cach22

Thanks for the feed back guys



the bog definatly won't hold the heat. I just used it to get the sort of shape i was thinking of to get some opinions. I would have to make up a sort of sleeve, to handle the heat. The difference with my setup compared to the sleeves discused on the rx7 forum, is that my port tunnel, runs in an upward motion rather than straight out. Im not sure how much of a benifit this would have but you would think it would have to help. Also i only used the D shape as that is what shape the housings i had used. I think the theory could be applied to any shape



I think for a turbo setup, you would do the usual port on the rotor housing, and have the port tunnel going in the upward direction, though have the tunnel expand in an outward motion along the length of the tunnel say on like a 3 - 5 degree angle on all sides for example. Though Not at the rapid rate the factory does. If that makes sence. In regards to the added EGT's would the addition of water injection help keep the egt's down. Also could the tune be changed to help lower the temps?



keep the feedback comming guys



cheers



Lance

fdracer

it'll definitely help port velocity, w/ minimal if any flow losses. the problem is the heat. not only do you need a sleeve to handle the heat, you need a manifold and turbine housing and wheel that can withstand it as well. wi won't help.

FrostRacing

would this in any way effect tq? It seems that having a slightly more restrictive exhaust creates more back pressure which in turn creates more tq



David

Jeff20B

Uh, backpressure is the devil. It always has been. You're porobably thinking of something else.

MPM

Backpressure is our enemy. Velocity is our friend.

FrostRacing

Yes i know this but wont the port make more back pressure or will it still flow the same

ArmyOfOne

How about removing the sleeves altogether and making an extension of the pipes at the flange that extends into the rotor housing? I have seen some pretty thick material pipe that I think would be up to the challenge. You could have this smaller diameter pipe feed into a larger one and then have the blowby from his pipe feed into the larger pipe on its way to the collector. Well it just sounds good enough for me so I'm gonna give it a shot. I'll have results in about a month.



BTW I'll post a drawing of what I mean later on tonight.



think thermal reactor... hint hint...

CypherNinja

Oh man, to anybody that hasn't, READ THE RX7CLUB ARTICLE. Its seriously worth it. Basically, the factory ports have the extremely rapid expansion in order to purposely induce tumble in the port. This helps reduce the temps and sound, but kills power. The ports which have a minimal area gain as they travel away from the rotor actually flow a fair amount more. The guy that did most of the work in that thread was saying like 30% more, without changing the shape of the port opening at all. But BEWARE! When you do this you will be unleashing the true nature of the rotary exhaust. Ceramic coatings and Inconel turbine wheels are your friends. But, as the author of the other thread said, turbo spool is un-freaking-believable. There is no loss of top end, simply huge across the board gains. The smoother higher velocity flow which is the cause of the reduced lag also means the engine will react more strongly to header tuning. This helps NA's and turbos alike.



Additionally, backpressure is the DEVIL! What started the whole backpressure = torque thing is header tuning. Tube diameter specifically. As you go down in diameter the velocity increases as well as (unfortunately) backpressure. The increased velocity helps scavenging and thus increases torque, but the backpressure does nothing but decrease power. The trick is to find a balance which yields the most. People prolly measured the increase in backpressure at some point and thought it was the cause, thus giving birth to an annoying urban legend that has never quite died.

cach22

ArmyOfOne: That is a good idea about making the manifold go into the acutually port, this way if the idea didn't work then you can allways fit a normal manifold back on. I think i understand where your comming from with the one pipe inside the other, though im not sure if there will be enough room in the port tunnel to fit it all in. Nice to see you want to give it a try. What sort of setup are you planning on trying it on?



CypherNinja: Have to agree the read on the rx7 thread is very impressive, and certainly worth the read. Good point about the back pressure etc. I have thrown this idea up on another forum we have in Australia, there has been so SAE papers submitted that have some details behind mazdas thoughts on the whole exhaust port design etc. And i have added some more details etc on there as well. Check it out at the follwoing link



ausrotary discusion



You might have to register to view it, but is worth it as there is heaps of other good info and stuff, on the rotor scene over here.



cheers



Lance

BigTurbo74

great info on both links. basically geared toward the higher spectrum of power goals but still very interesting. i wouldn't mind reading the rest of that article from the ausrotary thread...