e-shaft weber jets good idea for endurance race rebuild?
 

I am just about to put my GSL-SE 13b back together. I have crushed the rear pressure regulator and shimmed the front bypass as most builders seem to recommend. This should bump my pressure to ~90 psi.

My question is though, given the modified regulators is it a good idea to remove the e-shaft ball check oil jets in favor of the always open weber jets?

As mentioned this is my budget enduro chump/lemons car so while it is a racing application I am not going to be over-revving the motor but it will most likely live between 5-7k rpms.

My only concern is people seem to think having the weber jets takes oil away from the bearing in favor of the rotors....

Any experience here?

My only concern is people seem to think having the weber jets takes oil away from the bearing in favor of the rotors....

Any experience here?

You have it backwards.

You press in the Weber jets (or buy the MFR screw in jets) to RESTRICT oil flow into the rotors for cooling so the rotor bearings get more pressure at high rpms.

So I bought the screw in weber jets from Atkins. Have you run a motor with this modification?

Just wanted to know if anyone has done this with success.

No, I use the Mazda Factory Race oil jets

8553-11-411


https://cimg4.ibsrv.net/gimg/www.rx7...815646cd92.jpg


which are basically the same thing, but just a whole new screw in oil jet.

Your oil pressure will be lower at idle because they are always open unlike the production oil jets where the spring pushes the ball against the oil hole in the e-shaft at low rpm so the rotor receives no cooling oil (faster warm-up) and then the ball swings out of the way from centripetal force as engine rpms rise.

Your oil pressure will be higher at high rpms (though still limited by oil pressure regulator) as the race oil jets have a smaller orifice than the production ball check-valve ones.

This is why people mistakenly say the oil pressure decreases.

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Its like saying what flows more a 90mm throttle body or a 60mm pipe?

Well, depends on if the throttle body is open, closed or somewhere in-between.

The production rotor oil jets are rpm throttled.

[QUOTE=BLUE TII;12022203]No, I use the Mazda Factory Race oil jets

8553-11-411


https://cimg4.ibsrv.net/gimg/www.rx7...815646cd92.jpg


Those are exactly what I have. Thanks for the help here.

OK I think I will put them in then. I understand the lower oil pressure at idle but I suppose my main concern was that given I'm not building a 9k rpm motor, as like I said, the motor will probably live between ~4 to 7k that I might not even reach peak oil pressure at those engine speeds.

That makes sense that while they are fully open though, they have a smaller jet size to make up for the loss in pressure.

Thanks.

OK I think I will put them in then. I understand the lower oil pressure at idle but I suppose my main concern was that given I'm not building a 9k rpm motor, as like I said, the motor will probably live between ~4 to 7k that I might not even reach peak oil pressure at those engine speeds.

Oh, I see your concern.

You shouldn't have any issues there, my motors have been low rpm turbo motors.

From memory, on my set-up (all the wet sump oil mods) on a S5 13BT it would be maybe ~15-25psi at 800rpm idle(depending on oil weight, how watered down with gas and oil temps).

Revving 1,500- 2,000rpm pressure would quickly rise to the 40-60psi range.

and by 3,000-4,000rpm it was in the full 90-110psi range (race oil regulator).

If you held it near redline (8,000rpm) a while you could see the pressure drop a bit (which I always assumed was due to aeration).

Later I went to the FD pressure regulator (gave away race one to someone in need) and the behavior was the same but the peak pressure was more 90-100psi (not a lot of difference).

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I had a real problem with the oil pressure pushing the front cover away from the front side housing and the o-ring there getting pushed into the front cover and suck around the over-pressure relief valve. Once that happened oil pressure was a little lazier to build and often barely maintained 90psi (on the MFR regulator).

I never bothered to fix this when it happened (just kept racing the motor) and I never had oil system issues. So, don't worry if your oil pressure is a little lazier.

I fixed this issue by boring the old (mostly unused now) oil passage in the front side housing and putting a dowel in that fit into the front cover. So the o-ring was captured and could get pushed into the front cover.

I didn't want to plug that passage and disable the over-pressure relief valve as I like to get in the car and go without waking up the neighborhood idling to warm up the oil.