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Originally posted by warmonger:
Well, I"m not going to assign any numbers to it because I wouldn't know that without thorough testing. However, the cross sectional area of the SVT split ports, with the area of both ports added together, is significantly more than the cross sectional area of the oval port by itself.
Then if you add to it the fact that you can overbore it more if you wish and it will still retain structural integrity since it is aluminum, I think it makes it superior.
For NA motors this isn't necessarily what you are after, but for a turbo motor like his, the stock SVT split port can definitely flow more than the stock oval port if you base the comparison on constant pressure and square area of the ports. They aren't just a little bigger, they have like 20-30% more cross-sectional area.
A bigger hole is ofcourse gonna flow more air through... But how much air does the engine need? How much are you hurting the velocity when your overporting and how good is the fuel atomized?
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Originally posted by GoppelDanger:
Ideally, one would just create a single oval chamber above the "V" and have short runners to the heads. That is the best thing for forced induction. You just need to make sure the injectors fit, too. The plastic oval intake is the closest thing to that configuration.
Your theory is sound but the oval is too small. Airflow under boost takes precendece over manifold design in this instance.
I offer PnP Heads for all durtec's details at PnPheads.com or jesse@pnpheads.com for details.
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Originally posted by 96BlackSE:
But how much air does the engine need?
A LOT stock take what 260 CFM to make 200 fwhp, this bad boy needs to make 700 hp
Originally posted by 96BlackSE:
How much are you hurting the velocity when your overporting and how good is the fuel atomized?
Under 20+ psi of boost velocity and fuel atomoization are not as important as volume which takes precendence.
I offer PnP Heads for all durtec's details at PnPheads.com or jesse@pnpheads.com for details.
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In terms of the ST220 intake:
Is the lower intake manifold the same as the standard oval port 3.0L one we get on the Escape block here?
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2000 SVT Turbo 295hp/269ftlb@12psi
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Originally posted by gotapex:
In terms of the ST220 intake:
Is the lower intake manifold the same as the standard oval port 3.0L one we get on the Escape block here?
I 'believe' so might ask 96blackse to give us the measurements. The difference is in plenum volume which is much larger on the ST220 IIRC.
I offer PnP Heads for all durtec's details at PnPheads.com or jesse@pnpheads.com for details.
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Originally posted by GoppelDanger:
Which one has more interior surface area?
Does high boost on a dual plane manifold with no secondaries do anything between the two sets of runners?
How do these factors affect air velocity?
Ideally, one would just create a single oval chamber above the "V" and have short runners to the heads. That is the best thing for forced induction. You just need to make sure the injectors fit, too. The plastic oval intake is the closest thing to that configuration.
I don't know, you tell me!
As far as the surface area, I can sort of answer that:
Twin port, assuming 34 and 36mm (avg. guess) diameter runners of length L:
(34*Pi*L + 36*Pi*L) = 70*Pi*L
Ovalport, 57mm long by 23mm thick, or broken down to one circle and one rectangle where we take the surface area of the cylinder and just the two long sides of the rectangle:
(23*Pi + 34*L +34*L) = (23*Pi+68)*L
So lets assume that L of both intakes is equal, then:
S<split>= 220*L mm^2
S<oval>= 140*L mm^2
But to me, in this particular case, the surface area is much less of a factor influencing flow since they are on the same order of magnitude and therefore is not as relevant to our FI flow as the cross sectional area would be.
Cross sectional area of oval port:
(23*Pi/2)+(34*23) = 1197mm^2
Cross sectional area of split port:
(18^2)*Pi + (17^2)*Pi = 1926mm^2
% Larger cross section = 1926/1197 = 1.61 or 61% MORE cross sectional area.
% more S area = 220/140= 1.53 or 53% MORE surface area.
ratio of cross section to surface area (split) = 8.75
ratio of cross section to surface area (oval) = 8.55
*****************************************
My analysis of these numbers:
Okay, the split port has more cross sectional and surface area than the oval but that doesn't tell the whole story. These last numbers, the ratio of cross section to surface area show that the split port has a higher cross section to surface area ratio.
A true circle will have the best ratio of cross sectional area to surface area which approaches 9.0
Obviously the circle or cylinder is the most efficient shape for maximizing this ratio, we can indirectly see this in all kinds of piping as well.
This would be a good indicator of the Through-put of the piping system I think because it kind of reflects drag vs. volume if you assume the pipe roughness was equal and that the velocity of the airflow is the same (mass/time through the pipe).
So the split port has a better ratio than the oval port in this case, but they are pretty close so as I said I wouldn't let that bother me.
What does tell the story is the MUCH higher cross sectional area of the split port.
That means that assuming the drag is close to the same, it can flow near 50% more air volume than the oval.
Or at least that is what these numbers are telling me.
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Originally posted by kinger:
Originally posted by gotapex:
In terms of the ST220 intake:
Is the lower intake manifold the same as the standard oval port 3.0L one we get on the Escape block here?
I 'believe' so might ask 96blackse to give us the measurements. The difference is in plenum volume which is much larger on the ST220 IIRC.
96BlackSE:
What say you on the LIM? Happen to have the dimension on that? If it's identical to the stock one, at least I can save a bit of money there.
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The lower is shorter and aluminum.
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Originally posted by warmonger:
....
A true circle will have the best ratio of cross sectional area to surface area which approaches 9.0
...
I have to edit this and its too late, but this statement is true but the ratio equaling 9 is only in the case of a cylinder the same size. This is only usefull for comparing this particular problem I think. Sorry for any confusion.
Former owner of '99 CSVT - Silver #222/2760
356/334 wHP/TQ at 10psi on pump gas!
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'05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red
'06 Mazda5 Touring, 5spd,MTX, Black
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