I was concedering the s4 to s5 afm swap on my tII fb due to space restrictions. i was hesitant without knowing some real flow numbers tho. So i flowed both afm's today....

S4 380cfm @15" H2O

S5 430cfm @15" H2O

They where tested at 15" H2O to insure that they where fully open.

IM not real worried about any difference in output because i have an rtek 2.0 so i can make up for the minor differences if there are any. So im gonna swap it. The s5 not only is smaller it is also not sensitive to mounting position. Looks like a winner to me!

 

Great info, thanks for posting that. The more technical data, the better!

 

Here is a link to the diagram. as we can see the s5 afm is less restrictive. Numbers dont lie!

https://www.rx7club.com/showthread.php?t=177125

 

That link isn't working :-(
Great info though!

 

Testing procedure?
Equipment used?
Photos?

 

and did you use a N316 or N326 S4 AFM?

 

Test procedure was as follows....

I used a plate with a 6 inch length of three inch pipe coming out of it. The s4 afm has the rx7store cone filter adapter on it for even flow. The S5 afm had nothing on the intake side to enhance flow. The afms where tightened to the pipe using a coupler.

I dont have any pics of them on the flowbench. The bench used was a superflow s-600 model. I decided on 15"of h20 for the test because it was a bit more than was needed to fully open both of the meters.

the s4 afm used was the n 318

 

i know the 50 cfm jump isnt huge. and i dont know what kind of vacuum the car pulles behind it at full throttle. It was more of a test for me to be sure that the s5 sfm wasnt more restrictive. i wasnt going to put it on the car if it was even with the space savings. And i wouldnt reccomend it for anyone that didnt have a way to moniter and tune their fuel mix. next time i take the car out im going to log a pull and see how it affected my afr

 

Little bit over 10% of airflow difference?
Hmmm...


-Ted

 

i didnt do the swap for more power as i stated above. my setup (12psi on bnr stage 2) is not going to stretch the limit ot the s4 one. and yes the s5 isnt much better. its the space savings and lack of dependence on what position that im after. (i know the whole position thing is debated too, i wouldnt want to hit a bump in boost and have something happen tho. as i stated above i did this to be sure that the s5 wasnt more restrictive.

I just wanted to put more info out there for everyone.

 

Interesting. I had always assumed the S4 meter had better flow...