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High EGT at cruise and WOT

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I would like some input on some high EGT readings I get on my car and some other cars I tune.

My set up, custom tubular manifold with a TD04H-13C, autometer egt at the forth runner near the block port.

I see 750-800C at cruise @ 30-40deg, at WOT I will get to a max of 900C and lift.

Turbo MX5 97

Another setup: cast iron manifold with a TD04H-15G, aem egt in the middle of the manifold before the turbo, cruise 750-800C,

EGT will reach 900C in wot at the current gear...

Turbo MX5 05 VVT

Another setup: ebay tubular manifold with T28, aem egt on the forth runner in the middle, cruise 750-800C, wot will reach 900C in one or two gears...

Turbo MX5 95

another turbo MX5 05 with a complete flying miata kit - run very cool egt...GT2560R.

Normal ? Something I can do ?


From my own experience the EGT values you're seeing aren't out of the ballpark from what I'd expect to see given your application.

Our turbocharged 86 on pump gas will see 750 C at cruise and 900 C at WOT/full boost. The EGT is very dependent on ignition timing and AFR though and particularly if you're turbocharging a naturally aspirated engine (as we have with our 86), you may be limited on how much advance you can use under full boost so that you stay away from knock. This will result in higher EGT than if you could safely tune the ignition to MBT.

The other aspect that will affect EGT is the turbine side of the turbocharger - A larger turbine housing/turbine wheel will present less back pressure and you'll generally see a drop in EGT as a result. As a rule I don't like to see EGT exceed around 950 C on pump gas, but you also need to understand that the EGT reading will be affected by the type of sensor you're using (exposed tip on encased tip), and the location in the exhaust system.

Thanks alot Andre,

What is the first thing I can do in order to try and lower EGT ? given the spark is advanced as it can be.

I tried and found out that at cruise I can lower the EGT by adding fuel... alot of fuel... if I tune cruise to be at 13-13.5 the EGT will be around 600-650, this is a very expensive coolant...

What do you think ?

I had the same exact values with my Mazda MX5 on cruise and under WOT. Maybe a little less on cruise.

Have in mind that I was using a Rotrex S/C without IC and the EGT sensor about 15cm from the exhaust port,cylinder No1.

On WOT while chasing top speed I had about 950° on my Zeitronix dash.

Stock engine and piggy back ECU. Just a bigger radiator and coolant reroute and a lower thermostat to keep heat soaking low.

I don't pay much attention in my EGT gauge because its a supplementary gauge and not a tuning tool.

If your AFR and advance numbers are right don't worry about.

Just stay away from track days especially on summer months.

As mention above bigger turbo will generate less heat.You say that with the Flyin Miata kit 2560 turbo.Less restrictive than 2554.

I really wouldn't be concerned with your cruise EGT - It's not a problem and you really want to run at stoich at cruise unless you hate fuel economy.

Under WOT then I'll assume you're knock limited and hence can't reach MBT. Anything that will allow you to advance the ignition towards MBT will help here - higher octane fuel, better intercooling, water/methanol injection etc. Even so, for a relatively restrictive turbo I wouldn't be surprised to see 900 deg C and I wouldn't be worried.

Hi There


I have this problem on Landcruiser100, with 4500cc PETROL engine (1FZFE)

Cruise about 750-800 Degree C / AFR: 14

WOT about 900 Degree C / AFR: 11.5-12

it causes Turbocharger failure after about 4000Km driving(Normal Driving), I need to go to long distance travel now I afraid to much


Diesel Turbocharger, Turbine AR: 0.86 ( I used it on V8 BMW before and worked well for long long time)

Precission 46mm Wastgate

Log Style Cast Iron Turbo Manifold

3" steel Complete Exhaust

Air/Water Intercooler (big and cool)

AEM Water Methanol

to have about 7.5PSI Boost

Hi Hemad, the temperatures you're experiencing are really not out of the norm for a performance turbocharger. A general rule of thumb is to ensure that the peak temperature doesn't exceed 950-1000 C. If you're using a diesel turbo then this might be an issue since diesel engines for the most part don't see temperatures like we will in a gasoline engine. The only way you're going to get heat out of the exhaust gas is to run richer, optimise the timing to MBT (assuming it isn't already), or reduce exhaust back pressure (it's possible the turbo is a little restrictive).

Thanks Andre

you say add fuel for cruise to 13.5 ? Is it ok or more fuel?(already is about 14)

attached pls see ignition and fuel table by AEM FIC6

Attached Files

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