lonelydrifter

Alright guys just wanted to ask a quick one before purchasing an S15 Spec-R turbo. I have a stock SR T25 and a little CA T25 and I was spinning the turbine with my fingers. What seemed strange to me was that the ease of spin was about the same with the S15 turbo. Now I know both turbos have bearings but I was under the impression that a "ball bearing" turbo would have spun considerably easier making it more efficient. I compared a buddy's "non-ball bearing" aftermarket turbo and it spins for a few seconds after I introduce a force. So what im asking is should the S15 "ball bearing" or any ball bearing turbo for that matter spin freely with ease or is it just the difference between these stock turbos vs aftermarket?

allstar

oil is key here

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lonelydrifter

Come on guys I am lookign to purchase this turbo soon. Any input will help. Do all turbos become hard to spin after being pulled from car or should this spec-r be turning a lot easier that my other two stock t25's?

98koukile

When he said oil is key he meant it. When it's on the car it should spin easier with oil running through it. Ball bearings love constant lubrication to be most efficient. Once it's installed you'll notice the difference, as long as the turbo is still good

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SlowCoupe

some say too much oil flow thru BB turbos are bad thats why some use oil resrictors inline with the oil feed line.

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MegasquirtCA

put it this way before my S15 turbo blew, after shutting the motor off my turbo would still be spinning 1.15 mins after shutting the car off. Before even installing the turbo I messed around by blowing into the turbine and it would spin with ease.

And like everyone said oil will make it spin more freely as well. Prime the S15 turbo with oil.

infinitexsound

by priming he means filling the turbo with oil.. and hand turning the turbine..... hence your dont want to run it dry as a begining... which is super bad....! pre damaging shit!

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chibo

It's because too much oil pressure will force oil past seals or kill them prematurely.

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boosteds13

With my S15 T28, I can turn the car off, pop the hood, walk over to the intake filter and hear the turbo still spinning for a few seconds.

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MELLO*SOS

What kind of oil pressure do BB turbos like? Or what is considered a safe max for the oil seal? This would be very useful info for me (pressure testing)...

Also wouldn't installing an oil restrictor in the feed line raise the pressure and lower the volume? I'm thinking of a garden hose with a nozzle installed; less flow volume-wise, but a higher pressure...

johngriff

Ok.

The ball bearing, is not going to make it easier to induce a spin on the assembly. To induce a spin, you have to place inertia against the total mass(weight). This is going to remain a constant, between ball bearing and non ball bearing, because the weight of teh wheels and shaft will remain constant.

Ball bearings aid in the ammount of drag induced on the rotating mass once it has built inertia. IE, wheel speed.

So, once said assembly is spun to speed, because the ball bearing unit has less drag, the assembly will loose inertia at a slower rate, whenn compared to a traditional thrust bearing.

BUT, the rate at which two different turbo's will loose speed is different. If we take a gt2871r and a big gt40, spin them both to the same speed, the 2871r will slow down faster because it has less weight to keep it in motion.

By the same coin the gt40 will take more initial inertia to bring up to the same wheel speed as the 2871r because of its larger rotating mass.

In conclusion.

While you may notice some small difference in the resistance placed on the wheel while bringing it up to speed, ball bearings really aid in the decel rate of the assembly.

::Way to have a compressor wheel in your sig, and have no input on the OP's Question at hand::

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sr20tom

i know that after i put the BB turbo in, with an ATP oil restrictor, the over all pressure from the sensor has dramaticly increased, plus it makes a killer noise. lol

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MELLO*SOS

Out of curiosity what oil pressure are you seeing at various RPMs?

lonelydrifter

Thanks guys from what I learned from a few sources the turbo most likely spins sluggishly because it has been off the car for so long. Oil has probably dried and become sludge which is restricting the turbo from spinning. I heard that after the exhaust heat runs through the turbo that it will most likely free up.