I have a 1.8 turbo miata with begi-s kit non-intercooled 255lph HP walbro and RRFPR. I am running 1200 degrees while cruising on the hwy at about 70mph. What is everyone else running? I think i might be rich

 

I'm running a begi s5 with a t3/t4e and I see ~1300f on the highway at 70mph cruise (~10in of vacuum). I had to advance my timing to the 40s to get the egts that low, was ~1500f.

 

1350f at 4k cruise, 1600f at full load 7k rpm fourth gear

 

1350 at cruise, anything from 1400-1650 at full blast, depending on RPM.

 

pretty much the same here.

 

I guess I'm the odd man out. I'm also running a begi S5 with a t3/t4 and I see ~1000f on the highway at 70mph cruise (~10in of vacuum). The highest I've seen my EGTs ever is 1250f.

Would you care to explain now why is this?

 

That does seem unusually low. Like practically unattainable. Where's the probe located? Mine is right after the collector (tube header), just before the turbine flange. One thing to keep in mind is that EGTs are heavily influenced by many parts of the turbo system, not ONLY the ign timing and AF. And the lowest EGT is not necessarily the best. IMO the best way view your EGTs is after you've tuned the car. Remember what they are with a good tune and then know later if they've changed that something is up. No different than watching temps.

 

It sounds like he has it in the downpipe. Which is where mine will be. Read too many stories of people having the probe degrade and eat up turbine blades. I don't want/need anymore issues with this car. lol

 

The EGT probe(s) should be located as near the exhaust port as possible for accurate readings.
If you are going to install the probe on the backside of the turbo, you are not going to get accurate results. You might as well not bother with an EGT meter.

Tony

 

yeah ive heard its better to put the probe in pre-turbo but will it really make that much of a difference if its put in post-turbo?

I know it may be a little off but if you have a good tune your only checking to make sure the temps don't go crazy right?

 

I'm well aware of your first point, while it's also just as good to place the sensor as close as possible to the collector instead of the port so that you are getting a reading of each of the cylinder banks. I'd be more worried about the exhaust not flowing well enough out of the manifold and causing a problem rather than one cylinder leaning out. Proper fueling can cure that issue.
But plenty of members have stated that they utilize a post-turbo setup, and since I'll only be using my EGT gauge to monitor out-of-ordinary conditions, I'm none too concerned, and will bother with installing my EGT sensor.

 

Rotor is right. I have it in the downpipe; about 12 inches from the turbo. Most probably even less than 12".





This was also my way of thinking. I just needed a reference. I always use my AFR gauge to monitor everything. Let me give you an example: last week, my fuel filter was clogged and I was seeing my AFRs going way lean while in boost. In the meantime, my EGTs were reading similar values than before. I did see my EGTs raising to 1200 degrees.

 

I followed this procedure to a tee. I took the car to the Dyno and looked for changes in my EGTs after doing so. I also upped the boost from 8 to 12 psi and once again checked my EGTs. These went from 1000 degrees (at 8 psi) to around 1100 degrees (at 12 psi).

I feel that I have at least a reference to work with.

Thanks

 

Guaranteed to see much higher temps on the other side of the turbo.

Eric- the probe failures I've seen came from repeated exposure to excessive EGTs. The probe is supposed to be designed for that environment. But I suppose the only way to guarantee it won't see turbine blades is to put it on the other side. But like Tony said, I don't know how much that will tell you about combustion. Rafa would probably be the best reference. Rafa- what kind of EGT change do you see from the point of reaching boost target to redline? what about on the way to boost target?

 

I understand that they're made for it, it's just something that I'd rather not have eating away in the back of my mind. The car is my daily driver, and not having it running for this long has been a pain in the rear, I don't need or want to risk any more large issues that put it out of commission for extended periods of time.
Like I said, I'm not really trying to keep an eye on combustion with it, rather just want to use it for seeing something out of the ordinary. For tuning purposes I have an AEM WBo2.

 

I mean I imagine it would cool down at a certain rate on one side of the turbine to the other right? So where you put it doesnt matter as long as its in the normal range for that particular area.

Such as 1300 pre turbine = 1000 post turbine at cruise

and 1600 in boost = 1300 post turbine in boost?

Reason I am saying this is that I am planning to put mine in the downpipe.

 

how close do you think you should put the probe to the exhaust housing?

I have mine within 4 inches of the turbine housing and am reading 1200 degrees at cruising speeds (70mph with 10in vacuum). from what ive read i think that as long as you keep it close to the turbo even if its in the downpipe you should still be close to same temps as those that have it in the manifold.

 

I'll double check tomorrow but if I'm not mistaken: I see a change of about 150 degrees when I get to redline but that doesn't take place every time I go into boost. At least not as far as I can recall. I see those changes after going full wot a few times.

 

I'm gonna leave at as, use the EGT for personal reference on your turbo set up. If you have a good tune, make note of the egts and use those numbers for reference. Don't go comparing from one car to the next since there are a lot of variables that influence that number. And I would imagine that different turbos and manifolds have different impacts on post turbo numbers. My probe is about an inch from the turbine housing flange and about center up on the collector merge point.

The scientific thing to do is have 1/8" npt bungs both pre and post turbo and take measurements. Unfortunately I'm using the band clamp and ceramic gasket so I can't move mine without weld up a bung for a plug. Would make for an interesting comparison though.