THE throttle body mod thread (with airflow data)
11-06-07, 07:15 PM
#1
THE throttle body mod thread (with airflow data)
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 machine at my school as part of my project for one of my courses. SO I am doing a project on my rx7 throttle body.
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
here is the elbow I ported
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)
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
that is my data so far.
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 dont have fow data for my ported TB yet and its hard to tell minute HP increases so I don't really notice a huge power improvement but a very big 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. I have a streetport on mine with other various goodies. this is on an s4 NA
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
here is the elbow I ported
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)
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
that is my data so far.
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 dont have fow data for my ported TB yet and its hard to tell minute HP increases so I don't really notice a huge power improvement but a very big 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. I have a streetport on mine with other various goodies. this is on an s4 NA
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boricua077 (06-08-21)
11-07-07, 01:34 AM
#2
Pretty damm good project you have going on.
Going to test any other TB's or intake manifolds?
Would be nice to see the difference between the years mainly FD vs FC stuff.
Anyway good work.
Going to test any other TB's or intake manifolds?
Would be nice to see the difference between the years mainly FD vs FC stuff.
Anyway good work.
11-09-07, 08:13 PM
#7
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This information has very limited use without knowing the pressure drop at which you got those flow numbers.
Last edited by Kyrasis6; 11-09-07 at 08:19 PM.
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11-10-07, 07:49 AM
#9
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What did you set the monometer for when you setup the test?
For example lets say you got 650 cfm @ 20 inches of water, someone else does some testing and says they got 700 cfm. If the person also did that test at 20 inches of water then they got an improvement. Lets say they set it up different and ran it at 30 inches of water and got that flow number. Now you would have to convert his flow to what that would be at 20 inches of water in order to find out if that was an actual improvement or not.
It's sort of like fractions obviously 1/2 is much smaller than 3/2 but which is bigger 3/4 or 27/32??
For example lets say you got 650 cfm @ 20 inches of water, someone else does some testing and says they got 700 cfm. If the person also did that test at 20 inches of water then they got an improvement. Lets say they set it up different and ran it at 30 inches of water and got that flow number. Now you would have to convert his flow to what that would be at 20 inches of water in order to find out if that was an actual improvement or not.
It's sort of like fractions obviously 1/2 is much smaller than 3/2 but which is bigger 3/4 or 27/32??
11-10-07, 08:19 AM
#10
11-10-07, 08:22 AM
#11
11-10-07, 12:03 PM
#12
What did you set the monometer for when you setup the test?
For example lets say you got 650 cfm @ 20 inches of water, someone else does some testing and says they got 700 cfm. If the person also did that test at 20 inches of water then they got an improvement. Lets say they set it up different and ran it at 30 inches of water and got that flow number. Now you would have to convert his flow to what that would be at 20 inches of water in order to find out if that was an actual improvement or not.
It's sort of like fractions obviously 1/2 is much smaller than 3/2 but which is bigger 3/4 or 27/32??
For example lets say you got 650 cfm @ 20 inches of water, someone else does some testing and says they got 700 cfm. If the person also did that test at 20 inches of water then they got an improvement. Lets say they set it up different and ran it at 30 inches of water and got that flow number. Now you would have to convert his flow to what that would be at 20 inches of water in order to find out if that was an actual improvement or not.
It's sort of like fractions obviously 1/2 is much smaller than 3/2 but which is bigger 3/4 or 27/32??
okay just making sure were on the same page, they were all flowed at 25" of water.
the flowbench cant flow the TB at its max at 25" so it drops it down to whatever, in this case it was 21.
the flowcom (flow computer) on the bench automatically calculates it for you, when it can handle the flow.
my max values are calculated.
here is formula for pressure conversion:
(2nd flow pressure/1st flow pressure)^.5 multiplied by 1st flow CFM
so in this case it would be:
(21/25)^.5 X 597.4
the bench only flows up to 600CFM at 25" it flows to much for the superflow 600 bench.
now I gotta double check the velocity on them since I need to see if the flowcom accommodates for the velocity or not, I'll find that out monday.
recap:
597.4 CFM @ 21" water stock TB at WOT (either elbow)
627.4 CFM @ 19" water modified TB stock elbow at WOT
623.5 CFM @ 19" water modified TB modified elbow at WOT
Last edited by fidelity101; 11-10-07 at 12:10 PM.
