Awesome - would love to have tried some ideas on that myself . In some ways it's a pity you have so many other mods and could not explore this in isolation .

 

I still think four exhaust ports is the way to go, but the idea of welding the divider to the exhaust manifold is a great, but not new I believe, idea. Didn't we see that on an early NA header by somebody?

Hope you don't mind me nabbing your "removed sleeve" pic from your album.




edit: uploaded my center insert pic from renny #1 at 86K mileage all NA attached

 

Yes - but not with the sleeve removed .

 

So all the sleeves are only meant to retain heat for emissions only?

 

Well - it has to help retain heat for spinning up the turbo and preventing too much heat from being picked up by the surrounding water .


If I was going to try something I think I'd leave the sleeve in and just remove the divider . Then weld material to the housing so as to create a radius that covers about 1/2 the port . I think the deflection of gases would be enough to prevent any damage to the opposite rotor .

 

The roles of the exhaust sleeves have definitely shifted since the days of the peripheral exhaust ports in the aluminum rotor housings. They definitely served as more of a thermal barrier to protect the aluminum and coolant temps but also served as a medium to transfer/retain heat for emissions. But now that the exhaust ports have been moved to the cast iron side housings, they serve more as a medium to retain and transfer the heat rather than to mainly protect the housings and coolant temps. It really does make a lot of sense. Plus they did include this concept in an official SAE paper. (Keep in mind though, I wouldn't do this without adding additional countermeasures such as larger more efficient (or additional) radiator, high flow water pump, etc.)

4.2. Retaining Heat of the Exhaust Gas
In order to retain heat of the exhaust gas from the
combustion chamber to the catalyst, two measures were
taken: The exhaust port has a stainless thin-walled
insert (made of heat resisting stainless alloy) and the
exhaust manifold has two layers of air layer for heat
insulation and small volume thin-wall inner tube. This
allows for the retention of exhaust gas heat from
combustion chamber to the catalyst. Because of the
heat retention, gas temperature at a catalyst upstream
could increase about 140 degree C in the USA LA-4
mode drive, improving catalyst’s conversion capability.
Fig. 24 shows structure of the exhaust port insert and
exhaust manifold.

 

/\I hear ya . But I have seen dynos of an NA renesis with headers on and the centre tube glows red hot . With a turbo it has to be even hotter than NA . Seems like you would want to keep that away from the coolant .

 

Yeah, very true...this video comes to mind when I think of it...just another reason why I'm going methanol...
http://www.youtube.com/watch?v=uO1782B6RZw

 

Another satisfied NRS customer

 

Really!? That's rad!
That car was a work of art, I heard they're already rebuilding and getting ready to take another stab at the record.
Btw-I sent you an email about some corner seals...

 

man where did you get that heat shield???

 

Talk to this guy...Elliot from turblown.net
aka "1Revvin7" here on the club.

 

No, that's not the point. It won't suddenly blow your engine, but blasting the side seal, corner seal, and rotor side is going to greatly shorten the effective engine life particularly on long duration WOT runs

 

You forgot the Figure 24

 

Agreed . I still think the deflection of gas idea might work as opposed to a full divider - least line of resistance and all that .....

 

Thanks man

 

iron or housing or manifold? don't you mean iron?

What about using the air injection ports as more exhaust area also?

 

Yes -Iron . Got my terminology screwed up there .

doubt that 1/2" hole will do a lot to help but who knows ....

 

well, there are three of them. Have a cutaway view of them?

can you drill them larger?

 

do you really want more area/volume in the exhaust? enlarging the pipes will drop the velocity.

the side port area is larger than the peripheral exhaust port. it is the duration of the port that has been reduced. makes me think more duration is the key to more exhaust flow.

 

Good way of looking at it, but again, it depends on application, in my case yes, I'm looking for as much reasonably attainable exhaust volume to help offset the the smaller duration. Better/more top-end flow, and probably still a "satisfactory" (to me) bottom-end and decent mid-range.

 

Actually, Figure 9 from the paper shows these better.

 

This is a great photo too, I do like Fig. 24 because it actually shows the function of the inserts acting as a medium to transfer heat to the exhaust manifold. Fig. 9 does give you a better overall idea of the inserts in general though.
Thx Nemesis.

 

There is no way that that insert isn't designed to lessen heat transfer to the iron and hense the coolant. That small air gap allows more heat to be expelled into the exhaust and evens out the instantaneous pulse temps that the iron and the opposite rotor would see if it wasn't there.

I can't see how there will be a viable option with that removed completely...

I wish someone had data for the flow volumes through the 2 exhaust ports...I would thingk more goes to the outside ports,,,and much less through the center ports.

 

You're right, its design is two-fold, to lessen heat transfer AND act as a medium to transfer heat to the manifold for "improving catalyst's conversion capability", but remember what I said earlier?
I agree that combustion gases are most likely taking the path of least resistance toward the outer ports as well because their overall volume (in the runner itself) is much larger, less restrictive. So the idea is to remove the restrictive center sleeve and just weld a plate to the center port of the exhaust manifold that protrudes into the center exhaust port so it now serves as the divider. The port now has much more volume and can now flow more of the overall combustion gases from the chamber.