Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Terry Q again. The "restriction"

[QUOTE]Originally posted by Jason King:

The longer runners in the 2.5 are better at producing torque, the shorter runners in the 3.0 are better for hp. Hone extrude a 3.0
[/QB]

"The longer runners in the 2.5 are better at producing torque..."

Better at what? Relative to what?

"...the shorter runners in the 3.0 are better for hp."

These two statements imply that there is no relationship to horsepower and torque...AMONG other things. :rolleyes:

I hope you are trying to say that the longer runners in the 2.5 help maximize torque at lower rpm while the shorter runners help maximize torque at higher rpm.
Why would anyone want to give up the low rpm torque benefit of the 2.5 manifold by going with the 3.0 manifold which doesn't have short/long runners? The 2.5 SVT is already large enough except maybe right at the exit ports of the upper. I measured the ID of the uppers on the 2.5L and they are the SAME diameter for primary and secondary as the ports on the 3L upper. The SVT lower had larger secondaries than the 3L lower secondaries, and the svt lower primaries were the same size as the 3L lower primaries.
End result, no benefit in going with the 3L upper or lower if you already have svt manifolds. Smarter to just widen and smooth out all the passages that you can on the SVT stuff, and then retain all the benefits of the short/long runners.
Just my opinion after all.

warmonger

"The longer runners in the 2.5 are better at producing torque..."

Better at what? Relative to what?

The 2.5 upper plenum makes more torque then the 3.0 what is so hard to understand about that statment? -Jason

"...the shorter runners in the 3.0 are better for hp."

These two statements imply that there is no relationship to horsepower and torque...AMONG other things. :rolleyes:

I think you need to go back and check the post again. - Jason

Why would anyone want to give up the low rpm torque benefit of the 2.5 manifold by going with the 3.0 manifold which doesn't have short/long runners?

I think you need to go look a few 3.0's. - Jason

The SVT lower had larger secondaries than the 3L lower secondaries, and the svt lower primaries were the same size as the 3L lower primaries.

I never said anything about the lower. I specifically said UPPER plenum. AND the 3.0 DOES have the larger lower, check your facts, the post 99's came with 3.0 lowers - Jason

End result, no benefit in going with the 3L upper or lower if you already have svt manifolds. Smarter to just widen and smooth out all the passages that you can on the SVT stuff, and then retain all the benefits of the short/long runners.
Just my opinion after all.

Opinions are like *******s, everyone has one, but where do you base your opinion? Obviously not in facts since you don't even know that the 3.0 has 2 sets of runners.

[QUOTE]Originally posted by Jason King:

The 2.5 upper plenum makes more torque then the 3.0 what is so hard to understand about that statment? -Jason

Its hard to understand what you are trying to say when you say that one manifold makes more torque than another, and later you say that the other manifold makes more HP!

HP=((ft-lbs)*(2Pi/60)*RPM)/550

This says that if you increase your torque you increase your horsepower. If you say one manifold produces more torque and the other produces more HP, then you're incorrect.

"
I think you need to go look a few 3.0's. - Jason
I never said anything about the lower. I specifically said UPPER plenum. AND the 3.0 DOES have the larger lower, check your facts, the post 99's came with 3.0 lowers - Jason
Opinions are like *******s, everyone has one, but where do you base your opinion? Obviously not in facts since you don't even know that the 3.0 has 2 sets of runners.
"
Ok, I have a 99 3.0 right outside. Since we are only talking about the upper. The upper plenum is right on my bench. There are ONLY single passages (per cylinder)in the upper. On the 3.0 the split occurs as it mates to the lower. So I KNOW the 3.0 upper doesn't have two sets of runners. Sorry, strike two.

warmonger

Warmonger: Can you post proper measurements for all the stuff you've got? I have extensively measured both upper and lower IM's, non SVT. Please post the inlet and outlet measurements (although I'm more interested in outlet no.'s).

BTW-The non SVT lower IM has a cast in "2.5" on the bottom. It uses 1.25(32mm) throttle plates and (if I've got this right) it's the same on all Duratecs until the E1 went to a 3.0 lower. Outlet diameters are 1.125 (28.5mm) primary and secondary.

Ok, I have all the measurements except the heads since they are in the shop still. Here are all the measurements taking into account the variation from port to port:

SVT figures from 1999 model manufactured in October of 1998 with return style fuel.

