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Whats a safe EGT for our engines?
by
Powered by Spearco
on 03 Jun, 2011 23:02
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I'd like to know what EGT's you all are getting on a hard pull? I can reach 1200*F quickly and sustain 1400*F. Is that a safe range and for how long?
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#1
by
81 vw pu
on 04 Jun, 2011 05:46
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I'd like to know what EGT's you all are getting on a hard pull? I can reach 1200*F quickly and sustain 1400*F. Is that a safe range and for how long?
I try to limit my egt's to 1100-1200F since I run a NA block & head, but have stayed on the throttle to 1400F for a few seconds.
I think only the guys who have melted down their engines are going to have the answer. Better to be safe than to find max egt's.
Also in the Bentley it says compression temp can reach up to 900C/1650F and I've always wondered what role that plays on egt's.
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#2
by
vdubspeed
on 04 Jun, 2011 18:23
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my car...1.6NA with 98 TDI turbo, spearco intake, no intercooler, 1.5 turns on fuel screw, gov mod, fast acting k-type egt probe. Alarm is set at 1100. I can reach that FAST. On a WOT full pull I have seen 1500 but NEVER stay there for more than a second. It cools off instantly once I shift.
I thought about making an in car video to show the digital read out.
Also...no idea on how much boost I'm running. I'd like to run more boost/fuel but I need an intercooler first.
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#3
by
Powered by Spearco
on 04 Jun, 2011 18:28
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Yes I'm pre-turbo for my probe and its one from Aircraft spruce (1/8th in. NTP) gauge is correct and all valves seal tightly.
Definitely get a boost gauge.
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#4
by
DieselBalz
on 04 Jun, 2011 19:14
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I took the Eco over the Sunshine Skyway Bridge, in Tampa. Its the only real hill I have around here with a steep incline. I did it at about 10pm and the ambient temp was around 79-80F.
AC off, 5th gear keepin it at 60mph, boost spooling at 20 psi, 850F at the base, 1450F at the top. Threw it outta gear and let it coast down to cool down and the temps were under 800F by the time I got to the bottom Took 75 North home doing 65 the whole way and temps settled down to 850F. No issues. Did notice a difference in fuel consumption though.
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#5
by
vanagonturbo
on 04 Jun, 2011 20:46
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1700° is about the melt point.
coincidentally, I just did a run with a coworker in the rocco today to get some readings (gauges are not easy to see above the radio when watching the tach). I have an 8mm pump with everything screwed to the max. there is no more fuel available from this pump. 1k° @30psi. Kinda boring. Granted, the rocco is rather different than what we normally see here. The GTD hits about 14-1500 at WOT and climbs if i dont let off. The vanagon hits 1600 easily if I dont let off.
The differences in my vehicles are the downpipes. The rocco has a 3" DP and 2.5" full exhaust, the vanagon has a 2.5" dp and 2' of exhaust, and the GTD has a 2.5" dp with a full 2.5" exhaust.
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#6
by
Powered by Spearco
on 04 Jun, 2011 21:14
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Hmm. Very interesting info. So my 1400*F for the 3-5 seconds is ok.
I'm hoping that H2o/Meth will help with my numbers.
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#7
by
vanagonturbo
on 04 Jun, 2011 21:29
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what turbo are you running at 1400? I know I didnt mention what turbos are on my various cars. I tend to think the bigger the turbo, the more robust it is due to the larger area of metal to dissipate heat. tiny turbos melt faster
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#8
by
VW Smokr
on 05 Jun, 2011 15:14
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Listed melting point for inconel (turbocharger's turbine wheel and head's swirl cups) is 2540-2600° F, however, it can actually start to deform around 1600° F. Greater concern might even be re. effects of the even higher combustion "in-chamber" temps endured by the piston tops, rings, pre-cups, & valves, if the (just) pre-turbo EGT is showing 1300-1600° F. Seems that's pushing it a bit unless, of course, it's all in the name of 'research', with a corresponding budget.
OK, I'll admit to being conservative... can't stand buggering a good DD. YMMV
J.R.
