Sideways7

iTrader: (7)

I've looked around for a while, and can't find any real consensus on what is the max safe EGT. I've seen that 1600 is high, while other places say 1800-1900 is normal on a turbo rotary.
(to get to the real question, you can skip to the last paragraph.)

Now for the background - I have a S4 J-spec engine with a half bridge and a S5 BNR Stage IV with clipped p-trim wheel. Most of the time I am running wastegate pressure which is about 12 PSI. I also have RX-8 stat gears and external loop lines with a remote HP4 filter and adjustable oil pressure regulator. I have a E6X (and RA10 external reluctor adapter) with 550/1680 injectors and LS2 Truck coils. I have egt probes located in the both of the runners of the s5 stock manifold (pre-turbo). I also have an AEM methanol injection system using a D10 nozzle mounted in the TB elbow.

I previously blew a motor and thought it was because my exhaust temps spiked to 1700 due to my methanol controller failing, when previously with methanol they never saw higher than 1600. However, I just put my new motor together and even with methanol my temps would get over 1600 by 6k. I'm pretty sure this is because I previously had a s5 pulley hub so I could never get the timing right and had it backed off as a safety measure. Long story short, I discovered that my maps were jacked up and actually started reducing fuel above about 8 PSI, which is what caused my engine failure.

Now that I have everything sorted properly, I'd like to be able to drive the car without short shifting it. Do I need to worry about temps pushing past 1800? My AFRs are hovering around 9.5-10 due to the methanol. The only thing I'm unfamiliar with is timing, but from what I can tell it looks pretty good and on the conservative side.

Sideways7

iTrader: (7)

Oh yeah! I totally forgot about the intercooler. I know I'm going to catch some crap for this, but I'm running the top-mount stock intercooler. I know, I know, but my IAT never went above 100 on my logs. I know I will have to upgrade it before I really crank up the boost, but for the boost I'm running and the temps outside it does just fine. Additionally, I have a true cold air intake that is mounted next to the radiator where the washer bottle used to go.

Also, just for kicks I cranked up the boost to about 15-16 for a single pull (since it was in the 30's outside) and it barely made any difference to the EGT's. IAT peaked at 95.

j9fd3s

iTrader: (3)

i've put EGT on a couple of stock ecu rotaries, and stock the EGT won't go past 750c/1380f, Mazda needs to warranty the cat, and cats do not like too much heat.

i have heard that the stock apex seals have a limit of 1100c/2000f, and most JDM tuners seem to shoot for peak power around 900-950c, 1650-1750f.

if it was my car, i would start where the factory was, and then let it go to 850-900c, slowly.

timing is funny, the rotary doesn't want that much, especially compared to a piston engine, and has little effect on power, so it is easy to be greedy and run too much.

Sideways7

iTrader: (7)

After doing some more research, it turns out that my ignition timing was crazy conservative. I ended up advancing the timing some since it was down to about 4 degrees by 16 PSI. I think its at 15 with 4 split, but it pulls timing if the IAT gets above 100 so it takes it further back into the safety zone. From what I can tell, that's pretty safe when running water/meth.

Well, the engine loved it! The EGTs were lower and leveled out around 1650-1700 and it pulled even harder. After playing with it, I gradually increased boost up to the most it would run, which peaked at 17 and stabalized at 14. Before it would spin second, but now its occasionally spinning third once boost hits. Whats more, it was in the 70's outside, so my IATs where higher when all of this was happening.
I've looked it over and I added in a little fuel above 7 PSI and pulled some from 0-7 at higher RPMs since I was getting a rich stumble when feathering the throttle for corners. I just wrapped up smoothing the fuel curves out but its too late to take it (I don't want to make enemys with my neighbors!) so I'm going to see how it works in the morning.

So, does it look like I've done anything stupid? It feels pretty solid to me, but its also my first time doing a tune.

Sideways7

iTrader: (7)

After running it for a while and doing more research, I think my issue is that I am running a hybrid turbo on a half-bridgeported engine and it just has way too much backpressure. I'm running as much as 20 PSI of boost and the EGTs seam to peak at around 1750.

C. Ludwig

iTrader: (27)

That'll do it.