Please explain a blow through MAF
 

And any benefits or problems etc etc

Cheers

Here is some info Pat sent me regarding the blow through set up:

"Main benefit of blow through is a more sensible metering of the air actually entering the engine. Think of turbo spool. When it pressurises the pipework, it is drawing in more air than the engine is consuming. Result is that the engine runs rich and with too little advance. Opposite can happen on lift off, worse on partial lift off! Forward airflow can stall through the meter but the engine could still be running at 1 bar of boost. I even have a PowerFC log showing this! 1 bar boost, no airflow, no fuel, sh1tloads of timing. Not a recipe for engine longevity.

By placing the meter closer to the throttle, a more representative reading of actual engine air consumption is obtained and such hickups don't tend to happen"

Banny

cool, so where in my set up would something like this go?

https://www.scoobynet.com/group-buys...nt-anyone.html

Hope this pic helps, taken from Neil's (eclipse motor bodies) car:

http://i258.photobucket.com/albums/h...ny_sti/maf.jpg

Banny

I see, so would i tbe best to have the IC pipe modified to accept it, relocating the maf would be easier on mine as the fmic runs the opposite way round to that one.

Ideally you want the MAF at the end of a straight section of IC pipework (for stable airflow over the MAF element) and as close to the inlet manifold as possible. In this position the MAF is also reading a much more accurate temp for the air entering the engine (turbo has compressed and heated, then intercooler has cooled again). From what I have been told, it is critical to run a good catch can setup on blow-thru, to make sure no oil makes it's way into the IC pipework and onto the MAF.

Id say a proper Group A oil separator would be better than a catch can. As STiFreak has stated. Its vitally important that no oil vapour is blown on the the MAF element.

Just keep the breathers away from the inlet pipework. If running a blow through MAF then really the only take off needed for the inlet pipework is for the ISCV. Also the dump valve must be place before the MAF, it needn't be recirculating anymore since if I understand this right, the dumped air hasn't been metered yet. In fact some people are running without a BOV, but I think I'm going to run one with a stiff spring, and VTA so that hot air isn't put back into the system.

Frayz, could you please explain how these are designed and how they differ from a catch can arrangement?

Group a breather has an internal baffle and a return to sump so the oil actually gets separated and is allowed to return to the engine. As opposed to just a catch can which doesnt actually trap the oil vapour, it just catches some of it and fills up.

lol, so you are hoping that all the oil in suspension ONLY falls out and gets returned, not he petro-fumes or any of the other shyte?
I think theres a reason why we all used to run the breathers to atmos, only the nasty scruteneer was worried about the oil slicks on the tarmac so we had to change.
I have seen the contents of my catch can and while its your car/your choice, no thanks :)

This style breather has been used on race cars for year swith no problems inc 99% of big power road/track cosworths. Ive used both setups and am more than happy with a return to sump separator setup.

I guess the likes of Bailey and RCM also must not know what theyre doing either ?? :confused:

Where do the gasses go though? (not what is caught) It isn't back to the inlet unless stated in the requlations. So vent to atmosphere, what you do with your caught oil / watervapour etc is up to you, but in terms of contaminating the MAF if you don't return to the inlet pipework then the MAF will never see any of what is in the catchcan.

Peanuts was refering to just running the breathers straight to atmos, no can. However if you do use a can you still breath to atmos, but the issue of what is done with the can contents is immaterial WRT the MAF :)