Camshaft Discussion part II
TECH Senior Member
Joined: Nov 2001
Posts: 10,341
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Originally Posted by SilverSurfer
True the LSA is a byproduct, but I'm willing to bet that when the cam specs were being decided upon this byproduct was taken into great consideration.
Reduction in overlap (For smoother idle) Necessitates an aggressive (lift and ramp rate) small duration lobe.
The LSA is simply a byproduct of that calculation.
TECH Enthusiast
Joined: Feb 2004
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From: Foley, Alabama-southern Alabama
J-rod,now you are touching on something new to this thread I 'd like to see discussed in detail,intake runner cross-section area ,lenth and the header diameter,lenth and the collector type and size(4-2-1,HV MERGE.standard type).I have ask about the collector style with NO response and I know it can be answered on here.
Hey Ed at HPE,build a manifold similar to a 2 4 barrel tunnelram with a removable top,then you could make 1\2 spacers to put between the runners and the top(so you could tune),you could still use the single TB on the front.
Hey Ed at HPE,build a manifold similar to a 2 4 barrel tunnelram with a removable top,then you could make 1\2 spacers to put between the runners and the top(so you could tune),you could still use the single TB on the front.
Thread Starter
6600 rpm clutch dump of death Administrator
Joined: Dec 2001
Posts: 4,983
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From: Texas
Originally Posted by FASTONE
J-rod,now you are touching on something new to this thread I 'd like to see discussed in detail,intake runner cross-section area ,lenth and the header diameter,lenth and the collector type and size(4-2-1,HV MERGE.standard type).I have ask about the collector style with NO response and I know it can be answered on here.
Hey Ed at HPE,build a manifold similar to a 2 4 barrel tunnelram with a removable top,then you could make 1\2 spacers to put between the runners and the top(so you could tune),you could still use the single TB on the front.
Hey Ed at HPE,build a manifold similar to a 2 4 barrel tunnelram with a removable top,then you could make 1\2 spacers to put between the runners and the top(so you could tune),you could still use the single TB on the front.
Erik is at HPE
As for the tunnel Ram, All that would do is adjust plenum volume, not runner length unless you made up some trick spacer that fit runners and had separate openings for each runner.
Anyhow, I guess I was looking at total package. I can start a thread on header and intake tuning if folks want to discuss that. What I was trying to do is perhpas look at what is necessary to tune the intake and the header to compliment the cam or vice versa, and how you calculate optimal values for that.
TECH Enthusiast
Joined: Feb 2004
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From: Foley, Alabama-southern Alabama
Thats what I was talking about, a spacer that went between the 8 runners and the bottom of plenium, yes with the 8 holes to match the top of port runners. Lets do the exhaust and intake technical stuff,sounds cam related to me! 
TECH Junkie
Joined: Aug 2002
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From: Fort Collins, CO
Originally Posted by J-Rod
Anyhow, I guess I was looking at total package. I can start a thread on header and intake tuning if folks want to discuss that. What I was trying to do is perhpas look at what is necessary to tune the intake and the header to compliment the cam or vice versa, and how you calculate optimal values for that.
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On The Tree
Joined: Jul 2004
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Thats definitely an area that needs to be explored J-Rod.
As for formulas, I don't know any off the top of my head but its going to be a function of valve openings and closings at a specific RPM, the frequency will change as RPM increases (duh!). I would think overlap would play a significant part in that as well.
This would be more of a lab experiment IMO. Who's bringing the beers?
Frank
As for formulas, I don't know any off the top of my head but its going to be a function of valve openings and closings at a specific RPM, the frequency will change as RPM increases (duh!). I would think overlap would play a significant part in that as well.
This would be more of a lab experiment IMO. Who's bringing the beers?
Frank
J-rod,
I can calculate it after the camshaft has been figured for a specific combo. Optimum intake lengths, optimum header ID/Primary Length/and collector ID. Most are worried about header sizes seems, but those then spend time with intake lengths do see power gains. Gains are slight but in competition, every edge you can gain is an edge.