11-12-07, 04:47 PM
#15
alright its monday so news update.
first off the velocity reading above are in % velocity which doesnt mean **** so next week I will be re flowing everything to get the reading in Feet/Seconds.
my ported and polished TB goes as follows:
no elbow WOT it dropped from 25" of water to 14" and flowed 758.9cfm
stock elbow WOT on it went from 25" to 18" at 630.3CFM
ported elbow WOT on it went from 25" to 17" 630.2
stock elbow 1/2 throttle was at 25" and flowed 306cfm
ported elbow 1/2 throttle was at 25" and flowed 362cfm
as of right now disregard the spredsheet picture, it is going under revamp
first off the velocity reading above are in % velocity which doesnt mean **** so next week I will be re flowing everything to get the reading in Feet/Seconds.
my ported and polished TB goes as follows:
no elbow WOT it dropped from 25" of water to 14" and flowed 758.9cfm
stock elbow WOT on it went from 25" to 18" at 630.3CFM
ported elbow WOT on it went from 25" to 17" 630.2
stock elbow 1/2 throttle was at 25" and flowed 306cfm
ported elbow 1/2 throttle was at 25" and flowed 362cfm
as of right now disregard the spredsheet picture, it is going under revamp
Last edited by fidelity101; 11-12-07 at 04:58 PM.
11-13-07, 03:16 PM
#19
The only way that this is valid is to flow test the throttlebody with it attached to an intake manifold. You may very well have gotten a gain on the throttlebody and probably did but unless you are flowing the entire intake as a system, it doesn't tell you the whole story. Increasing flow in one area doesn't help if that area already flowed well compared to other areas in the system. My old bench (may it R.I.P.) was setup with an adapter I made to flow entire manifolds.
I am happy to see someone do airflow testing though. More people need to do this.
I am happy to see someone do airflow testing though. More people need to do this.
11-13-07, 03:34 PM
#20
The only way that this is valid is to flow test the throttlebody with it attached to an intake manifold. You may very well have gotten a gain on the throttlebody and probably did but unless you are flowing the entire intake as a system, it doesn't tell you the whole story. Increasing flow in one area doesn't help if that area already flowed well compared to other areas in the system. My old bench (may it R.I.P.) was setup with an adapter I made to flow entire manifolds.
I am happy to see someone do airflow testing though. More people need to do this.
I am happy to see someone do airflow testing though. More people need to do this.
but super accurate. I wish I could have done that and mixed things up a bit.
it doesnt tell the whole story but some is better than none heh.
11-13-07, 03:36 PM
#21
BTW: sweet job on the FD TB!
11-16-07, 10:21 AM
#23
I do need to point out that if you increase airflow in a system in an area that is not the biggest restriction, you do not increase power. You may change throttle response but not total power. That is the whole reason I stated that you need to flow the entire manifold to make a determination. An airflow increase isn't always useful information. You need to see the big picture for it to tell you anything. An increase doesn't always help if it is in a small area that doesn't need it. I'm not saying don't do this. It's a good mod for throttle response. Just don't expect a power increase out of it.
11-16-07, 12:23 PM
#24
I do need to point out that if you increase airflow in a system in an area that is not the biggest restriction, you do not increase power. You may change throttle response but not total power. That is the whole reason I stated that you need to flow the entire manifold to make a determination. An airflow increase isn't always useful information. You need to see the big picture for it to tell you anything. An increase doesn't always help if it is in a small area that doesn't need it. I'm not saying don't do this. It's a good mod for throttle response. Just don't expect a power increase out of it.
I don't really feel a power increase in it from driving, the colder Michigan weather is noticeable though. The possibility of a power increase is greater with a port job (which I have) but testing it with a dyno will probably result in such a small difference and the different runs create different results alone so it would be kind of inaccurate.
11-16-07, 12:50 PM
#25
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[QUOTE=fidelity101;7520209]post results when you got it done. is it just flowing a stock one or a modified one?
Firstly > Sorry,not meaning to hijack your thread,hopes its not seen as if i want to.
Sorry,meant that i`am busy porting( not physically flowing it on a flow bench) my TB.To give some background >Its a turbo manifold and TB but it will be used on a NA 4 port engine.aka turbo 13B with the old snail removed.So far i have taken out the step it has on the elbow side,and smoothed the part before the butterflies.Have also removed the second set of butterflies closer to th plenum.
Will try and post a pic,allthough not nearly as neat as the work your doing
Karis
Firstly > Sorry,not meaning to hijack your thread,hopes its not seen as if i want to.
Sorry,meant that i`am busy porting( not physically flowing it on a flow bench) my TB.To give some background >Its a turbo manifold and TB but it will be used on a NA 4 port engine.aka turbo 13B with the old snail removed.So far i have taken out the step it has on the elbow side,and smoothed the part before the butterflies.Have also removed the second set of butterflies closer to th plenum.
Will try and post a pic,allthough not nearly as neat as the work your doing
Karis