increasing fuel

[zagarus]

Just wondering, since everyone says to get more power by increasing boost you need to also increase the fuel.  Well i was wondering if you can JUST raise the fuel a bit right now without changing boost or anything, and still get some power difference.  Any ideas?

[vwmike]

Just wondering, since everyone says to get more power by increasing boost you need to also increase the fuel.  Well i was wondering if you can JUST raise the fuel a bit right now without changing boost or anything, and still get some power difference.  Any ideas?

It's possible but you really ought to consider installing an EGT gauge if you don't already have one. EGT's somewhat vary by car especially because you never know what has been done to it in the past so there is the possibility that increasing fuel could cook the engine on a long grade.

[zagarus]

so many variables, damnit this is hard!!

[zagarus]

what about the pre combustion chamber?

[jtanguay]

what about the pre combustion chamber?

He is talking about pre-ignition.  In a diesel you dont need to be concerned with this because the fuel is injected at the precise time that it is combusted immediately, unlike a gas powered engine.

Pre-combustion chamber is just a little chamber where the diesel gets injected into first, and then expands from there to the main chamber, and has nothing to do with pre-ignition.

[zagarus]

so the egt sensor should be placed in te exhaust manifold?  anyone nearby know how to do it?  not yet though, i need money first.

[veeman]

>>so the egt sensor should be placed in te exhaust manifold?

That's where most people seem to put it, however, others  have put it "post turbo" as well.  

From what I've read here, those readings aren't as accurate and could be 100-200 degrees less than the actual readings in the EM that you're aiming to measure.

FWIW, the install isn't really hard.  I have the simple VDO gauge / kit from Summit and once the manifold was off (the engine was out anyway), it was relatively simple to drill the hole, install the bung and the wiring.  

Here's mine...



"Short" thermocouple installed...



Not sure you could do it with the manifold on the engine because of the angles involved as well as the danger of leaving chips in the EM which could hurt the turbo...

[935racer]

I would highly discourage the use of a VDO EGT gauge, they are the slowest responding I have ever seen, they never climb to what your actual max EGT is because they climb so slow. I have had good luck with autometer and I remember DVST8R had like an  ispro or something that actually was probably the quickest responding EGT I have ever seen.

[vwmike]

I'd have to concur. My VDO gauge sucks.

I wonder if there is a faster VDO gauge available though. It not, are the threads the same for any of the other EGT probes? I already have a hole in my exhaust manifold so I might as well use it.

[fspGTD]

The older VDO "cockpit" pyrometer I have in my GTD autocrosser is very quick reacting.  When I first tried it I used an "SS White" thermocouple however it was horribly slow.  It got way quicker after swapping in a VDO thermocouple.  I remember the tip of the SS White thermocouple was more blunt while the VDO thermocouple was tapered at the tip, that could have caused the quicker reaction.

More recently I installed a VDO "vision" pyrometer and VDO thermocouple setup on a different engine (the VNT Rabbit.)  The vision gauge has better optics than the cockpit, but it also has different circuitry driving the gauge needle (needs switched power and ground to function.)  It's hard to say if VDO might have screwed up the reaction time when they made this change, but it's possible.  For whatever reason the vision gauge setup is slower, although I wouldn't rule out that the true temps actually might take longer to come up on this particular engine due to it not having piston cooling oil jets.

[veeman]

Hmmm... well, I don't have anything to compare it to, but I have the older "cockpit" style VDO gauge that Jake's talking about.  It seemed to go the best with my rabbit truck's interior, the kit seemed well made and it was very reasonably priced.

Jake...(and others) how fast do the others react in comparison?  Is it like an oil pressure gauge needle that moves quickly when you increase the revs at idle?

My gauge seems to climb pretty well every morning when I drive up a giant two mile hill on the way to work.  I hope ithe gauge is seeing the max EGT my engine is seeing on that long climb.

[vwmike]

I have the cockpit series one. What thermocouple was it that improved the reaction time?

[malone]

I have two Autometer Pyrometer gauges, both came complete with thermocouples w/ tapered tips. Both kits are identical except that one gauge has a silver coloured face and the other's black.

The silver one was in my MK2 Jetta 1.6TD and it was extremely fast & smooth responding, just perfect. The black one on my MK3 1.6TD seems sticky (the needle will stay stuck for a few seconds, and then jump 100 degrees) and slow responding.

I recall that the MK3 1.6TD thermocouple was too cramped in the exhaust manifold. The tip of the thermocouple is pressed against the opposite wall inside the manifold. It made me uncomfortable at first but I ignored it.. guess I shouldn't have.

Thermocouple placement seems to be key as well.

[vwmike]

Mine actually doesn't hit on the opposite side of the manifold as there was just barely enough room where I drilled. I actually wanted it closer to the exhaust port but there was just no room.

[veeman]

You can see my TC in the pic up above... Tapered tip and doesn't touch the opposite wall.  Doesn't seem to exhibit any slow response or sticking.  Before when the timing was off, the needle would really spike quickly sometimes....made me glad to have the thing to begin with.