QSVeilside

What temperatures are you folks getting at stock, supercharged, and smaller supercharger pulleys? Please include the location of sensor installed.

I did a search only to find that Gadget was running 1400 to 1450, which is well above the general 1200 deg gauge. I believe he installed it in the headers, which would explain the higher temp.

Anyone install an EGT sensor near the O2 sensor? Please speak up with your numbers. We should have a baseline to compare our temps to.

rimpainter.com

To properly obtain EGT's, you need to mount the probe 2" or so from the head. I tried to use the EGR block-off plate and my EGT's were only hitting 600 degrees. So, don't mount it by the 02 sensor(s), since they are way downstream of the EGR plate.

Maybe Mark (midiwall) will chime in. His EGT's range from 1000 to 1400 if I am not mistaken.

mt_goat

Those 1200 deg gauges are for diesel engines. My Isspro gauge goes to 1800 deg F.

midiwall

Hey that's me!


You're aiming to be 4-6" down the pipe from the exhaust port on the cylinder that's farthest from the fuel pump - that'll technically be the cylinder that will run the leanest, and lean = heat. On the 3.4L, that would be cylinder #1 (frontmost cylinder on the passenger side) but a lot of folks use #2 for convenience (frontmost cylinder on the driver side).

Gadget says 1450* is the top end before performance drops off due to heat cancelling out the kick. When I'm WOT at 8psi, I'm seeing 1425-1450*, andI can "easily" tune above and below that.

At idle I'm sitting at 600*, light acceleration around-town gets me at 1000*, under load (7% uphill grade at 40mph) sees about 1200*.




(Christian... you have a PM!)

QSVeilside

Hmmm... I'm not too sure if the 2000 model has an EGR. But thank you for the advice.

Looks like I might have to return this 1200 deg gauge. If memory serves me correctly, (it's been 5 years since I sold the beast), on my old 97 supra tt, I used to run temps of 480 idle to 800 with 19lbs of boost... but then again the probe was post turbo, ie. downpipe installation near the O2 sensor.

Thanks for the advice guys.

Any other numbers out there?

QSVeilside

Solid advice. Thanks Mark.

mt_goat

I've been getting some EGT numbers above 1450 F and closing in on 1500 F and was getting a little concerned not knowing for sure what the limit is before disaster, so after googling and searching I ran into this write-up that confirmed a suspicion I had about my EGT probe placement.
http://www.stevetek.com/R-EGTprobeLocation.html

My probe was placed here, mainly because I didn't want to try and weld up a hole in the stock double walled exhaust manifold;

But by placing it where it reads the combined temp of 3 cylinders it appears that my readings are higher than if the probe was just reading 1 cylinder. I hope that theory is right

Any input to that theory?

midiwall

Interesting... I don't have much input on the 3->1 theory being hotter or not, but the thing I've always understood is that the reason for the single-cylinder monitoring is 'cause you WANT to see what the temp is on JUST one cylinder since you're really not caring about the _exhaust_ temp as much as you're just using it as an indicator for what's going on in the cylinder. ya' know?

Also, the depth of the probe in the stream makes MUCH more of a difference than you'd expect. I could shift my temps by as much as 300* depending on how deep the probe was. I ended up adjusting it for the max temp at a given throttle setting, since again, you're looking to keep an eye out for worst case.

Physical temp wise... I was running around 1550* at WOT at the time I burned a valve. If you're pushing 1500* at a combination point in the exhaust stream, you might be okay, but I'd personally re-think not wanting to deal with the double-walled manifold.

mt_goat

Good point, I was trying for the middle of the pipe, is that where you found it the hottest?


I was wondering if you knew the EGT at the time you lost a valve, did it appear to be a melted valve?

midiwall

Yeup, that'll do it!


Nope... _burned_

(click for a larger *GASP!*)

(upper right valve in the leftmost cylinder)

The thought is that it got hot enough tio burn through the tempered edge on the valve. Once that happened, it exposed softer metal and basically just started burning. Keep in mind though that I drove the truck for about 3 1/2 months after the "poof!" before we tore it down. So the damage is worse that when it initially happened, but once you have a hole, you're done.

Two of the pistons were also pretty well torched, no holes, but definitely way too hot.

mt_goat

Mark is that the front most passinger side cyl? I guess that's the cyl you have your EGT probe huh? What kind of EGTs are you running now after your rebuild?

midiwall

Nope, front driver's side; Yeup that's where the probe was/is; and around 1250* at WOT.

mt_goat

Wow, you dropped your EGT 300 deg from before! What did you do that lowered it that much?

midiwall

Fun huh? I _think_ it's more about "why were they so high?" before the failure.

The general thought is that I was running too rich and not keeping enough of an eye on things with a wideband to really know what was going on. Running way rich can be just as damaging as running way lean. The burn will continue into the exhaust cycle, and/or you'll actually be blowing fire _in_ the exhaust.

I know I wasn't running lean. That would have been an act of modern science with the 370's in there.

mt_goat

I can see where a "fire breathing dragon effect" could cause higher EGTs but would that make the pistons and valves hotter too? What A/F are you running now at WOT?

midiwall

I think it was burning on the back-side of the valve... We're talking raw fuel out the exhaust.

I'm around 12-12.5:1...

mt_goat

Oh, are the smaller valves the exhaust valves? I was thinking the bigger valves were the exhaust. 12 huh.....I'm running richer than that at WOT.

midiwall

I think the larger ones _are_ the exhaust, which means I had fire burning during the intake cycle.

"hot"

A/FR at WOT is a weird science... I hear anything from 11.5-12.5. When Greedy and I got on a dyno a couple of months ago the tech was happy to see a flat 12.5 through the power band. When I went with him to another session (on a different dyno) the tech was looking for 12.0.

What _I_ do (which could mean that it's NOT right!) is to watch EGT at WOT. Add fuel to cool it off, take out fuel to heat it up. The target is said to be 1450* (that's a Gadget number which I've never seen anywhere else, so take it as you will). I haven't had the truck running well enough to do safe WOT tuning since the rebuild, hence my running it pretty cool right now. (well, as you've seen, it's not running much at all _right now_, but in concept...)

elnip

That is where I have mine on the #1 cylinder.
Consistent 1400-1475 at WOT depending on the load.

TC22RE

I know this thread is on the supercharged 3.4L but my custom turbod 22re runs EGT temps of about 1000 - 1200 crusing and 1350 - 1450 depending on how fast I really wanna go at WOT. Those peak numbers are with a 12.5:1 AFR once I hit boost from 1psi up through 15psi. My 2 cents.