Secondaries

[Paul]

I'm going with nik97 on this one. I agree the secondaries serve a vital pupose in the low end velocity as describled. I think the purpose of the butterflies outweighs the restriction. Why would they be there?

 

[SHOZ123]

If they would have had true segregated secondary runners of a shorter length compared to the primary runners the they would be some performance benefit. A true two runner per cylinder setup will offer two torque peaks. Anyone see this on a V8?

It is my opinion that the secondary set up is a gee wizz thing. And imagine if Ford would have brought out the V8 without any secondaries? It is barely accepted as it is as a Yamaha.

There may be some minor drive ability benefits at low rpms due to the primary intake valve and the swirl that is induced by having it open and the secondary valve closed off. But this is gone after 1500 rpm.

If you look at OEM programming the fuel is programed for the 14.5 A/F mix until the secondaries open. Then it goes richer at higher loads. The further under 1.00 the richer the commanded ratio. No comments Adam...

Here's a pic of my OEM AWL1 fuel tables. Look where it starts dropping below 1.00 and compare that to load and rpm. Load over .500 is at least 1/2 throttle, lower rpm=higher load per throttle opening compared to higher rpm.

So the kick in the seat from the secondaries on the V8 is more a function of A/F mix than the "tuned" intake. Probably why Ford took the secondaries out of the V6 3.0L Duratec for good as of late.

 

[Paul]

My bosses are continually manipulating facts with numbers. They learned it in college.