von

No need for ball bearing turbos at the time
They didnt know the PDs were going to fail
Headers would be to loud
Cone filter changes emisions slightly and loses low torque and gives an unecessary growling sound and sub zero is good for really cold climate and emisions


I really dont see why they didnt enlargen the ports just a tad and then smoothed them out and port matched them. Im guessing just way to much money.
LOL. Man that lower manifold was sure a shity *** cut.

OH heres an important one. Why the hell didnt they use those pineapple racing 6th port sleeves from the factory.
DOYYYYYYY

von

I bet they could have made a 180hp engine from the factory if they did this and also used one cat istead of 3 then leaned the engine out just a notch. Speaking of N/As of course

dre_2ooo

HAHAHHAHhaha! Good one!

I live in THE cold climate state and let me tell you. 2 winters w/o that crappy cold start POS and the car has fired up w/o a hitch EVERY time (I also did have it on for half a winter and it made no difference).

Oh yeah, wasn't there a service bulliten up on it saying it was useless or something?

von

No dre its for emisions during cold weather. It takes longer to heat up the cats to start efectively working wich is why the cold start is thier. I would take it off. Saves engine life.

silverrotor

iTrader: (1)

Not sure what you mean when you say "It takes longer to heat up the cats to start efectively working wich is why the cold start is thier".

BDoty311

The cats filter exhaust gases and for them to work they need to be hot. So if its 20 degrees outside it takes alittle longer to get them warmed up.

silverrotor

iTrader: (1)

Yes, I know that about the cats. But how Is the above applied to the cold start being their (sub zero start apparatus)?

von

Comon now. Its obvious. They want to save the enviornment so the cats have to be working as fast as possible. To do that you have to get the engine warm as fast as possible to do that you have to rev it pretty high. to do that you need the cold start. Im sure it was for something else to like I dont know but you never know

dre_2ooo

Von, the sub-zero system has NOTHING to do with warming the cats. I think you're thinking of the accelerated warm-up system (AWS).

That revs the bitch up to like 3k when you start it to get the cats ready.


The POS sub-zero system injects straight (not 50/50) coolant into the intake to "help" the engine start better when it's below freezing as ambient temp. IT is useless though.

*OK, NO MORE, let's try and keep this thread topic the same as it started out as *

silverrotor

iTrader: (1)

Thanks for finally having my question answered correctly

Ichiban

i am fully confused

mazdaspeed7

The sub zero assist and cold start assist are two completely seperate things.

Sub zero assist - It injects pure antifreeze into the intak emanifold during starting if the temp is below a certain point. It was designed to keep the intake from ingesting ice that may be inside the intake manifold by melting it with antifreeze. Mazda put out a TSB saying it was pretty much useless, and should be removed.

Cold start assist - increases the idle speed during engine warm up to heat up the engine and cats quicker.

silverrotor

iTrader: (1)

So than how Is It bad for your engine (anti-freeze), Inspite of the TSB?

I mean, all the motor will do Is combust It.

mazdaspeed7

Nobody ever said it was bad for your engine. But obviously mazda decided that it didnt do much, if any, good, and issued a TSB to remove it.

silverrotor

iTrader: (1)

Hey mazdaspeed7, I removed the Sub-zero assist (valve and resevoir) this weekend for Its apparent Irrelevance and Its weight this weekend and actually feel good that I did.

BDoty311

I just did this to my s4 n/a and it is definately worth it!! You can actually feel an increase in power and mine sounds really mean now. I also found out exactly what my 5th and 6th ports are and then I found out they arent working. They have been stuck open ever since i got the car. Well today my dad went to the junkyard and is hopefully coming back with some working parts.

Martyn

I have this done by my 86-88N/A. Unfortunatelly, I have completed the car with the manifolds allready ported so I cannot compare, but it goes nice :-))). Theoretically, by N/A the effect should be much smaller then by turbo.

Martyn

-----------------
..I also found out exactly what my 5th and 6th ports are and then I found out they arent working...
-----------------

i had the same problem, we simply removed the plates and the axes and blocked the holes :-)))

dre_2ooo

Actually, the gains on an N/A (S5 anyways) are higher than you'd expect.

Mazda reported ~1psi positive manifold pressure with the VDI system.. now tuning these ports and enlarging them can easily add our "boost creep" in excess of 2psi!

I'd say the gains are worth the day of labor and $25 or less in parts

spooledUP7

If you are going to make a claim like that, prove it. Put on a boost gauge and break out the digital, because I think you are full of high hopes.

von

I used about 50 bucks in 60 grit sanding drums for my 35,000 rpm dremel that costed 50 bucks. The porting was fun and a learning expierience as well. It nearly killed my dremel though.

I did Mild to agressive porting on my S5 engine. I will report the resolts her when I test drive it this week. I also modified my Pineapple sleeves by cutting them in half right where the insert goes. Then I dremeld the corners to an edge to help flow coming in. Its like mazdaspeed7s nylon inserts only with the sleeves now. Very nice.

silverrotor

iTrader: (1)

I'll be porting my Manifolds this weekend. I think my puny Dremel Is the best tool suited for this application. I'll try to remember to take some pics...

I'm likely to gasket match my ports on my S4. Not sure If I am going to go deeper. Will have to see.

Anyway, the bits I will be using are made of Silicon Carbide. Made for plenty of grinding time.

silverrotor

iTrader: (1)

l

silverrotor

iTrader: (1)

And for fine grinding Iwill be using Dremel #84922