Smile monitoring airflow... speed density, or MAF for 20b?
ok well i have a MAF that came with my motor... although the FD has a Speed Density system. i was wondering a few things. first off, why they decided to switch to speed density for the FD?

i may be understanding this wrong, BUT i thought the only difference between MAF and speed density, was that one uses a MAF sensor to monitor air flow, and the other relies on a TPS and load sensing to judge how far open the throttle is, so the ecu can "guess" how much air is flowing. but i notice what seems to be a TPS on my 20b TB... so i seem to be a bit confused. also, both use MAP sensors correct?

anyway, i was wondering.... for those of you using an aftermarket ECU.... how are you monitoring airflow? most likely ill be using the haltec for management.

also, i had a question (slightly of topic) about the 20b throttle body. does anyone know if it is the same as the 13b cosmo TB? i recently saw a picture of the 13b version and it is TINYYY! if the butterflys are the same size for the 20b, as the cosmo 13b ill most definatly be swaping in my spare FD TB.

thanks alot guys! the 20b section has been an invaluable source of info while i have been struggling with this conversion so, much thanks to everyone... your help has been greatly appriciated! the motor should be going in the car quite soon (although "soon" is quite relative ), and then the task ok building intake piping starts.... after that its all wiring/programing the computer which i have a feeling will be the most arduous task of all (especially considering my lack of knowledge ). anyway, thanks once again. -heath

 

MAP sensors are cheaper and easier to make than AFM's.

20B Cosmo parts are almost always exclusive and not shared with the 13B Cosmo versions.

I can't comment on the Cosmo use of the boost sensor, but the FC3S uses the boost sensor for ignition retard under boost.
Since the Cosmo came out about the same time as the FC3S, I suspect this is the case also.


-Ted

 

thanks REted.

does anyone else have any answers to the previously posted questions? thanks

 

So which is better MAF , MAP or AFM ?

 

It can be argued either way as there are pros and cons to each system. I'm using a MAP sensor on my 20B.

 

Speed-Density would probably be easier because that is the system used by nearly every aftermarket EMS on the market. MAF (or AFM) is nice because it will somewhat compensate for engine wear, but a budget MAF (or AFM) system will probably require the use of the stock Cosmo EMS or stock EMS from a 6-cylinder engine, which probably isn't the best route to take, even with a piggyback computer.

Both can use the TPS, but it's mostly for determining acceleration enrichment. The type of system that uses TPS as a primary load function is called Alpha-N. This article gives a basic overview:
http://www.carecstasy.com/index.htm?Technical/Efi.htm

I think it would be easiest to use MAP, and it would work well with a force-inducted engine. I'm not sure if it's worth the time and trouble to run the 20B with the stock AFM and EMS, but that is certainly an option. I don't know of anybody who has ever successfully run a 20B engine via MAF.