EGT guage install

[Mike Schmid]

I've read the VFAQs and the instructions, just curious how you guys have done it and how well it worked?  

It's an autometer one too, so 0-1600*.  I'm thinking I'll put it in #1 a little farther away than usual and call 1600 the danger point instead of 1700.  

Of the install methods which ones have you used successfully?  hole and clamp?  weld the bung on?

[Ryan Coft]

drill hole
tap hole
thread temp needle in
tighten nut

drink a beer

[Jovan Ceklaj]

I was under the impression that you should tap into the second runner.  The logic was that it will get hotter than number 1 because it has the radiated heat from cylinders 3 and 1 (as well as its own generated heat), while cylinder 1 only has the heat from number 2.  This may be wrong, but thats what I was told.  And if it is wrong, Andrew Scott has some serious explaining to do

Jovan

[Kevin Standeven]

what ryan said, but put it faaaar back in the runner.
I used the number one runner with an autometer guage, and cruising at 120km/h I'm right at 1600. I'm thinking about putting a tiny resistor in the EGT wire so it's not reading off the guage so often.

[Kimyee Lai]

Hey Jovan,
I don't think that theory is valid.  We are measuring exhaust gas temperatures here.  Radiated heat from a side runner will not have a chance to affect the gas temperature much.  Also remember that the gas is travelling VERY quickly.  Even if the runner has a water jacket around it I doubt the gas temperature will change significantly.

[Kevin Standeven]

Ah, didn't see Jovan's reply when I posted. I agree with Kimyee, number 1 would be the leanest and hottest; runners on either side would have little to no impact on the internal exhaust gas temperature.




http://www.stevetek.com/R-EGTprobeLocation.html

[Jovan Ceklaj]

Actually, what I was refering to was the actual cylinders, not the exhaust manifold.  I completely agree that the heat from the exhaust runners will have little to no effect on surrounding runners, but in the actual block, the second cylinder is surrounded by 2 other cylinders.  This, in turn, would radiate heat onto other cylinders.  That was the logic, but it doesn't matter.  Thanks for clarifying

Andrew, looks like you got your probe on the wrong runner

Jovan

[Mike Schmid]

Has anyone actually EGT'd each cylinder to see that #1 is in fact the leanest?  I'm not sure I agree with the theory that the fuel rail gets empty or loses pressure over it's length thus supplying the #1 injector with less fuel than the rest.  I dunno... I'm gonna put it in the #1 anyways.  

What I was asking about though was not EGT theory but the reliability of different install methods?  Like using the clamp seems kinda hokey pokey, but then if you drill and tap the manifold you deal with a close tolerance fit at high temperatures with dissimilar materials that have different expansion rates and that could cause alot of cracking and or corrosion in the manifold or sender.

[Gabriel Shim]

I have my EGT probe drilled in the exhaust manifold.  I can't see any cracks so far.  I've seen other ppl drill in the O2 housing or even in the downpipe.

[John Hartman]

I agree with Mike, I don't think that with a pump that can keep up, and no leaks, that there would be any of that leaning out on the drivers side.

I'd say that with a good pump and good pressure, that little fuel rail would fill just fine.

Of course this is where Lowell/Mike etc will provide empirical evidence to the contrary and I will shamefacedly retract my statement.

But until that time...

[Mike Schmid]

I know Buscher ran 10's on the stock fuel rail...

So if you can get that kind of HP out of the motor on a rail that's always running dry at the end of it... I dunno.

Gabriel, did you drill and tap?  or drill and clamp?

[Gabriel Shim]

drill and tap

[Kimyee Lai]

I know this is going somewhat OT again, but I can't stop...

The way I see it, since the cylinders are water cooler ANYWAY, you can probably assume that they are at pretty similar temperatures.  Again, even a 50 deg. C temp difference in the cylinder walls, relative to 1800-2000 deg. C combustion temperatures, for fractions of a second residence time will most likely not affect final exit temperature significantly, relative to temperature differences due to fuel mixture.

As for the fuel rail, physics dictate that when you have a flow through a pipe, there WILL be pressure drop across the pipe.  How much pressure drop depends on the speed of fluid flow, but it is inevitable that injector 1 will see lower pressure than injector 4.  Is that pressure difference significant?  It'll have to be calculated...

To a certain degree this is analogous to IC endtank/sheetmetal intake design.  The opposite to TB end of the sheet metal intake typically narrows down, in an attempt to maintain flow velocity into each cylinder.  You have similar dynamics at work with the fuel rail, but because of the much smaller flow rates and the denser fluid involved, the rail is a constant bore.

[Mike Schmid]

Yargh!  Who'd think we'd ever actually want Yves (pronounced: why-VES) around!?  Hahaha, inside joke, ask Jovan   :wink:  :laugh:

On a side note though too there is a pressure regulator bleeding off any pressure above x psi at the end of the rail, so injector 1 should never see less than the regulator's pressure.  I suppose that doesn't mean #4 couldn't see more than regulator pressure though...

Anyone ever flowmapped an intake manifold?  Seems to me that TB to cyl 4 corner is a tight one, might contribute to that cylinder running rich.  As well, the air might be flying in through the TB and piling up at the #1 side making that cylinder lean.  I suppose we need someone with some bench tests, computer models and a calculator, along with some really good fluid dynamics knowledge...

[Andrew Scott]

Andrew, looks like you got your probe on the wrong runner

eh? Lowell drilled and tapped the runner for me, I told him to do it on the one that would give me the best reading...