Chris
I can calculate it after the camshaft has been figured for a specific combo. Optimum intake lengths, optimum header ID/Primary Length/and collector ID. Most are worried about header sizes seems, but those then spend time with intake lengths do see power gains. Gains are slight but in competition, every edge you can gain is an edge.
Chris
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From: Fort Collins, CO
Originally Posted by Cstraub
J-rod,
I can calculate it after the camshaft has been figured for a specific combo. Optimum intake lengths, optimum header ID/Primary Length/and collector ID. Most are worried about header sizes seems, but those then spend time with intake lengths do see power gains. Gains are slight but in competition, every edge you can gain is an edge.
Chris
I can calculate it after the camshaft has been figured for a specific combo. Optimum intake lengths, optimum header ID/Primary Length/and collector ID. Most are worried about header sizes seems, but those then spend time with intake lengths do see power gains. Gains are slight but in competition, every edge you can gain is an edge.
Chris
On The Tree
Joined: Jul 2004
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Originally Posted by Cstraub
J-rod,
I can calculate it after the camshaft has been figured for a specific combo. Optimum intake lengths, optimum header ID/Primary Length/and collector ID. Most are worried about header sizes seems, but those then spend time with intake lengths do see power gains. Gains are slight but in competition, every edge you can gain is an edge.
Chris
I can calculate it after the camshaft has been figured for a specific combo. Optimum intake lengths, optimum header ID/Primary Length/and collector ID. Most are worried about header sizes seems, but those then spend time with intake lengths do see power gains. Gains are slight but in competition, every edge you can gain is an edge.
Chris
Reason I ask is don't you measure flow through all the components, i.e. from throttlebody to intake valve at different lift points etc, and then grind the cam?
Thread Starter
6600 rpm clutch dump of death Administrator
Joined: Dec 2001
Posts: 4,983
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From: Texas
Its a good question Merlin. I was't sure what other folks felt the "order of operation" or "order of importance" was in the cas eof laying this stuff out.
Anyhow, the math I have for headers is:
Header pipe length (in inches) = ((850*(360-EVO))/RPM – 3
Header diameter (in inches) = ((cylinder. disp. * 16.38 / ((hdr len + 3) * 25))) * 2.1
These formulas are from A. Graham Bell’s Performance Tuning in Theory and Practice. For a street engine, the RPM used should be the peak torque RPM. For a race engine, the peak hp RPM should be used. I most tune stuff for "race engine" as that is the way most of them are used.
Anyhow, the math I have for headers is:
Header pipe length (in inches) = ((850*(360-EVO))/RPM – 3
Header diameter (in inches) = ((cylinder. disp. * 16.38 / ((hdr len + 3) * 25))) * 2.1
These formulas are from A. Graham Bell’s Performance Tuning in Theory and Practice. For a street engine, the RPM used should be the peak torque RPM. For a race engine, the peak hp RPM should be used. I most tune stuff for "race engine" as that is the way most of them are used.
Thread Starter
6600 rpm clutch dump of death Administrator
Joined: Dec 2001
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From: Texas
Originally Posted by MUSTANGEATER
It'd be nice to make a post w/ just formula's and how to apply them.
J-rod your box is full
J-rod your box is full
In the meantime:
Exhaust Systems Tuned Length
Lt = (Eo x Vs) / N
Lt is the tuned length, in inches
Eo is the exhaust-open period, in degrees
Vs is wave speed in feet per second (1700 ft/sec at sea level)
N is crankshaft speed, in RPM
Length of Curved Pipe
L = R x .01745 x Z
L is length
R is radius of the pipe bend
Z is the angle of the bend
Diffuser Proportions
D2 = SQRT( D1^2 x 6.25 )
D2 is the diffuser outlet diameter
D1 is the diffuser inlet diameter
6.25 is the outlet/inlet ratio constant
Baffle Cones
Lr = Le/2
Lr is mean point of the reflection inside the baffle cone
Le is the length of the baffle cone
My box has space now...
