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Old 05-07-2004, 11:44 AM
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hp loss.?

how much hp loss would i get in a chevy 350 changing from 10 30 oil to 20 50.. would it matter it i go to a synthetic 20 50
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Old 05-07-2004, 11:47 AM
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Old 05-07-2004, 11:52 AM
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would it be noticable is basically what i am asking ... i know in lots newer vehicle they use 5 30 cause they get better gas miliage cause the oil is thinner or lighter
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Old 05-07-2004, 12:12 PM
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I dont think it would be anything that you as a driver would notice. But why are you switching in the first place?
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Old 05-07-2004, 12:24 PM
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i built a 350 for my firebird and well my oil pressure at idle is about 8-10 psi i just put the engine in about 2 months ago .. and i dont want to burn up the engine so i want to raise the oil pressure. i heard that royal purple is a good oil to use.
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Old 05-07-2004, 01:15 PM
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You say the oil pressure at idle is 8-10psi is this lower than it was when the engine was brand new? If it has decreased significantly then you may have a problem. what is oil pressure like at cruising rpm? 8-10 psi is acceptable for a warm engine at idle although a little on the low end of the scale. What kinda bearing clearances did you use?
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Old 05-07-2004, 02:15 PM
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8-15 at 7000 RPM H

Horsepower can be lost due to crank windage and mechanical drag.

I wouldn't worry about idle pressure as much as I might worry if it never came up with RPM.

Royal Purple is a great oil but WAYYY overkill at your power levels.
To expensive at 7$ a quart for general street use.
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Old 05-07-2004, 02:55 PM
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I had the same concern with my 350 after I rebuilt it. Since I live in a very hot climate the oil pressure would drop real low as the temps climbed outside. I went from 10w-30w to GTX 20w-50w to increase the viscosity at idle. The thicker oil will actually cost you about 3 - 5 rwhp, but the extra cushion on the bearings was worth it for my piece of mind. Like Johnsongrass1 and Robinson Robin said though, I would be concerned if the pressure didn't climb when the RPS's went up. If they don't then you may have a collapsed spring in your oil pump. If you have over 45 lbs of pressure at 2500 - 3000 rpms then you should be okay.

IMHO
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Old 05-07-2004, 03:18 PM
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Quote:
Originally posted by johnsongrass1
8-15 at 7000 RPM H

Horsepower can be lost due to crank windage and mechanical drag.

I wouldn't worry about idle pressure as much as I might worry if it never came up with RPM.

Royal Purple is a great oil but WAYYY overkill at your power levels.
To expensive at 7$ a quart for general street use.
7$ per quart?!?! thats a real cheap oil over here ... =) ...

iŽd guess that the oil over here is overpriced, a good oil
starts somewhere between 12-15$ ....
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Old 05-07-2004, 04:49 PM
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We used to use Royal Purple in our roundy round car but have since been using Mobil 1 Full synthetic. It's only 4 dollars a Qt. Our dry sump system holds 10 Qt's and we have to change it every weekend. It got to expensive for our budget cut's and we needed to afford a faster engine engine so we could run more gear. Now we run anywhere around 5.67 to 6.80 and turn 9200.

Our engine builder started showing less ring wear with Mobil 1. So we made the switch.

I'm glade we don't race in Sweden!! I thought we spend too much money now!
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Old 05-07-2004, 04:53 PM
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i dont know what the bearing clearance is. i had the crank and connecting rods and pistions all put in it for me i diddnt have the time to do that all i had to do was put in the cam and the oil pump, freeze plugs ect.. ect. when i first start the car the oil pressure is around 60 psi.. when it warms up it is around 8-12 psi at cruising speed it is at 40 psi and cruising speed is 3000 - 3200 rpms.. i heard that 15-40 oil would help and using royal purple would actually increase my hp..
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Old 05-07-2004, 04:56 PM
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Sooo.. why would you change over to a heavier oil? Is the engine buring oil?

If the engine anit burning oil, and/or leaking it, dont change to a heavier oil. If you are worried about breakdown of the oil, then use a 10-30syn.

There are plenty of threads about this if you search for it.
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Old 05-07-2004, 07:46 PM
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Royal Purple I don't care for. They use a moly in their oil, causes excessive wear in comparison to synthetics that don't. Such as Moble 1, which johnsongrass1 is probably why you had more ring wear with Royal Purple that Mobile 1.


Mike
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Old 05-07-2004, 09:47 PM
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The last two oil changes in my truck I used Royal Purple, $5 for SAE 30, $6 for 10W-30. It does make some HP.
I'm switching to AMSOIL the next oil change, it is about the same price, and I think it is pretty good oil.
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