Contour Enthusiasts Group Archives Forums Modifications 3.0L Duratec Use the 3L LIM???

Just curious but why can't one use the 3L lower intake manifold (and for us guys with the return fuel system) swap out the fuel rail and injectors??? This of course would be with the 3L heads. What am I missing here???

The secondary linkage is different and must be modified to fit. The fuel rail on the ones I had apart exit the opposite side of the engine and would need to be swapped out anyway. No need for the 3 liter heads to use this lower intake as it's the one I'm using on my 3 liter with the 2.5 heads. The ports are cast the same size on the two heads, no difference. Of course mine are "missing" the secondaries so no linkage modification was needed other than to remove it.

The lower IM's are the same for 3L and 2.5L except for one mounting boss for the fuel rail, and the linkage arm for the secondary butterflies.
Yes you can use the 3L lower, but it must have a way to bolt down the rail and the linkage needs some small changes.
The point of me posting this is why would you? The 99 and up SVT lower's are already the same size as the 3L lower, with the addition of xtrude honing. In effect you would be losing out somewhat if you go with the 3L.

warmonger

I didn't know they were the same size. I thought the 2.5L lower intake openings were smaller.

On the 01' 3L there are no secondary and there are just 6 oval ports....similar to the exhaust ports.

I'm going to post this one more time so that everyone here can take a pen and paper and write it down.
****This is for those that think the 3L parts flow better than SVT*****
Not!

Nupe. This is for your information so that you can make an educated decision on which parts to use.
The SVT lower IM is bored the same size as a 3L and then xtrude honed. It uses the same secondary butterfly valves and in reality it should flow better.
The SVT upper IM is xtrude honed and both passages are larger than the 3L upper.
Dimensions are as follows:
2.5 SVT UPPER
inlet at the throttle body = 67mm
outlet port primary runner = 30.5-31.2mm, ~31mm on average.
outlet port secondary runner = 32.8-33mm ~33mm average

SVT lower IM
primary runner inlet = 33.5 mm
primary runner exit = 32.7 mm
secondary runner inlet = 36 mm
secondary runner exit = 34 mm

3L upper IM (casting flash gives small variation)
inlet at throttle body = 63.75mm
primary runner exit = 30-30.3mm, ~30mm average
secondary runner exit = 31.8-32mm, ~32mm avg.

3L lower IM
primary runner inlet = 33.4-33.5mm, ~33.5mm avg.
primary runner exit = 32.75mm
secondary runner inlet = 35mm
secondary runner exit = 32.75mm

As far as SVT vs. 3L heads are concerned:
SVT primary inlet runners are roughly the same diameter as the 3L but narrow slightly to fit the 32mm valve seats at the combustion chamber.
SVT secondary inlet runners are approximately the same size at the inlet, but neck down considerably to fit the 32mm valves again.

The conclusion would be to use 01 3L heads and have them xtrude honed for best results along with all other SVT components. Using the 2.5L heads and installing the 3L valves with some moderate porting will accomplish exactly the same thing (if you don't count the lack of the extra oil return passage) and should be cheaper.
It all depends on who is doing the work and what it costs.

For someone who is not afraid of a little experimentation: Try using 35mm intakes and 32mm exhausts. The simulation programs show very good results with this setup and the 3L engine.
Using the 2.5L heads and keeping the compression around 10.5:1 with the bigger valves shows some pretty serious torque.

You may ask what I have concluded from all this.
Well, all SVT components flow better than 3L components. The xtrude hone more than makes up for the 3L intake passages being a bit larger because of the roughness.
The RESTRICTION as it is known is IMHO the valves, and it is the exhaust valves to be more specific.

warmonger

Good summary. Warmonger, are you sure the SVT lower IM is Extrude Honed? I thought it was just a regular 3L lower, is it smoother?

Have to say that I'm hard pressed to find that the std SVT intake ports/heads have better flow/larger area than the '01 3.0 oval intake ports!

No, its extrude honed. In the 3L lower, you can see the cicular machine marks (although they are still very smooth), whereas in the SVT lower they have the characteristic longitudinal markings of sanding grit that goes in the directional of flow.

Terry.
This brings up the old topic we had at the end of the last summer where you can have a smooth pipe with a slightly smaller diameter compared to a rough pipe, and the smooth pipe will allow laminar flow up to a higher velocity than the rough pipe. The laminar flow in the smaller pipe at higher velocity means more air volume per unit time will go into the cylinder than through a rough pipe whose transition to turbulent flow will happen at lower velocities.
In the past YOU have argued the point that higher intake air velocity will give better cylinder filling.
So, if you look at the post above and read the fine print:

as well as this:

Then yes, I think that I can stand by the rough relative assumption made in the statement that the SVT heads can be just as good with moderate porting.
Disclaimer:
Of course that is meant as a comparison against stock 'non-modded' 3L heads and not against 'raced-out' modded ones.
My posts are already too long as it is, so I don't put every little detail in them.
(although it must seem like it sometimes)

Is it getting any easier now?


warmonger

Forget the extrude hone etc, just look at the X section of the 'single' oval intake port on the 2001 3.0 Vs the two 'singles' on the 2.5...the area is much larger with a lot less restriction to flow plus the lack of bifurcated intake port...time for some flowbench data......