Cfm

[sdminus]

Is there a basic calculation that can be preformed to work out cfm.
Or does anybody know the CFM of the stock FD intercooler and pressure drop
cheers
scott

[sdminus]

Does anybody know the answer to this? or am I going to have to rely on No Pistons (again)

Scott

[Fish]

I think from memory its very difficult to calculate the cfm on a rotary. Due to the lack of interferance from valves and such.

It might be worth doing a search on RX7Club and NoPistons, but NoPistons have been having a couple of problems over the last couple of days. Such a great resource of information.

Fish

[sdminus]

Cheers mate, i\'ve posted it on there too so have to wait and see!

Yeah, No Pistons got hacked for some bizarre reason!

Cheers

Scott

[Carl]

Are you wanting to know the engine\'s CFM or the stock intercooler\'s CFM?
Regards
Carl

[sdminus]

The intercooler, reason being (scooby si beat me too it) deciding on intercooler situation and size or charge cooling - got various options

Cheers

Scott

[scooby_si]

on that subject any more with the V mount info, details etc Carl?
Cheers
Si

[zevans]

Originally posted by Fish
I think from memory its very difficult to calculate the cfm on a rotary. Due to the lack of interferance from valves and such.

It might be worth doing a search on RX7Club and NoPistons, but NoPistons have been having a couple of problems over the last couple of days. Such a great resource of information.

Fish

Off topic cos he\'s actually after the ICs CFM, but anyway...

Read somewhere the other day you can reckon on 90% of swept volume going through per cycle for a rotary, so that\'s 518cc per rev per rotor. I presume that\'s on a 6-porter standard port...

So at redline that\'s
= 7000 x 518
= 3,626,000 cc per minute
= 128 cubic feet

So, for two rotors that\'s 256 CFM.

If you\'re running 1 bar of boost that\'s twice as much air again... but for an intercooler does CFM refer to the equivalent amount of air at atmospheric, or does it refer to cubic feet of charge? 2 x 256 = 512 which seems the right sort of CFM number for 300ish horses looking at some turbo comparison charts I found on Google.

And is it 518cc per crank rev or rotor rev? I\'ve done it with crank revs here which doesn\'t feel right but the CFM seems to have come out right...

:confused:

[Carl]

In Naturally aspirated form the Mazda Rotary engine is able to go over 100% adaibetic efficiency.That means that it is able at certain revs and throttle being wide open to draw in more air than it\'s swept volume.
If the engine is turbo charged then it will do this even more so!
EG,if a turbo engine is running at around 1.2 bar over normal Barometric air pressure then the  engine can be roughly be reckoned to be taking in around about twice it\'s swept volume of .
These figures are VERY much a rough giude.
As to the stock FD intercooler,it is probably at it\'s limit at around 13-15 psi boost,from that point on it does not seem to be able to reduce the inlet temps down to a safe point. So say that the stock intercooler is probably able to accept about 1.7 times the volume of the engine at pretty well full power in a minute and you won\'t be far wrong.
Regards
Carl