Cool Down?
 

hey all,

when i put my truck in park and wait for the egt's to go down ,they hardly don't. Tonight i waited for about 5-6 minutes for it to get below 400*. is there anyway to these down faster, especially since it's colder i'd think they would go down faster.

thanks for the help. :tu:

I dont go by temps, if I was driving no load then I just give it one minute...............when I tow I do a few minutes

What whit said. Whats your Idle RPM? When mine was up above 800rpm it would never cool down below 400 or so.

its at about 800-850

Where is your temp probe located? Pre turbo you get much faster temp changes than post turbo from what I've noticed. Biggest thing is just givin the turbo time to spool down

isnt that pretty high for an idle?

mine idles at 6-650 and mine idles right around 400 degrees

i dont even have gauges yet and i always let it idle 1 to 2 mins just a good habit to get into especially stock and high mileage engines almost 300 k still stock

no i'm pretty sure 750-800 rpms are stock, but don't hold me to it. Plus my torque convertor is sh!t, when i put it in gear, the tach goes from about 800 down to like 550, 600 degrees.

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its mounted pre turbo, and yea it's not just about letting spool down, its about letting the oil circulate through the journal bearings too.

The oil is circulating as long as the engine is running, but if you shut it down with the turbo still spinning 10,000 rpms the oil isnt circulating anymore and thats what causes the problems with the turbos

o ok so its both letting it spool down and get oil circulation.

The turbos run on a thin film of oil for the bearing so if its still spinning faster then normal idle speed, shutting it down premature the oil isnt there anymore and it runs dry I guess is the best way to put it. There is a large line on top of the turbo between the exhaust and compressor housing that pours pressurized oil in the bearing. Then there is another line on the bottom that goes back in the oil pan that is th return line.

also letting it cool down help to keep the oil from "cooking" if you will in the turbo after you cut it off.

Good point, that too

yea thats pretty hard on em too, so let it spool down for about 2 minutes, should i watch the egts before shut down or just kill it after 2 minutes or so.

If someone had a tach it would be cool to know how long it actually takes for a turbo to come down to its idle speed.Ive seen tachs on turbine projects

yea that would be sweet to see how many rpms those things are pushin

i got a tach on mine that is pretty accurate so ill check it out in the mornin and let you guys know. what exactly do you want me to look for with the tach?

They are talkin about a tach on the turbo itself I think

yea like the compressor wheel would be my guess.

oh duh:argh: stupid on my part

o man ur fine. :tu:

i normally let my truck run about a min till i shut her down empty and normal driving, towing ar beating her i let her run a good five minets or so.

yea thats what i usually do thanks for the help all

had no idea. should i let it idle for a while before i take off too?

we are talking about letting it cool down just before shut down, but yes if its colder than 45* let it idle for 5 minutes or so, if its below freezing let it idle for up to 10 minutes.

since the shaft is "floating" on hot oil i imagine that even at idle it takes a long time to come down.I know my hy35 spins forever without oil pressure at shutdown( sometimes a full minute). the exhaust pulses at idle probably just push it right along at its "full load" speed.

Perhaps it is your pump settings that won't let you run low enough EGT's at idle. Mine idles at 300* Maybe it's your fuel pin? Or star wheel settings? I have my star wheel tweaked for less smoke because I was trying to get rid of the haze at idle.

On another note, if you read your instructions on the turbo you bought from Jacob, you only have to let the EGT's get below 410* before shutting it down. I still try to get mine to the 325-350 range though.

Yea mine hazes at idle so i could modify my pump, and i try to get my new turbo down to 350 but sometimes it takes to long or im in a hurry, so i have to shut down at 400.