the flyin' scotsman

Realise the engineers of the time were very cautious I'm curious as to the consensus on MAF screen revomal.

My car has 2 screens on the lower and upper side of the MAF.........given the altitude we are in (+3k ft) the car requires more air hence my thoughts as to depleting the screens. with keeping the stock air filter, housing and tubes in place what advantage could be gained?

Rich9928p

Advantage - nil to nothing. Disadvantage, big bit of bug gets on the hot wire, burns, ruins the MAF.

Mark

What Rich said!
I was just looking at one yesterday....

the flyin' scotsman

This time of the year we have a stone fly hatch commonly known as salmon flies............2.5 - 3.0 inches long................certainly don't want then sucked into the engine but have to wonder how they'd get passed the filter????

jpitman2

Watson reckons the screens are a big restriction at top end in MAFs. My argument is - If it can get through the air cleaner element it wont be stopped by those coarse screens....but people keep talking about finding large debris in the housing past the element..
jp 83 Euro S AT 49k

Tony

The one on the downwind side is point less IMHO...id keep the upwind side though. If you have stuff coming back up through your intake you have bigger problems!

John Speake

The screeens are intended to try and create a laminar airflow over the sensor element. They also will catch any large lunps that get past the airfilter - often because the engine airfilter element is not properly seated at the back, leaving a gap.

In the 928 the MAF is not the main restriction to airflow for maximum power. Removing one or both screeen will upset the airflow patterns through the MAF, this will change the fuelling in an unpredictable way. The system was mapped with the stock system.

the flyin' scotsman

Mixed opinions as usual............if there's little to be gained I'll leave the screens in place.

I was of the opinion that the screens were in situ to prevent 'debris' reaching the engine but as John has advised there are other design considerations.

Now that all being said I'll look for thoughts on providing the engine with more cool air........thx

cfc928gt

Last year at the 928OCIC in Wichita I ran my '89 GT on the dyno. I had removed my screens before hand thinking they had to be a restriction. When I put the top screen back on I gained 2 hp and 2 tq. While this could have been just a variance in runs it obviously shows the screens certainly don't hurt performance. I now have both screens back on.

Herr-Kuhn

I run aftermarket hotwires on the TTs...it is a Hitachi with no screens...no swallowed bugs yet either! I would say you have no advantage with removal whatsoever.

heinrich

I personally made about 7hp and 7ftlbs more without the screens, bringing me to 299hp/tq on a stock S4 after other airpath mods. However I returned the screens because I don't like the idea of that fine precious thread sitting there with no protection. Agreed, lower one is safe to delete.

cfc928gt

Nice numbers! What 'mods' to the intake did you make? Any exhaust mods?

heinrich

Thanks, I agree. To start, I had a very strong S4, it put down 287 with no mods. I added Mike Schmidt's einholer airbox which smooths the airflow, which got me to I think 293. Removing the screens got me 299. At this point I am not so interested in all that, because all you need is a supercharger to slam an additional 100 horses down onto the rollers.