throttle body spacer??

[turbo cat]

hmmm 100$ for a chunk of aluminum with a hole in it

 

[rurouni20xx]

okay guys heres the article in my book, that ill leave open for discussion:
"transients and modifiers
"to more accurately predict the dynamic fuel needs of an engine, EFI systems employ a model to predict the volume of fuel trapped on the manifold wall. this film is known as "tau" (t symbol). since no current port injection system has the ability to spray 100% of its fuel into the cylinder from a single injector pulse, part of this spray collects on the walls of the intake port. incoming air flowing past this "puddle" of fuel on the part walls carries part of it away into the cylinder as well. the more volume of air flowing past the tau puddle, the more this puddle is being decreased in mass. tau modeling systems use instantaneous airflow predictions to attemp to maintain a constant volume of tau. this means that increases in airflow require an increase in fuel to maintain constant tau volume and decreases in airflow allow for a decrease in fuel delivery to maintain constant tau."

the rest of the article goes into acceleration enrichment and decel enleanment and states that this anomolly has to be accounted for. the tau factor helps accel enrichment by letting the engine use some of the fuel that has already puddled to keep the engine from bogging. it also allows the injector to almost shut off and run on this puddle while decelerating to keep the engine from stalling during sudden closure of the throttle (dashpot tuning). this even includes port (sequentially) injected engines, so placing a helix spacer between the injector and the head of the runner or even before the injector in the runner will hurt this factor and cause major problems. ive seen several helix style spacers installed, all they do is make the engine whistle when you apply throttle.

as far as lengthening the runners w/ a phenolic spacer:
"longer runners are used to generate better torque at low and mid rpms. shorter runner are used to increase the ram tuning effect at high speed." this is covered in runner control systems, and how they are changed w/ dif systems. (4.0 port flaps are covered in this section of the book...) lengthening the runners w/ a phenolic spacer will help your torque number slightly, its best to do the math and see what you want to accomplish b4 attempting such a modification. youll actually run into a happy medium where a length of longer and shorter runner have the same characteristics for hp, but still have the effects of a longer runner for torque numbers. thats why longer runners are better than short runners, lengthening them slightly will have a slight torque enhancing effect.

gentlemen: start the arguing!! lol.

 

[Bob Ayers]

okay guys heres the article in my book, that ill leave open for discussion:
"transients and modifiers
"to more accurately predict the dynamic fuel needs of an engine, EFI systems employ a model to predict the volume of fuel trapped on the manifold wall. this film is known as "tau" (t symbol). since no current port injection system has the ability to spray 100% of its fuel into the cylinder from a single injector pulse, part of this spray collects on the walls of the intake port. incoming air flowing past this "puddle" of fuel on the part walls carries part of it away into the cylinder as well. the more volume of air flowing past the tau puddle, the more this puddle is being decreased in mass. tau modeling systems use instantaneous airflow predictions to attemp to maintain a constant volume of tau. this means that increases in airflow require an increase in fuel to maintain constant tau volume and decreases in airflow allow for a decrease in fuel delivery to maintain constant tau."

the rest of the article goes into acceleration enrichment and decel enleanment and states that this anomolly has to be accounted for. the tau factor helps accel enrichment by letting the engine use some of the fuel that has already puddled to keep the engine from bogging. it also allows the injector to almost shut off and run on this puddle while decelerating to keep the engine from stalling during sudden closure of the throttle (dashpot tuning). this even includes port (sequentially) injected engines, so placing a helix spacer between the injector and the head of the runner or even before the injector in the runner will hurt this factor and cause major problems. ive seen several helix style spacers installed, all they do is make the engine whistle when you apply throttle.

as far as lengthening the runners w/ a phenolic spacer:
"longer runners are used to generate better torque at low and mid rpms. shorter runner are used to increase the ram tuning effect at high speed." this is covered in runner control systems, and how they are changed w/ dif systems. (4.0 port flaps are covered in this section of the book...) lengthening the runners w/ a phenolic spacer will help your torque number slightly, its best to do the math and see what you want to accomplish b4 attempting such a modification. youll actually run into a happy medium where a length of longer and shorter runner have the same characteristics for hp, but still have the effects of a longer runner for torque numbers. thats why longer runners are better than short runners, lengthening them slightly will have a slight torque enhancing effect.

gentlemen: start the arguing!! lol.

Do you think Ford, and all the other vehicle manufacturers don't already know this? With CAFE standards, vehicle manufacturers already design their intake systems to be as efficient as possible. That's why I find it simply amazing that people fall for the aftermarket BS (like K&N, etc.)!!

 

[rurouni20xx]

exactly my point, putting other stuff in there does make a dif and skrews w/ these factors. if you put a power adder in w/o tuning you could potentially be skrewing yourself. it is in my belief that even when modifying a system (exhaust intake etc) on a system that learns (car and trk efi systems) they do compensate for these changes, but only to a point since the computer doesnt completely reflash itself for these changes. its best to take the vehicle (car trk bike etc) to a dyno or open road test w/ an air fuel meter and see what changes have been made and retune appropriately. bolt ons do have some effect, but only certain ones. throttlebody spacers and phenolic spacers do have some effect if tuned properly for the application for torque purposes, and checking the computer is def necessary. helix type spacers that "swirl" the airflow actually hurt the systems enrichment values, and only act as a flow restriction, they do add to runner length, but not for the cost of the damage done to the fuel system. a friend of mine has on his 4.2 v6 f150, b4 it was smooth and felt good. after the install the engine had a short lag and whistled hard then took off a little harder. he thinks its power, i think its lag produced by the spacer and the engine has to catch up. until i see whats going on at a dyno i cant be for certain, but ill def not be putting one on my trk to say the least.