Just as an engine has an operational "sweet" spot
where engine torque is maxed at a specific RPM
(IE. the volumetric efficient point that minimizes
an engine's pumping losses & exhaust backsliding),
is there not a "sweet" spot where a particular throttle-valve angle
optimizes the performance of the groove?
Would this optimal throttle-valve angle be at the intersection
of the plane on the back (intake manifold) side of the throttle valve
with the bottom of the back side of the groove (or slightly before it)?
In other words the wider the groove the more the throttle has to be
opened to reach this optimal performance point for the groove?
When I am driving around with my grooved engine, I notice that I have
to open-up the throttle more to get the big "push" from the groove effect
than how I normally drive with a very light touch. Maybe I needed a
3rd generation groove that was narrower (to reach an optimal throttle
angle sooner?) but still proportional (width to depth) & still has the same shape.
If an engine can be optimized with tuned intakes, exhaust, etc.
that are based upon mathematical equations, then could not the groove
be customized per the specific needs of an engine, driver, & application, etc.

Interesting, I had a thougt witch is that using the small bit for the sides the medium bit for the down going and the big bit in the bottom , what do yous think I want to try it out. it just seems airodynamically correct.

Karl posted some inaccurate information, so I deleted his post. I want only the most accurate info shared.

Here's his post with my comments:

Two of the first grooves that I did, there was an obvious indication that the groove was in the right spot... just like blowing across the top of a coke bottle, it whistled.

Both of these were carburetors. What was different about them compared to most of the TB's is that the plate angle was more define, ie: 25-30 degrees compared to the electronic TB's where the plate angle is 13-17 degrees. You don't get the whistle with the Electronic TB's.



Markus,

I think if I were to do something like that, I would go the other way...
large bit to the outside, small bit in the middle..

Thinking about the air flow within the groove and the impact at the center point.

Another thought too, particularly with the Chevrolet TB with the sloped venturi wall

The groove is applied with a slight angle away from the TB to accommodate the slope of the wall and I'm wondering if chasing the pocket with the small bit perpendicular to the throttle plate might enhance the effect somewhat.



I figure if it helps that's a plus, if it doesn't change anything... no harm no foul, if it takes away... Something to be said for JB Qwik.

Karl Fortner
Tacoma, Wa.
Gadgetman Tacoma

Yes, there is a sweet spot and the groove is it . When the air is tossed into the groove the engine is running at ease watch the vacum gauge and fuel trims. The load factor comes into play if you notice gradually stepping on throttle the fuel actually is taken away even though the speed goes up. I call this pressure coasting like in a race going to sling shot around the leader using his pull. Yes, I almost forgot, the ecu will actually start gradually training the throttle position to the groove watch the scanner and you`ll notice a change in the angle after awhile.

My car has a little whistel on idle and it becomes louder giving a little gas then it dissapears when tb opens more, I thought id have to change manifold gasget, but this is probably the groove.

Hi Markus, The whistle is definitely the Groove. It is an excellent indication that the vacuum is good. This is not a sure thing (as it is subjective), but my experience is that I was not getting results with my Suburban until the vacuum was adequate and when it was, she started to whistle. Any confirmations out there.

The whistle can be a negative as some customers do not like it. It is comforting to me as it is an indication it is working and it sort of sounds like a turbo whine which I thing sounds neat.