SoCal
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#9
by
R.O.R-2.0
on 05 Jun, 2011 15:37
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Listed melting point for inconel (turbocharger's turbine wheel and head's swirl cups) is 2540-2600° F, however, it can actually start to deform around 1600° F. Greater concern might even be re. effects of the even higher combustion "in-chamber" temps endured by the piston tops, rings, pre-cups, & valves, if the (just) pre-turbo EGT is showing 1300-1600° F. Seems that's pushing it a bit unless, of course, it's all in the name of 'research', with a corresponding budget.
OK, I'll admit to being conservative... can't stand buggering a good DD. YMMV
J.R.
SoCal
aluminum melts at like 1344*f.. pistons are aluminum.. i wouldnt go any higher than 1500 for short bursts. like 1250* sustained i believe to be the agreed upon standard.
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#10
by
nathan_b
on 05 Jun, 2011 21:45
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Good point, but I would wager that pistons are not pure aluminum, or anyone with a lathe and a drill press would me making their own...
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#11
by
Powered by Spearco
on 05 Jun, 2011 22:02
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I'm using the Mercedes 300SD Garrett T3 45 trim.
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#12
by
R.O.R-2.0
on 06 Jun, 2011 09:49
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Listed melting point for inconel (turbocharger's turbine wheel and head's swirl cups) is 2540-2600° F, however, it can actually start to deform around 1600° F. Greater concern might even be re. effects of the even higher combustion "in-chamber" temps endured by the piston tops, rings, pre-cups, & valves, if the (just) pre-turbo EGT is showing 1300-1600° F. Seems that's pushing it a bit unless, of course, it's all in the name of 'research', with a corresponding budget.
OK, I'll admit to being conservative... can't stand buggering a good DD. YMMV
J.R.
SoCal
aluminum melts at like 1344*f.. pistons are aluminum.. i wouldnt go any higher than 1500 for short bursts. like 1250* sustained i believe to be the agreed upon standard.
well, i was talking about pure aluminum melting at 1344* pistons are made from aluminum that expands very little, and im sure has a high silicon content or something like that.. anyways, i bet the pistons will stand up to a little more than 1344*
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#13
by
Mark(The Miser)UK
on 06 Jun, 2011 16:22
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Interesting thread…
A little research tells me that the aluminium alloy is likely to be Al Si. Si content varies, with manufacturer, but the range may be between 12 and 24%, giving melting points of 780 to 850 deg Centigrade respectively.
Even more interesting, is the construction of the diesel cast piston. The ring carrier is made first out of a special cast iron alloy that resists heat and pressure deformation molten at 1400deg C. To bond it to the rest of the piston, the carrier is plannished [dimpled] with ballbearings, bathed in a molten Al Si [6%], perhaps at 750 degC until a coating/chemical bond is formed of Fe Al3. This takes less than 20 minutes; then the main piston can be cast around the carrier.
My question is:
What is the temperature drop across the turbo, as post turbo EGT varies with load etc? Even with manifold tapping, temperature must vary from actual chamber temperatures due to how advanced or retarded the timing is, and whether some combustion is still going on beyond the exhaust valves.
Additionally, peak air temperatures are likely to be way in excess of the piston melting point, without harm, a bit like a saucepan with water boiling over a gas flame.
I guess I’d be looking for abnormal change from the ‘usual’
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#14
by
bugnut
on 06 Jun, 2011 17:44
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R.O.R. is right. 1250 F is the norm. Atleast in the cummins world that is. With the cummins you can hold 1250 all day long. Anything over that and you are taking a withdraw from the engine and bank account. How big of a withdraw depends on how hot you go and for how long. With my engine on the rabbit I see 1200 to 1500. Depends on how much boost I run on the LP turbo.
As for water injection I don't know if I am convinced yet or not. For short burst I don't see it working at all on my setup. But on a long hill once I get the water to start injecting I can see the egts go down from 800 to 700 or 650. I have 3 water injectors in my setup. 1 pre turbo. 1 inbetween the two turbos and the last one at the manifold. The last one is where the cooling takes place. The ones before that make the turbos more efficient.