Reliability on turbo 86

[Grady]

Originally Posted by ST185RC

What? No LS swap comments for power and reliability? I'm disgusted.

Best way to do an LS swap.....

A) figure out what LS engine you want.

B) go find the Corvette it was installed in and get rid of the car you have.

[Irace86.2.0]

Originally Posted by StraightOuttaCanadaEh

Thanks for clearing it up. I was recalling some old post I read some time ago and at a ripe old age of 33, my memory isn't what it used to be. The question that's been boiling my noodle lately is what can we do to address the oil pump insufficiency at low rpms?

There is a pump upgrade that spins more, or has a more aggressive gear ratio, but I have read others saying the extra flow goes to the head more than the block—a path of least resistance thing.

[gtengr]

Originally Posted by StraightOuttaCanadaEh

The question that's been boiling my noodle lately is what can we do to address the oil pump insufficiency at low rpms?

Gotta replace the rods before that's worth looking at.

From one of my posts in another thread on how low RPM torque stresses rods:

As the combustion gas expansion drives the piston down the cylinder, the cylinder volume is also increasing via piston travel. As the rpms are decreased, the gas expansion rate may stay about the same, but the slower cylinder volume expansion rate results in a harder push against the piston over less degrees of crank rotation.

An analogy is if you were hitting a punching bag that's rocking back and forth, it would be less stressful on your arm to punch it while it's moving away from you. The slower it's moving away from you, the more you'll feel that punch in your arm. That's what's happening with the rods at high torque and low RPM. That cylinder pressure is trying to expand, but the piston isn't getting out of the way as fast as it does at high RPM, and the result is more force in the rod.

[Irace86.2.0]

Originally Posted by gtengr

Gotta replace the rods before that's worth looking at.

Probably not before. More like while, as in while the rebuild is happening.


That’s the pump for reference.

Not saying this is needed or will fix the oil starvation issue. Just saying this and the larger capcity pump exist.

https://www.counterspacegarage.com/reimax-oil-pump-fa20

[Hags86]

Originally Posted by StraightOuttaCanadaEh

The question that's been boiling my noodle lately is what can we do to address the oil pump insufficiency at low rpms?

Oil pressure at low RPM is fine. It's at higher RPM that it has insufficient pressure. I'm moving to a 50 weight, and if that doesn't fix it, then I'll try a 60 weight.

[FRS Justin]

How and what you upgrade your motor with will depend on how you drive it....

[Irace86.2.0]

Originally Posted by Hags86

Oil pressure at low RPM is fine. It's at higher RPM that it has insufficient pressure. I'm moving to a 50 weight, and if that doesn't fix it, then I'll try a 60 weight.

Track and street are slightly different animals.

I hit peak boost at redline where a turbo with a wastegate can hit peak boost or the same boost at half of those rpms. Hitting the same peak torque at half the rpms where oil pressure is half as well is an issue. This, along with other properties of having relatively higher torque at lower rpms, is why turbos pose more risk than superchargers that have the same peak torque.

[DarkPira7e]

Originally Posted by Irace86.2.0

Track and street are slightly different animals.

I hit peak boost at redline where a turbo with a wastegate can hit peak boost or the same boost at half of those rpms. Hitting the same peak torque at half the rpms where oil pressure is half as well is an issue. This, along with other properties of having relatively higher torque at lower rpms, is why turbos pose more risk than superchargers that have the same peak torque.

This is something I've always tried to impart onto WRX/STI builders. They want the tune ramping up with max torque as early as possible, but it's far more stressful to the internals. Its like the stress difference trying to run as hard as you can from a standstill, vs taking a second to come up to a jog before sprinting. (Stress on the knees, obviously more understandable for overweight people to relate with)

[gtengr]

Originally Posted by Irace86.2.0

Track and street are slightly different animals.

I hit peak boost at redline where a turbo with a wastegate can hit peak boost or the same boost at half of those rpms. Hitting the same peak torque at half the rpms where oil pressure is half as well is an issue. This, along with other properties of having relatively higher torque at lower rpms, is why turbos pose more risk than superchargers that have the same peak torque.

RPM is lower though. In general, high RPM/inertial forces are the usual cause of bearing/oiling issues.

[86MLR]

Originally Posted by gtengr

RPM is lower though. In general, high RPM/inertial forces are the usual cause of bearing/oiling issues.

