Just a curious question:

Can anyone explain what does a rat next actually does do other than suck HP from an engine? And is the rat nest just as invasive on a 13b as on a 12a?

Thanks!

 

It does a little more good on a 13B than a 12A. The By-Pass Air Valve Solenoids are part of the rats nest. So it has part of the system that keeps the idle smooth. I've also heard that removing the rats nest on a 13B doesn't gain any HP.

 

First of all the rat's nest doesn't "suck HP" unless it's not working properly. And that's a maintenance issue, not a design issue.

I'm no expert, but basically the nest is there to do two things:

1. Improve fuel economy

2. Reduce emissions

All in all, worth the cost of maintenance for a variety of reasons.

I removed my rat's nest for a summer a couple years ago.

The engine bay looked great without the rats but the idle and throttle progression were never as good as with the nest installed, no matter how much I tweaked the system.

I just plain didn't like the performance.

There was absolutely no HP gain, if anything power suffered, mainly due to the herky jerky throttle progression.

And the worst part was the 3-5 mpg drop in fuel economy.

At the end of the summer I put the nest back in and instantly got my mpg's and performance back.

In my experience, that's what the rat's nest does.

 

Subscribed!
This should be good.

 

The exact list of functions a rat's nest has differs from model to model, as do the number of solenoids.

In essence, the rat's nest is the primary interface (on some models there are other solenoid valves on the carb or other places, too) between the car's electrical control system and the vaccum-operated functions of the engine. It lets the switches, sensors, and ECU control vacuum-operated functions.

There's a detailed list of the function of each solenoid on the 'Emissions' sticker on the inside of the hood of your car.

Some are emissions related (like ACV control, or EGR if you have one) , some are driveability-related (like the decel system & idle compensation) One related to the Air Conditioning system...

Some of the tubing is there just to move vacuum from one side of the engine to the other without having to use long vac hoses which slow responsiveness and go bad. Both of the vacuum advance feeds go through the rats nest tubing, for example, even though neither of them get controlled by the solenoids.

It doesn't have just one function; it's just a convenient place to accumulate a bunch of plumbing, wiring, and controls close to where it's needed.


And besides that, properly pimped out, they add a lovely, calliope-like look to the top of an otherwise-plain engine:



Feels like a circus!

 

Very well put DD. And you make a good point, the rat's nest adds a bit of color under the hood.

Here's the nest in the Silver One, not as pretty as yours but it works great:

 

I ended up removing the rats nest on my old car when I was still running the stock motor mainly because it was broken. I was also running a RB exhaust so no air pump or cats.

 

divin and ray's explanations are right on. its just how mazda turns vacuum operated things on and off. since everything is vacuum operated, it doesn't take any power, that is a myth. everything on the rack is passive and works on cruise, idle or deceleration only

on a GSL-SE the solenoids are for the Leading vacuum advance, the Trailing vacuum advance, there are two for the idle control, and that's it. there are two solenoids for the Air control valve, but they are on the firewall. not very invasive is it?

 

 

oh and actually i put all the emissions equipment back on a turbo 2, that had had the vacuum rack removed back in the day, and it looks like spaghetti, there are hoses that just go back and forth, its a real mess, but it works.

so this is another reason to keep the rack, someday you might have to smog the car

 

Well, I consider myself educated! Then why do so many people get fired up about removing the rat's nest?

 

cause they don't know what it does either.... just look at how many "i removed my rats nest and now the car does (or doesn't) do ______" there are.

 

Also, they don't realize just how pretty those rats are when they're working right.

Here's some videos I took special for the occasion while I was out jumping the Jeep off the Silver One this evening:

http://www.youtube.com/watch?v=ZBLteGgmmsM

http://www.youtube.com/watch?v=zlgTnR-2UhA

http://www.youtube.com/watch?v=AE__oCTSNpw

 

Not to mention, if you **** off the rats, you lose 4 ratpower of total output.

 

I removed everything the rat's nest controls anyway, and it makes the engine bay look messy and increases the chance of vacuum leaks. So of course I wasn't going to keep it. Besides, this car will never take another emissions test. I'd turn it into a track-only car before I'd install emissions crap on it again.

 

Thank you !
Anyone that removes it and has problems did something wrong.
Going to mechanical secondaries is not included in removing the nest, contrary to some peoples repeated complaints of having had have had "problems" with gas mileage.
Cars prior to the early 70's had no need for all that crap. Do you think they put it on there for performance? Hey we gotta put a rats nest on this race car for performance.LOL.

It's starting to get good.

 

ROFFL at the ad down the bottom saying Rodent control solutuions!

 

The rast nest has to be removed if you go with an aftermarket carb. Thats the main
reason it should get pulled. Its almost required if you stay with a stock, unmodified
nikki (Rays case).

A lot of newbies think its cool to remove and do so without understanding the impact
on the other susystems in the engine like the carb or emissions. Then they complain
because it runs bad or has bad gas mileage. Like anything, a car is a collection of
dependent subsystems. If you rip one out you had better understand how to
deal with the impact on the other systems in the car.

I run all the mods in my sig and get basically the same MPG Ray does with my Dell.
Its not magic, its all about sorting the systems and making sure everything works
as it should.