Just bringing up a point to ponder this. 3L engines equipped with the SVT manifold benefit upon further honing thus additional internal volume.
I'd like to hear your reasons as to why you think it won't help much if you don't mind sharing?
Further honing also increases runner diameter, and reduces stangation points in the manifold. These decrease resistance to flow, and consequently improve power if the rest of the engine can accomodate the increased airflow potential. The increased internal volume is minimal and coincidental.
i contacted outlaw enginerring a couple of years ago about making some pheno's for use...the said that the stock gaskets kept the manifolds from touching,so they didnt see a need for one. except for the tb to uim. i've had phenos on several probe gt's they help'd for sure..but werent good for boost,and require longer bolts and occasional re-tq'ing of them. air leaks are common
Phenolic spacers have historically been used for two seperate reasons. One is to increase volume, either of the runners themselves (increased length) or of the plenum. The second is to put a thermal barrier between sections of the intake manifold to prevent heat transfer into the bulk of the manifold in an effort to decrease air intake temperatures. In the case of the Duratech manifolds, increasing runner length would be undesirable, because of the resutling decrease in the torque peak rpm. Increasing plenum volume is still debated and Joey is going to give it a try. The thermal barrier is not likely to be of much benefit because of the gasket designs used on most of the 3Ls.
Which manifold is better, IMO, would be the one that is used with the correct port style which is what the huge arguments stem over. It's gotten confused that we were not arguing so much as to which one is best but, the fact that this frankenstein combination was being displayed as beneficial. Which I have found no evidence of compared to oval manifolds of similar performance intent.
I don't think anyone claims the "frankenstein" combination of split port manifolds over the top of ported oval port heads is beneficial. Typically it could better be described as "adequate for many people". Sure it gives up some efficiency in flow, and removes most of the multi-peak runner effect of the split ports, sure it makes fuel spray patterns less than ideal; but the fact is, despite these issues, they still run pretty damn well. Better than I would have ever expected. Optimal? No, certainly not. Adequate? Yeah, in many cases it is, especially when you consider that most 3L Contours have some level of traction issues on the street as it is.
Then you can consider the same setup, but with Joey's custom lower instead of porting the heads. This setup fixes the fuel injector spray pattern concerns, and gains a decent bit of the lost flow efficiency. Still not perfect, but that's the nature of what its trying to do, mate a split port manifold w/ an oval port head.
Obviously, it would be ideal to keep oval port heads with a good oval port intake, and split port heads w/ a good split port intake, but not all the oval port intakes are good for a high revving engine. And not everyone can get thier hands on an ST220 manifold. I've probably got more connections than just about anyone on here, and even I really lucked into getting my ST220 manifold.
ST220 would be best production for oval ports
Yes, this is presently true, but the 05+ Escape manifold isn't very far behind according to some of the internal Ford data I've seen.
and there has been evidence that the pre oval 3L is better for split ports. I would now contest to say that the benifits may only be higher up in the rev range. Unsure of overall benefit to the other parts of the TQ band though. This would need to be analyzed.
What evidence do you speak of? I'd imagine that any evidence of this nature points to the split port 3L HEADS for any improvement rather than the manifold itself. The split port design provides the greatest area under the curve for cylinder filling (flow is a function of both cross sectional area and flow velocity) and the 3L split ports have the largest intake valves of any of the split port heads.
The fact that 3L engines still benefit to a good extent from further honing is still a point of contempt to there being sufficient internal volume. What factors are contributing to heightend performance is what I would like to know if plenum volume is not the major underlying issue. I'm after these specifics to the actual design of the manifold vs. dynamometer tests as I have a good idea of the outcome already.
The reason additional honing improves flow is elementary, you increase the cross sectional area of the runners, and you improve the amount of air you can flow at high rpm. It's very simple. Extrude honing does not significantly increase the volume of areas where flow is slower in the manifold, namely the plenum. The plenum is sized for the SVT manifold to a level that provides sufficient flow to each individual runner, while maintaining good flow velocity in the plenum as well. Ideally, you want to gradually accelerate the air through the entire intake tract, not accelerate it up to the plenum, and slow it way down, then speed it right back up into the runners. Too large of a plenum is not helpful. Personally, I don't believe Joey's plenum spacer will result in a significant power change for the SVT manifold. I believe that for the most power out of basically off the shelf parts on an NA 3L, you would need split port heads with 3L valves and extrude honed (or expertly ported is even better) ports, and a maximum extrude honed SVT manifold with matching lower intake (while keeping the function of the secondary port throttles for low rpm response and power).
Also, I stress that power figures do not tell the whole story as to how the engine will perform. That is, transient acceleration and the time for gas speed (intake and exhaust) to rise upon throttle opening. Hence why 'time' is a very importnat variable to look at. Getting from point A to point B the quickest is the idea of racing. This may be beyond the scope of what a chassis dyno can illustrate and most likely will not show signifcant impact on power figures if at all.
Transient response is important, but is more a factor of calibration. If you optimize an intake system for transient response, it will end up far too small for maximum power at high rpm. A compromise must be struck, and this is where the whole concept of the secondary port throttles comes from. These provide a far better transient response than the plain oval port designs (which use intake manifold design, cam specs and calibration to improve response) while offering minimal resistance to flow when open. IMHO the WORST thing done by people here for transient response is gutting secondaries . . . All that said, poor transient response is always manageable by getting on the throttle sooner.
The bottom line is that even the worst of the combinations provides reasonably good results for 90% of the potential users . . . and most of the differences between the different combinations would really get lost in the repeatibility of a chassis dyno.
Not everyone comes with the same mind set and thank goodness for it. Lighten up...