Low rpm and high load can/will do rods and bearings, amongst other things, oil temp being a big one.

This is why alot of turbo cars lunch themselves, well, the driver is responsible for the lunch date.

Flooring the pedal at 2k rpm is a sure way to put a bay window in your block.

Smarter than me guy talking turbo >

[Irace86.2.0]

Originally Posted by gtengr

RPM is lower though. In general, high RPM/inertial forces are the usual cause of bearing/oiling issues.

Like 86MLR said, high load with low rpms is a problem for rods n bearings. Preignition is one thing mentioned in the video, and I mentioned it earlier; oil pressure builds proportional to rpm, so low pressure with high loads is a problem.

If oil pressure is a problem at high rpms then it usually is because of an oil temp issue or an oil starvation issue like lacking baffling in the oil pan while taking a long, high-g turn.

[gtengr]

Originally Posted by 86MLR

Low rpm and high load can/will do rods and bearings, amongst other things, oil temp being a big one.

This is why alot of turbo cars lunch themselves, well, the driver is responsible for the lunch date.

Flooring the pedal at 2k rpm is a sure way to put a bay window in your block.

Smarter than me guy talking turbo >

That's usually your rods going, not the bearings. I was specific to bearing/oiling issues, and I qualified that it's in general, so not necessarily applicable to extremely high torque or high torque at rpm's that lug the motor. So to elaborate, if one is prematurely wearing rod bearings due to low rpm torque with an oiling system that can support 7500 rpm, they're likely running a pretty obscene amount of torque on a stock oiling system, which is foolish, or applying torque at very low rpm in a high gear, which is also foolish.

Originally Posted by Irace86.2.0

Like 86MLR said, high load with low rpms is a problem for rods n bearings. Preignition is one thing mentioned in the video, and I mentioned it earlier; oil pressure builds proportional to rpm, so low pressure with high loads is a problem.

If oil pressure is a problem at high rpms then it usually is because of an oil temp issue or an oil starvation issue like lacking baffling in the oil pan while taking a long, high-g turn.

I've already pointed it out with the rods, including the why, and it agrees with what you both posted, so let's not put words in my mouth. Your last paragraph is off. Adequate oil pressure, in general, is a high rpm problem.

[86MLR]

Originally Posted by gtengr

That's usually your rods going, not the bearings. I was specific to bearing/oiling issues, and I qualified that it's in general, so not necessarily applicable to extremely high torque or high torque at rpm's that lug the motor. So to elaborate, if one is prematurely wearing rod bearings due to low rpm torque with an oiling system that can support 7500 rpm, they're likely running a pretty obscene amount of torque on a stock oiling system, which is foolish, or applying torque at very low rpm in a high gear, which is also foolish.



I've already pointed it out with the rods, including the why, and it agrees with what you both posted, so let's not put words in my mouth. Your last paragraph is off. Adequate oil pressure, in general, is a high rpm problem.

What is the effect on bearings at high load and low RPM, lets say for example 3k rpm and 300nm, as apposed ti 6k rpm and 300nm.

[Irace86.2.0]

Originally Posted by gtengr

I've already pointed it out with the rods, including the why, and it agrees with what you both posted, so let's not put words in my mouth. Your last paragraph is off. Adequate oil pressure, in general, is a high rpm problem.

The oil problems you mentioed, related to oil starvation during sustained inertial lateral g’s and with thinning oil from heat buildup from sustained high rpm’s are problems that exist for the NA 86s, for the supercharged 86s, as well as, the turbocharged 86s. There may be more heat in a turbocharged 86, or rather stated, the turbocharged 86 may require more cooling mods, but these are track problems, not supercharger reliability issues.

The topic was talking about the reliability differences between a supercharger and a turbocharger. It seems to be common knowledge that even if a turbo and SC system share peak hp and torque, the fact that the turbo will hit peak torque earlier in the rpms was one reason why there is a known greater risk of going the turbo route. In fact, Delicious Tuning has meantioned in threads that they tend to tune for less low end torque, even on the superchargers, in order to protect the rods. They offered the same to me or to go more aggressive, and I opted to be conservative for my SC. As mentioned before, the source of why low end torque is an issue is due to a higher likelihood of preignition and lower oil pressures. These are reliability concerns that transcend the track world into everyday driving situations.