 1 Like
on
1 Post
Originally Posted by SideStep
Well I an engineer and all my undergraduate work was concentrated in math, so let us pretend I can understand all those fancy numbers the "average guy" cannot ...
if your are not going to post real material why post at all....
Ed
08-16-2005, 08:30 AM
#18
Thanks.. I appreciate you cleaning that up for me...
Just because someone has the ability to comprehend does not mean they have had the exposure. That is what I am asking for... material, experiences, theories and opinions on the subject... Not "It is just too complicated to explain" to the average guy (what ever that means).....
Just because someone has the ability to comprehend does not mean they have had the exposure. That is what I am asking for... material, experiences, theories and opinions on the subject... Not "It is just too complicated to explain" to the average guy (what ever that means).....
Last edited by SideStep; 08-17-2005 at 05:28 PM.
