Pellegrini808

Going for the first start up with new forged pistons, rods, and bearings. Ive read that its bad to keep it at idle or a constant rpm, i have no turbo timer, and i usually leave the car on for 2 min after i park to let te turbo cool down. What should i do now? how bad is it to leave the car in idle for a min or 2 with new forged internals?

The Show Stopper

No turbo timer needed.

turbohatch96y7

iTrader: (15)

Turbo timers are effective if you do wot pulls and or drive the car really hard for a period of time and you just want to hop out.
If you're driving normal then the oil temps shouldn't be high enough to damage the turbo.

TheShodan

iTrader: (14)

they actually are. Even with highway driving with no load, egt temps get about 1400-1500 degrees. The problem with hot shut down is that people don't believe that the oil their using will actually start turning into carbon, where it "cokes" on the journal bearings. Especially when no running water lines to assist the oil that both lubricates the shaft and bearings as well as dissipate heat coming from the turbine housing. The most dangerous time for a turbo is after a regular drive; that turbine heat will transfer itself into the cartridge once the car is shut down. If the car's oil hasn't cooled a bit, it will turn to carbon and "coke" onto the bearing system.

Drag racers don't need it as much because the car literally is barely on long enough for the oil to reach operating temperature. By the time it actually reaches that operating temp, the race is over, and they shut the car down before the oil gets a chance to heat up enough to coke. Its the daily drivers, the road racers and abusers that have to watch out.

Here's an example of when Californiadad didn't run water.



Because of his long commute of over 160 miles per day, he was over 1400 degrees for over an hour or so at a time!! With 2 minute cool downs, and using a different oil than he does now, the oil was coking on the turbine shaft bearing (far right), and started to coke on the compressor side bearing (middle). (The right shows what a new bearing looks like as a comparison).

the thrust bearing also suffered in this case. Now... the turbo still ran fine, he just caught this before it got bad. Since his turbo had optional water lines, he opted to run those... just like the OEMs.. he's been fine ever since.

The bottom line is, Just because you don't have a timer, doesn't mean you shouldn't cool down. Depending upon your driivng habits, its better to give yourself 1 minute to 1:30 on regular days of stop & go and about 2-3 minutes on long highway drives, whether or not you "get into the throttle". The bearings stay lubricated and healthy. Especially when you use a GOOD oil to lubricate the turbo with, such as something with a high zinc and phosphorous content like Brad Penn "Green", Valvoline VR1 "blue", or in some cases, T6 Rotella oil for E85 users.

wantboost

iTrader: (2)

yea with my s13 (sr20det, stock motor/turbo/intake manifold, divided 3" turbo elbow, 3" downpipe 3.5" Apexi GT exhaust, FMIC, Koyo rad, SPAL 16" shrouded fan hardwired constant on with ignition on, Z32 maf, aem uego, ran 14psi at the intake manifold, etc. tuned it myself with the safc.. car didn't have enough work done to warrant any actual ecu tuning, I got idle, cruising, and wot afrs perfect)

Just cruising down the highway at a steady rpm for a long time, the EGTs would stay between 1400-1600 (probe in runner 3, exposed junction quick response probe, oldschool HKS EGT gauge) when doing a quick WOT run to pass someone (in 4th or 5th) it made 14psi in seconds and the EGTs would get up around 1800F, both when passing or going up a long hill, etc. With the stock t25 it was hard to stay out of boost, even cruising doing 55-65 in 5th, it had insane response

That response coupled with the restrictive stock manifold, and a stock turbo that had a small a/r turbine housing and small wheel, along with all of the exhaust parts meant that while I had boost and torque everywhere, the pre-turbo backpressure was high enough to cause exhaust to back up or "stall/revert" and would skyrocket EGTs to the moon