SVT upper:
inlet=67mm outlet primary=30.5-31.2mm
outlet secondary=32.8-33mm

SVT Lower: (has "2.5" cast in it)
inlet Pri.=33.5mm outlet pri.=32.7mm
inlet sec.=36mm outlet sec.=34mm

1999 3.0L duratech(less than 1k miles)
upper:
inlet=63.75mm
outlet :(there are only 6 oval shaped runners, one for each cylinder with a divider right at the end that splits the air into primary and secondary.)
outlet pri.=30-30.3mm outlet sec.=31.8-32mm

Lower: (has 3.0 cast in it.)
inlet pri.=33.4-33.5mm outlet pri.=32.75mm
inlet sec.=35mm outlet sec.=32.75mm

Throttle bodies:
Both throttle bodies have "3.0" cast into the back. They are identical castings except there is an idle air passage on the one from the 3.0L. Both have 60mm diameter (outlet side).

Thats everything I have for now, I will take measurements of the head port diameters when they come back. I did preliminary measurements but didn't write them down. I also measured the valve offsets in each head and I found that they are identical. This means that each head has the same distances between the centers of all four valves. I took a picture with the micrometer held on each head and showing the center-center distances. When the roll of film is done I will develope it and post pics. This is to prove once and for all (for 1999 at least) that the 3L valves fit and only require seat modifications, no special reinforcement stuff. In fact, they look like they are from castings that are almost identical. It should be no problem to remove the extra "shrouding" on the 2.5l heads in order to make it look and act more like the 3.0L heads. Will also lower the peak compression ratio a little and help with detonation.

Hope this helps you bradness, and everyone.

warmonger

Thanks Warmonger. From your posting, it looks like Ford used a different cutter/end mill on the SVT lower IM (2.5 version). I crunched the numbers and unless the secondary throttle plates were bigger than 1.25, there can't be any gain by going with a bigger secondary outlet diameter due to the bore restriction from the shaft/plate assembly. Anyone else like to add their 2 cents worth?

Bradness, you are correct. And damn! I forgot to measure the sided to side throttle blade diameter. Oh well.
Either way, the throttle blades were the exact same size from the svt to the 3.0.
The bore on both lower IM's tapers as you can see from the #'s. The butterfly valves are about halfway down so you can roughly guess the port diameter in the middle. I think it is about 33 mm. However you know that the butterflys are NOT perfectly round. They are designed to contact at an angle, so the mounting axis is the same size as the bore(~33mm) but the long side may be 34mm.
Here is what I did last weekend. I removed the butterflys and shafts and proceeded to widen out the primary and secondary ports by at 2-3mm on the primary and 1-2 on the secondary. I was matching them close to the gasket diameter. When I reassembled it yesterday, the butterflys still retained and angle, but there was a small gap on either side. They still operate normaly, but there is a little endplay now. If you are careful not to widen the middle of the bore to much, then the endplay is acceptable. That way you can get significant improvement in port diameter. The little gaps on the axis sides now will take the place of cracking the secondaries even though the secondaries are still closed. That is my HOPE at least.

Summary, (my two cents) widening the input side of the lower IM won't do any good since its already bigger than the middle or bottom. The taper already exists, probably to increase the velocity of the air as it enters the head. If you widen the ports, primary or secondary then you need to keep the taper in the bore, and you must widden the middle in order to make it effective. Then the upper manifold outlets must also be increased in diameter so that you aren't going from a restriction to a wide area then restriction again. And so on with the head ports. I just finished doing this to my intake system,when the heads come back I will widen the intakes similarly so that the new system is bigger overall than the older one, but has the same design intent.

ONe last thought, you could easily widen the sides of the bores that are perpendicular to the throttle blade shaft axis in order to gain an increase in area at that point and still have no endplay. I would have done it that way if I'f thought of it first :rolleyes:

Warmonger

I've taken extensive measurements and crunched the numbers. For the stock, non SVT lower IM there are no gains by opening up the casting. The smallest/narrowest point in the casting is the bore at the shaft/plate assembly. I'm not interested (at this time) in going to larger plates, as this is the only way I figure to get an increase in flow quantity. I have been able to improve quality though. Upper is basically the same (non SVT).

Did you remove the shafts when you did your work? If so, did you re-install them?

Yes to both questions.

I pulled off all the butterfly valves and then just rotated and pulled the shafts until they came out. More scum buildup hinderes it so you may want to clean really well first. Then there are two spring-loaded contacts, one in each of the thick dividers. they com up from the bottom to apply pressure to the shaft upwards, probably to keep it stable. I used a piece of angled coathanger to push them down when reinserting the shafts. Clean the area real well before putting the shafts back. Thats it.

warmonger