what difference does that make to the temperature of the exhaust gas that you are monitoring?

 

Why don't our trucks come with a pyro stock, because at the stock hp there is no need. for most stock semi's there is no real need for a pyro, so it doesn't matter where it is at (pre or post). Add enough fuel to double the hp of that same truck and there is a big need for a pyro, also a need to accurately monitor egt's, which means pre-turbo

Randy

 

Cummins, you know the maker of our engines, strongly recomends that the probe is POST turbo. Reason enough for me.......

 

I don't know how much horsepower or torque mine is developing but I have the pyro in the pacbrake pre tapped fitting and have put over 10000 miles on it mostly pulling the 5'rs. I don't run over 1000*. My understanding is the danger begins in running over 1250* at the cylinder for any length of time.

 

so take your post turbo temp of 1000* and add atleast 300* to get pre-turbo and it puts you @ 1300*.

 

Charlie8301, I agree that the temp would be 1300*.
I should have been more clear. I don't let it run at 1000* for any time.
It only got that high when the turbo hose was leaking and max boost was 11# at 2500 rpm, mine usually runs about 550-650*.

 

You can add at least 300 but in some cases it can be over 500. I ran pre and post pyros for about a year and trust me, there is a huge difference during various traffic/towing/play conditions.

On one local hill here in my town, i can comfortable pull it in 6th gear at 850-900 post turbo. The truck is just motoring along with out a whimper. Except at that same post turbo temp, the truck is running 1400 pre turbo. That's a very toasty 500 degree difference on a 1 1/2 mile hill!!!! A gear change down to 5th brought the temps down to acceptable but I wouldn't have known or even thought of downshifting if I didn't have the pre turbo pyro.

You can use the add 300 degrees rule of thumb, I did for some time and never thought anything of it until I put in the pre turbo pyro. I don't recommend post turbo at all.

The choice of location is entirely up to you where it goes. Drilling for pre turbo is minor and could save you some serious damage.

Jeff

 

look guys all I'm saying is this, on stock or slightly modified trucks, post-turbo readings might be acceptable, but on higher hp engines egt's need to be monitored more accurately which means pre-turbo

Randy

 

...the difference here is that 99% of the idiots here have take a perfectly good truck and tweeked and twisted it's output making it able to expand the pistons beyond the cylinder wall spec. You either have your pyro probe in the manifold (monitoring the rear three) or you have it wrong. Being i'm an idiot myself I'm quite sure I could lug my truck pulling my trailer with my mild mods and melt my #6 and prove my point......nahhhhhh .

 

You obviuosly have not driven a semi. If you think that an owner/ operator is happy with the power given you really don't know what you are talking about.
Not only that, a semi is pulling alot more weight for alot longer of a period, such as a mountain pull. Egt's on a semi in a hard pull if not driven properly can go through the roof, even at advertised hp.

 

Well said. I'm willing to take a very slight risk for the sake of much increased accuracy.

And I'd rather buy a replacement turbo, than rebuild and engine with a melted piston.

And what we do is not exactly comperable to a class 8 truck, or any other stock applacation either.

 

I have been wondering where I should run my pyro probe also. I asked alot of people what they think, and many told me pre-turbo, but all the guys who drive or work on semi's told me to run the probe post-turbo. One guy told me to just add 300 degree's because of the amount of heat energy it takes to spin the turbo would lower the exhuast temputer 300 degree's, which makes sense, but what about those of us who are have larger turbos on our CTD's? I switched to a PS 62, so if I ran my probe post turbo, would I back off at a lower temp as compared to my stock turbo? Am I making any sense, or am I just thinkin to hard about this?

 

sorry to stir the pot.
anyway, I would not advise this but I have seen 1400 post turbo on 2 occasions. so I guess I was at 1700 degrees well My engine has 291K miles on it and still going.
about 8 months ago I started slipping my clutch on the dyno at 1700 RPM I was at 329HP and 948 Torque. If I could reach peak HP and torque I should be near 400 and 1050. All with a first gen, distributor pump engine.
I just think drilling the manifold is a bit over rated and you should get to know your truck and know its limitations.
HMM, that was a "Dirty Harry" line, " A man has got to know his limitations"
If the pyro is reading to high, I guess its time for bigger turbo, maybe bigger air charge cooler, or less fuel.
Its all in good fun!

 

be careful what you assume, I drive a semi almost daily, '93 international with a n14 cummins, and guess what, no pyro.

 

There have been people that have run pre and post pyro's at the same time, and the difference is not always 300* sometimes it is drastically more.

Post is better than no pyro, but on a modded truck pre is the way to go. Drilling and tapping the manifold is not really a big deal. And that is where the higher temps are.