TheSamba.com :: View topic

Sun Apr 03, 2016 3:43 am

Hi all,

As above, nearly 800°C. Oil temp 85°C, water under 90°C, boost 5 bar max.
The EGT drops quickly from 600°C to 350°C (at 900 rpm) then takes 5 seconds to drop from 350 to below 300.

Pump timing .95mm
Engine "SB" from a GTD Golf.

Any ideas?
Ta.

Sun Apr 03, 2016 3:19 pm

Don't drive it.....

Sun Apr 03, 2016 3:49 pm

Good idea!
Have you got any others?

Sun Apr 03, 2016 4:13 pm

Where are you measuring the EGTs? If this is at full load then 800°F doesn't sound that hot to me.

Sun Apr 03, 2016 4:25 pm

in the exhaust manifold where it meets the turbo [800deg centigrade!].
I'm surprised its so high as the max fuel screw still has the tamper proof coller on.

Sun Apr 03, 2016 4:41 pm

800C = 1472F

That's way too high for my comfort. Under what circumstances are you seeing this high of EGT? Are you sure the gauge is accurate? Your high oil temps may indicate that the pyrometer is indeed telling some sort of story about excessive heat in the engine

Sun Apr 03, 2016 4:47 pm

Sorry, I missed the 800° was Centigrade, yes that would be awfully hot.

Sun Apr 03, 2016 4:53 pm

85 c too hot?it was 130c before I fitted an oil cooler!
700 to 800c is in top gear up hill,i change down to third gear to bring the temp down of course.
ps I used a test meter to check that egt gauge is correct.

Sun Apr 03, 2016 4:54 pm

Hi -- I don't know that it is a problem -- perhaps others can share what they would expect.

I fly airplanes that run on gasoline. 1450F is a normal temperature at TIT, Turbo inlet temperature. CHTs are much more important than EGTs because they cool very quickly and it depends on where you measure them from.

Sun Apr 03, 2016 7:00 pm

dave Friday wrote: Hi all,as above nearly 800 deg c ..oil temp 85 c water under90 c boost.5 bar max
The EGT drops quickly from 600 c to 350 c (at 900 rpm) then takes 5 seconds to drop from350 to below 300
Pump timing .95mm
Engine "sb" from a gtd golf.
Any ideas?
Ta.
I think your boost pressure is kind of low. That's only about 7 psi. A GTD Golf would run closer to 1 bar boost pressure stock, IIRC.

If you crank up your boost pressure, I would bet your EGT drops to more like 675*C in the same circumstances.

Boost cools EGT in a turbodiesel.

edit - I bet you have a pretty smoky exhaust at full go pedal, right? I suspect you're overfueled, relative to your boost pressure.

You haven't said what kind of turbo is on this thing, but there are a couple of simple ways to cheat the peak pressure up higher, depending on what you have. Either you can play with the wastegate setting right on the turbo, or install an external boost controller valve or "bleed". They all basically cheat the wastegate diaphragm from seeing the full amount of pressure built by the turbo, so the wastegate opens at higher pressure.

As for oil temps, 85*C isn't even hot enough to boil the water condensation out of the oil, so I'd say that was fine.

Free advice, worth every cent, YMMV, etc.

Sun Apr 03, 2016 7:05 pm

above 1600°F you have to expect engine damage. 1450°F sounds reasonable under full load.

Sun Apr 03, 2016 11:56 pm

Thanks all,off to catch a 'plane to the UK.
Will type later.

Sun May 06, 2018 1:38 am

Well...the EGT probe/sensor failed,so I fitted the(exposed tip )sensor that I had been meaning to fit ..
Guess what? EGT now max 450/500 deg c!
Lesson learnt.

Sun May 06, 2018 7:00 am

Neato! This is nomination #2 for bump of the month. :D Thanks for the follow-up. Did you have a good visit to the UK?

Sun May 06, 2018 7:25 am

Thanks Jim ,yes it's nice to visit the uk but I wouldn't want to live there(anymore )

Mon Aug 17, 2020 9:03 am

Hi all,well the exposed tip EGT sensor failed! So I replaced it but,the exposed tip sensor reads about 250 deg c higher than the enclosed type sensor
Tested by sticking them ( sensors ) in the Gas ring..
Kr.

Mon Aug 17, 2020 10:02 pm

I suggest that you are overfueled, possibly because you are not getting enough boost or maybe your oxygen sensor is fouled, or both. My AAZ really gets hot EGT at high elevations when it is overfueling. Apparently the hydrocarbons combust in an oxygen deficit and produce no power but a lot of exhaust heat. 800c is about the max for safety, so take it easy.

Tue Aug 18, 2020 4:08 pm

Hi Gnarlodious and thanks for the advice,I did adjust the wastegate to get the boost up a bit...a month ago I replaced the turbo( £200 Chinese ,looks good )the van runs as it normally does but the EGT sensor is faulty 1.3k ohms between element and casing!
Now the EGT is just over 600deg c ( foot to the floor up hill in third or top gear!)
I now need to repair my boost gauge,and check that the EGT gauge is reading ok( with my new meter)
Kr,Baz

Tue Aug 18, 2020 4:15 pm

jimf909 wrote: Neato! This is nomination #2 for bump of the month. :D Thanks for the follow-up. Did you have a good visit to the UK?

No,it rained mainly on the plane.

Most of the instruments sold into these markets are junk with 50% tolerances or worse

Tue Aug 18, 2020 6:10 pm

Abscate hi,I agree about the quality? Of the gauges etc,EGT sensors ( the cheap ones ) don't last long..
What I have found is that a £10 multimeter with a temperature setting works well as a EGT gauge,possibily for other sensors..
We live in the mountains at 2350 ft and get some interesting weather,
When the rain in Spain is falling mainly on the plains,up here it's raining golf ball sized hail,dents in your car!! This time of year it's 40 deg c a lot..