Dear forum,

I have been chasing down what's causing the extremely high rear rotor EGT. After one WOT pull, my front EGT max out around 860 C (~1580 F) while the rear can skyrocket to over 970 C (~1780 F). My engine tuner suggested it could be the Turblown IWG Turbo Manifold, where the rear exhaust runner has two 90 degree bends and hence more restriction. So far, I have found another REW-swapped RX-8 having the exact same issue: https://www.facebook.com/groups/3063...4214422719819/ https://www.facebook.com/groups/3063...0461739761752/

I'd like to know if there's others using this IWG turbo manifold and monitoring the EGTs, what numbers do we see, as I don't want to jump to the conclusion here. If anyone has more even EGTs, then I know for sure there's a mechanical or tuning related problem on my car.

My Setup:
- Street Ported 13B-REW by Lucky 7 Racing
- EFR 8474 IWG .92 A/R
- IGN-1A Smart Coils
- Full Function Engineering Hall-Effect Trigger Wheel
- Haltech Nexus R3
- ID1050X primary injectos, 1700X secondary injectors

So far I have tried:
- Replacing the ignition coils and wires.
- Swapping the front and rear EGT probes & Trying a new unit
- Swapping the front and rear injectors on both primary and secondary fuel rails
- Compressions are 101/102/95 psi Front, 97/97/90 psi Rear. Normalized to 250 RPM and standard atomsphere.

I am about to pull the spark plugs and trying new ones, just in case it's the rear leading plug causing it all. I'm open to suggestions. I know that Turblown is making a V2 IWG manifold that has larger rear runner diameter which seems to improve things a bit.

 

please post a picture of your LIM area and heat shielding

 

Pretty common, rear rotor is probably getting cooler denser air with slightly higher VE from straighter runners, resulting in leaner charge than front rotor with same fuelling. Fuel trim, heat shield turbine housing to reduce heating of front intake runners.

 

Broadly documented historically, and not discounting impact of Turblown V1 manifold design, but other contributing factors to rear rotor running hotter include:
- inherent temperature gradient across the engine due to coolant flow design (front to rear)
- factory intake manifolds don't distribute air evenly amongst the housings, with rear getting slightly more

 

Others I feel are spot on with their assumptions. I would try and isolate heat as best you can. I might also suggest you find an Xcessive or equal LIM to help balance flow better. Worse case you can add a few % fuel to see if that helps cool down the EGT.