Do your Coolant temps and AIT's a favor
 

Plug the exhaust port passages in your housings. I know there are a few 2nd gen owners in the middle of rebuilds now so I thought I'd post this here as well.

Recently I rebuilt a motor and the ONLY thing that I changed, aside from the seals and the housings, was to plug the exhaust port passages in the housings. In my case, they were RE housings and have a HUGE port with an insert in them. I first tried tapping the insert for 1/4" NPT but the insert started spinning. So I drove that out and tried for 3/8" NPT. No dice as the housing would have to be machined. Instead what I ended up doing was taking my plate of 3/8" 5052 aluminum and cutting out something that resembled a circle of about .6". Then I spent a fair amount of time hand fitting it to .550" with a slight taper in it. I then drove that mother into the passage blocking all the exhaust gas from making it's way through the housing, into the LIM which, obviously, has the ACV & EGR passages blocked. I was quite proud of those little pieces. Here they lay

http://rotarycarclub.com/rotary_foru...1&d=1245729971

So, what was the result? Sadly I cannot speak intelligently on the AIT's as I'm measuring them pre-TB. Coolant temps however......... mine are retarded to begin with, generally they were around 174-175* on the highway and never getting above 187*. They are consistantly ~4* colder and the ambient temp has risen about 10* on average. All that from blocking the little f'n port underneath the exhaust sleeves. I will NEVER build another motor with these things left open.

Good stuff :icon_tup:. Thanks for sharing, I'll definitely keep it in mind when I do my monster motor build (assuming we're still driving cars by that time)

i'm sorry i don't think i'm completely understanding this from the image shown. Did you block the COOLANT passages around the exhaust port? ...cuz i'm currently in the middle of a rebuild. and always interesed in lowering coolant temps lol

wait, okay that was a stupid question lol. i think i see what you did there. Is it possible to post another pic to clarify? i'll have to take a look at my housings i guess

Im not getting it. Could you elaborate on this a little more?

Sorry, no more pics. I thought that one would explain everything that needs to be explained.

If you dissassemble an engine and look at the irons and the housings you will see a few passageways that allow extremely hot exhaust gasses to move to other places of the motor besides the exhaust/turbo mani. The passageways lead to the LIM where they enter the LIM enroute to the ACV. Most people have long since removed thier ACV so sending hot exhaust gasses to it does nothing beneficial. All it does is heat the LIM and the charge air as well.

While getting to the LIM the exhaust gas is confined in the housings and irons and transfering exhaust gas heat to these pieces which is being absorbed into the material and also heating the coolant more.

By plugging that little passageway you are preventing the exhaust gas from going anywhere but out the exhaust sleeve where it belongs.

Make sense?

I just took some pics of what your talking about.
The rotor housing here is from an s5 na.
I took out the sleeve.

http://i184.photobucket.com/albums/x...h/DSC02956.jpg
The sleeve has two small holes, one of them hidden in the picture but on the other side of that one hole.
And the exhaust port has a hole that leads to a chamber in the housing, this hole is hidden under the sleeve, also notice the two small holes under the exhaust port.
Picture of the "chamber":
http://i184.photobucket.com/albums/x...h/DSC02958.jpg

I guess that "chamber" leads to a passage way in the irons which end up in the avc / lim.
Basically you have hot exhaust gases running through your engine along side the coolant passageways.

Thats not cool.

pun intended?:)

An added benefit that is not mentioned yet is that isolating the exhaust gases to be away from coolant passages such as these you actually allow more exhaust gas energy to transfer out of the engine completely. What this means is that your turbo will then benefit and decrease the amount of temperatures your metal sees at all operating conditions. Combine this with the knowledge that the 13B is already able to transfer more energy to a turbo charger than most other engines are able to dream of, we are able to raise the bar just a little bit.

Summary: Coolant Temps go down, AIT's go down, Spool time goes down, More heat rejected through efficient means and further able to be used down the exhaust stream (another turbo if you wanted).

I doubt this makes a significant difference.
I'd be surprised you get 1hp out of the whole ordeal.


-Ted

I wouldn't imagine HP would be measurable at all, but allowing the exhaust gases to travel to the turbine directly and not get rejected through the cooling system will increase spool response, also increasing the temperature and pressure differential of the turbine. Though as you said I doubt it would be significant if at all.

I see now.

Makes a lot more sense now, thanks!

It's a shame teddy put me on his ignore list for disagreeing with him. He might have learned something. Such as my logged 4* DECREASE in coolant temps..... which, btw, were down to 168* this morning on the cold drive out to PA

Yeah, and if you cannot comprehend what I just said...
I claimed that HORSEPOWER GAIN (or loss) is going to be insignificant.
Your minor change in temperature can be also due to other factors...hell, I bet the sensor deviation is within those ranges.

Besides, you just plugged up ONE way the exhaust gets through to the intake manifold.
You do realize that the exhaust gases still get around the exhaust sleeve by the leading edge, right?
Mazda designed the EGR system to be like that.

You're might be onto something significant, but don't pat yourself in the back too much yet...


-Ted