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

If you would be so kind as to give me another opinion. Take a look at my mods below (in sig). Assume I were to 1) remove precats to complete the opening up of the exhaust, 2) FINISH up my mods with a dyno session that tuned my A/F ratio to optimum with chip, Apexi-AFC, etc.

Where do you think the intake flow restiction would be..? Nice easy multiple choice Q.

A) 60 mm throttle body
B) Extrude Honed upper intake (32mm secondaries)
C) 34mm butterflies in lower intake
D) intake ports in heads/valves
E) More than one
F) None of the above - eveything is perfect!
G) None of the above - hopeless case!
H) None of the above - what are you talking about!

A, B, and C are relatively fixable. Probably would not do head porting or big valves at present. Alot of people have chimed in on this but I want to know what you had to say.. Thanks once again

Work can be done in all of the areas you mention BUT the one you didnt is the one I think can give the most gain.If you notice on the intake when the throttle is at WOT the intake air almost 'dead heads' against the back of the intake manifold and then has to do a 90 deg right & left turn to the plenums,then another 90 deg turn!.A previous post was on the right track in this area but for the wrong reasons.What will happen to the flow if the axis point of the throttle body X shaft is moved away from the mating face of the intake manifold?.Think of 4 brl carbs with the 90 deg deck under the carb to the runners,when will the gas flow best? at WOT or with the butterfly not exactly at 90 deg to the manifold floor? and how could you make that flow smoother/better......

A mini throttle body on each end of the runners perhaps?

PS DemonSVT has proof that the 60mm TB is a flow restrictor. It is pointless adding a huge MAF if the downstream TB is still the same, the system will only flow as much as the TB can handle, regardless if you MAF is 1m in diameter!
Until people realise this, we will be talking our selves in circles.

My idea of optimising the SVT (N/A) or any Duratec, within reason is as follows:

Good intake filter
65mm TB
MAF? (Maybe a Pro-M, but a 70mm MAF is still bigger than the TB)
Chip with improved timing curve
A'PEXi S-AFC (to tune everything in)
Headers
True duals

Everything else like dual TB's, porting polishing and stuff like that is a lot more work, and even though it may yireld good results is more than I wish to undertake, except of course for a Turbo!

Ideal but not that easy,think about the 'dead heading' problem!!!

hey terry, toss me an email. I have some thoughts that may assist in making a solution to the "dead-head" problem even easier to implement.

Terry would you mind expanding on this a bit? If I understand correctly you're referring to the vertical "divider" which is cast internally in the upper IM to force airflow to the right and left plenums.

My solution would be 1 of or a combination of the following: add a spacer of XX thickness between the t-body and the upper IM entry; rotate the t-body 90 degrees; cut open the upper IM horizontally and port to smooth airflow. Did I miss any, and which is preferred?

Your on track!!!

Terry, Interesting thread. would putting some sort of splitter behind the tb and in front of where the air dead heads be of benefit. I'm kind of thinking it would start the air transitioning to the right or left just behind the TB to make the air flow smoother. Kind of taking a corner and hitting the apex at the right spot. Does this make sense

....and your 'on track' too!!!!!!

Like to continue this discussion. I have actually been thinking of this for quite some time. Have you done something like this already to your tour???