Fidelity101
12-10-2008, 11:13 PM
everyone has rumors and concerns or thoughts and questions about the TB mod, especially on the non turbo ones but I have access to a flow bench
I followed the DIY here
http://fc3spro.com/TECH/HOWTO/TBM/tbm.html
..to a point. I was unsure on weather or not a bolt would be worse than filling it with JB weld and smoothing it to match the TB surface. it makes a good project. Basically going on the theory if there is that hole left there or a gap the airflow would be the same effect as an airplane up in the sky and someone opens a door, the fast air passing over the smooth surfaces will suck out the air inside and cause turbulence, and the only turbulence you want it near the combustion chamber for a better fuel/air mix burn. This is why don't polish the intake side on a cylinder head, keep it a little rough to create turbulence.
here is the elbow I ported
http://img509.imageshack.us/img509/735/1000236uc1.jpg
http://img509.imageshack.us/img509/6639/1000237bj4.jpg
Basically just smoothed out the sharp cut and the ridge on the inlet side.
and here is the TB all mounted and ported and polished. (i'll have better pics of it when its off the car soon to flow)
http://img116.imageshack.us/img116/6468/1000240ny2.jpg
http://img221.imageshack.us/img221/7966/1000241mj9.jpg
my project is comparing velocity and CFM increases for these various combinations.
100% stock throttle body with stock intake elbow
stock throttle body with ported elbow above
Shafts removed throttle body with jb weld fix, stock elbow
Shafts removed throttle body with jb weld fix, ported elbow
Shafts removed throttle body with threaded bolt fix, stock elbow
Shafts removed throttle body with threaded bolt fix, ported elbow
^^ all throttle bodies above have no porting or polishing done
fully ported and polished TB with no shafts and stock elbow
fully ported and polished TB with no shafts and ported elbow
.
so as of now stock TB should use the stock elbow, the ported elbow on stock TB does not flow as much at midrange power, the smaller size elbow helps the air charge speed maintain velocity.
the shafts removed increased 67CFM alone, which is huge.
the stock TB flowed 651 CFM (no matter the elbow) and the modified one flowed 719.7/715.2 CFM (ported/stock elbow) but on this one the ported elbow flowed 74.8 CFM more in comparison to the stock elbow.
my driveablity improved, my hesitation went away (my secondaries were sticking) and throttle response improved. I a very big throttle response improvement. with the mods I have the TB mod helped out, I don't know how it will be different on a stock ported engine. at the time I had a s4 streetport on mine with other various goodies. When airflow is concerned it matters for power at the smallest orifice which is your intake port on the iron or your valve area in your cylinder head if any of you have piston engines heh.
here is the data:
http://img117.imageshack.us/img117/5383/airflowdatajl1.jpg
throttle bodies are typically flowed on a bench with no elbow on them and measured at WOT and typically flowed at a pressure of 1.5" of HG (mercury)
so I have that on the chart now. so if you see like a 650CFM carb thats what its tested at 1.5" Hg. Considering the more pressure you force air through a given orifice, it will yield more flow. so I could have it tested at an even higher level of inches of water and get more CFM but 25" is the magic number it seems for when people are comparing things to another such as intake manifolds, heads, headers and etc...
this test was basically to see the difference in using a bolt to fill the hole or JB weld and see how P&P affects airflow etc etc. there is a very minimal difference in CFM for the JB weld fix or using a bolt, hell if you dont have a thread and tap kit you can fill it with jb weld then run a bolt through it heh, but that would be redundant.
the velocity was all measured at WOT on the bench with no elbow
you gain more velocity through a smaller port with the same pressure so widening the throttle body lowers the velocity through there but it gives more CFM, its kind of a trade off but looking at the results a ported and polished throttle body is definitely an upgrade in comparison.
so use JB weld or a threaded bolt, your not going to be able to tell the difference unless you ended screwing up and getting a leak :P
I followed the DIY here
http://fc3spro.com/TECH/HOWTO/TBM/tbm.html
..to a point. I was unsure on weather or not a bolt would be worse than filling it with JB weld and smoothing it to match the TB surface. it makes a good project. Basically going on the theory if there is that hole left there or a gap the airflow would be the same effect as an airplane up in the sky and someone opens a door, the fast air passing over the smooth surfaces will suck out the air inside and cause turbulence, and the only turbulence you want it near the combustion chamber for a better fuel/air mix burn. This is why don't polish the intake side on a cylinder head, keep it a little rough to create turbulence.
here is the elbow I ported
http://img509.imageshack.us/img509/735/1000236uc1.jpg
http://img509.imageshack.us/img509/6639/1000237bj4.jpg
Basically just smoothed out the sharp cut and the ridge on the inlet side.
and here is the TB all mounted and ported and polished. (i'll have better pics of it when its off the car soon to flow)
http://img116.imageshack.us/img116/6468/1000240ny2.jpg
http://img221.imageshack.us/img221/7966/1000241mj9.jpg
my project is comparing velocity and CFM increases for these various combinations.
100% stock throttle body with stock intake elbow
stock throttle body with ported elbow above
Shafts removed throttle body with jb weld fix, stock elbow
Shafts removed throttle body with jb weld fix, ported elbow
Shafts removed throttle body with threaded bolt fix, stock elbow
Shafts removed throttle body with threaded bolt fix, ported elbow
^^ all throttle bodies above have no porting or polishing done
fully ported and polished TB with no shafts and stock elbow
fully ported and polished TB with no shafts and ported elbow
.
so as of now stock TB should use the stock elbow, the ported elbow on stock TB does not flow as much at midrange power, the smaller size elbow helps the air charge speed maintain velocity.
the shafts removed increased 67CFM alone, which is huge.
the stock TB flowed 651 CFM (no matter the elbow) and the modified one flowed 719.7/715.2 CFM (ported/stock elbow) but on this one the ported elbow flowed 74.8 CFM more in comparison to the stock elbow.
my driveablity improved, my hesitation went away (my secondaries were sticking) and throttle response improved. I a very big throttle response improvement. with the mods I have the TB mod helped out, I don't know how it will be different on a stock ported engine. at the time I had a s4 streetport on mine with other various goodies. When airflow is concerned it matters for power at the smallest orifice which is your intake port on the iron or your valve area in your cylinder head if any of you have piston engines heh.
here is the data:
http://img117.imageshack.us/img117/5383/airflowdatajl1.jpg
throttle bodies are typically flowed on a bench with no elbow on them and measured at WOT and typically flowed at a pressure of 1.5" of HG (mercury)
so I have that on the chart now. so if you see like a 650CFM carb thats what its tested at 1.5" Hg. Considering the more pressure you force air through a given orifice, it will yield more flow. so I could have it tested at an even higher level of inches of water and get more CFM but 25" is the magic number it seems for when people are comparing things to another such as intake manifolds, heads, headers and etc...
this test was basically to see the difference in using a bolt to fill the hole or JB weld and see how P&P affects airflow etc etc. there is a very minimal difference in CFM for the JB weld fix or using a bolt, hell if you dont have a thread and tap kit you can fill it with jb weld then run a bolt through it heh, but that would be redundant.
the velocity was all measured at WOT on the bench with no elbow
you gain more velocity through a smaller port with the same pressure so widening the throttle body lowers the velocity through there but it gives more CFM, its kind of a trade off but looking at the results a ported and polished throttle body is definitely an upgrade in comparison.
so use JB weld or a threaded bolt, your not going to be able to tell the difference unless you ended screwing up and getting a leak :P