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Engine Specific Info and Questions => IDI Engine => Topic started by: zagarus on December 13, 2005, 09:29:12 pm
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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?
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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.
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so many variables, damnit this is hard!!
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what about the pre combustion chamber?
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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.
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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.
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>>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...
(http://www.hostdub.com/albums/veeman_album07/em_probe2.jpg) (http://www.hostdub.com/veeman_album07:em_probe2)
"Short" thermocouple installed...
(http://www.hostdub.com/albums/veeman_album07/em_probe1.jpg) (http://www.hostdub.com/veeman_album07:em_probe1)
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...
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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.
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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.
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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.
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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.
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I have the cockpit series one. What thermocouple was it that improved the reaction time?
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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.
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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.
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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.
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The thermocouple tip from my quick reacting VDO setup:
(http://www.imagestation.com/picture/sraid197/pe5da32ffca64d4979bb35fa232fe5cbb/f10e1fd1.jpg)
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Where did you get that thermocouple?
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The older VDO "cockpit" pyrometer I have in my GTD autocrosser is very quick reacting.
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More recently I installed a VDO "vision" pyrometer and VDO thermocouple setup on a different engine (the VNT Rabbit.)
Jake, since you have easy access to both these vehicles, is there any chance you might experiment by swapping the fast-acting VDO "Cockpit" pyrometer in to attach to the thermocouple installed with the VDO "Vision" pyrometer? I assume both gauges can be connected to either thermocouple (maybe a false assumption - but it being Xmas and all, and hoping for gifts, I'd like to believe that even the Autometer pyro could connect to any existing VDO TC, too!).
Swapping the two VDO gauges would narrow down the issue as to whether the slowness of reaction time is in the gauge, or in the TC itself.
My own VDO thermocouple is mounted at one extreme end of the exhaust manifold, so it is only picking up temps from cylinder 4. I suppose it would have been better to mount it in the middle, immediately prior to the turbo, like you and Veeman have done. I expect that would give a better "averaging" of all 4 cylinder exhaust temps, but it's too late to change it now. (That's another reason I'd like to believe the Autometer gauge can connect to the VDO TC).
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Otis2: As I understand it, you can mix and match different brand thermocouples and gauges no problem. AFAIK all the ones used to measure automotive-application exhaust gas temperatures are all the same types and therefore are electrically compatible.
I could indeed temporarility swap the cockpit gauge into the VNT Rabbit to see if the gauges respond differently, but I probably won't get to it anytime soon since both pryometers setups are working adequately and I've got a lot of other projects on my plate that are higher in priority.
VWMike: I think bought the VDO thermocouple from Seattle speedometer several years aho, but I think they went out of business for a while now. I found a great VDO supplier/distributor in Seattle, Blanchard Auto Electric, that I get my VDO stuff from nowadays.