skeeg

im researching and putting together a turbo setup, want to do it on my own not a kit, but ive been reading on the omp and pre-mixing.

from what i read, its a good idea and has been done on the rx7's for sometime now, but will put the rx8 into limp mode. ive searched if cobb unit can fix this, but only read that it can up the pressure of the unit not delete it all together.

so my question is, can the cobb unit with removed omp and running premix run correctly ie. limp mode.


if this has been answered and im too dumb to find it im sorry haha

skeeg

also i would like to add another question, on return style conversion. i kinda want to hit in the 400hp area, or just below and wondering if this is worth while. once again im not finding a single thing of tuning for it, or if its indeed needed only to run the return to the driver side of the tank.

im starting to think i may need a full stand alone unit, or am i just over killling for what i want vs need?

NgoRX8

iTrader: (1)

You cannot completely disconnect the OMP. The Cobb AP only adjusts the injection rate. The OMP has to be connected electrically. You can disconnect it from the engine but it needs to stay plugged in to the harness or you will get limp mode.

MazdaManiac

iTrader: (3)

https://www.rx8club.com/series-i-major-horsepower-upgrades-93/another-top-mount-setup-200371/
https://www.rx8club.com/mazdamaniac-183/cobb-accessport-discussion-140117/
https://www.rx8club.com/series-i-specific-performance-mods-97/my-new-install-project-176409/

skeeg

okay another haha... prob could search this one out easy but w.e....

ive owned 240's my whole life actually just swapped motor out today, but i ran a maf and ran it in the cold pipe about 15inch from intake and was able to run my BOV to atm without sutter or dying at idle.. is that not the same with the rx8 because i have yet to see a similar setup.

and thanks for the links, ive skimmed through them already but ill read into them a bit more.

skeeg

this omp thing is blowing my mind right now lol. i think i need to go look at this thing in person and see how it works, because reading is not helping haha

Beodude

iTrader: (3)

I would not disconnect the OMP completely. Due to the nature of a side exhaust port, your side seals see a lot more stress than in previous periphery exhausts.That's why they have the oil injectors on the sides.

If you remove the oil supply from the OMP and premix only, you will get side seal failure. Especially with increased heat loads from a turbo.

olddragger

iTrader: (3)

run the mop--if you dont the side seal springs will suffer. Pre mixing cannot lub that area well. Do not compare premixing the older style rotary engine to this one.
Read some more
MM trying to direct you.
OD

Beodude

iTrader: (3)

https://www.rx8club.com/series-i-tech-garage-22/possible-new-renesis-engine-failure-theory-210194/

Lots of good stuff in that thread.

MazdaManiac

iTrader: (3)

Any particular reason you threw a giant pic of 09Factor's OMP setup into the thread?

sauceyI986

i never never seen that pic.. before

skeeg

wasn't that big when i selected it haha.

i just need to look see and feel it and all, just blowing my mind how its in the glove box. is there any write ups of a relocation or block off, im triyng to find one to hopefully help me understand it more. i just need to see where it sits, what it looks like with it off, and the lines... honestly i just need to read and see more.

but on the fuel thing, any input... pros or cons to switching from return-less to returned? or the bov / maf location?

shaunv74

BHR (Walbro) fuel pump upgrade+larger injectors+CobbAP+recirculate BOV and you're done. There are a couple of great threads already with a bunch of guys that have turbo'd the car.

Search for boost overlords in the major hp upgrades section.

skeeg

i understand what i need, ive owned other cars with a turbo installed by my myself. just looking for more in depth info on a few parts, as its different then the ka24deT and sr20det's that ive worked on.

still curious on if u can run the maf in the cold pipe like i did with my ka-t setup. had it intake-maf-bov and had it run better and smoother then the maf in the intake. haven't seen it done on here from the builds ive looked over.

returnless fuel system for the car has seem to hold up fine judging other builds also so i spose i dont need to get into that for now.

also, just so i got this original omp questions figured out... when its removed, but still hooked up to keep the car happy, its a block off plate where the orig. location was? with this mod, i need to put 128/1 or so premix with every fill up.. did i get that right?

NgoRX8

iTrader: (1)

what do you mean maf in the cold pipe? all the piping before and after the compressor is considered 'cold side plumbing.'

skeeg

well, if im mistaken from the pictures ive seen they run the maf sensor in the intake piping before turbo inlet, with a recirculating bov config.

what ive done on my 240, is vent bov to atmosphere and have my maf between the throttle body and the bov, on the 240 its required to keep the maf about 12 inches from intake so taken into account it was like so

[intake throttle body]====maf====bov==={intercooler}========compressor

basically it allowed for the cool atmospheric type blow off and looks, while being able to run a shorter or no intake piping. it is known to me as a "blow through" setup, instead of the "suck through" theory is that it can read the latest air metering before entering the engine resulting in smoother and more responsive tuning.

NgoRX8

iTrader: (1)

If you use a standalone that is no problem, as most account for Pressure and don't really need the MAF.

If you do flash tuning such as with the Cobb, it is still possible. It is however harder to make work because of the turbulence in the piping. The MAF works best in laminar (smooth and uniform) flow. Also the MAF range must be altered and expanding it will affect the resolution in the low flow idle and cruise range. Not impossible, and done on a few 8s out there, but for most of us, draw through works plenty well.

I run draw (suck) through with bov vented to atm. No stalling, but easier backfires.