There are plenty of way to get fresh airflow over the K&N, even when the filter is left open. I worked with DSMs for years, and the difference between an open K&N and stock aircan at 40mph was less than 10 degrees. That's not dramatic. In traffic, yea, it was pretty high. But I don't drive my turbo cars back and forth to work, so I don't worry about it.

Fuel cut is a pretty generic program. Just like on other MAF vehicles, it cuts all fuel. The motor in a DSM actually dies, then is re-fired by the jumpstart of your forward motion. I haven't hit it in my T2 yet, but I imagine it's about the same feeling.

 

In my testing of the air being sucked into an exposed pod filter, the only time you could get the air temp to within 10deg of ambient was at a high-speed, low-load cruise. Driving around in normal traffic saw much higher temps, and every time I stopped they rose further still. Temps would also start to get quite high when driving the car hard, even at when at speed. This is because all the extra heat the engine is producing is being rejected by the radiator into the engine bay.

 

What I meant was: A new top that provides a shorter/better route for cold air to get to a K&N flat filter installed into the stock bottom portion of the air box.

The article recommended 350-400 square cm's, a stock filter has an area of 500 square cm's. I don't think that the filter is the culprit in this problem

 

I think it depends on the configuration of the engine bay, the hp level of the engine, and where the filter is placed. I helped a friend test his Sport fitted with a K&N filter on the end of a tube intake, and it only showed an increase in intake temperatures at a stop. Once the vehicle exceeded about 30mph, the intake air was more or less the same temperature as ambient. The intake air temperature rose almost instantly every time the vehicle came to a stop, which was much more dynamic than I had expected.

 

That's good in theory, but how would you do it in an RX-7? The reason the FC's airbox has a squashed oval intake duct is because that's what fits in the engine bay. How are you going to get a 3" (or preferably 4") duct up to and into the top of the airbox? Most airboxes are much deeper than ours, and have the inlet on the bottom half of the box, which makes this idea much easier to do.

True, but engine power will only be a factor under load. An engine idling or cruising produces the same amount of heat whether it's stock or highly modded.
Amazing isn't it? What many don't realise is that if you sit stationary for a bit (traffic lights, staging lane) and then accelerate away at full noise, without a proper cold air intake you're sucking in very hot air. Not only will be missing a big chunk of power, but an engine that doesn't detonate under normal circumstances might ping it's head off when sucking in 150degF air.

 

something i noticed...when i recently took out my drop in k&n filter, i noticed that only the far passenger half of the filter was dirty. so pretty much only half of the filter is getting air?

 

It's not that half the filter isn't getting air, it's just that the turbulence and flow patterns within the airbox are causing more air to pass through one side than the other.

Out of curiosity, do you remember which side?

 

yeh, mine too, the side away from the stock inlet...I just turn it 180* and let the other side get dirty for a while...

 

yah, same thing i just noticed today....the outter side of the filter is dirty

 

Makes sense- you wouldn't think the air would take a hard 90* turn as soon as it entered the airbox...The system would probably flow better if the AFM intake was on the far side of the box, vs. the near side...

 

Yeah, it probably would. Because the inlet and exit are both at one end of the box, a large chuck of the air is travelling across the top of the box, passing through the filter at the other end as it turns though 180deg, and then travelling back along the bottom of the box to the exit.

 

Go hit fuel cut a few times then come back and tell us when you're getting a rebuild. Don't be so naive!

Guys OPEN your FREAKING eyes, that's an FC box.......the dates are clearly a typing error.

 

I have, and she's still running just fine.

If we're so naive, share your knowledge. Why exactly do you think fuel cut is going to blow a motor? Keep in mind this is the same technique most car manufacturers use to limit boost in factory turbos cars, and is a function available on most aftermarket EMS's...