They should be able to build anything you want

Exhaust Components - SPD Home Page B

I would recommend 2" minimum ...

 

Great --thanks guys.
I considered making the transition to a 2 inch primary and while I THINK I understand why this engine doesnt follow a lot of the known header theory, I wasnt sure if the transition to the 2 inch primary pipe would be too big at the port? While we are at the port , the gasket size change and the difference between the port and primary tube size--just doesnt make sense?
I am trying to keep the transitions as smooth and bend free as possible so I also wasnt sure if the 2 inch primary tube would cause too steep of an angle at the collector? It seems to me that this system would be sensitive to that angle/ junction?
Maybe I will also need bigger than 3 inch exhaust--maybe 3.25? Isnt the 3 inch flow ( single exhaust) max at around the cfm of approx 335hp?
I have learned to listen. Project on hold while I do some more thinking. I want to do it the best I can the first time.

 

The only way to do it the best the first time is to copy someone else's suitably documented and proven system. However, unlike the n/a intake, the saving grace of the exhaust is that it's reasonably hard to completely screw things up.

If you've not done dyno runs to document your present situation, how will you tell if there's a change afterwards?

 

I have dynoed.

 

+1

 

decision made.
even though i think more power will be available with a true 2 inch primary pipe, I have decided to proceed with the 1.75 primary pipes (T 304 ss), flowing as smoothly as possible with the room available to a slip fit 3 inch collector ( thanks KMA!). I am extending the primary pipes by 12 inches. I will be removing one resonator from my Mazsport mid pipe to do so. I will be using a v band clamp for that junction. The transition pipe -- I still havent decided.
Appropiate shielding will be in place--no ceramic coatings or wrap will be used.
For now I will keep the RB catback and I do not have the oem chokepoint at the midpipe catback junction. The exhaust will be 3 inches.
This will be a system that others could easily make and not cost $2000.
Later I may decide to do a 2 inch primary with a 3inch collector to a 3.25 exhaust pipe size and a different catback. IDK for sure. It depends on Santa Claus.
As soon as I decide what to do with the transition--all parts will be ordered. I have a good welder on standby.

 

I don't want to know what happens when your family finds out your retirement fund suddenly became a 350rwhp rx8 OD.
Please mail me pics of the transitions, i'm curious!

 

will do!

 

No Problem OD.

You should do a direct comparison, same day, same dyno if possible.

 

OT but I had never seen this one before. A company called Tifaria in Japan makes it.

 

i dont like the collector on that one--but the pipes are pretty--probably dang good welds

 

all parts now ordered through Columbia --hopefully they will be here next week and the fabing can begin.

 

parts will be here in 7 days. I will be going with a straight pipe transition. best for a street car--I am told. 3inch collector --to 3 inch pipe.

 

I am still of the opinion that my design from page #9 should be tried to at least either directly prove or disprove it's merit. I gave up caring enough to try long ago though.

 

Page 9?

 

He probably has it setup as 25 posts per page, if you have it as 50 posts per page like I do it's on Page 5.

 

Ah, gotcha. Post #205.

 

Quick Link to the post: https://www.rx8club.com/aftermarket-...5/#post2574609

 

if the price is right with the shop im working with, i can try that setup..

 

A few posts down from the one with the pdf's CAD sketch, RG said that a couple of the dimensions were shown wrong. Best to clarify that with him before spending money.

 

it would be interesting but with no overlap I dont think you will see much if any percentage of a gain over a long tubed header.
My thoughts and they are just thoughts--so anyone can shoot holes in them at any point--are that the collector slows the velocity and this is delayed by a long tube header. There is also not as big on a difference in the exhaust velocity between the two areas as in a short tube header. The long tube cools the exhaust a little more and the gas has traveled further before it hits the collector so I am thinking it a slower ttransition of velocity changes.
Wave tuning/harmonics cant be totally ignored but I just dont see it having a profound affect.
If I had more room and since I am forced inducted I would go with at least a 2 inch primary long tube to a 3.5 collector--if i had the room without modifications.
This is interesting stuff.

 

Yes I did get the correct dimensions, thanks for the look out though.

 

ok starting soon--of course the o2 sensor will have to be placed on the side of the collector transition--no room for a top mount.
Does anyone know if anyone makes a front o2 sensor harness extension?
I would prefer to not cut wires and I rather not make one myself.

 

Try again ... if I have at least a semi-correct understanding of how this works, velocity is only important for inertial scavanging (wave tuning?). You get higher velocities at the cost of higher average backpressure. The garden hose is quite analogous here; put your thumb over the end and water velocity coming out increases, but so does the pressure in the hose and the gallons/minute, drops.

Inertial scavanging can reduce the pressure locally, at the time of exhaust port opening, but requires tuning for that condition. If you don't successfully tune for that condition, crimping down on exhaust pipe diameter (for more exhaust velocity), will only increase backpressure for no gain.

 

Intake and exhaust tuning by Smith